build(deps): bump actions/upload-artifact from 3.1.2 to 3.1.3 (#39852)

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 3.1.2 to 3.1.3.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](0b7f8abb15...a8a3f3ad30)

---
updated-dependencies:
- dependency-name: actions/upload-artifact
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/audit.yaml

@@ -22,7 +22,7 @@ jobs:
       matrix:
         operating_system: ["ubuntu-latest", "macos-latest"]
     steps:
-    - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # @v2
+    - uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # @v2
     - uses: actions/setup-python@61a6322f88396a6271a6ee3565807d608ecaddd1 # @v2
       with:
         python-version: ${{inputs.python_version}}

.github/workflows/bootstrap.yml

@@ -24,7 +24,7 @@ jobs:
               make patch unzip which xz python3 python3-devel tree \
               cmake bison bison-devel libstdc++-static
       - name: Checkout
-        uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9
+        uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac
         with:
           fetch-depth: 0
       - name: Setup non-root user
@@ -62,7 +62,7 @@ jobs:
               make patch unzip xz-utils python3 python3-dev tree \
               cmake bison
       - name: Checkout
-        uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9
+        uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac
         with:
           fetch-depth: 0
       - name: Setup non-root user
@@ -99,7 +99,7 @@ jobs:
               bzip2 curl file g++ gcc gfortran git gnupg2 gzip \
               make patch unzip xz-utils python3 python3-dev tree
       - name: Checkout
-        uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9
+        uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac
         with:
           fetch-depth: 0
       - name: Setup non-root user
@@ -133,7 +133,7 @@ jobs:
               make patch unzip which xz python3 python3-devel tree \
               cmake bison
       - name: Checkout
-        uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9
+        uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac
         with:
           fetch-depth: 0
       - name: Setup repo
@@ -158,7 +158,7 @@ jobs:
         run: |
           brew install cmake bison@2.7 tree
       - name: Checkout
-        uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9
+        uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac
       - name: Bootstrap clingo
         run: |
           source share/spack/setup-env.sh
@@ -179,7 +179,7 @@ jobs:
         run: |
           brew install tree
       - name: Checkout
-        uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9
+        uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac
       - name: Bootstrap clingo
         run: |
           set -ex
@@ -204,7 +204,7 @@ jobs:
     runs-on: ubuntu-20.04
     steps:
       - name: Checkout
-        uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9
+        uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac
         with:
           fetch-depth: 0
       - name: Setup repo
@@ -247,7 +247,7 @@ jobs:
               bzip2 curl file g++ gcc patchelf gfortran git gzip \
               make patch unzip xz-utils python3 python3-dev tree
       - name: Checkout
-        uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9
+        uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac
         with:
           fetch-depth: 0
       - name: Setup non-root user
@@ -283,7 +283,7 @@ jobs:
               make patch unzip xz-utils python3 python3-dev tree \
               gawk
       - name: Checkout
-        uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9
+        uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac
         with:
           fetch-depth: 0
       - name: Setup non-root user
@@ -316,7 +316,7 @@ jobs:
           # Remove GnuPG since we want to bootstrap it
           sudo rm -rf /usr/local/bin/gpg
       - name: Checkout
-        uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9
+        uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac
       - name: Bootstrap GnuPG
         run: |
           source share/spack/setup-env.sh
@@ -333,7 +333,7 @@ jobs:
           # Remove GnuPG since we want to bootstrap it
           sudo rm -rf /usr/local/bin/gpg
       - name: Checkout
-        uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9
+        uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac
       - name: Bootstrap GnuPG
         run: |
           source share/spack/setup-env.sh

.github/workflows/build-containers.yml

@@ -56,7 +56,7 @@ jobs:
     if: github.repository == 'spack/spack'
     steps:
       - name: Checkout
-        uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # @v2
+        uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # @v2
 
       - name: Set Container Tag Normal (Nightly)
         run: |
@@ -86,7 +86,7 @@ jobs:
           fi
 
       - name: Upload Dockerfile
-        uses: actions/upload-artifact@0b7f8abb1508181956e8e162db84b466c27e18ce
+        uses: actions/upload-artifact@a8a3f3ad30e3422c9c7b888a15615d19a852ae32
         with:
           name: dockerfiles
           path: dockerfiles
@@ -95,7 +95,7 @@ jobs:
         uses: docker/setup-qemu-action@2b82ce82d56a2a04d2637cd93a637ae1b359c0a7 # @v1
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@4c0219f9ac95b02789c1075625400b2acbff50b1 # @v1
+        uses: docker/setup-buildx-action@885d1462b80bc1c1c7f0b00334ad271f09369c55 # @v1
 
       - name: Log in to GitHub Container Registry
         uses: docker/login-action@465a07811f14bebb1938fbed4728c6a1ff8901fc # @v1

.github/workflows/ci.yaml

@@ -35,7 +35,7 @@ jobs:
       core: ${{ steps.filter.outputs.core }}
       packages: ${{ steps.filter.outputs.packages }}
     steps:
-      - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # @v2
+      - uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # @v2
         if: ${{ github.event_name == 'push' }}
         with:
           fetch-depth: 0

.github/workflows/nightly-win-builds.yml

@@ -14,7 +14,7 @@ jobs:
   build-paraview-deps:
     runs-on: windows-latest
     steps:
-    - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9
+    - uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac
       with:
         fetch-depth: 0
     - uses: actions/setup-python@61a6322f88396a6271a6ee3565807d608ecaddd1

.github/workflows/unit_tests.yaml

@@ -47,7 +47,7 @@ jobs:
           on_develop: false
 
     steps:
-    - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # @v2
+    - uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # @v2
       with:
         fetch-depth: 0
     - uses: actions/setup-python@61a6322f88396a6271a6ee3565807d608ecaddd1 # @v2
@@ -94,7 +94,7 @@ jobs:
   shell:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # @v2
+    - uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # @v2
       with:
         fetch-depth: 0
     - uses: actions/setup-python@61a6322f88396a6271a6ee3565807d608ecaddd1 # @v2
@@ -133,7 +133,7 @@ jobs:
           dnf install -y \
               bzip2 curl file gcc-c++ gcc gcc-gfortran git gnupg2 gzip \
               make patch tcl unzip which xz
-    - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # @v2
+    - uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # @v2
     - name: Setup repo and non-root user
       run: |
           git --version
@@ -152,7 +152,7 @@ jobs:
   clingo-cffi:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # @v2
+    - uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # @v2
       with:
         fetch-depth: 0
     - uses: actions/setup-python@61a6322f88396a6271a6ee3565807d608ecaddd1 # @v2
@@ -187,7 +187,7 @@ jobs:
       matrix:
         python-version: ["3.10"]
     steps:
-    - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # @v2
+    - uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # @v2
       with:
         fetch-depth: 0
     - uses: actions/setup-python@61a6322f88396a6271a6ee3565807d608ecaddd1 # @v2

.github/workflows/valid-style.yml

@@ -18,7 +18,7 @@ jobs:
   validate:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # @v2
+    - uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # @v2
     - uses: actions/setup-python@61a6322f88396a6271a6ee3565807d608ecaddd1 # @v2
       with:
         python-version: '3.11'
@@ -35,7 +35,7 @@ jobs:
   style:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # @v2
+    - uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # @v2
       with:
         fetch-depth: 0
     - uses: actions/setup-python@61a6322f88396a6271a6ee3565807d608ecaddd1 # @v2
@@ -68,7 +68,7 @@ jobs:
           dnf install -y \
               bzip2 curl file gcc-c++ gcc gcc-gfortran git gnupg2 gzip \
               make patch tcl unzip which xz
-      - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # @v2
+      - uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # @v2
       - name: Setup repo and non-root user
         run: |
           git --version

.github/workflows/windows_python.yml

@@ -15,7 +15,7 @@ jobs:
   unit-tests:
     runs-on: windows-latest
     steps:
-    - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9
+    - uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac
       with:
         fetch-depth: 0
     - uses: actions/setup-python@61a6322f88396a6271a6ee3565807d608ecaddd1
@@ -39,7 +39,7 @@ jobs:
   unit-tests-cmd:
     runs-on: windows-latest
     steps:
-    - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9
+    - uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac
       with:
         fetch-depth: 0
     - uses: actions/setup-python@61a6322f88396a6271a6ee3565807d608ecaddd1
@@ -63,7 +63,7 @@ jobs:
   build-abseil:
     runs-on: windows-latest
     steps:
-    - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9
+    - uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac
       with:
         fetch-depth: 0
     - uses: actions/setup-python@61a6322f88396a6271a6ee3565807d608ecaddd1
@@ -75,6 +75,5 @@ jobs:
     - name: Build Test
       run: |
         spack compiler find
-        spack external find cmake
-        spack external find ninja
+        spack -d external find cmake ninja
         spack -d install abseil-cpp

SECURITY.md

@@ -2,24 +2,26 @@
 
 ## Supported Versions
 
-We provide security updates for the following releases.
+We provide security updates for `develop` and for the last two
+stable (`0.x`) release series of Spack. Security updates will be
+made available as patch (`0.x.1`, `0.x.2`, etc.) releases.
+
 For more on Spack's release structure, see
 [`README.md`](https://github.com/spack/spack#releases).
 
-
-| Version | Supported          |
-| ------- | ------------------ |
-| develop | :white_check_mark: |
-| 0.19.x  | :white_check_mark: |
-| 0.18.x  | :white_check_mark: |
-
 ## Reporting a Vulnerability
 
-To report a vulnerability or other security
-issue, email maintainers@spack.io.
+You can report a vulnerability using GitHub's private reporting
+feature:
 
-You can expect to hear back within two days.
-If your security issue is accepted, we will do
-our best to release a fix within a week. If
-fixing the issue will take longer than this,
-we will discuss timeline options with you.
+1. Go to [github.com/spack/spack/security](https://github.com/spack/spack/security).
+2. Click "Report a vulnerability" in the upper right corner of that page.
+3. Fill out the form and submit your draft security advisory.
+
+More details are available in
+[GitHub's docs](https://docs.github.com/en/code-security/security-advisories/guidance-on-reporting-and-writing/privately-reporting-a-security-vulnerability).
+
+You can expect to hear back about security issues within two days.
+If your security issue is accepted, we will do our best to release
+a fix within a week. If fixing the issue will take longer than
+this, we will discuss timeline options with you.

bin/spack.bat

@@ -14,7 +14,7 @@
 ::
 @echo off
 
-set spack=%SPACK_ROOT%\bin\spack
+set spack="%SPACK_ROOT%"\bin\spack
 
 ::#######################################################################
 :: This is a wrapper around the spack command that forwards calls to
@@ -51,65 +51,43 @@ setlocal enabledelayedexpansion
 :: subcommands will never start with '-'
 :: everything after the subcommand is an arg
 
-:: we cannot allow batch "for" loop to directly process CL args
-:: a number of batch reserved characters are commonly passed to
-:: spack and allowing batch's "for" method to process the raw inputs
-:: results in a large number of formatting issues
-:: instead, treat the entire CLI as one string
-:: and split by space manually
-:: capture cl args in variable named cl_args
-set cl_args=%*
+
 :process_cl_args
-rem  tokens=1* returns the first processed token produced
-rem  by tokenizing the input string cl_args on spaces into
-rem  the named variable %%g
-rem  While this make look like a for loop, it only
-rem  executes a single time for each of the cl args
-rem  the actual iterative loop is performed by the
-rem  goto process_cl_args stanza
-rem  we are simply leveraging the "for" method's string
-rem  tokenization
-for /f "tokens=1*" %%g in ("%cl_args%") do (
-    set t=%%~g
-    rem  remainder of string is composed into %%h
-    rem  these are the cl args yet to be processed
-    rem  assign cl_args var to only the args to be processed
-    rem  effectively discarding the current arg %%g
-    rem  this will be nul when we have no further tokens to process
-    set cl_args=%%h
-    rem  process the first space delineated cl arg
-    rem  of this iteration
-    if "!t:~0,1!" == "-" (
-        if defined _sp_subcommand (
-            rem  We already have a subcommand, processing args now
-            if not defined _sp_args (
-                set "_sp_args=!t!"
-            ) else (
-                set "_sp_args=!_sp_args! !t!"
-            )
-        ) else (
-            if not defined _sp_flags (
-                set "_sp_flags=!t!"
-                shift
-            ) else (
-                set "_sp_flags=!_sp_flags! !t!"
-                shift
-            )
-        )
-    ) else if not defined _sp_subcommand (
-        set "_sp_subcommand=!t!"
-        shift
-    ) else (
+rem Set first cl argument (denoted by %1) to be processed
+set t=%1
+rem shift moves all cl positional arguments left by one
+rem meaning %2 is now %1, this allows us to iterate over each
+rem argument
+shift
+rem assign next "first" cl argument to cl_args, will be null when
+rem there are now further arguments to process
+set cl_args=%1
+if "!t:~0,1!" == "-" (
+    if defined _sp_subcommand (
+        rem  We already have a subcommand, processing args now
         if not defined _sp_args (
             set "_sp_args=!t!"
-            shift
         ) else (
             set "_sp_args=!_sp_args! !t!"
-            shift
+        )
+    ) else (
+        if not defined _sp_flags (
+            set "_sp_flags=!t!"
+        ) else (
+            set "_sp_flags=!_sp_flags! !t!"
         )
     )
+) else if not defined _sp_subcommand (
+    set "_sp_subcommand=!t!"
+) else (
+    if not defined _sp_args (
+        set "_sp_args=!t!"
+    ) else (
+        set "_sp_args=!_sp_args! !t!"
+    )
 )
-rem  if this is not nil, we have more tokens to process
+
+rem  if this is not nu;ll, we have more tokens to process
 rem  start above process again with remaining unprocessed cl args
 if defined cl_args goto :process_cl_args
 

bin/spack.ps1

@@ -39,12 +39,26 @@ function Read-SpackArgs {
     return $SpackCMD_params, $SpackSubCommand, $SpackSubCommandArgs
 }
 
+function Set-SpackEnv {
+    # This method is responsible
+    # for processing the return from $(spack <command>)
+    # which are returned as System.Object[]'s containing
+    # a list of env commands
+    # Invoke-Expression can only handle one command at a time
+    # so we iterate over the list to invoke the env modification
+    # expressions one at a time
+    foreach($envop in $args[0]){
+        Invoke-Expression $envop
+    }
+}
+
+
 function Invoke-SpackCD {
     if (Compare-CommonArgs $SpackSubCommandArgs) {
-        python $Env:SPACK_ROOT/bin/spack cd -h
+        python "$Env:SPACK_ROOT/bin/spack" cd -h
     }
     else {
-        $LOC = $(python $Env:SPACK_ROOT/bin/spack location $SpackSubCommandArgs)
+        $LOC = $(python "$Env:SPACK_ROOT/bin/spack" location $SpackSubCommandArgs)
         if (($NULL -ne $LOC)){
             if ( Test-Path -Path $LOC){
                 Set-Location $LOC
@@ -61,7 +75,7 @@ function Invoke-SpackCD {
 
 function Invoke-SpackEnv {
     if (Compare-CommonArgs $SpackSubCommandArgs[0]) {
-        python $Env:SPACK_ROOT/bin/spack env -h
+        python "$Env:SPACK_ROOT/bin/spack" env -h
     }
     else {
         $SubCommandSubCommand = $SpackSubCommandArgs[0]
@@ -69,46 +83,46 @@ function Invoke-SpackEnv {
         switch ($SubCommandSubCommand) {
             "activate" {
                 if (Compare-CommonArgs $SubCommandSubCommandArgs) {
-                    python $Env:SPACK_ROOT/bin/spack env activate $SubCommandSubCommandArgs
+                    python "$Env:SPACK_ROOT/bin/spack" env activate $SubCommandSubCommandArgs
                 }
                 elseif ([bool]($SubCommandSubCommandArgs.Where({$_ -eq "--pwsh"}))) {
-                    python $Env:SPACK_ROOT/bin/spack env activate $SubCommandSubCommandArgs
+                    python "$Env:SPACK_ROOT/bin/spack" env activate $SubCommandSubCommandArgs
                 }
                 elseif (!$SubCommandSubCommandArgs) {
-                    python $Env:SPACK_ROOT/bin/spack env activate $SubCommandSubCommandArgs
+                    python "$Env:SPACK_ROOT/bin/spack" env activate $SubCommandSubCommandArgs
                 }
                 else {
-                    $SpackEnv = $(python $Env:SPACK_ROOT/bin/spack $SpackCMD_params env activate "--pwsh" $SubCommandSubCommandArgs)
-                    $ExecutionContext.InvokeCommand($SpackEnv)
+                    $SpackEnv = $(python "$Env:SPACK_ROOT/bin/spack" $SpackCMD_params env activate "--pwsh" $SubCommandSubCommandArgs)
+                    Set-SpackEnv $SpackEnv
                 }
             }
             "deactivate" {
                 if ([bool]($SubCommandSubCommandArgs.Where({$_ -eq "--pwsh"}))) {
-                    python $Env:SPACK_ROOT/bin/spack env deactivate $SubCommandSubCommandArgs
+                    python"$Env:SPACK_ROOT/bin/spack" env deactivate $SubCommandSubCommandArgs
                 }
                 elseif($SubCommandSubCommandArgs) {
-                    python $Env:SPACK_ROOT/bin/spack env deactivate -h
+                    python "$Env:SPACK_ROOT/bin/spack" env deactivate -h
                 }
                 else {
-                    $SpackEnv = $(python $Env:SPACK_ROOT/bin/spack $SpackCMD_params env deactivate --pwsh)
-                    $ExecutionContext.InvokeCommand($SpackEnv)
+                    $SpackEnv = $(python "$Env:SPACK_ROOT/bin/spack" $SpackCMD_params env deactivate "--pwsh")
+                    Set-SpackEnv $SpackEnv
                 }
             }
-            default {python $Env:SPACK_ROOT/bin/spack $SpackCMD_params $SpackSubCommand $SpackSubCommandArgs}
+            default {python "$Env:SPACK_ROOT/bin/spack" $SpackCMD_params $SpackSubCommand $SpackSubCommandArgs}
         }
     }
 }
 
 function Invoke-SpackLoad {
     if (Compare-CommonArgs $SpackSubCommandArgs) {
-        python $Env:SPACK_ROOT/bin/spack $SpackCMD_params $SpackSubCommand $SpackSubCommandArgs
+        python "$Env:SPACK_ROOT/bin/spack" $SpackCMD_params $SpackSubCommand $SpackSubCommandArgs
     }
     elseif ([bool]($SpackSubCommandArgs.Where({($_ -eq "--pwsh") -or ($_ -eq "--list")}))) {
-        python $Env:SPACK_ROOT/bin/spack $SpackCMD_params $SpackSubCommand $SpackSubCommandArgs
+        python "$Env:SPACK_ROOT/bin/spack" $SpackCMD_params $SpackSubCommand $SpackSubCommandArgs
     }
     else {
-        $SpackEnv = $(python $Env:SPACK_ROOT/bin/spack $SpackCMD_params $SpackSubCommand "--pwsh" $SpackSubCommandArgs)
-        $ExecutionContext.InvokeCommand($SpackEnv)
+        $SpackEnv = $(python "$Env:SPACK_ROOT/bin/spack" $SpackCMD_params $SpackSubCommand "--pwsh" $SpackSubCommandArgs)
+        Set-SpackEnv $SpackEnv
     }
 }
 
@@ -116,7 +130,7 @@ function Invoke-SpackLoad {
 $SpackCMD_params, $SpackSubCommand, $SpackSubCommandArgs = Read-SpackArgs $args
 
 if (Compare-CommonArgs $SpackCMD_params) {
-    python $Env:SPACK_ROOT/bin/spack $SpackCMD_params $SpackSubCommand $SpackSubCommandArgs
+    python "$Env:SPACK_ROOT/bin/spack" $SpackCMD_params $SpackSubCommand $SpackSubCommandArgs
     exit $LASTEXITCODE
 }
 
@@ -128,5 +142,5 @@ switch($SpackSubCommand)
     "env"    {Invoke-SpackEnv}
     "load"   {Invoke-SpackLoad}
     "unload" {Invoke-SpackLoad}
-    default  {python $Env:SPACK_ROOT/bin/spack $SpackCMD_params $SpackSubCommand $SpackSubCommandArgs}
+    default  {python "$Env:SPACK_ROOT/bin/spack" $SpackCMD_params $SpackSubCommand $SpackSubCommandArgs}
 }

etc/spack/defaults/concretizer.yaml

@@ -36,3 +36,9 @@ concretizer:
   # on each root spec, allowing different versions and variants of the same package in
   # an environment.
   unify: true
+  # Option to deal with possible duplicate nodes (i.e. different nodes from the same package) in the DAG.
+  duplicates:
+    # "none": allows a single node for any package in the DAG.
+    # "minimal": allows the duplication of 'build-tools' nodes only (e.g. py-setuptools, cmake etc.)
+    # "full" (experimental): allows separation of the entire build-tool stack (e.g. the entire "cmake" subDAG)
+    strategy: none

etc/spack/defaults/packages.yaml

@@ -60,7 +60,7 @@ packages:
       xxd: [xxd-standalone, vim]
       yacc: [bison, byacc]
       ziglang: [zig]
-      zlib-api: [zlib, zlib-ng+compat]
+      zlib-api: [zlib-ng+compat, zlib]
     permissions:
       read: world
       write: user

lib/spack/docs/build_systems/bundlepackage.rst

@@ -9,9 +9,32 @@
 Bundle
 ------
 
-``BundlePackage`` represents a set of packages that are expected to work well
-together, such as a collection of commonly used software libraries.  The
-associated software is specified as bundle dependencies.
+``BundlePackage`` represents a set of packages that are expected to work
+well together, such as a collection of commonly used software libraries.
+The associated software is specified as dependencies.
+
+If it makes sense, variants, conflicts, and requirements can be added to
+the package. :ref:`Variants <variants>` ensure that common build options
+are consistent across the packages supporting them.  :ref:`Conflicts
+and requirements <packaging_conflicts>` prevent attempts to build with known
+bugs or limitations.
+
+For example, if ``MyBundlePackage`` is known to only build on ``linux``,
+it could use the ``require`` directive as follows:
+
+.. code-block:: python
+
+    require("platform=linux", msg="MyBundlePackage only builds on linux")
+
+Spack has a number of built-in bundle packages, such as:
+
+* `AmdAocl <https://github.com/spack/spack/blob/develop/var/spack/repos/builtin/packages/amd-aocl/package.py>`_
+* `EcpProxyApps <https://github.com/spack/spack/blob/develop/var/spack/repos/builtin/packages/ecp-proxy-apps/package.py>`_
+* `Libc <https://github.com/spack/spack/blob/develop/var/spack/repos/builtin/packages/libc/package.py>`_
+* `Xsdk <https://github.com/spack/spack/blob/develop/var/spack/repos/builtin/packages/xsdk/package.py>`_
+
+where ``Xsdk`` also inherits from ``CudaPackage`` and ``RocmPackage`` and
+``Libc`` is a virtual bundle package for the C standard library.
 
 
 ^^^^^^^^

lib/spack/docs/gpu_configuration.rst

@@ -0,0 +1,113 @@
+.. Copyright 2013-2023 Lawrence Livermore National Security, LLC and other
+   Spack Project Developers. See the top-level COPYRIGHT file for details.
+
+   SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+==========================
+Using External GPU Support
+==========================
+
+Many packages come with a ``+cuda`` or ``+rocm`` variant. With no added
+configuration Spack will download and install the needed components.
+It may be preferable to use existing system support: the following sections
+help with using a system installation of GPU libraries.
+
+-----------------------------------
+Using an External ROCm Installation
+-----------------------------------
+
+Spack breaks down ROCm into many separate component packages. The following
+is an example ``packages.yaml`` that organizes a consistent set of ROCm
+components for use by dependent packages:
+
+.. code-block:: yaml
+
+   packages:
+     all:
+       compiler: [rocmcc@=5.3.0]
+       variants: amdgpu_target=gfx90a
+     hip:
+       buildable: false
+       externals:
+       - spec: hip@5.3.0
+         prefix: /opt/rocm-5.3.0/hip
+     hsa-rocr-dev:
+       buildable: false
+       externals:
+       - spec: hsa-rocr-dev@5.3.0
+         prefix: /opt/rocm-5.3.0/
+     llvm-amdgpu:
+       buildable: false
+       externals:
+       - spec: llvm-amdgpu@5.3.0
+         prefix: /opt/rocm-5.3.0/llvm/
+     comgr:
+       buildable: false
+       externals:
+       - spec: comgr@5.3.0
+         prefix: /opt/rocm-5.3.0/
+     hipsparse:
+       buildable: false
+       externals:
+       - spec: hipsparse@5.3.0
+         prefix: /opt/rocm-5.3.0/
+     hipblas:
+       buildable: false
+       externals:
+       - spec: hipblas@5.3.0
+         prefix: /opt/rocm-5.3.0/
+     rocblas:
+       buildable: false
+       externals:
+       - spec: rocblas@5.3.0
+         prefix: /opt/rocm-5.3.0/
+     rocprim:
+       buildable: false
+       externals:
+       - spec: rocprim@5.3.0
+         prefix: /opt/rocm-5.3.0/rocprim/
+
+This is in combination with the following compiler definition:
+
+.. code-block:: yaml
+
+   compilers:
+   - compiler:
+       spec: rocmcc@=5.3.0
+       paths:
+         cc: /opt/rocm-5.3.0/bin/amdclang
+         cxx: /opt/rocm-5.3.0/bin/amdclang++
+         f77: null
+         fc: /opt/rocm-5.3.0/bin/amdflang
+       operating_system: rhel8
+       target: x86_64
+
+This includes the following considerations:
+
+- Each of the listed externals specifies ``buildable: false`` to force Spack
+  to use only the externals we defined.
+- ``spack external find`` can automatically locate some of the ``hip``/``rocm``
+  packages, but not all of them, and furthermore not in a manner that
+  guarantees a complementary set if multiple ROCm installations are available.
+- The ``prefix`` is the same for several components, but note that others
+  require listing one of the subdirectories as a prefix.
+
+-----------------------------------
+Using an External CUDA Installation
+-----------------------------------
+
+CUDA is split into fewer components and is simpler to specify:
+
+.. code-block:: yaml
+
+   packages:
+     all:
+       variants:
+       - cuda_arch=70
+     cuda:
+       buildable: false
+       externals:
+       - spec: cuda@11.0.2
+         prefix: /opt/cuda/cuda-11.0.2/
+
+where ``/opt/cuda/cuda-11.0.2/lib/`` contains ``libcudart.so``.

lib/spack/docs/index.rst

@@ -77,6 +77,7 @@ or refer to the full manual below.
    extensions
    pipelines
    signing
+   gpu_configuration
 
 .. toctree::
    :maxdepth: 2

lib/spack/docs/packaging_guide.rst

@@ -363,6 +363,42 @@ one of these::
 If Spack finds none of these variables set, it will look for ``vim``, ``vi``, ``emacs``,
 ``nano``, and ``notepad``, in that order.
 
+^^^^^^^^^^^^^^^^^
+Bundling software
+^^^^^^^^^^^^^^^^^
+
+If you have a collection of software expected to work well together with
+no source code of its own, you can create a :ref:`BundlePackage <bundlepackage>`.
+Examples where bundle packages can be useful include defining suites of
+applications (e.g, `EcpProxyApps
+<https://github.com/spack/spack/blob/develop/var/spack/repos/builtin/packages/ecp-proxy-apps/package.py>`_), commonly used libraries
+(e.g., `AmdAocl <https://github.com/spack/spack/blob/develop/var/spack/repos/builtin/packages/amd-aocl/package.py>`_),
+and software development kits (e.g., `EcpDataVisSdk <https://github.com/spack/spack/blob/develop/var/spack/repos/builtin/packages/ecp-data-vis-sdk/package.py>`_).
+
+These versioned packages primarily consist of dependencies on the associated
+software packages. They can include :ref:`variants <variants>` to ensure
+common build options are consistently applied to dependencies. Known build
+failures, such as not building on a platform or when certain compilers or
+variants are used, can be flagged with :ref:`conflicts <packaging_conflicts>`.
+Build requirements, such as only building with specific compilers, can similarly
+be flagged with :ref:`requires <packaging_conflicts>`.
+
+The ``spack create --template bundle`` command will create a skeleton
+``BundlePackage`` ``package.py`` for you:
+
+.. code-block:: console
+
+   $ spack create --template bundle --name coolsdk
+
+Now you can fill in the basic package documentation, version(s), and software
+package dependencies along with any other relevant customizations.
+
+.. note::
+
+   Remember that bundle packages have no software of their own so there
+   is nothing to download.
+
+
 ^^^^^^^^^^^^^^^^^^^^^^^^^
 Non-downloadable software
 ^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -610,7 +646,16 @@ add a line like this in the package class:
        version("8.2.0", md5="1c9f62f0778697a09d36121ead88e08e")
        version("8.1.2", md5="d47dd09ed7ae6e7fd6f9a816d7f5fdf6")
 
-Versions should be listed in descending order, from newest to oldest.
+.. note::
+
+   By convention, we list versions in descending order, from newest to oldest.
+
+.. note::
+
+   :ref:`Bundle packages  <bundlepackage>` do not have source code so
+   there is nothing to fetch. Consequently, their version directives
+   consist solely of the version name (e.g., ``version("202309")``).
+
 
 ^^^^^^^^^^^^^
 Date Versions
@@ -2678,7 +2723,7 @@ Conflicts and requirements
 --------------------------
 
 Sometimes packages have known bugs, or limitations, that would prevent them
-to build e.g. against other dependencies or with certain compilers. Spack
+from building e.g. against other dependencies or with certain compilers. Spack
 makes it possible to express such constraints with the ``conflicts`` directive.
 
 Adding the following to a package:
@@ -4773,17 +4818,17 @@ For example, running:
 
 results in spack checking that the installation created the following **file**:
 
-* ``self.prefix/bin/reframe``
+* ``self.prefix.bin.reframe``
 
 and the following **directories**:
 
-* ``self.prefix/bin``
-* ``self.prefix/config``
-* ``self.prefix/docs``
-* ``self.prefix/reframe``
-* ``self.prefix/tutorials``
-* ``self.prefix/unittests``
-* ``self.prefix/cscs-checks``
+* ``self.prefix.bin``
+* ``self.prefix.config``
+* ``self.prefix.docs``
+* ``self.prefix.reframe``
+* ``self.prefix.tutorials``
+* ``self.prefix.unittests``
+* ``self.prefix.cscs-checks``
 
 If **any** of these paths are missing, then Spack considers the installation
 to have failed.
@@ -4927,7 +4972,7 @@ installed executable. The check is implemented as follows:
        @on_package_attributes(run_tests=True)
        def check_list(self):
             with working_dir(self.stage.source_path):
-                reframe = Executable(join_path(self.prefix, "bin", "reframe"))
+                reframe = Executable(self.prefix.bin.reframe)
                 reframe("-l")
 
 .. warning::
@@ -5147,8 +5192,8 @@ embedded test parts.
            for example in ["ex1", "ex2"]:
                with test_part(
                    self,
-                   "test_example_{0}".format(example),
-                   purpose="run installed {0}".format(example),
+                   f"test_example_{example}",
+                   purpose=f"run installed {example}",
                 ):
                     exe = which(join_path(self.prefix.bin, example))
                     exe()
@@ -5226,11 +5271,10 @@ Below illustrates using this feature to compile an example.
            ...
            cxx = which(os.environ["CXX"])
            cxx(
-               "-L{0}".format(self.prefix.lib),
-               "-I{0}".format(self.prefix.include),
-               "{0}.cpp".format(exe),
-               "-o",
-               exe
+               f"-L{self.prefix.lib}",
+               f"-I{self.prefix.include}",
+               f"{exe}.cpp",
+               "-o", exe
            )
            cxx_example = which(exe)
            cxx_example()
@@ -5247,14 +5291,14 @@ Saving build-time files
     We highly recommend re-using build-time test sources and pared down
     input files for testing installed software. These files are easier
     to keep synchronized with software capabilities since they reside
-    within the software's repository. 
-    
+    within the software's repository.
+
     If that is not possible, you can add test-related files to the package
     repository (see :ref:`adding custom files <cache_custom_files>`). It
     will be important to maintain them so they work across listed or supported
     versions of the package.
 
-You can use the ``cache_extra_test_sources`` method to copy directories
+You can use the ``cache_extra_test_sources`` helper to copy directories
 and or files from the source build stage directory to the package's
 installation directory.
 
@@ -5262,10 +5306,15 @@ The signature for ``cache_extra_test_sources`` is:
 
 .. code-block:: python
 
-   def cache_extra_test_sources(self, srcs):
+   def cache_extra_test_sources(pkg, srcs):
+
+where each argument has the following meaning:
+
+* ``pkg`` is an instance of the package for the spec under test.
+
+* ``srcs`` is a string *or* a list of strings corresponding to the
+  paths of subdirectories and or files needed for stand-alone testing.
 
-where ``srcs`` is a string *or* a list of strings corresponding to the
-paths of subdirectories and or files needed for stand-alone testing. 
 The paths must be relative to the staged source directory. Contents of
 subdirectories and files are copied to a special test cache subdirectory
 of the installation prefix. They are automatically copied to the appropriate
@@ -5286,21 +5335,18 @@ and using ``foo.c`` in a test method is illustrated below.
            srcs = ["tests",
                    join_path("examples", "foo.c"),
                    join_path("examples", "bar.c")]
-           self.cache_extra_test_sources(srcs)
+           cache_extra_test_sources(self, srcs)
 
        def test_foo(self):
            exe = "foo"
-           src_dir = join_path(
-               self.test_suite.current_test_cache_dir, "examples"
-           )
+           src_dir = self.test_suite.current_test_cache_dir.examples
            with working_dir(src_dir):
                cc = which(os.environ["CC"])
                cc(
-                   "-L{0}".format(self.prefix.lib),
-                   "-I{0}".format(self.prefix.include),
-                   "{0}.c".format(exe),
-                   "-o",
-                   exe
+                   f"-L{self.prefix.lib}",
+                   f"-I{self.prefix.include}",
+                   f"{exe}.c",
+                   "-o", exe
                )
                foo = which(exe)
                foo()
@@ -5326,9 +5372,9 @@ the files using the ``self.test_suite.current_test_cache_dir`` property.
 In our example above, test methods can use the following paths to reference
 the copy of each entry listed in ``srcs``, respectively:
 
-* ``join_path(self.test_suite.current_test_cache_dir, "tests")``
-* ``join_path(self.test_suite.current_test_cache_dir, "examples", "foo.c")``
-* ``join_path(self.test_suite.current_test_cache_dir, "examples", "bar.c")``
+* ``self.test_suite.current_test_cache_dir.tests``
+* ``join_path(self.test_suite.current_test_cache_dir.examples, "foo.c")``
+* ``join_path(self.test_suite.current_test_cache_dir.examples, "bar.c")``
 
 .. admonition:: Library packages should build stand-alone tests
 
@@ -5347,7 +5393,7 @@ the copy of each entry listed in ``srcs``, respectively:
     If one or more of the copied files needs to be modified to reference
     the installed software, it is recommended that those changes be made
     to the cached files **once** in the ``copy_test_sources`` method and
-    ***after** the call to ``self.cache_extra_test_sources()``. This will
+    ***after** the call to ``cache_extra_test_sources()``. This will
     reduce the amount of unnecessary work in the test method **and** avoid
     problems testing in shared instances and facility deployments.
 
@@ -5394,7 +5440,7 @@ property as shown below.
            """build and run custom-example"""
            data_dir = self.test_suite.current_test_data_dir
            exe = "custom-example"
-           src = datadir.join("{0}.cpp".format(exe))
+           src = datadir.join(f"{exe}.cpp")
            ...
            # TODO: Build custom-example using src and exe
            ...
@@ -5410,7 +5456,7 @@ Reading expected output from a file
 
 The helper function ``get_escaped_text_output`` is available for packages
 to retrieve and properly format the text from a file that contains the
-expected output from running an executable that may contain special 
+expected output from running an executable that may contain special
 characters.
 
 The signature for ``get_escaped_text_output`` is:
@@ -5444,7 +5490,7 @@ added to the package's ``test`` subdirectory.
                db_filename, ".dump", output=str.split, error=str.split
            )
            for exp in expected:
-               assert re.search(exp, out), "Expected '{0}' in output".format(exp)
+               assert re.search(exp, out), f"Expected '{exp}' in output"
 
 If the file was instead copied from the ``tests`` subdirectory of the staged
 source code, the path would be obtained as shown below.
@@ -5457,7 +5503,7 @@ source code, the path would be obtained as shown below.
            db_filename = test_cache_dir.join("packages.db")
 
 Alternatively, if the file was copied to the ``share/tests`` subdirectory
-as part of the installation process, the test could access the path as 
+as part of the installation process, the test could access the path as
 follows:
 
 .. code-block:: python
@@ -5494,9 +5540,12 @@ Invoking the method is the equivalent of:
 
 .. code-block:: python
 
+   errors = []
    for check in expected:
        if not re.search(check, actual):
-           raise RuntimeError("Expected '{0}' in output '{1}'".format(check, actual))
+           errors.append(f"Expected '{check}' in output '{actual}'")
+   if errors:
+       raise RuntimeError("\n ".join(errors))
 
 
 .. _accessing-files:
@@ -5536,7 +5585,7 @@ repository, and installation.
      - ``self.test_suite.test_dir_for_spec(self.spec)``
    * - Current Spec's Build-time Files
      - ``self.test_suite.current_test_cache_dir``
-     - ``join_path(self.test_suite.current_test_cache_dir, "examples", "foo.c")``
+     - ``join_path(self.test_suite.current_test_cache_dir.examples, "foo.c")``
    * - Current Spec's Custom Test Files
      - ``self.test_suite.current_test_data_dir``
      - ``join_path(self.test_suite.current_test_data_dir, "hello.f90")``
@@ -5551,7 +5600,7 @@ Inheriting stand-alone tests
 Stand-alone tests defined in parent (.e.g., :ref:`build-systems`) and
 virtual (e.g., :ref:`virtual-dependencies`) packages are executed by
 packages that inherit from or provide interface implementations for those
-packages, respectively. 
+packages, respectively.
 
 The table below summarizes the stand-alone tests that will be executed along
 with those implemented in the package itself.
@@ -5621,7 +5670,7 @@ for ``openmpi``:
    SKIPPED: test_version_oshcc: oshcc is not installed
    ...
    ==> [2023-03-10-16:04:02.215227] Completed testing
-   ==> [2023-03-10-16:04:02.215597] 
+   ==> [2023-03-10-16:04:02.215597]
    ======================== SUMMARY: openmpi-4.1.4-ubmrigj ========================
    Openmpi::test_bin_mpirun .. PASSED
    Openmpi::test_bin_ompi_info .. PASSED
@@ -6071,7 +6120,7 @@ in the extra attributes can implement this method like this:
    @classmethod
    def validate_detected_spec(cls, spec, extra_attributes):
        """Check that "compilers" is in the extra attributes."""
-       msg = ("the extra attribute "compilers" must be set for "
+       msg = ("the extra attribute 'compilers' must be set for "
               "the detected spec '{0}'".format(spec))
        assert "compilers" in extra_attributes, msg
 

lib/spack/docs/requirements.txt

@@ -1,13 +1,13 @@
-sphinx==6.2.1
+sphinx==7.2.5
 sphinxcontrib-programoutput==0.17
 sphinx_design==0.5.0
-sphinx-rtd-theme==1.2.2
+sphinx-rtd-theme==1.3.0
 python-levenshtein==0.21.1
 docutils==0.18.1
 pygments==2.16.1
 urllib3==2.0.4
-pytest==7.4.0
+pytest==7.4.2
 isort==5.12.0
 black==23.7.0
 flake8==6.1.0
-mypy==1.5.0
+mypy==1.5.1

lib/spack/llnl/util/filesystem.py

@@ -18,11 +18,13 @@
 import sys
 import tempfile
 from contextlib import contextmanager
+from itertools import accumulate
 from typing import Callable, Iterable, List, Match, Optional, Tuple, Union
 
+import llnl.util.symlink
 from llnl.util import tty
 from llnl.util.lang import dedupe, memoized
-from llnl.util.symlink import islink, symlink
+from llnl.util.symlink import islink, readlink, resolve_link_target_relative_to_the_link, symlink
 
 from spack.util.executable import Executable, which
 from spack.util.path import path_to_os_path, system_path_filter
@@ -101,7 +103,7 @@ def _nop(args, ns=None, follow_symlinks=None):
             pass
 
         # follow symlinks (aka don't not follow symlinks)
-        follow = follow_symlinks or not (os.path.islink(src) and os.path.islink(dst))
+        follow = follow_symlinks or not (islink(src) and islink(dst))
         if follow:
             # use the real function if it exists
             def lookup(name):
@@ -169,7 +171,7 @@ def rename(src, dst):
     if sys.platform == "win32":
         # Windows path existence checks will sometimes fail on junctions/links/symlinks
         # so check for that case
-        if os.path.exists(dst) or os.path.islink(dst):
+        if os.path.exists(dst) or islink(dst):
             os.remove(dst)
     os.rename(src, dst)
 
@@ -566,7 +568,7 @@ def set_install_permissions(path):
     # If this points to a file maintained in a Spack prefix, it is assumed that
     # this function will be invoked on the target. If the file is outside a
     # Spack-maintained prefix, the permissions should not be modified.
-    if os.path.islink(path):
+    if islink(path):
         return
     if os.path.isdir(path):
         os.chmod(path, 0o755)
@@ -635,7 +637,7 @@ def chmod_x(entry, perms):
 @system_path_filter
 def copy_mode(src, dest):
     """Set the mode of dest to that of src unless it is a link."""
-    if os.path.islink(dest):
+    if islink(dest):
         return
     src_mode = os.stat(src).st_mode
     dest_mode = os.stat(dest).st_mode
@@ -721,26 +723,12 @@ def install(src, dest):
     copy(src, dest, _permissions=True)
 
 
-@system_path_filter
-def resolve_link_target_relative_to_the_link(link):
-    """
-    os.path.isdir uses os.path.exists, which for links will check
-    the existence of the link target. If the link target is relative to
-    the link, we need to construct a pathname that is valid from
-    our cwd (which may not be the same as the link's directory)
-    """
-    target = os.readlink(link)
-    if os.path.isabs(target):
-        return target
-    link_dir = os.path.dirname(os.path.abspath(link))
-    return os.path.join(link_dir, target)
-
-
 @system_path_filter
 def copy_tree(
     src: str,
     dest: str,
     symlinks: bool = True,
+    allow_broken_symlinks: bool = sys.platform != "win32",
     ignore: Optional[Callable[[str], bool]] = None,
     _permissions: bool = False,
 ):
@@ -763,6 +751,8 @@ def copy_tree(
         src (str): the directory to copy
         dest (str): the destination directory
         symlinks (bool): whether or not to preserve symlinks
+        allow_broken_symlinks (bool): whether or not to allow broken (dangling) symlinks,
+            On Windows, setting this to True will raise an exception. Defaults to true on unix.
         ignore (typing.Callable): function indicating which files to ignore
         _permissions (bool): for internal use only
 
@@ -770,6 +760,8 @@ def copy_tree(
         IOError: if *src* does not match any files or directories
         ValueError: if *src* is a parent directory of *dest*
     """
+    if allow_broken_symlinks and sys.platform == "win32":
+        raise llnl.util.symlink.SymlinkError("Cannot allow broken symlinks on Windows!")
     if _permissions:
         tty.debug("Installing {0} to {1}".format(src, dest))
     else:
@@ -783,6 +775,11 @@ def copy_tree(
     if not files:
         raise IOError("No such file or directory: '{0}'".format(src))
 
+    # For Windows hard-links and junctions, the source path must exist to make a symlink. Add
+    # all symlinks to this list while traversing the tree, then when finished, make all
+    # symlinks at the end.
+    links = []
+
     for src in files:
         abs_src = os.path.abspath(src)
         if not abs_src.endswith(os.path.sep):
@@ -805,7 +802,7 @@ def copy_tree(
             ignore=ignore,
             follow_nonexisting=True,
         ):
-            if os.path.islink(s):
+            if islink(s):
                 link_target = resolve_link_target_relative_to_the_link(s)
                 if symlinks:
                     target = os.readlink(s)
@@ -819,7 +816,9 @@ def escaped_path(path):
                             tty.debug("Redirecting link {0} to {1}".format(target, new_target))
                             target = new_target
 
-                    symlink(target, d)
+                    links.append((target, d, s))
+                    continue
+
                 elif os.path.isdir(link_target):
                     mkdirp(d)
                 else:
@@ -834,9 +833,17 @@ def escaped_path(path):
                 set_install_permissions(d)
                 copy_mode(s, d)
 
+    for target, d, s in links:
+        symlink(target, d, allow_broken_symlinks=allow_broken_symlinks)
+        if _permissions:
+            set_install_permissions(d)
+            copy_mode(s, d)
+
 
 @system_path_filter
-def install_tree(src, dest, symlinks=True, ignore=None):
+def install_tree(
+    src, dest, symlinks=True, ignore=None, allow_broken_symlinks=sys.platform != "win32"
+):
     """Recursively install an entire directory tree rooted at *src*.
 
     Same as :py:func:`copy_tree` with the addition of setting proper
@@ -847,12 +854,21 @@ def install_tree(src, dest, symlinks=True, ignore=None):
         dest (str): the destination directory
         symlinks (bool): whether or not to preserve symlinks
         ignore (typing.Callable): function indicating which files to ignore
+        allow_broken_symlinks (bool): whether or not to allow broken (dangling) symlinks,
+            On Windows, setting this to True will raise an exception.
 
     Raises:
         IOError: if *src* does not match any files or directories
         ValueError: if *src* is a parent directory of *dest*
     """
-    copy_tree(src, dest, symlinks=symlinks, ignore=ignore, _permissions=True)
+    copy_tree(
+        src,
+        dest,
+        symlinks=symlinks,
+        allow_broken_symlinks=allow_broken_symlinks,
+        ignore=ignore,
+        _permissions=True,
+    )
 
 
 @system_path_filter
@@ -1256,7 +1272,12 @@ def traverse_tree(
     Keyword Arguments:
         order (str): Whether to do pre- or post-order traversal. Accepted
             values are 'pre' and 'post'
-        ignore (typing.Callable): function indicating which files to ignore
+        ignore (typing.Callable): function indicating which files to ignore. This will also
+            ignore symlinks if they point to an ignored file (regardless of whether the symlink
+            is explicitly ignored); note this only supports one layer of indirection (i.e. if
+            you have x -> y -> z, and z is ignored but x/y are not, then y would be ignored
+            but not x). To avoid this, make sure the ignore function also ignores the symlink
+            paths too.
         follow_nonexisting (bool): Whether to descend into directories in
             ``src`` that do not exit in ``dest``. Default is True
         follow_links (bool): Whether to descend into symlinks in ``src``
@@ -1283,11 +1304,24 @@ def traverse_tree(
         dest_child = os.path.join(dest_path, f)
         rel_child = os.path.join(rel_path, f)
 
+        # If the source path is a link and the link's source is ignored, then ignore the link too,
+        # but only do this if the ignore is defined.
+        if ignore is not None:
+            if islink(source_child) and not follow_links:
+                target = readlink(source_child)
+                all_parents = accumulate(target.split(os.sep), lambda x, y: os.path.join(x, y))
+                if any(map(ignore, all_parents)):
+                    tty.warn(
+                        f"Skipping {source_path} because the source or a part of the source's "
+                        f"path is included in the ignores."
+                    )
+                    continue
+
         # Treat as a directory
         # TODO: for symlinks, os.path.isdir looks for the link target. If the
         # target is relative to the link, then that may not resolve properly
         # relative to our cwd - see resolve_link_target_relative_to_the_link
-        if os.path.isdir(source_child) and (follow_links or not os.path.islink(source_child)):
+        if os.path.isdir(source_child) and (follow_links or not islink(source_child)):
             # When follow_nonexisting isn't set, don't descend into dirs
             # in source that do not exist in dest
             if follow_nonexisting or os.path.exists(dest_child):
@@ -1313,7 +1347,11 @@ def traverse_tree(
 
 def lexists_islink_isdir(path):
     """Computes the tuple (lexists(path), islink(path), isdir(path)) in a minimal
-    number of stat calls."""
+    number of stat calls on unix. Use os.path and symlink.islink methods for windows."""
+    if sys.platform == "win32":
+        if not os.path.lexists(path):
+            return False, False, False
+        return os.path.lexists(path), islink(path), os.path.isdir(path)
     # First try to lstat, so we know if it's a link or not.
     try:
         lst = os.lstat(path)
@@ -1528,7 +1566,7 @@ def remove_if_dead_link(path):
     Parameters:
         path (str): The potential dead link
     """
-    if os.path.islink(path) and not os.path.exists(path):
+    if islink(path) and not os.path.exists(path):
         os.unlink(path)
 
 
@@ -1587,7 +1625,7 @@ def remove_linked_tree(path):
         kwargs["onerror"] = readonly_file_handler(ignore_errors=True)
 
     if os.path.exists(path):
-        if os.path.islink(path):
+        if islink(path):
             shutil.rmtree(os.path.realpath(path), **kwargs)
             os.unlink(path)
         else:
@@ -1754,9 +1792,14 @@ def find(root, files, recursive=True):
         files = [files]
 
     if recursive:
-        return _find_recursive(root, files)
+        tty.debug(f"Find (recursive): {root} {str(files)}")
+        result = _find_recursive(root, files)
     else:
-        return _find_non_recursive(root, files)
+        tty.debug(f"Find (not recursive): {root} {str(files)}")
+        result = _find_non_recursive(root, files)
+
+    tty.debug(f"Find complete: {root} {str(files)}")
+    return result
 
 
 @system_path_filter
@@ -2688,7 +2731,7 @@ def remove_directory_contents(dir):
     """Remove all contents of a directory."""
     if os.path.exists(dir):
         for entry in [os.path.join(dir, entry) for entry in os.listdir(dir)]:
-            if os.path.isfile(entry) or os.path.islink(entry):
+            if os.path.isfile(entry) or islink(entry):
                 os.unlink(entry)
             else:
                 shutil.rmtree(entry)

lib/spack/llnl/util/symlink.py

@@ -2,77 +2,188 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-import errno
 import os
+import re
 import shutil
+import subprocess
 import sys
 import tempfile
-from os.path import exists, join
 
-from llnl.util import lang
+from llnl.util import lang, tty
+
+from spack.error import SpackError
+from spack.util.path import system_path_filter
 
 if sys.platform == "win32":
     from win32file import CreateHardLink
 
+is_windows = sys.platform == "win32"
 
-def symlink(real_path, link_path):
-    """
-    Create a symbolic link.
 
-    On Windows, use junctions if os.symlink fails.
+def symlink(source_path: str, link_path: str, allow_broken_symlinks: bool = not is_windows):
     """
-    if sys.platform != "win32":
-        os.symlink(real_path, link_path)
-    elif _win32_can_symlink():
-        # Windows requires target_is_directory=True when the target is a dir.
-        os.symlink(real_path, link_path, target_is_directory=os.path.isdir(real_path))
-    else:
-        try:
-            # Try to use junctions
-            _win32_junction(real_path, link_path)
-        except OSError as e:
-            if e.errno == errno.EEXIST:
-                # EEXIST error indicates that file we're trying to "link"
-                # is already present, don't bother trying to copy which will also fail
-                # just raise
-                raise
+    Create a link.
+
+    On non-Windows and Windows with System Administrator
+    privleges this will be a normal symbolic link via
+    os.symlink.
+
+    On Windows without privledges the link will be a
+    junction for a directory and a hardlink for a file.
+    On Windows the various link types are:
+
+    Symbolic Link: A link to a file or directory on the
+    same or different volume (drive letter) or even to
+    a remote file or directory (using UNC in its path).
+    Need System Administrator privileges to make these.
+
+    Hard Link: A link to a file on the same volume (drive
+    letter) only. Every file (file's data) has at least 1
+    hard link (file's name). But when this method creates
+    a new hard link there will be 2. Deleting all hard
+    links effectively deletes the file. Don't need System
+    Administrator privileges.
+
+    Junction: A link to a directory on the same or different
+    volume (drive letter) but not to a remote directory. Don't
+    need System Administrator privileges.
+
+    Parameters:
+        source_path (str): The real file or directory that the link points to.
+            Must be absolute OR relative to the link.
+        link_path (str): The path where the link will exist.
+        allow_broken_symlinks (bool): On Linux or Mac, don't raise an exception if the source_path
+            doesn't exist. This will still raise an exception on Windows.
+    """
+    source_path = os.path.normpath(source_path)
+    win_source_path = source_path
+    link_path = os.path.normpath(link_path)
+
+    # Never allow broken links on Windows.
+    if sys.platform == "win32" and allow_broken_symlinks:
+        raise ValueError("allow_broken_symlinks parameter cannot be True on Windows.")
+
+    if not allow_broken_symlinks:
+        # Perform basic checks to make sure symlinking will succeed
+        if os.path.lexists(link_path):
+            raise SymlinkError(f"Link path ({link_path}) already exists. Cannot create link.")
+
+        if not os.path.exists(source_path):
+            if os.path.isabs(source_path) and not allow_broken_symlinks:
+                # An absolute source path that does not exist will result in a broken link.
+                raise SymlinkError(
+                    f"Source path ({source_path}) is absolute but does not exist. Resulting "
+                    f"link would be broken so not making link."
+                )
             else:
-                # If all else fails, fall back to copying files
-                shutil.copyfile(real_path, link_path)
+                # os.symlink can create a link when the given source path is relative to
+                # the link path. Emulate this behavior and check to see if the source exists
+                # relative to the link patg ahead of link creation to prevent broken
+                # links from being made.
+                link_parent_dir = os.path.dirname(link_path)
+                relative_path = os.path.join(link_parent_dir, source_path)
+                if os.path.exists(relative_path):
+                    # In order to work on windows, the source path needs to be modified to be
+                    # relative because hardlink/junction dont resolve relative paths the same
+                    # way as os.symlink. This is ignored on other operating systems.
+                    win_source_path = relative_path
+                elif not allow_broken_symlinks:
+                    raise SymlinkError(
+                        f"The source path ({source_path}) is not relative to the link path "
+                        f"({link_path}). Resulting link would be broken so not making link."
+                    )
+
+    # Create the symlink
+    if sys.platform == "win32" and not _windows_can_symlink():
+        _windows_create_link(win_source_path, link_path)
+    else:
+        os.symlink(source_path, link_path, target_is_directory=os.path.isdir(source_path))
 
 
-def islink(path):
-    return os.path.islink(path) or _win32_is_junction(path)
+def islink(path: str) -> bool:
+    """Override os.islink to give correct answer for spack logic.
+
+    For Non-Windows: a link can be determined with the os.path.islink method.
+    Windows-only methods will return false for other operating systems.
+
+    For Windows: spack considers symlinks, hard links, and junctions to
+    all be links, so if any of those are True, return True.
+
+    Args:
+        path (str): path to check if it is a link.
+
+    Returns:
+         bool - whether the path is any kind link or not.
+    """
+    return any([os.path.islink(path), _windows_is_junction(path), _windows_is_hardlink(path)])
 
 
-# '_win32' functions based on
-# https://github.com/Erotemic/ubelt/blob/master/ubelt/util_links.py
-def _win32_junction(path, link):
-    # junctions require absolute paths
-    if not os.path.isabs(link):
-        link = os.path.abspath(link)
+def _windows_is_hardlink(path: str) -> bool:
+    """Determines if a path is a windows hard link. This is accomplished
+    by looking at the number of links using os.stat. A non-hard-linked file
+    will have a st_nlink value of 1, whereas a hard link will have a value
+    larger than 1. Note that both the original and hard-linked file will
+    return True because they share the same inode.
 
-    # os.symlink will fail if link exists, emulate the behavior here
-    if exists(link):
-        raise OSError(errno.EEXIST, "File  exists: %s -> %s" % (link, path))
+    Args:
+        path (str): Windows path to check for a hard link
 
-    if not os.path.isabs(path):
-        parent = os.path.join(link, os.pardir)
-        path = os.path.join(parent, path)
-        path = os.path.abspath(path)
+    Returns:
+         bool - Whether the path is a hard link or not.
+    """
+    if sys.platform != "win32" or os.path.islink(path) or not os.path.exists(path):
+        return False
 
-    CreateHardLink(link, path)
+    return os.stat(path).st_nlink > 1
+
+
+def _windows_is_junction(path: str) -> bool:
+    """Determines if a path is a windows junction. A junction can be
+    determined using a bitwise AND operation between the file's
+    attribute bitmask and the known junction bitmask (0x400).
+
+    Args:
+        path (str): A non-file path
+
+    Returns:
+        bool - whether the path is a junction or not.
+    """
+    if sys.platform != "win32" or os.path.islink(path) or os.path.isfile(path):
+        return False
+
+    import ctypes.wintypes
+
+    get_file_attributes = ctypes.windll.kernel32.GetFileAttributesW  # type: ignore[attr-defined]
+    get_file_attributes.argtypes = (ctypes.wintypes.LPWSTR,)
+    get_file_attributes.restype = ctypes.wintypes.DWORD
+
+    invalid_file_attributes = 0xFFFFFFFF
+    reparse_point = 0x400
+    file_attr = get_file_attributes(str(path))
+
+    if file_attr == invalid_file_attributes:
+        return False
+
+    return file_attr & reparse_point > 0
 
 
 @lang.memoized
-def _win32_can_symlink():
+def _windows_can_symlink() -> bool:
+    """
+    Determines if windows is able to make a symlink depending on
+    the system configuration and the level of the user's permissions.
+    """
+    if sys.platform != "win32":
+        tty.warn("windows_can_symlink method can't be used on non-Windows OS.")
+        return False
+
     tempdir = tempfile.mkdtemp()
 
-    dpath = join(tempdir, "dpath")
-    fpath = join(tempdir, "fpath.txt")
+    dpath = os.path.join(tempdir, "dpath")
+    fpath = os.path.join(tempdir, "fpath.txt")
 
-    dlink = join(tempdir, "dlink")
-    flink = join(tempdir, "flink.txt")
+    dlink = os.path.join(tempdir, "dlink")
+    flink = os.path.join(tempdir, "flink.txt")
 
     import llnl.util.filesystem as fs
 
@@ -96,24 +207,136 @@ def _win32_can_symlink():
     return can_symlink_directories and can_symlink_files
 
 
-def _win32_is_junction(path):
+def _windows_create_link(source: str, link: str):
     """
-    Determines if a path is a win32 junction
+    Attempts to create a Hard Link or Junction as an alternative
+    to a symbolic link. This is called when symbolic links cannot
+    be created.
     """
-    if os.path.islink(path):
-        return False
+    if sys.platform != "win32":
+        raise SymlinkError("windows_create_link method can't be used on non-Windows OS.")
+    elif os.path.isdir(source):
+        _windows_create_junction(source=source, link=link)
+    elif os.path.isfile(source):
+        _windows_create_hard_link(path=source, link=link)
+    else:
+        raise SymlinkError(
+            f"Cannot create link from {source}. It is neither a file nor a directory."
+        )
 
-    if sys.platform == "win32":
-        import ctypes.wintypes
 
-        GetFileAttributes = ctypes.windll.kernel32.GetFileAttributesW
-        GetFileAttributes.argtypes = (ctypes.wintypes.LPWSTR,)
-        GetFileAttributes.restype = ctypes.wintypes.DWORD
+def _windows_create_junction(source: str, link: str):
+    """Duly verify that the path and link are eligible to create a junction,
+    then create the junction.
+    """
+    if sys.platform != "win32":
+        raise SymlinkError("windows_create_junction method can't be used on non-Windows OS.")
+    elif not os.path.exists(source):
+        raise SymlinkError("Source path does not exist, cannot create a junction.")
+    elif os.path.lexists(link):
+        raise SymlinkError("Link path already exists, cannot create a junction.")
+    elif not os.path.isdir(source):
+        raise SymlinkError("Source path is not a directory, cannot create a junction.")
 
-        INVALID_FILE_ATTRIBUTES = 0xFFFFFFFF
-        FILE_ATTRIBUTE_REPARSE_POINT = 0x400
+    import subprocess
 
-        res = GetFileAttributes(path)
-        return res != INVALID_FILE_ATTRIBUTES and bool(res & FILE_ATTRIBUTE_REPARSE_POINT)
+    cmd = ["cmd", "/C", "mklink", "/J", link, source]
+    proc = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+    out, err = proc.communicate()
+    tty.debug(out.decode())
+    if proc.returncode != 0:
+        err = err.decode()
+        tty.error(err)
+        raise SymlinkError("Make junction command returned a non-zero return code.", err)
 
-    return False
+
+def _windows_create_hard_link(path: str, link: str):
+    """Duly verify that the path and link are eligible to create a hard
+    link, then create the hard link.
+    """
+    if sys.platform != "win32":
+        raise SymlinkError("windows_create_hard_link method can't be used on non-Windows OS.")
+    elif not os.path.exists(path):
+        raise SymlinkError(f"File path {path} does not exist. Cannot create hard link.")
+    elif os.path.lexists(link):
+        raise SymlinkError(f"Link path ({link}) already exists. Cannot create hard link.")
+    elif not os.path.isfile(path):
+        raise SymlinkError(f"File path ({link}) is not a file. Cannot create hard link.")
+    else:
+        tty.debug(f"Creating hard link {link} pointing to {path}")
+        CreateHardLink(link, path)
+
+
+def readlink(path: str):
+    """Spack utility to override of os.readlink method to work cross platform"""
+    if _windows_is_hardlink(path):
+        return _windows_read_hard_link(path)
+    elif _windows_is_junction(path):
+        return _windows_read_junction(path)
+    else:
+        return os.readlink(path)
+
+
+def _windows_read_hard_link(link: str) -> str:
+    """Find all of the files that point to the same inode as the link"""
+    if sys.platform != "win32":
+        raise SymlinkError("Can't read hard link on non-Windows OS.")
+    link = os.path.abspath(link)
+    fsutil_cmd = ["fsutil", "hardlink", "list", link]
+    proc = subprocess.Popen(fsutil_cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True)
+    out, err = proc.communicate()
+    if proc.returncode != 0:
+        raise SymlinkError(f"An error occurred while reading hard link: {err.decode()}")
+
+    # fsutil response does not include the drive name, so append it back to each linked file.
+    drive, link_tail = os.path.splitdrive(os.path.abspath(link))
+    links = set([os.path.join(drive, p) for p in out.decode().splitlines()])
+    links.remove(link)
+    if len(links) == 1:
+        return links.pop()
+    elif len(links) > 1:
+        # TODO: How best to handle the case where 3 or more paths point to a single inode?
+        raise SymlinkError(f"Found multiple paths pointing to the same inode {links}")
+    else:
+        raise SymlinkError("Cannot determine hard link source path.")
+
+
+def _windows_read_junction(link: str):
+    """Find the path that a junction points to."""
+    if sys.platform != "win32":
+        raise SymlinkError("Can't read junction on non-Windows OS.")
+
+    link = os.path.abspath(link)
+    link_basename = os.path.basename(link)
+    link_parent = os.path.dirname(link)
+    fsutil_cmd = ["dir", "/a:l", link_parent]
+    proc = subprocess.Popen(fsutil_cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True)
+    out, err = proc.communicate()
+    if proc.returncode != 0:
+        raise SymlinkError(f"An error occurred while reading junction: {err.decode()}")
+    matches = re.search(rf"<JUNCTION>\s+{link_basename} \[(.*)]", out.decode())
+    if matches:
+        return matches.group(1)
+    else:
+        raise SymlinkError("Could not find junction path.")
+
+
+@system_path_filter
+def resolve_link_target_relative_to_the_link(link):
+    """
+    os.path.isdir uses os.path.exists, which for links will check
+    the existence of the link target. If the link target is relative to
+    the link, we need to construct a pathname that is valid from
+    our cwd (which may not be the same as the link's directory)
+    """
+    target = readlink(link)
+    if os.path.isabs(target):
+        return target
+    link_dir = os.path.dirname(os.path.abspath(link))
+    return os.path.join(link_dir, target)
+
+
+class SymlinkError(SpackError):
+    """Exception class for errors raised while creating symlinks,
+    junctions and hard links
+    """

lib/spack/llnl/util/tty/log.py

@@ -780,7 +780,7 @@ def __enter__(self):
             raise RuntimeError("file argument must be set by __init__ ")
 
         # Open both write and reading on logfile
-        if type(self.logfile) == io.StringIO:
+        if isinstance(self.logfile, io.StringIO):
             self._ioflag = True
             # cannot have two streams on tempfile, so we must make our own
             sys.stdout = self.logfile

lib/spack/spack/binary_distribution.py

@@ -9,7 +9,6 @@
 import io
 import itertools
 import json
-import multiprocessing.pool
 import os
 import re
 import shutil
@@ -49,6 +48,7 @@
 import spack.util.gpg
 import spack.util.spack_json as sjson
 import spack.util.spack_yaml as syaml
+import spack.util.timer as timer
 import spack.util.url as url_util
 import spack.util.web as web_util
 from spack.caches import misc_cache_location
@@ -876,32 +876,18 @@ def _read_specs_and_push_index(file_list, read_method, cache_prefix, db, temp_di
         db: A spack database used for adding specs and then writing the index.
         temp_dir (str): Location to write index.json and hash for pushing
         concurrency (int): Number of parallel processes to use when fetching
-
-    Return:
-        None
     """
+    for file in file_list:
+        contents = read_method(file)
+        # Need full spec.json name or this gets confused with index.json.
+        if file.endswith(".json.sig"):
+            specfile_json = Spec.extract_json_from_clearsig(contents)
+            fetched_spec = Spec.from_dict(specfile_json)
+        elif file.endswith(".json"):
+            fetched_spec = Spec.from_json(contents)
+        else:
+            continue
 
-    def _fetch_spec_from_mirror(spec_url):
-        spec_file_contents = read_method(spec_url)
-
-        if spec_file_contents:
-            # Need full spec.json name or this gets confused with index.json.
-            if spec_url.endswith(".json.sig"):
-                specfile_json = Spec.extract_json_from_clearsig(spec_file_contents)
-                return Spec.from_dict(specfile_json)
-            if spec_url.endswith(".json"):
-                return Spec.from_json(spec_file_contents)
-
-    tp = multiprocessing.pool.ThreadPool(processes=concurrency)
-    try:
-        fetched_specs = tp.map(
-            llnl.util.lang.star(_fetch_spec_from_mirror), [(f,) for f in file_list]
-        )
-    finally:
-        tp.terminate()
-        tp.join()
-
-    for fetched_spec in fetched_specs:
         db.add(fetched_spec, None)
         db.mark(fetched_spec, "in_buildcache", True)
 
@@ -1813,10 +1799,11 @@ def _tar_strip_component(tar: tarfile.TarFile, prefix: str):
                 m.linkname = m.linkname[result.end() :]
 
 
-def extract_tarball(spec, download_result, unsigned=False, force=False):
+def extract_tarball(spec, download_result, unsigned=False, force=False, timer=timer.NULL_TIMER):
     """
     extract binary tarball for given package into install area
     """
+    timer.start("extract")
     if os.path.exists(spec.prefix):
         if force:
             shutil.rmtree(spec.prefix)
@@ -1896,7 +1883,9 @@ def extract_tarball(spec, download_result, unsigned=False, force=False):
 
     os.remove(tarfile_path)
     os.remove(specfile_path)
+    timer.stop("extract")
 
+    timer.start("relocate")
     try:
         relocate_package(spec)
     except Exception as e:
@@ -1917,6 +1906,7 @@ def extract_tarball(spec, download_result, unsigned=False, force=False):
         if os.path.exists(filename):
             os.remove(filename)
         _delete_staged_downloads(download_result)
+    timer.stop("relocate")
 
 
 def _ensure_common_prefix(tar: tarfile.TarFile) -> str:
@@ -2383,22 +2373,12 @@ def __init__(self, all_architectures):
 
         self.possible_specs = specs
 
-    def __call__(self, spec, **kwargs):
+    def __call__(self, spec: Spec, **kwargs):
         """
         Args:
-            spec (str): The spec being searched for in its string representation or hash.
+            spec: The spec being searched for
         """
-        matches = []
-        if spec.startswith("/"):
-            # Matching a DAG hash
-            query_hash = spec.replace("/", "")
-            for candidate_spec in self.possible_specs:
-                if candidate_spec.dag_hash().startswith(query_hash):
-                    matches.append(candidate_spec)
-        else:
-            # Matching a spec constraint
-            matches = [s for s in self.possible_specs if s.satisfies(spec)]
-        return matches
+        return [s for s in self.possible_specs if s.satisfies(spec)]
 
 
 class FetchIndexError(Exception):

lib/spack/spack/bootstrap/config.py

@@ -124,9 +124,9 @@ def _read_and_sanitize_configuration() -> Dict[str, Any]:
 def _bootstrap_config_scopes() -> Sequence["spack.config.ConfigScope"]:
     tty.debug("[BOOTSTRAP CONFIG SCOPE] name=_builtin")
     config_scopes: MutableSequence["spack.config.ConfigScope"] = [
-        spack.config.InternalConfigScope("_builtin", spack.config.config_defaults)
+        spack.config.InternalConfigScope("_builtin", spack.config.CONFIG_DEFAULTS)
     ]
-    configuration_paths = (spack.config.configuration_defaults_path, ("bootstrap", _config_path()))
+    configuration_paths = (spack.config.CONFIGURATION_DEFAULTS_PATH, ("bootstrap", _config_path()))
     for name, path in configuration_paths:
         platform = spack.platforms.host().name
         platform_scope = spack.config.ConfigScope(

lib/spack/spack/bootstrap/core.py

@@ -476,15 +476,22 @@ def ensure_executables_in_path_or_raise(
 def _add_externals_if_missing() -> None:
     search_list = [
         # clingo
-        spack.repo.PATH.get_pkg_class("cmake"),
-        spack.repo.PATH.get_pkg_class("bison"),
+        "cmake",
+        "bison",
         # GnuPG
-        spack.repo.PATH.get_pkg_class("gawk"),
+        "gawk",
+        # develop deps
+        "git",
     ]
     if IS_WINDOWS:
-        search_list.append(spack.repo.PATH.get_pkg_class("winbison"))
-    detected_packages = spack.detection.by_executable(search_list)
-    spack.detection.update_configuration(detected_packages, scope="bootstrap")
+        search_list.append("winbison")
+    externals = spack.detection.by_path(search_list)
+    # System git is typically deprecated, so mark as non-buildable to force it as external
+    non_buildable_externals = {k: externals.pop(k) for k in ("git",) if k in externals}
+    spack.detection.update_configuration(externals, scope="bootstrap", buildable=True)
+    spack.detection.update_configuration(
+        non_buildable_externals, scope="bootstrap", buildable=False
+    )
 
 
 def clingo_root_spec() -> str:

lib/spack/spack/bootstrap/environment.py

@@ -15,14 +15,15 @@
 
 from llnl.util import tty
 
-import spack.build_environment
 import spack.environment
 import spack.tengine
+import spack.util.cpus
 import spack.util.executable
 from spack.environment import depfile
 
 from ._common import _root_spec
 from .config import root_path, spec_for_current_python, store_path
+from .core import _add_externals_if_missing
 
 
 class BootstrapEnvironment(spack.environment.Environment):
@@ -136,7 +137,7 @@ def _install_with_depfile(self) -> None:
             "-C",
             str(self.environment_root()),
             "-j",
-            str(spack.build_environment.determine_number_of_jobs(parallel=True)),
+            str(spack.util.cpus.determine_number_of_jobs(parallel=True)),
             **kwargs,
         )
 
@@ -185,6 +186,7 @@ def pytest_root_spec() -> str:
 
 def ensure_environment_dependencies() -> None:
     """Ensure Spack dependencies from the bootstrap environment are installed and ready to use"""
+    _add_externals_if_missing()
     with BootstrapEnvironment() as env:
         env.update_installations()
         env.update_syspath_and_environ()

lib/spack/spack/build_environment.py

@@ -68,7 +68,7 @@
 from spack.error import NoHeadersError, NoLibrariesError
 from spack.install_test import spack_install_test_log
 from spack.installer import InstallError
-from spack.util.cpus import cpus_available
+from spack.util.cpus import determine_number_of_jobs
 from spack.util.environment import (
     SYSTEM_DIRS,
     EnvironmentModifications,
@@ -537,39 +537,6 @@ def update_compiler_args_for_dep(dep):
     env.set(SPACK_RPATH_DIRS, ":".join(rpath_dirs))
 
 
-def determine_number_of_jobs(
-    parallel=False, command_line=None, config_default=None, max_cpus=None
-):
-    """
-    Packages that require sequential builds need 1 job. Otherwise we use the
-    number of jobs set on the command line. If not set, then we use the config
-    defaults (which is usually set through the builtin config scope), but we
-    cap to the number of CPUs available to avoid oversubscription.
-
-    Parameters:
-        parallel (bool or None): true when package supports parallel builds
-        command_line (int or None): command line override
-        config_default (int or None): config default number of jobs
-        max_cpus (int or None): maximum number of CPUs available. When None, this
-            value is automatically determined.
-    """
-    if not parallel:
-        return 1
-
-    if command_line is None and "command_line" in spack.config.scopes():
-        command_line = spack.config.get("config:build_jobs", scope="command_line")
-
-    if command_line is not None:
-        return command_line
-
-    max_cpus = max_cpus or cpus_available()
-
-    # in some rare cases _builtin config may not be set, so default to max 16
-    config_default = config_default or spack.config.get("config:build_jobs", 16)
-
-    return min(max_cpus, config_default)
-
-
 def set_module_variables_for_package(pkg):
     """Populate the Python module of a package with some useful global names.
     This makes things easier for package writers.
@@ -1027,7 +994,7 @@ def get_cmake_prefix_path(pkg):
 
 
 def _setup_pkg_and_run(
-    serialized_pkg, function, kwargs, child_pipe, input_multiprocess_fd, jsfd1, jsfd2
+    serialized_pkg, function, kwargs, write_pipe, input_multiprocess_fd, jsfd1, jsfd2
 ):
     context = kwargs.get("context", "build")
 
@@ -1048,12 +1015,12 @@ def _setup_pkg_and_run(
                 pkg, dirty=kwargs.get("dirty", False), context=context
             )
         return_value = function(pkg, kwargs)
-        child_pipe.send(return_value)
+        write_pipe.send(return_value)
 
     except StopPhase as e:
         # Do not create a full ChildError from this, it's not an error
         # it's a control statement.
-        child_pipe.send(e)
+        write_pipe.send(e)
     except BaseException:
         # catch ANYTHING that goes wrong in the child process
         exc_type, exc, tb = sys.exc_info()
@@ -1102,10 +1069,10 @@ def _setup_pkg_and_run(
             context,
             package_context,
         )
-        child_pipe.send(ce)
+        write_pipe.send(ce)
 
     finally:
-        child_pipe.close()
+        write_pipe.close()
         if input_multiprocess_fd is not None:
             input_multiprocess_fd.close()
 
@@ -1149,7 +1116,7 @@ def child_fun():
     For more information on `multiprocessing` child process creation
     mechanisms, see https://docs.python.org/3/library/multiprocessing.html#contexts-and-start-methods
     """
-    parent_pipe, child_pipe = multiprocessing.Pipe()
+    read_pipe, write_pipe = multiprocessing.Pipe(duplex=False)
     input_multiprocess_fd = None
     jobserver_fd1 = None
     jobserver_fd2 = None
@@ -1174,7 +1141,7 @@ def child_fun():
                 serialized_pkg,
                 function,
                 kwargs,
-                child_pipe,
+                write_pipe,
                 input_multiprocess_fd,
                 jobserver_fd1,
                 jobserver_fd2,
@@ -1183,6 +1150,12 @@ def child_fun():
 
         p.start()
 
+        # We close the writable end of the pipe now to be sure that p is the
+        # only process which owns a handle for it. This ensures that when p
+        # closes its handle for the writable end, read_pipe.recv() will
+        # promptly report the readable end as being ready.
+        write_pipe.close()
+
     except InstallError as e:
         e.pkg = pkg
         raise
@@ -1192,7 +1165,16 @@ def child_fun():
         if input_multiprocess_fd is not None:
             input_multiprocess_fd.close()
 
-    child_result = parent_pipe.recv()
+    def exitcode_msg(p):
+        typ = "exit" if p.exitcode >= 0 else "signal"
+        return f"{typ} {abs(p.exitcode)}"
+
+    try:
+        child_result = read_pipe.recv()
+    except EOFError:
+        p.join()
+        raise InstallError(f"The process has stopped unexpectedly ({exitcode_msg(p)})")
+
     p.join()
 
     # If returns a StopPhase, raise it
@@ -1212,6 +1194,10 @@ def child_fun():
         child_result.print_context()
         raise child_result
 
+    # Fallback. Usually caught beforehand in EOFError above.
+    if p.exitcode != 0:
+        raise InstallError(f"The process failed unexpectedly ({exitcode_msg(p)})")
+
     return child_result
 
 

lib/spack/spack/build_systems/autotools.py

@@ -55,7 +55,8 @@ def flags_to_build_system_args(self, flags):
         setattr(self, "configure_flag_args", [])
         for flag, values in flags.items():
             if values:
-                values_str = "{0}={1}".format(flag.upper(), " ".join(values))
+                var_name = "LIBS" if flag == "ldlibs" else flag.upper()
+                values_str = "{0}={1}".format(var_name, " ".join(values))
                 self.configure_flag_args.append(values_str)
         # Spack's fflags are meant for both F77 and FC, therefore we
         # additionaly set FCFLAGS if required.

lib/spack/spack/build_systems/cmake.py

@@ -274,7 +274,6 @@ def std_args(pkg, generator=None):
             generator,
             define("CMAKE_INSTALL_PREFIX", pathlib.Path(pkg.prefix).as_posix()),
             define("CMAKE_BUILD_TYPE", build_type),
-            define("BUILD_TESTING", pkg.run_tests),
         ]
 
         # CMAKE_INTERPROCEDURAL_OPTIMIZATION only exists for CMake >= 3.9
@@ -451,7 +450,6 @@ def cmake_args(self):
 
             * CMAKE_INSTALL_PREFIX
             * CMAKE_BUILD_TYPE
-            * BUILD_TESTING
 
         which will be set automatically.
         """

lib/spack/spack/build_systems/cuda.py

@@ -154,7 +154,7 @@ def cuda_flags(arch_list):
         conflicts("%pgi@:15.3,15.5:", when="+cuda ^cuda@7.5 target=x86_64:")
         conflicts("%pgi@:16.2,16.0:16.3", when="+cuda ^cuda@8 target=x86_64:")
         conflicts("%pgi@:15,18:", when="+cuda ^cuda@9.0:9.1 target=x86_64:")
-        conflicts("%pgi@:16,19:", when="+cuda ^cuda@9.2.88:10 target=x86_64:")
+        conflicts("%pgi@:16,19:", when="+cuda ^cuda@9.2.88:10.0 target=x86_64:")
         conflicts("%pgi@:17,20:", when="+cuda ^cuda@10.1.105:10.2.89 target=x86_64:")
         conflicts("%pgi@:17,21:", when="+cuda ^cuda@11.0.2:11.1.0 target=x86_64:")
         conflicts("%clang@:3.4", when="+cuda ^cuda@:7.5 target=x86_64:")

lib/spack/spack/build_systems/nmake.py

@@ -95,7 +95,7 @@ def makefile_root(self):
         return self.stage.source_path
 
     @property
-    def nmakefile_name(self):
+    def makefile_name(self):
         """Name of the current makefile. This is currently an empty value.
         If a project defines this value, it will be used with the /f argument
         to provide nmake an explicit makefile. This is usefule in scenarios where
@@ -126,8 +126,8 @@ def build(self, pkg, spec, prefix):
         """Run "nmake" on the build targets specified by the builder."""
         opts = self.std_nmake_args
         opts += self.nmake_args()
-        if self.nmakefile_name:
-            opts.append("/f {}".format(self.nmakefile_name))
+        if self.makefile_name:
+            opts.append("/F{}".format(self.makefile_name))
         with fs.working_dir(self.build_directory):
             inspect.getmodule(self.pkg).nmake(
                 *opts, *self.build_targets, ignore_quotes=self.ignore_quotes
@@ -139,8 +139,8 @@ def install(self, pkg, spec, prefix):
         opts = self.std_nmake_args
         opts += self.nmake_args()
         opts += self.nmake_install_args()
-        if self.nmakefile_name:
-            opts.append("/f {}".format(self.nmakefile_name))
+        if self.makefile_name:
+            opts.append("/F{}".format(self.makefile_name))
         opts.append(self.define("PREFIX", prefix))
         with fs.working_dir(self.build_directory):
             inspect.getmodule(self.pkg).nmake(

lib/spack/spack/build_systems/python.py

@@ -30,7 +30,7 @@
 
 
 class PythonExtension(spack.package_base.PackageBase):
-    maintainers("adamjstewart", "pradyunsg")
+    maintainers("adamjstewart")
 
     @property
     def import_modules(self):
@@ -300,8 +300,8 @@ def get_external_python_for_prefix(self):
         if python_externals_configured:
             return python_externals_configured[0]
 
-        python_externals_detection = spack.detection.by_executable(
-            [spack.repo.PATH.get_pkg_class("python")], path_hints=[self.spec.external_path]
+        python_externals_detection = spack.detection.by_path(
+            ["python"], path_hints=[self.spec.external_path]
         )
 
         python_externals_detected = [

lib/spack/spack/build_systems/racket.py

@@ -10,9 +10,10 @@
 import llnl.util.tty as tty
 
 import spack.builder
-from spack.build_environment import SPACK_NO_PARALLEL_MAKE, determine_number_of_jobs
+from spack.build_environment import SPACK_NO_PARALLEL_MAKE
 from spack.directives import build_system, extends, maintainers
 from spack.package_base import PackageBase
+from spack.util.cpus import determine_number_of_jobs
 from spack.util.environment import env_flag
 from spack.util.executable import Executable, ProcessError
 
@@ -92,7 +93,7 @@ def install(self, pkg, spec, prefix):
                 "--copy",
                 "-i",
                 "-j",
-                str(determine_number_of_jobs(parallel)),
+                str(determine_number_of_jobs(parallel=parallel)),
                 "--",
                 os.getcwd(),
             ]

lib/spack/spack/caches.py

@@ -20,9 +20,9 @@
 
 
 def misc_cache_location():
-    """The ``misc_cache`` is Spack's cache for small data.
+    """The ``MISC_CACHE`` is Spack's cache for small data.
 
-    Currently the ``misc_cache`` stores indexes for virtual dependency
+    Currently the ``MISC_CACHE`` stores indexes for virtual dependency
     providers and for which packages provide which tags.
     """
     path = spack.config.get("config:misc_cache", spack.paths.default_misc_cache_path)
@@ -35,7 +35,7 @@ def _misc_cache():
 
 
 #: Spack's cache for small data
-misc_cache: Union[
+MISC_CACHE: Union[
     spack.util.file_cache.FileCache, llnl.util.lang.Singleton
 ] = llnl.util.lang.Singleton(_misc_cache)
 
@@ -91,6 +91,6 @@ def symlink(self, mirror_ref):
 
 
 #: Spack's local cache for downloaded source archives
-fetch_cache: Union[
+FETCH_CACHE: Union[
     spack.fetch_strategy.FsCache, llnl.util.lang.Singleton
 ] = llnl.util.lang.Singleton(_fetch_cache)

lib/spack/spack/cmd/__init__.py

@@ -342,9 +342,9 @@ def iter_groups(specs, indent, all_headers):
             print()
 
         header = "%s{%s} / %s{%s}" % (
-            spack.spec.architecture_color,
+            spack.spec.ARCHITECTURE_COLOR,
             architecture if architecture else "no arch",
-            spack.spec.compiler_color,
+            spack.spec.COMPILER_COLOR,
             f"{compiler.display_str}" if compiler else "no compiler",
         )
 

lib/spack/spack/cmd/bootstrap.py

@@ -69,11 +69,10 @@
 
 def _add_scope_option(parser):
     scopes = spack.config.scopes()
-    scopes_metavar = spack.config.scopes_metavar
     parser.add_argument(
         "--scope",
         choices=scopes,
-        metavar=scopes_metavar,
+        metavar=spack.config.SCOPES_METAVAR,
         help="configuration scope to read/modify",
     )
 
@@ -170,7 +169,7 @@ def _reset(args):
         if not ok_to_continue:
             raise RuntimeError("Aborting")
 
-    for scope in spack.config.config.file_scopes:
+    for scope in spack.config.CONFIG.file_scopes:
         # The default scope should stay untouched
         if scope.name == "defaults":
             continue
@@ -187,7 +186,7 @@ def _reset(args):
         if os.path.exists(bootstrap_yaml):
             shutil.move(bootstrap_yaml, backup_file)
 
-        spack.config.config.clear_caches()
+        spack.config.CONFIG.clear_caches()
 
 
 def _root(args):

lib/spack/spack/cmd/buildcache.py

@@ -20,6 +20,7 @@
 import spack.cmd.common.arguments as arguments
 import spack.config
 import spack.environment as ev
+import spack.error
 import spack.mirror
 import spack.relocate
 import spack.repo
@@ -78,6 +79,11 @@ def setup_parser(subparser: argparse.ArgumentParser):
         "Alternatively, one can decide to build a cache for only the package or only the "
         "dependencies",
     )
+    push.add_argument(
+        "--fail-fast",
+        action="store_true",
+        help="stop pushing on first failure (default is best effort)",
+    )
     arguments.add_common_arguments(push, ["specs"])
     push.set_defaults(func=push_fn)
 
@@ -149,12 +155,11 @@ def setup_parser(subparser: argparse.ArgumentParser):
 
     # used to construct scope arguments below
     scopes = spack.config.scopes()
-    scopes_metavar = spack.config.scopes_metavar
 
     check.add_argument(
         "--scope",
         choices=scopes,
-        metavar=scopes_metavar,
+        metavar=spack.config.SCOPES_METAVAR,
         default=spack.config.default_modify_scope(),
         help="configuration scope containing mirrors to check",
     )
@@ -297,6 +302,7 @@ def push_fn(args):
         tty.info(f"Selected {len(specs)} specs to push to {url}")
 
     skipped = []
+    failed = []
 
     # tty printing
     color = clr.get_color_when()
@@ -327,11 +333,17 @@ def push_fn(args):
         except bindist.NoOverwriteException:
             skipped.append(format_spec(spec))
 
+        # Catch any other exception unless the fail fast option is set
+        except Exception as e:
+            if args.fail_fast or isinstance(e, (bindist.PickKeyException, bindist.NoKeyException)):
+                raise
+            failed.append((format_spec(spec), e))
+
     if skipped:
         if len(specs) == 1:
             tty.info("The spec is already in the buildcache. Use --force to overwrite it.")
         elif len(skipped) == len(specs):
-            tty.info("All specs are already in the buildcache. Use --force to overwite them.")
+            tty.info("All specs are already in the buildcache. Use --force to overwrite them.")
         else:
             tty.info(
                 "The following {} specs were skipped as they already exist in the buildcache:\n"
@@ -341,6 +353,17 @@ def push_fn(args):
                 )
             )
 
+    if failed:
+        if len(failed) == 1:
+            raise failed[0][1]
+
+        raise spack.error.SpackError(
+            f"The following {len(failed)} errors occurred while pushing specs to the buildcache",
+            "\n".join(
+                elide_list([f"    {spec}: {e.__class__.__name__}: {e}" for spec, e in failed], 5)
+            ),
+        )
+
 
 def install_fn(args):
     """install from a binary package"""

lib/spack/spack/cmd/ci.py

@@ -19,6 +19,7 @@
 import spack.hash_types as ht
 import spack.mirror
 import spack.util.gpg as gpg_util
+import spack.util.timer as timer
 import spack.util.url as url_util
 import spack.util.web as web_util
 
@@ -253,6 +254,8 @@ def ci_rebuild(args):
     check a single spec against the remote mirror, and rebuild it from source if the mirror does
     not contain the hash
     """
+    rebuild_timer = timer.Timer()
+
     env = spack.cmd.require_active_env(cmd_name="ci rebuild")
 
     # Make sure the environment is "gitlab-enabled", or else there's nothing
@@ -289,6 +292,10 @@ def ci_rebuild(args):
     rebuild_everything = os.environ.get("SPACK_REBUILD_EVERYTHING")
     require_signing = os.environ.get("SPACK_REQUIRE_SIGNING")
 
+    # If signing key was provided via "SPACK_SIGNING_KEY", then try to import it.
+    if signing_key:
+        spack_ci.import_signing_key(signing_key)
+
     # Fail early if signing is required but we don't have a signing key
     sign_binaries = require_signing is not None and require_signing.lower() == "true"
     if sign_binaries and not spack_ci.can_sign_binaries():
@@ -418,11 +425,6 @@ def ci_rebuild(args):
                 dst_file = os.path.join(repro_dir, file_name)
                 shutil.copyfile(src_file, dst_file)
 
-    # If signing key was provided via "SPACK_SIGNING_KEY", then try to
-    # import it.
-    if signing_key:
-        spack_ci.import_signing_key(signing_key)
-
     # Write this job's spec json into the reproduction directory, and it will
     # also be used in the generated "spack install" command to install the spec
     tty.debug("job concrete spec path: {0}".format(job_spec_json_path))
@@ -679,7 +681,7 @@ def ci_rebuild(args):
                 input_spec=job_spec,
                 buildcache_mirror_url=buildcache_mirror_url,
                 pipeline_mirror_url=pipeline_mirror_url,
-                sign_binaries=sign_binaries,
+                sign_binaries=spack_ci.can_sign_binaries(),
             ):
                 msg = tty.msg if result.success else tty.warn
                 msg(
@@ -737,6 +739,14 @@ def ci_rebuild(args):
 
         print(reproduce_msg)
 
+    rebuild_timer.stop()
+    try:
+        with open("install_timers.json", "w") as timelog:
+            extra_attributes = {"name": ".ci-rebuild"}
+            rebuild_timer.write_json(timelog, extra_attributes=extra_attributes)
+    except Exception as e:
+        tty.debug(str(e))
+
     # Tie job success/failure to the success/failure of building the spec
     return install_exit_code
 

lib/spack/spack/cmd/clean.py

@@ -118,7 +118,7 @@ def clean(parser, args):
 
     if args.downloads:
         tty.msg("Removing cached downloads")
-        spack.caches.fetch_cache.destroy()
+        spack.caches.FETCH_CACHE.destroy()
 
     if args.failures:
         tty.msg("Removing install failure marks")
@@ -126,7 +126,7 @@ def clean(parser, args):
 
     if args.misc_cache:
         tty.msg("Removing cached information on repositories")
-        spack.caches.misc_cache.destroy()
+        spack.caches.MISC_CACHE.destroy()
 
     if args.python_cache:
         tty.msg("Removing python cache files")

lib/spack/spack/cmd/commands.py

@@ -812,6 +812,9 @@ def bash(args: Namespace, out: IO) -> None:
     parser = spack.main.make_argument_parser()
     spack.main.add_all_commands(parser)
 
+    aliases = ";".join(f"{key}:{val}" for key, val in spack.main.aliases.items())
+    out.write(f'SPACK_ALIASES="{aliases}"\n\n')
+
     writer = BashCompletionWriter(parser.prog, out, args.aliases)
     writer.write(parser)
 

lib/spack/spack/cmd/compiler.py

@@ -24,7 +24,6 @@ def setup_parser(subparser):
     sp = subparser.add_subparsers(metavar="SUBCOMMAND", dest="compiler_command")
 
     scopes = spack.config.scopes()
-    scopes_metavar = spack.config.scopes_metavar
 
     # Find
     find_parser = sp.add_parser(
@@ -36,7 +35,7 @@ def setup_parser(subparser):
     find_parser.add_argument(
         "--scope",
         choices=scopes,
-        metavar=scopes_metavar,
+        metavar=spack.config.SCOPES_METAVAR,
         default=spack.config.default_modify_scope("compilers"),
         help="configuration scope to modify",
     )
@@ -50,7 +49,7 @@ def setup_parser(subparser):
     remove_parser.add_argument(
         "--scope",
         choices=scopes,
-        metavar=scopes_metavar,
+        metavar=spack.config.SCOPES_METAVAR,
         default=None,
         help="configuration scope to modify",
     )
@@ -60,7 +59,7 @@ def setup_parser(subparser):
     list_parser.add_argument(
         "--scope",
         choices=scopes,
-        metavar=scopes_metavar,
+        metavar=spack.config.SCOPES_METAVAR,
         default=spack.config.default_list_scope(),
         help="configuration scope to read from",
     )
@@ -71,7 +70,7 @@ def setup_parser(subparser):
     info_parser.add_argument(
         "--scope",
         choices=scopes,
-        metavar=scopes_metavar,
+        metavar=spack.config.SCOPES_METAVAR,
         default=spack.config.default_list_scope(),
         help="configuration scope to read from",
     )
@@ -93,7 +92,7 @@ def compiler_find(args):
         n = len(new_compilers)
         s = "s" if n > 1 else ""
 
-        config = spack.config.config
+        config = spack.config.CONFIG
         filename = config.get_config_filename(args.scope, "compilers")
         tty.msg("Added %d new compiler%s to %s" % (n, s, filename))
         colify(reversed(sorted(c.spec.display_str for c in new_compilers)), indent=4)
@@ -186,7 +185,7 @@ def compiler_list(args):
         os_str = os
         if target:
             os_str += "-%s" % target
-        cname = "%s{%s} %s" % (spack.spec.compiler_color, name, os_str)
+        cname = "%s{%s} %s" % (spack.spec.COMPILER_COLOR, name, os_str)
         tty.hline(colorize(cname), char="-")
         colify(reversed(sorted(c.spec.display_str for c in compilers)))
 

lib/spack/spack/cmd/compilers.py

@@ -13,12 +13,11 @@
 
 def setup_parser(subparser):
     scopes = spack.config.scopes()
-    scopes_metavar = spack.config.scopes_metavar
 
     subparser.add_argument(
         "--scope",
         choices=scopes,
-        metavar=scopes_metavar,
+        metavar=spack.config.SCOPES_METAVAR,
         help="configuration scope to read/modify",
     )
 

lib/spack/spack/cmd/config.py

@@ -27,13 +27,12 @@
 
 def setup_parser(subparser):
     scopes = spack.config.scopes()
-    scopes_metavar = spack.config.scopes_metavar
 
     # User can only choose one
     subparser.add_argument(
         "--scope",
         choices=scopes,
-        metavar=scopes_metavar,
+        metavar=spack.config.SCOPES_METAVAR,
         help="configuration scope to read/modify",
     )
 
@@ -45,7 +44,7 @@ def setup_parser(subparser):
         help="configuration section to print\n\noptions: %(choices)s",
         nargs="?",
         metavar="section",
-        choices=spack.config.section_schemas,
+        choices=spack.config.SECTION_SCHEMAS,
     )
 
     blame_parser = sp.add_parser(
@@ -55,7 +54,7 @@ def setup_parser(subparser):
         "section",
         help="configuration section to print\n\noptions: %(choices)s",
         metavar="section",
-        choices=spack.config.section_schemas,
+        choices=spack.config.SECTION_SCHEMAS,
     )
 
     edit_parser = sp.add_parser("edit", help="edit configuration file")
@@ -64,7 +63,7 @@ def setup_parser(subparser):
         help="configuration section to edit\n\noptions: %(choices)s",
         metavar="section",
         nargs="?",
-        choices=spack.config.section_schemas,
+        choices=spack.config.SECTION_SCHEMAS,
     )
     edit_parser.add_argument(
         "--print-file", action="store_true", help="print the file name that would be edited"
@@ -146,10 +145,10 @@ def config_get(args):
     scope, section = _get_scope_and_section(args)
 
     if section is not None:
-        spack.config.config.print_section(section)
+        spack.config.CONFIG.print_section(section)
 
     elif scope and scope.startswith("env:"):
-        config_file = spack.config.config.get_config_filename(scope, section)
+        config_file = spack.config.CONFIG.get_config_filename(scope, section)
         if os.path.exists(config_file):
             with open(config_file) as f:
                 print(f.read())
@@ -162,7 +161,7 @@ def config_get(args):
 
 def config_blame(args):
     """Print out line-by-line blame of merged YAML."""
-    spack.config.config.print_section(args.section, blame=True)
+    spack.config.CONFIG.print_section(args.section, blame=True)
 
 
 def config_edit(args):
@@ -181,7 +180,7 @@ def config_edit(args):
         scope, section = _get_scope_and_section(args)
         if not scope and not section:
             tty.die("`spack config edit` requires a section argument or an active environment.")
-        config_file = spack.config.config.get_config_filename(scope, section)
+        config_file = spack.config.CONFIG.get_config_filename(scope, section)
 
     if args.print_file:
         print(config_file)
@@ -194,7 +193,7 @@ def config_list(args):
 
     Used primarily for shell tab completion scripts.
     """
-    print(" ".join(list(spack.config.section_schemas)))
+    print(" ".join(list(spack.config.SECTION_SCHEMAS)))
 
 
 def config_add(args):
@@ -251,19 +250,19 @@ def _can_update_config_file(scope: spack.config.ConfigScope, cfg_file):
 
 def config_update(args):
     # Read the configuration files
-    spack.config.config.get_config(args.section, scope=args.scope)
+    spack.config.CONFIG.get_config(args.section, scope=args.scope)
     updates: List[spack.config.ConfigScope] = list(
         filter(
             lambda s: not isinstance(
                 s, (spack.config.InternalConfigScope, spack.config.ImmutableConfigScope)
             ),
-            spack.config.config.format_updates[args.section],
+            spack.config.CONFIG.format_updates[args.section],
         )
     )
 
     cannot_overwrite, skip_system_scope = [], False
     for scope in updates:
-        cfg_file = spack.config.config.get_config_filename(scope.name, args.section)
+        cfg_file = spack.config.CONFIG.get_config_filename(scope.name, args.section)
         can_be_updated = _can_update_config_file(scope, cfg_file)
         if not can_be_updated:
             if scope.name == "system":
@@ -302,7 +301,7 @@ def config_update(args):
             " the latest schema format:\n\n"
         )
         for scope in updates:
-            cfg_file = spack.config.config.get_config_filename(scope.name, args.section)
+            cfg_file = spack.config.CONFIG.get_config_filename(scope.name, args.section)
             msg += "\t[scope={0}, file={1}]\n".format(scope.name, cfg_file)
         msg += (
             "\nIf the configuration files are updated, versions of Spack "
@@ -325,7 +324,7 @@ def config_update(args):
         # Make a backup copy and rewrite the file
         bkp_file = cfg_file + ".bkp"
         shutil.copy(cfg_file, bkp_file)
-        spack.config.config.update_config(args.section, data, scope=scope.name, force=True)
+        spack.config.CONFIG.update_config(args.section, data, scope=scope.name, force=True)
         tty.msg(f'File "{cfg_file}" update [backup={bkp_file}]')
 
 
@@ -337,13 +336,13 @@ def _can_revert_update(scope_dir, cfg_file, bkp_file):
 
 
 def config_revert(args):
-    scopes = [args.scope] if args.scope else [x.name for x in spack.config.config.file_scopes]
+    scopes = [args.scope] if args.scope else [x.name for x in spack.config.CONFIG.file_scopes]
 
     # Search for backup files in the configuration scopes
     Entry = collections.namedtuple("Entry", ["scope", "cfg", "bkp"])
     to_be_restored, cannot_overwrite = [], []
     for scope in scopes:
-        cfg_file = spack.config.config.get_config_filename(scope, args.section)
+        cfg_file = spack.config.CONFIG.get_config_filename(scope, args.section)
         bkp_file = cfg_file + ".bkp"
 
         # If the backup files doesn't exist move to the next scope
@@ -457,7 +456,7 @@ def config_prefer_upstream(args):
     existing = spack.config.get("packages", scope=scope)
     new = spack.config.merge_yaml(existing, pkgs)
     spack.config.set("packages", new, scope)
-    config_file = spack.config.config.get_config_filename(scope, section)
+    config_file = spack.config.CONFIG.get_config_filename(scope, section)
 
     tty.msg("Updated config at {0}".format(config_file))
 

lib/spack/spack/cmd/env.py

@@ -239,6 +239,13 @@ def env_deactivate_setup_parser(subparser):
         const="bat",
         help="print bat commands to activate the environment",
     )
+    shells.add_argument(
+        "--pwsh",
+        action="store_const",
+        dest="shell",
+        const="pwsh",
+        help="print pwsh commands to activate the environment",
+    )
 
 
 def env_deactivate(args):

lib/spack/spack/cmd/external.py

@@ -6,6 +6,7 @@
 import errno
 import os
 import sys
+from typing import List, Optional
 
 import llnl.util.tty as tty
 import llnl.util.tty.colify as colify
@@ -13,6 +14,7 @@
 import spack
 import spack.cmd
 import spack.cmd.common.arguments
+import spack.config
 import spack.cray_manifest as cray_manifest
 import spack.detection
 import spack.error
@@ -27,7 +29,6 @@ def setup_parser(subparser):
     sp = subparser.add_subparsers(metavar="SUBCOMMAND", dest="external_command")
 
     scopes = spack.config.scopes()
-    scopes_metavar = spack.config.scopes_metavar
 
     find_parser = sp.add_parser("find", help="add external packages to packages.yaml")
     find_parser.add_argument(
@@ -47,14 +48,14 @@ def setup_parser(subparser):
     find_parser.add_argument(
         "--scope",
         choices=scopes,
-        metavar=scopes_metavar,
+        metavar=spack.config.SCOPES_METAVAR,
         default=spack.config.default_modify_scope("packages"),
         help="configuration scope to modify",
     )
     find_parser.add_argument(
         "--all", action="store_true", help="search for all packages that Spack knows about"
     )
-    spack.cmd.common.arguments.add_common_arguments(find_parser, ["tags"])
+    spack.cmd.common.arguments.add_common_arguments(find_parser, ["tags", "jobs"])
     find_parser.add_argument("packages", nargs=argparse.REMAINDER)
     find_parser.epilog = (
         'The search is by default on packages tagged with the "build-tools" or '
@@ -120,52 +121,29 @@ def external_find(args):
             else:
                 tty.warn("Unable to read manifest, unexpected error: {0}".format(str(e)), skip_msg)
 
-    # If the user didn't specify anything, search for build tools by default
-    if not args.tags and not args.all and not args.packages:
-        args.tags = ["core-packages", "build-tools"]
+    # Outside the Cray manifest, the search is done by tag for performance reasons,
+    # since tags are cached.
 
     # If the user specified both --all and --tag, then --all has precedence
-    if args.all and args.tags:
-        args.tags = []
+    if args.all or args.packages:
+        # Each detectable package has at least the detectable tag
+        args.tags = ["detectable"]
+    elif not args.tags:
+        # If the user didn't specify anything, search for build tools by default
+        args.tags = ["core-packages", "build-tools"]
 
-    # Construct the list of possible packages to be detected
-    pkg_cls_to_check = []
-
-    # Add the packages that have been required explicitly
-    if args.packages:
-        pkg_cls_to_check = [spack.repo.PATH.get_pkg_class(pkg) for pkg in args.packages]
-        if args.tags:
-            allowed = set(spack.repo.PATH.packages_with_tags(*args.tags))
-            pkg_cls_to_check = [x for x in pkg_cls_to_check if x.name in allowed]
-
-    if args.tags and not pkg_cls_to_check:
-        # If we arrived here we didn't have any explicit package passed
-        # as argument, which means to search all packages.
-        # Since tags are cached it's much faster to construct what we need
-        # to search directly, rather than filtering after the fact
-        pkg_cls_to_check = [
-            spack.repo.PATH.get_pkg_class(pkg_name)
-            for tag in args.tags
-            for pkg_name in spack.repo.PATH.packages_with_tags(tag)
-        ]
-        pkg_cls_to_check = list(set(pkg_cls_to_check))
-
-    # If the list of packages is empty, search for every possible package
-    if not args.tags and not pkg_cls_to_check:
-        pkg_cls_to_check = list(spack.repo.PATH.all_package_classes())
-
-    # If the user specified any packages to exclude from external find, add them here
-    if args.exclude:
-        pkg_cls_to_check = [pkg for pkg in pkg_cls_to_check if pkg.name not in args.exclude]
-
-    detected_packages = spack.detection.by_executable(pkg_cls_to_check, path_hints=args.path)
-    detected_packages.update(spack.detection.by_library(pkg_cls_to_check, path_hints=args.path))
+    candidate_packages = packages_to_search_for(
+        names=args.packages, tags=args.tags, exclude=args.exclude
+    )
+    detected_packages = spack.detection.by_path(
+        candidate_packages, path_hints=args.path, max_workers=args.jobs
+    )
 
     new_entries = spack.detection.update_configuration(
         detected_packages, scope=args.scope, buildable=not args.not_buildable
     )
     if new_entries:
-        path = spack.config.config.get_config_filename(args.scope, "packages")
+        path = spack.config.CONFIG.get_config_filename(args.scope, "packages")
         msg = "The following specs have been detected on this system and added to {0}"
         tty.msg(msg.format(path))
         spack.cmd.display_specs(new_entries)
@@ -173,6 +151,19 @@ def external_find(args):
         tty.msg("No new external packages detected")
 
 
+def packages_to_search_for(
+    *, names: Optional[List[str]], tags: List[str], exclude: Optional[List[str]]
+):
+    result = []
+    for current_tag in tags:
+        result.extend(spack.repo.PATH.packages_with_tags(current_tag))
+    if names:
+        result = [x for x in result if x in names]
+    if exclude:
+        result = [x for x in result if x not in exclude]
+    return result
+
+
 def external_read_cray_manifest(args):
     _collect_and_consume_cray_manifest_files(
         manifest_file=args.file,

lib/spack/spack/cmd/info.py

@@ -64,11 +64,11 @@ def section_title(s):
 
 
 def version(s):
-    return spack.spec.version_color + s + plain_format
+    return spack.spec.VERSION_COLOR + s + plain_format
 
 
 def variant(s):
-    return spack.spec.enabled_variant_color + s + plain_format
+    return spack.spec.ENABLED_VARIANT_COLOR + s + plain_format
 
 
 class VariantFormatter:

lib/spack/spack/cmd/load.py

@@ -52,6 +52,13 @@ def setup_parser(subparser):
         const="bat",
         help="print bat commands to load the package",
     )
+    shells.add_argument(
+        "--pwsh",
+        action="store_const",
+        dest="shell",
+        const="pwsh",
+        help="print pwsh commands to load the package",
+    )
 
     subparser.add_argument(
         "--first",

lib/spack/spack/cmd/mirror.py

@@ -90,7 +90,6 @@ def setup_parser(subparser):
 
     # used to construct scope arguments below
     scopes = spack.config.scopes()
-    scopes_metavar = spack.config.scopes_metavar
 
     # Add
     add_parser = sp.add_parser("add", help=mirror_add.__doc__)
@@ -99,7 +98,7 @@ def setup_parser(subparser):
     add_parser.add_argument(
         "--scope",
         choices=scopes,
-        metavar=scopes_metavar,
+        metavar=spack.config.SCOPES_METAVAR,
         default=spack.config.default_modify_scope(),
         help="configuration scope to modify",
     )
@@ -119,7 +118,7 @@ def setup_parser(subparser):
     remove_parser.add_argument(
         "--scope",
         choices=scopes,
-        metavar=scopes_metavar,
+        metavar=spack.config.SCOPES_METAVAR,
         default=spack.config.default_modify_scope(),
         help="configuration scope to modify",
     )
@@ -138,7 +137,7 @@ def setup_parser(subparser):
     set_url_parser.add_argument(
         "--scope",
         choices=scopes,
-        metavar=scopes_metavar,
+        metavar=spack.config.SCOPES_METAVAR,
         default=spack.config.default_modify_scope(),
         help="configuration scope to modify",
     )
@@ -167,7 +166,7 @@ def setup_parser(subparser):
     set_parser.add_argument(
         "--scope",
         choices=scopes,
-        metavar=scopes_metavar,
+        metavar=spack.config.SCOPES_METAVAR,
         default=spack.config.default_modify_scope(),
         help="configuration scope to modify",
     )
@@ -178,7 +177,7 @@ def setup_parser(subparser):
     list_parser.add_argument(
         "--scope",
         choices=scopes,
-        metavar=scopes_metavar,
+        metavar=spack.config.SCOPES_METAVAR,
         default=spack.config.default_list_scope(),
         help="configuration scope to read from",
     )

lib/spack/spack/cmd/repo.py

@@ -20,7 +20,6 @@
 def setup_parser(subparser):
     sp = subparser.add_subparsers(metavar="SUBCOMMAND", dest="repo_command")
     scopes = spack.config.scopes()
-    scopes_metavar = spack.config.scopes_metavar
 
     # Create
     create_parser = sp.add_parser("create", help=repo_create.__doc__)
@@ -45,7 +44,7 @@ def setup_parser(subparser):
     list_parser.add_argument(
         "--scope",
         choices=scopes,
-        metavar=scopes_metavar,
+        metavar=spack.config.SCOPES_METAVAR,
         default=spack.config.default_list_scope(),
         help="configuration scope to read from",
     )
@@ -56,7 +55,7 @@ def setup_parser(subparser):
     add_parser.add_argument(
         "--scope",
         choices=scopes,
-        metavar=scopes_metavar,
+        metavar=spack.config.SCOPES_METAVAR,
         default=spack.config.default_modify_scope(),
         help="configuration scope to modify",
     )
@@ -69,7 +68,7 @@ def setup_parser(subparser):
     remove_parser.add_argument(
         "--scope",
         choices=scopes,
-        metavar=scopes_metavar,
+        metavar=spack.config.SCOPES_METAVAR,
         default=spack.config.default_modify_scope(),
         help="configuration scope to modify",
     )

lib/spack/spack/cmd/solve.py

@@ -137,7 +137,7 @@ def solve(parser, args):
     # these are the same options as `spack spec`
     install_status_fn = spack.spec.Spec.install_status
 
-    fmt = spack.spec.display_format
+    fmt = spack.spec.DISPLAY_FORMAT
     if args.namespaces:
         fmt = "{namespace}." + fmt
 

lib/spack/spack/cmd/spec.py

@@ -77,7 +77,7 @@ def setup_parser(subparser):
 def spec(parser, args):
     install_status_fn = spack.spec.Spec.install_status
 
-    fmt = spack.spec.display_format
+    fmt = spack.spec.DISPLAY_FORMAT
     if args.namespaces:
         fmt = "{namespace}." + fmt
 

lib/spack/spack/cmd/unit_test.py

@@ -209,12 +209,11 @@ def unit_test(parser, args, unknown_args):
     # mock configuration used by unit tests
     # Note: skip on windows here because for the moment,
     # clingo is wholly unsupported from bootstrap
-    if sys.platform != "win32":
-        with spack.bootstrap.ensure_bootstrap_configuration():
-            spack.bootstrap.ensure_core_dependencies()
-            if pytest is None:
-                spack.bootstrap.ensure_environment_dependencies()
-                import pytest
+    with spack.bootstrap.ensure_bootstrap_configuration():
+        spack.bootstrap.ensure_core_dependencies()
+        if pytest is None:
+            spack.bootstrap.ensure_environment_dependencies()
+            import pytest
 
     if args.pytest_help:
         # make the pytest.main help output more accurate

lib/spack/spack/cmd/unload.py

@@ -51,6 +51,13 @@ def setup_parser(subparser):
         const="bat",
         help="print bat commands to load the package",
     )
+    shells.add_argument(
+        "--pwsh",
+        action="store_const",
+        dest="shell",
+        const="pwsh",
+        help="print pwsh commands to load the package",
+    )
 
     subparser.add_argument(
         "-a", "--all", action="store_true", help="unload all loaded Spack packages"

lib/spack/spack/compilers/__init__.py

@@ -135,7 +135,7 @@ def _init_compiler_config(*, scope):
 
 def compiler_config_files():
     config_files = list()
-    config = spack.config.config
+    config = spack.config.CONFIG
     for scope in config.file_scopes:
         name = scope.name
         compiler_config = config.get("compilers", scope=name)
@@ -169,7 +169,7 @@ def remove_compiler_from_config(compiler_spec, scope=None):
     """
     candidate_scopes = [scope]
     if scope is None:
-        candidate_scopes = spack.config.config.scopes.keys()
+        candidate_scopes = spack.config.CONFIG.scopes.keys()
 
     removal_happened = False
     for current_scope in candidate_scopes:
@@ -523,7 +523,7 @@ def compiler_for_spec(compiler_spec, arch_spec):
 
 @_auto_compiler_spec
 def get_compiler_duplicates(compiler_spec, arch_spec):
-    config = spack.config.config
+    config = spack.config.CONFIG
 
     scope_to_compilers = {}
     for scope in config.scopes:

lib/spack/spack/compilers/gcc.py

@@ -99,6 +99,28 @@ def cxx17_flag(self):
         else:
             return "-std=c++17"
 
+    @property
+    def cxx20_flag(self):
+        if self.real_version < Version("8.0"):
+            raise spack.compiler.UnsupportedCompilerFlag(
+                self, "the C++20 standard", "cxx20_flag", "< 8.0"
+            )
+        elif self.real_version < Version("11.0"):
+            return "-std=c++2a"
+        else:
+            return "-std=c++20"
+
+    @property
+    def cxx23_flag(self):
+        if self.real_version < Version("11.0"):
+            raise spack.compiler.UnsupportedCompilerFlag(
+                self, "the C++23 standard", "cxx23_flag", "< 11.0"
+            )
+        elif self.real_version < Version("14.0"):
+            return "-std=c++2b"
+        else:
+            return "-std=c++23"
+
     @property
     def c99_flag(self):
         if self.real_version < Version("4.5"):

lib/spack/spack/compilers/msvc.py

@@ -29,6 +29,90 @@
 }
 
 
+class CmdCall:
+    """Compose a call to `cmd` for an ordered series of cmd commands/scripts"""
+
+    def __init__(self, *cmds):
+        if not cmds:
+            raise RuntimeError(
+                """Attempting to run commands from CMD without specifying commands.
+                Please add commands to be run."""
+            )
+        self._cmds = cmds
+
+    def __call__(self):
+        out = subprocess.check_output(self.cmd_line, stderr=subprocess.STDOUT)  # novermin
+        return out.decode("utf-16le", errors="replace")  # novermin
+
+    @property
+    def cmd_line(self):
+        base_call = "cmd /u /c "
+        commands = " && ".join([x.command_str() for x in self._cmds])
+        # If multiple commands are being invoked by a single subshell
+        # they must be encapsulated by a double quote. Always double
+        # quote to be sure of proper handling
+        # cmd will properly resolve nested double quotes as needed
+        #
+        # `set`` writes out the active env to the subshell stdout,
+        # and in this context we are always trying to obtain env
+        # state so it should always be appended
+        return base_call + f'"{commands} && set"'
+
+
+class VarsInvocation:
+    def __init__(self, script):
+        self._script = script
+
+    def command_str(self):
+        return f'"{self._script}"'
+
+    @property
+    def script(self):
+        return self._script
+
+
+class VCVarsInvocation(VarsInvocation):
+    def __init__(self, script, arch, msvc_version):
+        super(VCVarsInvocation, self).__init__(script)
+        self._arch = arch
+        self._msvc_version = msvc_version
+
+    @property
+    def sdk_ver(self):
+        """Accessor for Windows SDK version property
+
+        Note: This property may not be set by
+        the calling context and as such this property will
+        return an empty string
+
+        This property will ONLY be set if the SDK package
+        is a dependency somewhere in the Spack DAG of the package
+        for which we are constructing an MSVC compiler env.
+        Otherwise this property should be unset to allow the VCVARS
+        script to use its internal heuristics to determine appropriate
+        SDK version
+        """
+        if getattr(self, "_sdk_ver", None):
+            return self._sdk_ver + ".0"
+        return ""
+
+    @sdk_ver.setter
+    def sdk_ver(self, val):
+        self._sdk_ver = val
+
+    @property
+    def arch(self):
+        return self._arch
+
+    @property
+    def vcvars_ver(self):
+        return f"-vcvars_ver={self._msvc_version}"
+
+    def command_str(self):
+        script = super(VCVarsInvocation, self).command_str()
+        return f"{script} {self.arch} {self.sdk_ver} {self.vcvars_ver}"
+
+
 def get_valid_fortran_pth(comp_ver):
     cl_ver = str(comp_ver)
     sort_fn = lambda fc_ver: StrictVersion(fc_ver)
@@ -75,22 +159,48 @@ class Msvc(Compiler):
     # file based on compiler executable path.
 
     def __init__(self, *args, **kwargs):
-        new_pth = [pth if pth else get_valid_fortran_pth(args[0].version) for pth in args[3]]
-        args[3][:] = new_pth
+        # This positional argument "paths" is later parsed and process by the base class
+        # via the call to `super` later in this method
+        paths = args[3]
+        # This positional argument "cspec" is also parsed and handled by the base class
+        # constructor
+        cspec = args[0]
+        new_pth = [pth if pth else get_valid_fortran_pth(cspec.version) for pth in paths]
+        paths[:] = new_pth
         super().__init__(*args, **kwargs)
-        if os.getenv("ONEAPI_ROOT"):
+        # To use the MSVC compilers, VCVARS must be invoked
+        # VCVARS is located at a fixed location, referencable
+        # idiomatically by the following relative path from the
+        # compiler.
+        # Spack first finds the compilers via VSWHERE
+        # and stores their path, but their respective VCVARS
+        # file must be invoked before useage.
+        env_cmds = []
+        compiler_root = os.path.join(self.cc, "../../../../../../..")
+        vcvars_script_path = os.path.join(compiler_root, "Auxiliary", "Build", "vcvars64.bat")
+        # get current platform architecture and format for vcvars argument
+        arch = spack.platforms.real_host().default.lower()
+        arch = arch.replace("-", "_")
+        self.vcvars_call = VCVarsInvocation(vcvars_script_path, arch, self.msvc_version)
+        env_cmds.append(self.vcvars_call)
+        # Below is a check for a valid fortran path
+        # paths has c, cxx, fc, and f77 paths in that order
+        # paths[2] refers to the fc path and is a generic check
+        # for a fortran compiler
+        if paths[2]:
             # If this found, it sets all the vars
-            self.setvarsfile = os.path.join(os.getenv("ONEAPI_ROOT"), "setvars.bat")
-        else:
-            # To use the MSVC compilers, VCVARS must be invoked
-            # VCVARS is located at a fixed location, referencable
-            # idiomatically by the following relative path from the
-            # compiler.
-            # Spack first finds the compilers via VSWHERE
-            # and stores their path, but their respective VCVARS
-            # file must be invoked before useage.
-            self.setvarsfile = os.path.abspath(os.path.join(self.cc, "../../../../../../.."))
-            self.setvarsfile = os.path.join(self.setvarsfile, "Auxiliary", "Build", "vcvars64.bat")
+            oneapi_root = os.getenv("ONEAPI_ROOT")
+            oneapi_root_setvars = os.path.join(oneapi_root, "setvars.bat")
+            oneapi_version_setvars = os.path.join(
+                oneapi_root, "compiler", str(self.ifx_version), "env", "vars.bat"
+            )
+            # order matters here, the specific version env must be invoked first,
+            # otherwise it will be ignored if the root setvars sets up the oneapi
+            # env first
+            env_cmds.extend(
+                [VarsInvocation(oneapi_version_setvars), VarsInvocation(oneapi_root_setvars)]
+            )
+        self.msvc_compiler_environment = CmdCall(*env_cmds)
 
     @property
     def msvc_version(self):
@@ -119,16 +229,30 @@ def platform_toolset_ver(self):
         """
         return self.msvc_version[:2].joined.string[:3]
 
-    @property
-    def cl_version(self):
-        """Cl toolset version"""
+    def _compiler_version(self, compiler):
+        """Returns version object for given compiler"""
+        # ignore_errors below is true here due to ifx's
+        # non zero return code if it is not provided
+        # and input file
         return Version(
             re.search(
                 Msvc.version_regex,
-                spack.compiler.get_compiler_version_output(self.cc, version_arg=None),
+                spack.compiler.get_compiler_version_output(
+                    compiler, version_arg=None, ignore_errors=True
+                ),
             ).group(1)
         )
 
+    @property
+    def cl_version(self):
+        """Cl toolset version"""
+        return self._compiler_version(self.cc)
+
+    @property
+    def ifx_version(self):
+        """Ifx compiler version associated with this version of MSVC"""
+        return self._compiler_version(self.fc)
+
     @property
     def vs_root(self):
         # The MSVC install root is located at a fix level above the compiler
@@ -146,27 +270,12 @@ def setup_custom_environment(self, pkg, env):
         # output, sort into dictionary, use that to make the build
         # environment.
 
-        # get current platform architecture and format for vcvars argument
-        arch = spack.platforms.real_host().default.lower()
-        arch = arch.replace("-", "_")
         # vcvars can target specific sdk versions, force it to pick up concretized sdk
         # version, if needed by spec
-        sdk_ver = (
-            ""
-            if "win-sdk" not in pkg.spec or pkg.name == "win-sdk"
-            else pkg.spec["win-sdk"].version.string + ".0"
-        )
-        # provide vcvars with msvc version selected by concretization,
-        # not whatever it happens to pick up on the system (highest available version)
-        out = subprocess.check_output(  # novermin
-            'cmd /u /c "{}" {} {} {} && set'.format(
-                self.setvarsfile, arch, sdk_ver, "-vcvars_ver=%s" % self.msvc_version
-            ),
-            stderr=subprocess.STDOUT,
-        )
-        if sys.version_info[0] >= 3:
-            out = out.decode("utf-16le", errors="replace")  # novermin
+        if pkg.name != "win-sdk" and "win-sdk" in pkg.spec:
+            self.vcvars_call.sdk_ver = pkg.spec["win-sdk"].version.string
 
+        out = self.msvc_compiler_environment()
         int_env = dict(
             (key, value)
             for key, _, value in (line.partition("=") for line in out.splitlines())

lib/spack/spack/concretize.py

@@ -28,6 +28,7 @@
 
 import spack.abi
 import spack.compilers
+import spack.config
 import spack.environment
 import spack.error
 import spack.platforms
@@ -37,7 +38,6 @@
 import spack.tengine
 import spack.util.path
 import spack.variant as vt
-from spack.config import config
 from spack.package_prefs import PackagePrefs, is_spec_buildable, spec_externals
 from spack.version import ClosedOpenRange, VersionList, ver
 
@@ -76,7 +76,7 @@ class Concretizer:
 
     def __init__(self, abstract_spec=None):
         if Concretizer.check_for_compiler_existence is None:
-            Concretizer.check_for_compiler_existence = not config.get(
+            Concretizer.check_for_compiler_existence = not spack.config.get(
                 "config:install_missing_compilers", False
             )
         self.abstract_spec = abstract_spec

lib/spack/spack/config.py

@@ -47,6 +47,8 @@
 import spack.platforms
 import spack.schema
 import spack.schema.bootstrap
+import spack.schema.cdash
+import spack.schema.ci
 import spack.schema.compilers
 import spack.schema.concretizer
 import spack.schema.config
@@ -64,7 +66,7 @@
 from spack.util.cpus import cpus_available
 
 #: Dict from section names -> schema for that section
-section_schemas = {
+SECTION_SCHEMAS = {
     "compilers": spack.schema.compilers.schema,
     "concretizer": spack.schema.concretizer.schema,
     "mirrors": spack.schema.mirrors.schema,
@@ -80,16 +82,16 @@
 
 # Same as above, but including keys for environments
 # this allows us to unify config reading between configs and environments
-all_schemas = copy.deepcopy(section_schemas)
-all_schemas.update({spack.schema.env.TOP_LEVEL_KEY: spack.schema.env.schema})
+_ALL_SCHEMAS = copy.deepcopy(SECTION_SCHEMAS)
+_ALL_SCHEMAS.update({spack.schema.env.TOP_LEVEL_KEY: spack.schema.env.schema})
 
 #: Path to the default configuration
-configuration_defaults_path = ("defaults", os.path.join(spack.paths.etc_path, "defaults"))
+CONFIGURATION_DEFAULTS_PATH = ("defaults", os.path.join(spack.paths.etc_path, "defaults"))
 
 #: Hard-coded default values for some key configuration options.
 #: This ensures that Spack will still work even if config.yaml in
 #: the defaults scope is removed.
-config_defaults = {
+CONFIG_DEFAULTS = {
     "config": {
         "debug": False,
         "connect_timeout": 10,
@@ -105,10 +107,10 @@
 
 #: metavar to use for commands that accept scopes
 #: this is shorter and more readable than listing all choices
-scopes_metavar = "{defaults,system,site,user}[/PLATFORM] or env:ENVIRONMENT"
+SCOPES_METAVAR = "{defaults,system,site,user}[/PLATFORM] or env:ENVIRONMENT"
 
 #: Base name for the (internal) overrides scope.
-overrides_base_name = "overrides-"
+_OVERRIDES_BASE_NAME = "overrides-"
 
 
 class ConfigScope:
@@ -134,7 +136,7 @@ def get_section_filename(self, section):
     def get_section(self, section):
         if section not in self.sections:
             path = self.get_section_filename(section)
-            schema = section_schemas[section]
+            schema = SECTION_SCHEMAS[section]
             data = read_config_file(path, schema)
             self.sections[section] = data
         return self.sections[section]
@@ -145,7 +147,7 @@ def _write_section(self, section):
 
         # We copy data here to avoid adding defaults at write time
         validate_data = copy.deepcopy(data)
-        validate(validate_data, section_schemas[section])
+        validate(validate_data, SECTION_SCHEMAS[section])
 
         try:
             mkdirp(self.path)
@@ -317,7 +319,7 @@ def __init__(self, name, data=None):
             data = InternalConfigScope._process_dict_keyname_overrides(data)
             for section in data:
                 dsec = data[section]
-                validate({section: dsec}, section_schemas[section])
+                validate({section: dsec}, SECTION_SCHEMAS[section])
                 self.sections[section] = _mark_internal(syaml.syaml_dict({section: dsec}), name)
 
     def get_section_filename(self, section):
@@ -333,7 +335,7 @@ def _write_section(self, section):
         """This only validates, as the data is already in memory."""
         data = self.get_section(section)
         if data is not None:
-            validate(data, section_schemas[section])
+            validate(data, SECTION_SCHEMAS[section])
         self.sections[section] = _mark_internal(data, self.name)
 
     def __repr__(self):
@@ -430,7 +432,7 @@ def file_scopes(self) -> List[ConfigScope]:
         return [
             s
             for s in self.scopes.values()
-            if (type(s) == ConfigScope or type(s) == SingleFileScope)
+            if (type(s) is ConfigScope or type(s) is SingleFileScope)
         ]
 
     def highest_precedence_scope(self) -> ConfigScope:
@@ -711,11 +713,11 @@ def override(path_or_scope, value=None):
     """
     if isinstance(path_or_scope, ConfigScope):
         overrides = path_or_scope
-        config.push_scope(path_or_scope)
+        CONFIG.push_scope(path_or_scope)
     else:
-        base_name = overrides_base_name
+        base_name = _OVERRIDES_BASE_NAME
         # Ensure the new override gets a unique scope name
-        current_overrides = [s.name for s in config.matching_scopes(r"^{0}".format(base_name))]
+        current_overrides = [s.name for s in CONFIG.matching_scopes(r"^{0}".format(base_name))]
         num_overrides = len(current_overrides)
         while True:
             scope_name = "{0}{1}".format(base_name, num_overrides)
@@ -725,19 +727,19 @@ def override(path_or_scope, value=None):
                 break
 
         overrides = InternalConfigScope(scope_name)
-        config.push_scope(overrides)
-        config.set(path_or_scope, value, scope=scope_name)
+        CONFIG.push_scope(overrides)
+        CONFIG.set(path_or_scope, value, scope=scope_name)
 
     try:
-        yield config
+        yield CONFIG
     finally:
-        scope = config.remove_scope(overrides.name)
+        scope = CONFIG.remove_scope(overrides.name)
         assert scope is overrides
 
 
 #: configuration scopes added on the command line
 #: set by ``spack.main.main()``.
-command_line_scopes: List[str] = []
+COMMAND_LINE_SCOPES: List[str] = []
 
 
 def _add_platform_scope(cfg, scope_type, name, path):
@@ -781,14 +783,14 @@ def create():
     cfg = Configuration()
 
     # first do the builtin, hardcoded defaults
-    builtin = InternalConfigScope("_builtin", config_defaults)
+    builtin = InternalConfigScope("_builtin", CONFIG_DEFAULTS)
     cfg.push_scope(builtin)
 
     # Builtin paths to configuration files in Spack
     configuration_paths = [
         # Default configuration scope is the lowest-level scope. These are
         # versioned with Spack and can be overridden by systems, sites or users
-        configuration_defaults_path
+        CONFIGURATION_DEFAULTS_PATH
     ]
 
     disable_local_config = "SPACK_DISABLE_LOCAL_CONFIG" in os.environ
@@ -815,7 +817,7 @@ def create():
         _add_platform_scope(cfg, ConfigScope, name, path)
 
     # add command-line scopes
-    _add_command_line_scopes(cfg, command_line_scopes)
+    _add_command_line_scopes(cfg, COMMAND_LINE_SCOPES)
 
     # we make a special scope for spack commands so that they can
     # override configuration options.
@@ -825,7 +827,7 @@ def create():
 
 
 #: This is the singleton configuration instance for Spack.
-config: Union[Configuration, llnl.util.lang.Singleton] = llnl.util.lang.Singleton(create)
+CONFIG: Union[Configuration, llnl.util.lang.Singleton] = llnl.util.lang.Singleton(create)
 
 
 def add_from_file(filename, scope=None):
@@ -838,7 +840,7 @@ def add_from_file(filename, scope=None):
     # update all sections from config dict
     # We have to iterate on keys to keep overrides from the file
     for section in data.keys():
-        if section in section_schemas.keys():
+        if section in SECTION_SCHEMAS.keys():
             # Special handling for compiler scope difference
             # Has to be handled after we choose a section
             if scope is None:
@@ -849,18 +851,18 @@ def add_from_file(filename, scope=None):
             new = merge_yaml(existing, value)
 
             # We cannot call config.set directly (set is a type)
-            config.set(section, new, scope)
+            CONFIG.set(section, new, scope)
 
 
 def add(fullpath, scope=None):
     """Add the given configuration to the specified config scope.
     Add accepts a path. If you want to add from a filename, use add_from_file"""
-
     components = process_config_path(fullpath)
 
     has_existing_value = True
     path = ""
     override = False
+    value = syaml.load_config(components[-1])
     for idx, name in enumerate(components[:-1]):
         # First handle double colons in constructing path
         colon = "::" if override else ":" if path else ""
@@ -881,14 +883,14 @@ def add(fullpath, scope=None):
             existing = get_valid_type(path)
 
             # construct value from this point down
-            value = syaml.load_config(components[-1])
             for component in reversed(components[idx + 1 : -1]):
                 value = {component: value}
             break
 
+    if override:
+        path += "::"
+
     if has_existing_value:
-        path, _, value = fullpath.rpartition(":")
-        value = syaml.load_config(value)
         existing = get(path, scope=scope)
 
     # append values to lists
@@ -897,12 +899,12 @@ def add(fullpath, scope=None):
 
     # merge value into existing
     new = merge_yaml(existing, value)
-    config.set(path, new, scope)
+    CONFIG.set(path, new, scope)
 
 
 def get(path, default=None, scope=None):
     """Module-level wrapper for ``Configuration.get()``."""
-    return config.get(path, default, scope)
+    return CONFIG.get(path, default, scope)
 
 
 def set(path, value, scope=None):
@@ -910,26 +912,26 @@ def set(path, value, scope=None):
 
     Accepts the path syntax described in ``get()``.
     """
-    return config.set(path, value, scope)
+    return CONFIG.set(path, value, scope)
 
 
 def add_default_platform_scope(platform):
     plat_name = os.path.join("defaults", platform)
-    plat_path = os.path.join(configuration_defaults_path[1], platform)
-    config.push_scope(ConfigScope(plat_name, plat_path))
+    plat_path = os.path.join(CONFIGURATION_DEFAULTS_PATH[1], platform)
+    CONFIG.push_scope(ConfigScope(plat_name, plat_path))
 
 
 def scopes():
     """Convenience function to get list of configuration scopes."""
-    return config.scopes
+    return CONFIG.scopes
 
 
 def _validate_section_name(section):
     """Exit if the section is not a valid section."""
-    if section not in section_schemas:
+    if section not in SECTION_SCHEMAS:
         raise ConfigSectionError(
             "Invalid config section: '%s'. Options are: %s"
-            % (section, " ".join(section_schemas.keys()))
+            % (section, " ".join(SECTION_SCHEMAS.keys()))
         )
 
 
@@ -990,7 +992,7 @@ def read_config_file(filename, schema=None):
         if data:
             if not schema:
                 key = next(iter(data))
-                schema = all_schemas[key]
+                schema = _ALL_SCHEMAS[key]
             validate(data, schema)
         return data
 
@@ -1089,7 +1091,7 @@ def get_valid_type(path):
         test_data = {component: test_data}
 
     try:
-        validate(test_data, section_schemas[section])
+        validate(test_data, SECTION_SCHEMAS[section])
     except (ConfigFormatError, AttributeError) as e:
         jsonschema_error = e.validation_error
         if jsonschema_error.validator == "type":
@@ -1229,11 +1231,17 @@ def they_are(t):
     return copy.copy(source)
 
 
-#
-# Process a path argument to config.set() that may contain overrides ('::' or
-# trailing ':')
-#
 def process_config_path(path):
+    """Process a path argument to config.set() that may contain overrides ('::' or
+    trailing ':')
+
+    Note: quoted value path components will be processed as a single value (escaping colons)
+        quoted path components outside of the value will be considered ill formed and will
+        raise.
+        e.g. `this:is:a:path:'value:with:colon'` will yield:
+
+            [this, is, a, path, value:with:colon]
+    """
     result = []
     if path.startswith(":"):
         raise syaml.SpackYAMLError("Illegal leading `:' in path `{0}'".format(path), "")
@@ -1261,6 +1269,17 @@ def process_config_path(path):
             front.append = True
 
         result.append(front)
+
+        quote = "['\"]"
+        not_quote = "[^'\"]"
+
+        if re.match(f"^{quote}", path):
+            m = re.match(rf"^({quote}{not_quote}+{quote})$", path)
+            if not m:
+                raise ValueError("Quotes indicate value, but there are additional path entries")
+            result.append(m.group(1))
+            break
+
     return result
 
 
@@ -1278,9 +1297,9 @@ def default_modify_scope(section="config"):
             If this is not 'compilers', a general (non-platform) scope is used.
     """
     if section == "compilers":
-        return spack.config.config.highest_precedence_scope().name
+        return CONFIG.highest_precedence_scope().name
     else:
-        return spack.config.config.highest_precedence_non_platform_scope().name
+        return CONFIG.highest_precedence_non_platform_scope().name
 
 
 def default_list_scope():
@@ -1337,18 +1356,18 @@ def use_configuration(*scopes_or_paths):
     Returns:
         Configuration object associated with the scopes passed as arguments
     """
-    global config
+    global CONFIG
 
     # Normalize input and construct a Configuration object
     configuration = _config_from(scopes_or_paths)
-    config.clear_caches(), configuration.clear_caches()
+    CONFIG.clear_caches(), configuration.clear_caches()
 
-    saved_config, config = config, configuration
+    saved_config, CONFIG = CONFIG, configuration
 
     try:
         yield configuration
     finally:
-        config = saved_config
+        CONFIG = saved_config
 
 
 @llnl.util.lang.memoized

lib/spack/spack/container/writers/__init__.py

@@ -5,8 +5,8 @@
 """Writers for different kind of recipes and related
 convenience functions.
 """
-import collections
 import copy
+from collections import namedtuple
 from typing import Optional
 
 import spack.environment as ev
@@ -159,13 +159,13 @@ def depfile(self):
     @tengine.context_property
     def run(self):
         """Information related to the run image."""
-        Run = collections.namedtuple("Run", ["image"])
+        Run = namedtuple("Run", ["image"])
         return Run(image=self.final_image)
 
     @tengine.context_property
     def build(self):
         """Information related to the build image."""
-        Build = collections.namedtuple("Build", ["image"])
+        Build = namedtuple("Build", ["image"])
         return Build(image=self.build_image)
 
     @tengine.context_property
@@ -176,12 +176,13 @@ def strip(self):
     @tengine.context_property
     def paths(self):
         """Important paths in the image"""
-        Paths = collections.namedtuple("Paths", ["environment", "store", "hidden_view", "view"])
+        Paths = namedtuple("Paths", ["environment", "store", "view_parent", "view", "former_view"])
         return Paths(
             environment="/opt/spack-environment",
             store="/opt/software",
-            hidden_view="/opt/._view",
-            view="/opt/view",
+            view_parent="/opt/views",
+            view="/opt/views/view",
+            former_view="/opt/view",  # /opt/view -> /opt/views/view for backward compatibility
         )
 
     @tengine.context_property
@@ -257,7 +258,7 @@ def _package_info_from(self, package_list):
 
         update, install, clean = commands_for(os_pkg_manager)
 
-        Packages = collections.namedtuple("Packages", ["update", "install", "list", "clean"])
+        Packages = namedtuple("Packages", ["update", "install", "list", "clean"])
         return Packages(update=update, install=install, list=package_list, clean=clean)
 
     def _os_pkg_manager(self):
@@ -273,7 +274,7 @@ def _os_pkg_manager(self):
 
     @tengine.context_property
     def extra_instructions(self):
-        Extras = collections.namedtuple("Extra", ["build", "final"])
+        Extras = namedtuple("Extra", ["build", "final"])
         extras = self.container_config.get("extra_instructions", {})
         build, final = extras.get("build", None), extras.get("final", None)
         return Extras(build=build, final=final)
@@ -295,7 +296,7 @@ def bootstrap(self):
             context = {"bootstrap": {"image": self.bootstrap_image, "spack_checkout": command}}
             bootstrap_recipe = env.get_template(template_path).render(**context)
 
-        Bootstrap = collections.namedtuple("Bootstrap", ["image", "recipe"])
+        Bootstrap = namedtuple("Bootstrap", ["image", "recipe"])
         return Bootstrap(image=self.bootstrap_image, recipe=bootstrap_recipe)
 
     @tengine.context_property
@@ -303,7 +304,7 @@ def render_phase(self):
         render_bootstrap = bool(self.bootstrap_image)
         render_build = not (self.last_phase == "bootstrap")
         render_final = self.last_phase in (None, "final")
-        Render = collections.namedtuple("Render", ["bootstrap", "build", "final"])
+        Render = namedtuple("Render", ["bootstrap", "build", "final"])
         return Render(bootstrap=render_bootstrap, build=render_build, final=render_final)
 
     def __call__(self):

lib/spack/spack/detection/__init__.py

@@ -3,12 +3,11 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 from .common import DetectedPackage, executable_prefix, update_configuration
-from .path import by_executable, by_library, executables_in_path
+from .path import by_path, executables_in_path
 
 __all__ = [
     "DetectedPackage",
-    "by_library",
-    "by_executable",
+    "by_path",
     "executables_in_path",
     "executable_prefix",
     "update_configuration",

lib/spack/spack/detection/common.py

@@ -13,13 +13,13 @@
 The module also contains other functions that might be useful across different
 detection mechanisms.
 """
-import collections
 import glob
 import itertools
 import os
 import os.path
 import re
 import sys
+from typing import Dict, List, NamedTuple, Optional, Set, Tuple, Union
 
 import llnl.util.tty
 
@@ -29,12 +29,28 @@
 import spack.util.spack_yaml
 import spack.util.windows_registry
 
-#: Information on a package that has been detected
-DetectedPackage = collections.namedtuple("DetectedPackage", ["spec", "prefix"])
+
+class DetectedPackage(NamedTuple):
+    """Information on a package that has been detected."""
+
+    #: Spec that was detected
+    spec: spack.spec.Spec
+    #: Prefix of the spec
+    prefix: str
+
+    def __reduce__(self):
+        return DetectedPackage.restore, (str(self.spec), self.prefix, self.spec.extra_attributes)
+
+    @staticmethod
+    def restore(
+        spec_str: str, prefix: str, extra_attributes: Optional[Dict[str, str]]
+    ) -> "DetectedPackage":
+        spec = spack.spec.Spec.from_detection(spec_str=spec_str, extra_attributes=extra_attributes)
+        return DetectedPackage(spec=spec, prefix=prefix)
 
 
-def _externals_in_packages_yaml():
-    """Return all the specs mentioned as externals in packages.yaml"""
+def _externals_in_packages_yaml() -> Set[spack.spec.Spec]:
+    """Returns all the specs mentioned as externals in packages.yaml"""
     packages_yaml = spack.config.get("packages")
     already_defined_specs = set()
     for pkg_name, package_configuration in packages_yaml.items():
@@ -43,7 +59,12 @@ def _externals_in_packages_yaml():
     return already_defined_specs
 
 
-def _pkg_config_dict(external_pkg_entries):
+ExternalEntryType = Union[str, Dict[str, str]]
+
+
+def _pkg_config_dict(
+    external_pkg_entries: List[DetectedPackage],
+) -> Dict[str, Union[bool, List[Dict[str, ExternalEntryType]]]]:
     """Generate a package specific config dict according to the packages.yaml schema.
 
     This does not generate the entire packages.yaml. For example, given some
@@ -65,7 +86,10 @@ def _pkg_config_dict(external_pkg_entries):
         if not _spec_is_valid(e.spec):
             continue
 
-        external_items = [("spec", str(e.spec)), ("prefix", e.prefix)]
+        external_items: List[Tuple[str, ExternalEntryType]] = [
+            ("spec", str(e.spec)),
+            ("prefix", e.prefix),
+        ]
         if e.spec.external_modules:
             external_items.append(("modules", e.spec.external_modules))
 
@@ -83,15 +107,14 @@ def _pkg_config_dict(external_pkg_entries):
     return pkg_dict
 
 
-def _spec_is_valid(spec):
+def _spec_is_valid(spec: spack.spec.Spec) -> bool:
     try:
         str(spec)
     except spack.error.SpackError:
-        # It is assumed here that we can at least extract the package name from
-        # the spec so we can look up the implementation of
-        # determine_spec_details
-        msg = "Constructed spec for {0} does not have a string representation"
-        llnl.util.tty.warn(msg.format(spec.name))
+        # It is assumed here that we can at least extract the package name from the spec so we
+        # can look up the implementation of determine_spec_details
+        msg = f"Constructed spec for {spec.name} does not have a string representation"
+        llnl.util.tty.warn(msg)
         return False
 
     try:
@@ -106,7 +129,7 @@ def _spec_is_valid(spec):
     return True
 
 
-def path_to_dict(search_paths):
+def path_to_dict(search_paths: List[str]):
     """Return dictionary[fullpath]: basename from list of paths"""
     path_to_lib = {}
     # Reverse order of search directories so that a lib in the first
@@ -124,7 +147,7 @@ def path_to_dict(search_paths):
     return path_to_lib
 
 
-def is_executable(file_path):
+def is_executable(file_path: str) -> bool:
     """Return True if the path passed as argument is that of an executable"""
     return os.path.isfile(file_path) and os.access(file_path, os.X_OK)
 
@@ -146,7 +169,7 @@ def _convert_to_iterable(single_val_or_multiple):
         return [x]
 
 
-def executable_prefix(executable_dir):
+def executable_prefix(executable_dir: str) -> str:
     """Given a directory where an executable is found, guess the prefix
     (i.e. the "root" directory of that installation) and return it.
 
@@ -167,12 +190,12 @@ def executable_prefix(executable_dir):
     return os.sep.join(components[:idx])
 
 
-def library_prefix(library_dir):
-    """Given a directory where an library is found, guess the prefix
+def library_prefix(library_dir: str) -> str:
+    """Given a directory where a library is found, guess the prefix
     (i.e. the "root" directory of that installation) and return it.
 
     Args:
-        library_dir: directory where an library is found
+        library_dir: directory where a library is found
     """
     # Given a prefix where an library is found, assuming that prefix
     # contains /lib/ or /lib64/, strip off the 'lib' or 'lib64' directory
@@ -195,13 +218,17 @@ def library_prefix(library_dir):
         return library_dir
 
 
-def update_configuration(detected_packages, scope=None, buildable=True):
+def update_configuration(
+    detected_packages: Dict[str, List[DetectedPackage]],
+    scope: Optional[str] = None,
+    buildable: bool = True,
+) -> List[spack.spec.Spec]:
     """Add the packages passed as arguments to packages.yaml
 
     Args:
-        detected_packages (list): list of DetectedPackage objects to be added
-        scope (str): configuration scope where to add the detected packages
-        buildable (bool): whether the detected packages are buildable or not
+        detected_packages: list of DetectedPackage objects to be added
+        scope: configuration scope where to add the detected packages
+        buildable: whether the detected packages are buildable or not
     """
     predefined_external_specs = _externals_in_packages_yaml()
     pkg_to_cfg, all_new_specs = {}, []
@@ -209,7 +236,10 @@ def update_configuration(detected_packages, scope=None, buildable=True):
         new_entries = [e for e in entries if (e.spec not in predefined_external_specs)]
 
         pkg_config = _pkg_config_dict(new_entries)
-        all_new_specs.extend([spack.spec.Spec(x["spec"]) for x in pkg_config.get("externals", [])])
+        external_entries = pkg_config.get("externals", [])
+        assert not isinstance(external_entries, bool), "unexpected value for external entry"
+
+        all_new_specs.extend([spack.spec.Spec(x["spec"]) for x in external_entries])
         if buildable is False:
             pkg_config["buildable"] = False
         pkg_to_cfg[package_name] = pkg_config
@@ -222,16 +252,19 @@ def update_configuration(detected_packages, scope=None, buildable=True):
     return all_new_specs
 
 
-def _windows_drive():
-    """Return Windows drive string extracted from PROGRAMFILES
-    env var, which is garunteed to be defined for all logins"""
-    drive = re.match(r"([a-zA-Z]:)", os.environ["PROGRAMFILES"]).group(1)
-    return drive
+def _windows_drive() -> str:
+    """Return Windows drive string extracted from the PROGRAMFILES environment variable,
+    which is guaranteed to be defined for all logins.
+    """
+    match = re.match(r"([a-zA-Z]:)", os.environ["PROGRAMFILES"])
+    if match is None:
+        raise RuntimeError("cannot read the PROGRAMFILES environment variable")
+    return match.group(1)
 
 
 class WindowsCompilerExternalPaths:
     @staticmethod
-    def find_windows_compiler_root_paths():
+    def find_windows_compiler_root_paths() -> List[str]:
         """Helper for Windows compiler installation root discovery
 
         At the moment simply returns location of VS install paths from VSWhere
@@ -239,7 +272,7 @@ def find_windows_compiler_root_paths():
         return list(winOs.WindowsOs.vs_install_paths)
 
     @staticmethod
-    def find_windows_compiler_cmake_paths():
+    def find_windows_compiler_cmake_paths() -> List[str]:
         """Semi hard-coded search path for cmake bundled with MSVC"""
         return [
             os.path.join(
@@ -249,7 +282,7 @@ def find_windows_compiler_cmake_paths():
         ]
 
     @staticmethod
-    def find_windows_compiler_ninja_paths():
+    def find_windows_compiler_ninja_paths() -> List[str]:
         """Semi hard-coded search heuristic for locating ninja bundled with MSVC"""
         return [
             os.path.join(path, "Common7", "IDE", "CommonExtensions", "Microsoft", "CMake", "Ninja")
@@ -257,7 +290,7 @@ def find_windows_compiler_ninja_paths():
         ]
 
     @staticmethod
-    def find_windows_compiler_bundled_packages():
+    def find_windows_compiler_bundled_packages() -> List[str]:
         """Return all MSVC compiler bundled packages"""
         return (
             WindowsCompilerExternalPaths.find_windows_compiler_cmake_paths()
@@ -266,14 +299,15 @@ def find_windows_compiler_bundled_packages():
 
 
 class WindowsKitExternalPaths:
+    plat_major_ver = None
     if sys.platform == "win32":
         plat_major_ver = str(winOs.windows_version()[0])
 
     @staticmethod
-    def find_windows_kit_roots():
+    def find_windows_kit_roots() -> Optional[str]:
         """Return Windows kit root, typically %programfiles%\\Windows Kits\\10|11\\"""
         if sys.platform != "win32":
-            return []
+            return None
         program_files = os.environ["PROGRAMFILES(x86)"]
         kit_base = os.path.join(
             program_files, "Windows Kits", WindowsKitExternalPaths.plat_major_ver
@@ -281,21 +315,23 @@ def find_windows_kit_roots():
         return kit_base
 
     @staticmethod
-    def find_windows_kit_bin_paths(kit_base=None):
+    def find_windows_kit_bin_paths(kit_base: Optional[str] = None) -> List[str]:
         """Returns Windows kit bin directory per version"""
         kit_base = WindowsKitExternalPaths.find_windows_kit_roots() if not kit_base else kit_base
+        assert kit_base is not None, "unexpected value for kit_base"
         kit_bin = os.path.join(kit_base, "bin")
         return glob.glob(os.path.join(kit_bin, "[0-9]*", "*\\"))
 
     @staticmethod
-    def find_windows_kit_lib_paths(kit_base=None):
+    def find_windows_kit_lib_paths(kit_base: Optional[str] = None) -> List[str]:
         """Returns Windows kit lib directory per version"""
         kit_base = WindowsKitExternalPaths.find_windows_kit_roots() if not kit_base else kit_base
+        assert kit_base is not None, "unexpected value for kit_base"
         kit_lib = os.path.join(kit_base, "Lib")
         return glob.glob(os.path.join(kit_lib, "[0-9]*", "*", "*\\"))
 
     @staticmethod
-    def find_windows_driver_development_kit_paths():
+    def find_windows_driver_development_kit_paths() -> List[str]:
         """Provides a list of all installation paths
         for the WDK by version and architecture
         """
@@ -303,7 +339,7 @@ def find_windows_driver_development_kit_paths():
         return WindowsKitExternalPaths.find_windows_kit_lib_paths(wdk_content_root)
 
     @staticmethod
-    def find_windows_kit_reg_installed_roots_paths():
+    def find_windows_kit_reg_installed_roots_paths() -> List[str]:
         reg = spack.util.windows_registry.WindowsRegistryView(
             "SOFTWARE\\Microsoft\\Windows Kits\\Installed Roots",
             root_key=spack.util.windows_registry.HKEY.HKEY_LOCAL_MACHINE,
@@ -316,7 +352,7 @@ def find_windows_kit_reg_installed_roots_paths():
         )
 
     @staticmethod
-    def find_windows_kit_reg_sdk_paths():
+    def find_windows_kit_reg_sdk_paths() -> List[str]:
         reg = spack.util.windows_registry.WindowsRegistryView(
             "SOFTWARE\\WOW6432Node\\Microsoft\\Microsoft SDKs\\Windows\\v%s.0"
             % WindowsKitExternalPaths.plat_major_ver,
@@ -330,7 +366,7 @@ def find_windows_kit_reg_sdk_paths():
         )
 
 
-def find_win32_additional_install_paths():
+def find_win32_additional_install_paths() -> List[str]:
     """Not all programs on Windows live on the PATH
     Return a list of other potential install locations.
     """
@@ -357,13 +393,12 @@ def find_win32_additional_install_paths():
     return windows_search_ext
 
 
-def compute_windows_program_path_for_package(pkg):
-    """Given a package, attempt to compute its Windows
-    program files location, return list of best guesses
+def compute_windows_program_path_for_package(pkg: "spack.package_base.PackageBase") -> List[str]:
+    """Given a package, attempts to compute its Windows program files location,
+    and returns the list of best guesses.
 
     Args:
-        pkg (spack.package_base.PackageBase): package for which
-                           Program Files location is to be computed
+        pkg: package for which Program Files location is to be computed
     """
     if sys.platform != "win32":
         return []
@@ -378,7 +413,7 @@ def compute_windows_program_path_for_package(pkg):
     ]
 
 
-def compute_windows_user_path_for_package(pkg):
+def compute_windows_user_path_for_package(pkg: "spack.package_base.PackageBase") -> List[str]:
     """Given a package attempt to compute its user scoped
     install location, return list of potential locations based
     on common heuristics. For more info on Windows user specific

lib/spack/spack/detection/path.py

@@ -6,11 +6,13 @@
 and running executables.
 """
 import collections
+import concurrent.futures
 import os
 import os.path
 import re
 import sys
 import warnings
+from typing import Dict, List, Optional, Set, Tuple
 
 import llnl.util.filesystem
 import llnl.util.tty
@@ -18,7 +20,7 @@
 import spack.util.environment
 import spack.util.ld_so_conf
 
-from .common import (  # find_windows_compiler_bundled_packages,
+from .common import (
     DetectedPackage,
     WindowsCompilerExternalPaths,
     WindowsKitExternalPaths,
@@ -31,8 +33,13 @@
     path_to_dict,
 )
 
+#: Timeout used for package detection (seconds)
+DETECTION_TIMEOUT = 60
+if sys.platform == "win32":
+    DETECTION_TIMEOUT = 120
 
-def common_windows_package_paths():
+
+def common_windows_package_paths() -> List[str]:
     paths = WindowsCompilerExternalPaths.find_windows_compiler_bundled_packages()
     paths.extend(find_win32_additional_install_paths())
     paths.extend(WindowsKitExternalPaths.find_windows_kit_bin_paths())
@@ -41,7 +48,7 @@ def common_windows_package_paths():
     return paths
 
 
-def executables_in_path(path_hints):
+def executables_in_path(path_hints: List[str]) -> Dict[str, str]:
     """Get the paths of all executables available from the current PATH.
 
     For convenience, this is constructed as a dictionary where the keys are
@@ -52,7 +59,7 @@ def executables_in_path(path_hints):
     assumed there are two different instances of the executable.
 
     Args:
-        path_hints (list): list of paths to be searched. If None the list will be
+        path_hints: list of paths to be searched. If None the list will be
             constructed based on the PATH environment variable.
     """
     if sys.platform == "win32":
@@ -61,7 +68,9 @@ def executables_in_path(path_hints):
     return path_to_dict(search_paths)
 
 
-def libraries_in_ld_and_system_library_path(path_hints=None):
+def libraries_in_ld_and_system_library_path(
+    path_hints: Optional[List[str]] = None,
+) -> Dict[str, str]:
     """Get the paths of all libraries available from LD_LIBRARY_PATH,
     LIBRARY_PATH, DYLD_LIBRARY_PATH, DYLD_FALLBACK_LIBRARY_PATH, and
     standard system library paths.
@@ -74,7 +83,7 @@ def libraries_in_ld_and_system_library_path(path_hints=None):
     assumed there are two different instances of the library.
 
     Args:
-        path_hints (list): list of paths to be searched. If None the list will be
+        path_hints: list of paths to be searched. If None the list will be
             constructed based on the set of LD_LIBRARY_PATH, LIBRARY_PATH,
             DYLD_LIBRARY_PATH, and DYLD_FALLBACK_LIBRARY_PATH environment
             variables as well as the standard system library paths.
@@ -90,7 +99,7 @@ def libraries_in_ld_and_system_library_path(path_hints=None):
     return path_to_dict(search_paths)
 
 
-def libraries_in_windows_paths(path_hints):
+def libraries_in_windows_paths(path_hints: List[str]) -> Dict[str, str]:
     path_hints.extend(spack.util.environment.get_path("PATH"))
     search_paths = llnl.util.filesystem.search_paths_for_libraries(*path_hints)
     # on Windows, some libraries (.dlls) are found in the bin directory or sometimes
@@ -106,218 +115,250 @@ def libraries_in_windows_paths(path_hints):
     return path_to_dict(search_paths)
 
 
-def _group_by_prefix(paths):
+def _group_by_prefix(paths: Set[str]) -> Dict[str, Set[str]]:
     groups = collections.defaultdict(set)
     for p in paths:
         groups[os.path.dirname(p)].add(p)
-    return groups.items()
+    return groups
 
 
-# TODO consolidate this with by_executable
-# Packages should be able to define both .libraries and .executables in the future
-# determine_spec_details should get all relevant libraries and executables in one call
-def by_library(packages_to_check, path_hints=None):
-    # Techniques for finding libraries is determined on a per recipe basis in
-    # the determine_version class method. Some packages will extract the
-    # version number from a shared libraries filename.
-    # Other libraries could use the strings function to extract it as described
-    # in https://unix.stackexchange.com/questions/58846/viewing-linux-library-executable-version-info
-    """Return the list of packages that have been detected on the system,
-    searching by LD_LIBRARY_PATH, LIBRARY_PATH, DYLD_LIBRARY_PATH,
-    DYLD_FALLBACK_LIBRARY_PATH, and standard system library paths.
+class Finder:
+    """Inspects the file-system looking for packages. Guesses places where to look using PATH."""
 
-    Args:
-        packages_to_check (list): list of packages to be detected
-        path_hints (list): list of paths to be searched. If None the list will be
-            constructed based on the LD_LIBRARY_PATH, LIBRARY_PATH,
-            DYLD_LIBRARY_PATH, DYLD_FALLBACK_LIBRARY_PATH environment variables
-            and standard system library paths.
-    """
-    # If no path hints from command line, intialize to empty list so
-    # we can add default hints on a per package basis
-    path_hints = [] if path_hints is None else path_hints
+    def path_hints(
+        self, *, pkg: "spack.package_base.PackageBase", initial_guess: Optional[List[str]] = None
+    ) -> List[str]:
+        """Returns the list of paths to be searched.
 
-    lib_pattern_to_pkgs = collections.defaultdict(list)
-    for pkg in packages_to_check:
-        if hasattr(pkg, "libraries"):
-            for lib in pkg.libraries:
-                lib_pattern_to_pkgs[lib].append(pkg)
-        path_hints.extend(compute_windows_user_path_for_package(pkg))
-        path_hints.extend(compute_windows_program_path_for_package(pkg))
+        Args:
+            pkg: package being detected
+            initial_guess: initial list of paths from caller
+        """
+        result = initial_guess or []
+        result.extend(compute_windows_user_path_for_package(pkg))
+        result.extend(compute_windows_program_path_for_package(pkg))
+        return result
 
-    path_to_lib_name = (
-        libraries_in_ld_and_system_library_path(path_hints=path_hints)
-        if sys.platform != "win32"
-        else libraries_in_windows_paths(path_hints)
-    )
+    def search_patterns(self, *, pkg: "spack.package_base.PackageBase") -> List[str]:
+        """Returns the list of patterns used to match candidate files.
 
-    pkg_to_found_libs = collections.defaultdict(set)
-    for lib_pattern, pkgs in lib_pattern_to_pkgs.items():
-        compiled_re = re.compile(lib_pattern)
-        for path, lib in path_to_lib_name.items():
-            if compiled_re.search(lib):
-                for pkg in pkgs:
-                    pkg_to_found_libs[pkg].add(path)
+        Args:
+            pkg: package being detected
+        """
+        raise NotImplementedError("must be implemented by derived classes")
 
-    pkg_to_entries = collections.defaultdict(list)
-    resolved_specs = {}  # spec -> lib found for the spec
+    def candidate_files(self, *, patterns: List[str], paths: List[str]) -> List[str]:
+        """Returns a list of candidate files found on the system.
 
-    for pkg, libs in pkg_to_found_libs.items():
+        Args:
+            patterns: search patterns to be used for matching files
+            paths: paths where to search for files
+        """
+        raise NotImplementedError("must be implemented by derived classes")
+
+    def prefix_from_path(self, *, path: str) -> str:
+        """Given a path where a file was found, returns the corresponding prefix.
+
+        Args:
+            path: path of a detected file
+        """
+        raise NotImplementedError("must be implemented by derived classes")
+
+    def detect_specs(
+        self, *, pkg: "spack.package_base.PackageBase", paths: List[str]
+    ) -> List[DetectedPackage]:
+        """Given a list of files matching the search patterns, returns a list of detected specs.
+
+        Args:
+            pkg: package being detected
+            paths: files matching the package search patterns
+        """
         if not hasattr(pkg, "determine_spec_details"):
-            llnl.util.tty.warn(
-                "{0} must define 'determine_spec_details' in order"
-                " for Spack to detect externally-provided instances"
-                " of the package.".format(pkg.name)
+            warnings.warn(
+                f"{pkg.name} must define 'determine_spec_details' in order"
+                f" for Spack to detect externally-provided instances"
+                f" of the package."
             )
-            continue
+            return []
 
-        for prefix, libs_in_prefix in sorted(_group_by_prefix(libs)):
-            try:
-                specs = _convert_to_iterable(pkg.determine_spec_details(prefix, libs_in_prefix))
-            except Exception as e:
-                specs = []
-                msg = 'error detecting "{0}" from prefix {1} [{2}]'
-                warnings.warn(msg.format(pkg.name, prefix, str(e)))
-
-            if not specs:
-                llnl.util.tty.debug(
-                    "The following libraries in {0} were decidedly not "
-                    "part of the package {1}: {2}".format(
-                        prefix, pkg.name, ", ".join(_convert_to_iterable(libs_in_prefix))
-                    )
-                )
-
-            for spec in specs:
-                pkg_prefix = library_prefix(prefix)
-
-                if not pkg_prefix:
-                    msg = "no lib/ or lib64/ dir found in {0}. Cannot "
-                    "add it as a Spack package"
-                    llnl.util.tty.debug(msg.format(prefix))
-                    continue
-
-                if spec in resolved_specs:
-                    prior_prefix = ", ".join(_convert_to_iterable(resolved_specs[spec]))
-
-                    llnl.util.tty.debug(
-                        "Libraries in {0} and {1} are both associated"
-                        " with the same spec {2}".format(prefix, prior_prefix, str(spec))
-                    )
-                    continue
-                else:
-                    resolved_specs[spec] = prefix
-
-                try:
-                    spec.validate_detection()
-                except Exception as e:
-                    msg = (
-                        '"{0}" has been detected on the system but will '
-                        "not be added to packages.yaml [reason={1}]"
-                    )
-                    llnl.util.tty.warn(msg.format(spec, str(e)))
-                    continue
-
-                if spec.external_path:
-                    pkg_prefix = spec.external_path
-
-                pkg_to_entries[pkg.name].append(DetectedPackage(spec=spec, prefix=pkg_prefix))
-
-    return pkg_to_entries
-
-
-def by_executable(packages_to_check, path_hints=None):
-    """Return the list of packages that have been detected on the system,
-    searching by path.
-
-    Args:
-        packages_to_check (list): list of package classes to be detected
-        path_hints (list): list of paths to be searched. If None the list will be
-            constructed based on the PATH environment variable.
-    """
-    path_hints = spack.util.environment.get_path("PATH") if path_hints is None else path_hints
-    exe_pattern_to_pkgs = collections.defaultdict(list)
-    for pkg in packages_to_check:
-        if hasattr(pkg, "executables"):
-            for exe in pkg.platform_executables():
-                exe_pattern_to_pkgs[exe].append(pkg)
-        # Add Windows specific, package related paths to the search paths
-        path_hints.extend(compute_windows_user_path_for_package(pkg))
-        path_hints.extend(compute_windows_program_path_for_package(pkg))
-
-    path_to_exe_name = executables_in_path(path_hints=path_hints)
-    pkg_to_found_exes = collections.defaultdict(set)
-    for exe_pattern, pkgs in exe_pattern_to_pkgs.items():
-        compiled_re = re.compile(exe_pattern)
-        for path, exe in path_to_exe_name.items():
-            if compiled_re.search(exe):
-                for pkg in pkgs:
-                    pkg_to_found_exes[pkg].add(path)
-
-    pkg_to_entries = collections.defaultdict(list)
-    resolved_specs = {}  # spec -> exe found for the spec
-
-    for pkg, exes in pkg_to_found_exes.items():
-        if not hasattr(pkg, "determine_spec_details"):
-            llnl.util.tty.warn(
-                "{0} must define 'determine_spec_details' in order"
-                " for Spack to detect externally-provided instances"
-                " of the package.".format(pkg.name)
-            )
-            continue
-
-        for prefix, exes_in_prefix in sorted(_group_by_prefix(exes)):
+        result = []
+        for candidate_path, items_in_prefix in sorted(_group_by_prefix(set(paths)).items()):
             # TODO: multiple instances of a package can live in the same
             # prefix, and a package implementation can return multiple specs
             # for one prefix, but without additional details (e.g. about the
             # naming scheme which differentiates them), the spec won't be
             # usable.
             try:
-                specs = _convert_to_iterable(pkg.determine_spec_details(prefix, exes_in_prefix))
+                specs = _convert_to_iterable(
+                    pkg.determine_spec_details(candidate_path, items_in_prefix)
+                )
             except Exception as e:
                 specs = []
-                msg = 'error detecting "{0}" from prefix {1} [{2}]'
-                warnings.warn(msg.format(pkg.name, prefix, str(e)))
-
-            if not specs:
-                llnl.util.tty.debug(
-                    "The following executables in {0} were decidedly not "
-                    "part of the package {1}: {2}".format(
-                        prefix, pkg.name, ", ".join(_convert_to_iterable(exes_in_prefix))
-                    )
+                warnings.warn(
+                    f'error detecting "{pkg.name}" from prefix {candidate_path} [{str(e)}]'
                 )
 
-            for spec in specs:
-                pkg_prefix = executable_prefix(prefix)
+            if not specs:
+                files = ", ".join(_convert_to_iterable(items_in_prefix))
+                llnl.util.tty.debug(
+                    f"The following files in {candidate_path} were decidedly not "
+                    f"part of the package {pkg.name}: {files}"
+                )
 
-                if not pkg_prefix:
-                    msg = "no bin/ dir found in {0}. Cannot add it as a Spack package"
-                    llnl.util.tty.debug(msg.format(prefix))
+            resolved_specs: Dict[spack.spec.Spec, str] = {}  # spec -> exe found for the spec
+            for spec in specs:
+                prefix = self.prefix_from_path(path=candidate_path)
+                if not prefix:
                     continue
 
                 if spec in resolved_specs:
                     prior_prefix = ", ".join(_convert_to_iterable(resolved_specs[spec]))
-
                     llnl.util.tty.debug(
-                        "Executables in {0} and {1} are both associated"
-                        " with the same spec {2}".format(prefix, prior_prefix, str(spec))
+                        f"Files in {candidate_path} and {prior_prefix} are both associated"
+                        f" with the same spec {str(spec)}"
                     )
                     continue
-                else:
-                    resolved_specs[spec] = prefix
 
+                resolved_specs[spec] = candidate_path
                 try:
                     spec.validate_detection()
                 except Exception as e:
                     msg = (
-                        '"{0}" has been detected on the system but will '
-                        "not be added to packages.yaml [reason={1}]"
+                        f'"{spec}" has been detected on the system but will '
+                        f"not be added to packages.yaml [reason={str(e)}]"
                     )
-                    llnl.util.tty.warn(msg.format(spec, str(e)))
+                    warnings.warn(msg)
                     continue
 
                 if spec.external_path:
-                    pkg_prefix = spec.external_path
+                    prefix = spec.external_path
 
-                pkg_to_entries[pkg.name].append(DetectedPackage(spec=spec, prefix=pkg_prefix))
+                result.append(DetectedPackage(spec=spec, prefix=prefix))
 
-    return pkg_to_entries
+        return result
+
+    def find(
+        self, *, pkg_name: str, initial_guess: Optional[List[str]] = None
+    ) -> List[DetectedPackage]:
+        """For a given package, returns a list of detected specs.
+
+        Args:
+            pkg_name: package being detected
+            initial_guess: initial list of paths to search from the caller
+        """
+        import spack.repo
+
+        pkg_cls = spack.repo.PATH.get_pkg_class(pkg_name)
+        patterns = self.search_patterns(pkg=pkg_cls)
+        if not patterns:
+            return []
+        path_hints = self.path_hints(pkg=pkg_cls, initial_guess=initial_guess)
+        candidates = self.candidate_files(patterns=patterns, paths=path_hints)
+        result = self.detect_specs(pkg=pkg_cls, paths=candidates)
+        return result
+
+
+class ExecutablesFinder(Finder):
+    def search_patterns(self, *, pkg: "spack.package_base.PackageBase") -> List[str]:
+        result = []
+        if hasattr(pkg, "executables") and hasattr(pkg, "platform_executables"):
+            result = pkg.platform_executables()
+        return result
+
+    def candidate_files(self, *, patterns: List[str], paths: List[str]) -> List[str]:
+        executables_by_path = executables_in_path(path_hints=paths)
+        patterns = [re.compile(x) for x in patterns]
+        result = []
+        for compiled_re in patterns:
+            for path, exe in executables_by_path.items():
+                if compiled_re.search(exe):
+                    result.append(path)
+        return list(sorted(set(result)))
+
+    def prefix_from_path(self, *, path: str) -> str:
+        result = executable_prefix(path)
+        if not result:
+            msg = f"no bin/ dir found in {path}. Cannot add it as a Spack package"
+            llnl.util.tty.debug(msg)
+        return result
+
+
+class LibrariesFinder(Finder):
+    """Finds libraries on the system, searching by LD_LIBRARY_PATH, LIBRARY_PATH,
+    DYLD_LIBRARY_PATH, DYLD_FALLBACK_LIBRARY_PATH, and standard system library paths
+    """
+
+    def search_patterns(self, *, pkg: "spack.package_base.PackageBase") -> List[str]:
+        result = []
+        if hasattr(pkg, "libraries"):
+            result = pkg.libraries
+        return result
+
+    def candidate_files(self, *, patterns: List[str], paths: List[str]) -> List[str]:
+        libraries_by_path = (
+            libraries_in_ld_and_system_library_path(path_hints=paths)
+            if sys.platform != "win32"
+            else libraries_in_windows_paths(paths)
+        )
+        patterns = [re.compile(x) for x in patterns]
+        result = []
+        for compiled_re in patterns:
+            for path, exe in libraries_by_path.items():
+                if compiled_re.search(exe):
+                    result.append(path)
+        return result
+
+    def prefix_from_path(self, *, path: str) -> str:
+        result = library_prefix(path)
+        if not result:
+            msg = f"no lib/ or lib64/ dir found in {path}. Cannot add it as a Spack package"
+            llnl.util.tty.debug(msg)
+        return result
+
+
+def by_path(
+    packages_to_search: List[str],
+    *,
+    path_hints: Optional[List[str]] = None,
+    max_workers: Optional[int] = None,
+) -> Dict[str, List[DetectedPackage]]:
+    """Return the list of packages that have been detected on the system,
+    searching by path.
+
+    Args:
+        packages_to_search: list of package classes to be detected
+        path_hints: initial list of paths to be searched
+    """
+    # TODO: Packages should be able to define both .libraries and .executables in the future
+    # TODO: determine_spec_details should get all relevant libraries and executables in one call
+    executables_finder, libraries_finder = ExecutablesFinder(), LibrariesFinder()
+
+    executables_path_guess = (
+        spack.util.environment.get_path("PATH") if path_hints is None else path_hints
+    )
+    libraries_path_guess = [] if path_hints is None else path_hints
+    detected_specs_by_package: Dict[str, Tuple[concurrent.futures.Future, ...]] = {}
+
+    result = collections.defaultdict(list)
+    with concurrent.futures.ProcessPoolExecutor(max_workers=max_workers) as executor:
+        for pkg in packages_to_search:
+            executable_future = executor.submit(
+                executables_finder.find, pkg_name=pkg, initial_guess=executables_path_guess
+            )
+            library_future = executor.submit(
+                libraries_finder.find, pkg_name=pkg, initial_guess=libraries_path_guess
+            )
+            detected_specs_by_package[pkg] = executable_future, library_future
+
+        for pkg_name, futures in detected_specs_by_package.items():
+            for future in futures:
+                try:
+                    detected = future.result(timeout=DETECTION_TIMEOUT)
+                    if detected:
+                        result[pkg_name].extend(detected)
+                except Exception:
+                    llnl.util.tty.debug(
+                        f"[EXTERNAL DETECTION] Skipping {pkg_name}: timeout reached"
+                    )
+
+    return result

lib/spack/spack/directives.py

@@ -42,6 +42,7 @@ class OpenMpi(Package):
 import spack.patch
 import spack.spec
 import spack.url
+import spack.util.crypto
 import spack.variant
 from spack.dependency import Dependency, canonical_deptype, default_deptype
 from spack.fetch_strategy import from_kwargs
@@ -407,10 +408,7 @@ def version(
 
 def _execute_version(pkg, ver, **kwargs):
     if (
-        any(
-            s in kwargs
-            for s in ("sha256", "sha384", "sha512", "md5", "sha1", "sha224", "checksum")
-        )
+        (any(s in kwargs for s in spack.util.crypto.hashes) or "checksum" in kwargs)
         and hasattr(pkg, "has_code")
         and not pkg.has_code
     ):
@@ -760,7 +758,7 @@ def _execute_variant(pkg):
         when_spec = make_when_spec(when)
         when_specs = [when_spec]
 
-        if not re.match(spack.spec.identifier_re, name):
+        if not re.match(spack.spec.IDENTIFIER_RE, name):
             directive = "variant"
             msg = "Invalid variant name in {0}: '{1}'"
             raise DirectiveError(directive, msg.format(pkg.name, name))

lib/spack/spack/directory_layout.py

@@ -11,6 +11,7 @@
 import shutil
 import sys
 from contextlib import contextmanager
+from pathlib import Path
 
 import llnl.util.filesystem as fs
 import llnl.util.tty as tty
@@ -104,7 +105,7 @@ def relative_path_for_spec(self, spec):
 
         projection = spack.projections.get_projection(self.projections, spec)
         path = spec.format(projection)
-        return path
+        return str(Path(path))
 
     def write_spec(self, spec, path):
         """Write a spec out to a file."""

lib/spack/spack/environment/environment.py

@@ -1504,7 +1504,7 @@ def _concretize_separately(self, tests=False):
         start = time.time()
         max_processes = min(
             len(arguments),  # Number of specs
-            spack.config.get("config:build_jobs"),  # Cap on build jobs
+            spack.util.cpus.determine_number_of_jobs(parallel=True),
         )
 
         # TODO: revisit this print as soon as darwin is parallel too
@@ -1994,14 +1994,10 @@ def get_one_by_hash(self, dag_hash):
 
     def all_matching_specs(self, *specs: spack.spec.Spec) -> List[Spec]:
         """Returns all concretized specs in the environment satisfying any of the input specs"""
-        # Look up abstract hashes ahead of time, to avoid O(n^2) traversal.
-        specs = [s.lookup_hash() for s in specs]
-
-        # Avoid double lookup by directly calling _satisfies.
         return [
             s
             for s in traverse.traverse_nodes(self.concrete_roots(), key=traverse.by_dag_hash)
-            if any(s._satisfies(t) for t in specs)
+            if any(s.satisfies(t) for t in specs)
         ]
 
     @spack.repo.autospec
@@ -2062,7 +2058,7 @@ def matching_spec(self, spec):
         # If multiple root specs match, it is assumed that the abstract
         # spec will most-succinctly summarize the difference between them
         # (and the user can enter one of these to disambiguate)
-        fmt_str = "{hash:7}  " + spack.spec.default_format
+        fmt_str = "{hash:7}  " + spack.spec.DEFAULT_FORMAT
         color = clr.get_color_when()
         match_strings = [
             f"Root spec {abstract.format(color=color)}\n  {concrete.format(fmt_str, color=color)}"
@@ -2370,7 +2366,7 @@ def display_specs(concretized_specs):
     def _tree_to_display(spec):
         return spec.tree(
             recurse_dependencies=True,
-            format=spack.spec.display_format,
+            format=spack.spec.DISPLAY_FORMAT,
             status_fn=spack.spec.Spec.install_status,
             hashlen=7,
             hashes=True,
@@ -2448,13 +2444,13 @@ def make_repo_path(root):
 def prepare_config_scope(env):
     """Add env's scope to the global configuration search path."""
     for scope in env.config_scopes():
-        spack.config.config.push_scope(scope)
+        spack.config.CONFIG.push_scope(scope)
 
 
 def deactivate_config_scope(env):
     """Remove any scopes from env from the global config path."""
     for scope in env.config_scopes():
-        spack.config.config.remove_scope(scope.name)
+        spack.config.CONFIG.remove_scope(scope.name)
 
 
 def manifest_file(env_name_or_dir):
@@ -2668,6 +2664,26 @@ def __init__(self, manifest_dir: Union[pathlib.Path, str]) -> None:
         self.yaml_content = with_defaults_added
         self.changed = False
 
+    def _all_matches(self, user_spec: str) -> List[str]:
+        """Maps the input string to the first equivalent user spec in the manifest,
+        and returns it.
+
+        Args:
+            user_spec: user spec to be found
+
+        Raises:
+            ValueError: if no equivalent match is found
+        """
+        result = []
+        for yaml_spec_str in self.pristine_configuration["specs"]:
+            if Spec(yaml_spec_str) == Spec(user_spec):
+                result.append(yaml_spec_str)
+
+        if not result:
+            raise ValueError(f"cannot find a spec equivalent to {user_spec}")
+
+        return result
+
     def add_user_spec(self, user_spec: str) -> None:
         """Appends the user spec passed as input to the list of root specs.
 
@@ -2688,8 +2704,9 @@ def remove_user_spec(self, user_spec: str) -> None:
             SpackEnvironmentError: when the user spec is not in the list
         """
         try:
-            self.pristine_configuration["specs"].remove(user_spec)
-            self.configuration["specs"].remove(user_spec)
+            for key in self._all_matches(user_spec):
+                self.pristine_configuration["specs"].remove(key)
+                self.configuration["specs"].remove(key)
         except ValueError as e:
             msg = f"cannot remove {user_spec} from {self}, no such spec exists"
             raise SpackEnvironmentError(msg) from e

lib/spack/spack/environment/shell.py

@@ -43,7 +43,7 @@ def activate_header(env, shell, prompt=None):
         # TODO: despacktivate
         # TODO: prompt
     elif shell == "pwsh":
-        cmds += "$Env:SPACK_ENV=%s\n" % env.path
+        cmds += "$Env:SPACK_ENV='%s'\n" % env.path
     else:
         if "color" in os.getenv("TERM", "") and prompt:
             prompt = colorize("@G{%s}" % prompt, color=True, enclose=True)
@@ -82,7 +82,7 @@ def deactivate_header(shell):
         # TODO: despacktivate
         # TODO: prompt
     elif shell == "pwsh":
-        cmds += "Remove-Item Env:SPACK_ENV"
+        cmds += "Set-Item -Path Env:SPACK_ENV\n"
     else:
         cmds += "if [ ! -z ${SPACK_ENV+x} ]; then\n"
         cmds += "unset SPACK_ENV; export SPACK_ENV;\n"

lib/spack/spack/filesystem_view.py

@@ -590,9 +590,9 @@ def print_status(self, *specs, **kwargs):
                     print()
 
                 header = "%s{%s} / %s{%s}" % (
-                    spack.spec.architecture_color,
+                    spack.spec.ARCHITECTURE_COLOR,
                     architecture,
-                    spack.spec.compiler_color,
+                    spack.spec.COMPILER_COLOR,
                     compiler,
                 )
                 tty.hline(colorize(header), char="-")

lib/spack/spack/installer.py

@@ -90,6 +90,16 @@
 STATUS_REMOVED = "removed"
 
 
+def _write_timer_json(pkg, timer, cache):
+    extra_attributes = {"name": pkg.name, "cache": cache, "hash": pkg.spec.dag_hash()}
+    try:
+        with open(pkg.times_log_path, "w") as timelog:
+            timer.write_json(timelog, extra_attributes=extra_attributes)
+    except Exception as e:
+        tty.debug(str(e))
+        return
+
+
 class InstallAction:
     #: Don't perform an install
     NONE = 0
@@ -399,6 +409,8 @@ def _install_from_cache(
         return False
     t.stop()
     tty.debug("Successfully extracted {0} from binary cache".format(pkg_id))
+
+    _write_timer_json(pkg, t, True)
     _print_timer(pre=_log_prefix(pkg.name), pkg_id=pkg_id, timer=t)
     _print_installed_pkg(pkg.spec.prefix)
     spack.hooks.post_install(pkg.spec, explicit)
@@ -481,7 +493,7 @@ def _process_binary_cache_tarball(
 
     with timer.measure("install"), spack.util.path.filter_padding():
         binary_distribution.extract_tarball(
-            pkg.spec, download_result, unsigned=unsigned, force=False
+            pkg.spec, download_result, unsigned=unsigned, force=False, timer=timer
         )
 
         pkg.installed_from_binary_cache = True
@@ -592,7 +604,9 @@ def dump_packages(spec: "spack.spec.Spec", path: str) -> None:
         if node is spec:
             spack.repo.PATH.dump_provenance(node, dest_pkg_dir)
         elif source_pkg_dir:
-            fs.install_tree(source_pkg_dir, dest_pkg_dir)
+            fs.install_tree(
+                source_pkg_dir, dest_pkg_dir, allow_broken_symlinks=(sys.platform != "win32")
+            )
 
 
 def get_dependent_ids(spec: "spack.spec.Spec") -> List[str]:
@@ -1316,7 +1330,6 @@ def _prepare_for_install(self, task: BuildTask) -> None:
         """
         Check the database and leftover installation directories/files and
         prepare for a new install attempt for an uninstalled package.
-
         Preparation includes cleaning up installation and stage directories
         and ensuring the database is up-to-date.
 
@@ -2092,7 +2105,6 @@ def install(self) -> None:
                 # another process has a write lock so must be (un)installing
                 # the spec (or that process is hung).
                 ltype, lock = self._ensure_locked("read", pkg)
-
             # Requeue the spec if we cannot get at least a read lock so we
             # can check the status presumably established by another process
             # -- failed, installed, or uninstalled -- on the next pass.
@@ -2372,8 +2384,7 @@ def run(self) -> bool:
 
             # Stop the timer and save results
             self.timer.stop()
-            with open(self.pkg.times_log_path, "w") as timelog:
-                self.timer.write_json(timelog)
+            _write_timer_json(self.pkg, self.timer, False)
 
         print_install_test_log(self.pkg)
         _print_timer(pre=self.pre, pkg_id=self.pkg_id, timer=self.timer)
@@ -2394,7 +2405,9 @@ def _install_source(self) -> None:
         src_target = os.path.join(pkg.spec.prefix, "share", pkg.name, "src")
         tty.debug("{0} Copying source to {1}".format(self.pre, src_target))
 
-        fs.install_tree(pkg.stage.source_path, src_target)
+        fs.install_tree(
+            pkg.stage.source_path, src_target, allow_broken_symlinks=(sys.platform != "win32")
+        )
 
     def _real_install(self) -> None:
         import spack.builder

lib/spack/spack/main.py

@@ -51,7 +51,7 @@
 stat_names = pstats.Stats.sort_arg_dict_default
 
 #: top-level aliases for Spack commands
-aliases = {"rm": "remove"}
+aliases = {"concretise": "concretize", "containerise": "containerize", "rm": "remove"}
 
 #: help levels in order of detail (i.e., number of commands shown)
 levels = ["short", "long"]
@@ -602,10 +602,10 @@ def setup_main_options(args):
 
         key = syaml.syaml_str("repos")
         key.override = True
-        spack.config.config.scopes["command_line"].sections["repos"] = syaml.syaml_dict(
+        spack.config.CONFIG.scopes["command_line"].sections["repos"] = syaml.syaml_dict(
             [(key, [spack.paths.mock_packages_path])]
         )
-        spack.repo.PATH = spack.repo.create(spack.config.config)
+        spack.repo.PATH = spack.repo.create(spack.config.CONFIG)
 
     # If the user asked for it, don't check ssl certs.
     if args.insecure:
@@ -930,7 +930,7 @@ def _main(argv=None):
 
     # make spack.config aware of any command line configuration scopes
     if args.config_scopes:
-        spack.config.command_line_scopes = args.config_scopes
+        spack.config.COMMAND_LINE_SCOPES = args.config_scopes
 
     # ensure options on spack command come before everything
     setup_main_options(args)

lib/spack/spack/modules/common.py

@@ -178,7 +178,7 @@ def merge_config_rules(configuration, spec):
         if spec.satisfies(constraint):
             if hasattr(constraint, "override") and constraint.override:
                 spec_configuration = {}
-            update_dictionary_extending_lists(spec_configuration, action)
+            update_dictionary_extending_lists(spec_configuration, copy.deepcopy(action))
 
     # Transform keywords for dependencies or prerequisites into a list of spec
 
@@ -833,7 +833,7 @@ def ensure_modules_are_enabled_or_warn():
         return
 
     # Check if we have custom TCL module sections
-    for scope in spack.config.config.file_scopes:
+    for scope in spack.config.CONFIG.file_scopes:
         # Skip default configuration
         if scope.name.startswith("default"):
             continue

lib/spack/spack/multimethod.py

@@ -236,7 +236,7 @@ def install(self, prefix):
 
         # Create a multimethod with this name if there is not one already
         original_method = MultiMethodMeta._locals.get(method.__name__)
-        if not type(original_method) == SpecMultiMethod:
+        if not isinstance(original_method, SpecMultiMethod):
             original_method = SpecMultiMethod(original_method)
 
         if self.spec is not None:

lib/spack/spack/package.py

@@ -96,6 +96,7 @@
     on_package_attributes,
 )
 from spack.spec import InvalidSpecDetected, Spec
+from spack.util.cpus import determine_number_of_jobs
 from spack.util.executable import *
 from spack.variant import (
     any_combination_of,

lib/spack/spack/package_base.py

@@ -180,6 +180,8 @@ class DetectablePackageMeta:
     for the detection function.
     """
 
+    TAG = "detectable"
+
     def __init__(cls, name, bases, attr_dict):
         if hasattr(cls, "executables") and hasattr(cls, "libraries"):
             msg = "a package can have either an 'executables' or 'libraries' attribute"
@@ -195,6 +197,11 @@ def __init__(cls, name, bases, attr_dict):
         # If a package has the executables or libraries  attribute then it's
         # assumed to be detectable
         if hasattr(cls, "executables") or hasattr(cls, "libraries"):
+            # Append a tag to each detectable package, so that finding them is faster
+            if hasattr(cls, "tags"):
+                getattr(cls, "tags").append(DetectablePackageMeta.TAG)
+            else:
+                setattr(cls, "tags", [DetectablePackageMeta.TAG])
 
             @classmethod
             def platform_executables(cls):

lib/spack/spack/parser.py

@@ -288,9 +288,6 @@ def next_spec(
                     )
                     raise SpecParsingError(msg, self.ctx.current_token, self.literal_str)
 
-                if root_spec.concrete:
-                    raise spack.spec.RedundantSpecError(root_spec, "^" + str(dependency))
-
                 root_spec._add_dependency(dependency, deptypes=(), virtuals=())
 
             else:
@@ -306,13 +303,12 @@ def all_specs(self) -> List[spack.spec.Spec]:
 class SpecNodeParser:
     """Parse a single spec node from a stream of tokens"""
 
-    __slots__ = "ctx", "has_compiler", "has_version", "has_hash"
+    __slots__ = "ctx", "has_compiler", "has_version"
 
     def __init__(self, ctx):
         self.ctx = ctx
         self.has_compiler = False
         self.has_version = False
-        self.has_hash = False
 
     def parse(self, initial_spec: Optional[spack.spec.Spec] = None) -> Optional[spack.spec.Spec]:
         """Parse a single spec node from a stream of tokens
@@ -343,7 +339,6 @@ def parse(self, initial_spec: Optional[spack.spec.Spec] = None) -> Optional[spac
 
         while True:
             if self.ctx.accept(TokenType.COMPILER):
-                self.hash_not_parsed_or_raise(initial_spec, self.ctx.current_token.value)
                 if self.has_compiler:
                     raise spack.spec.DuplicateCompilerSpecError(
                         f"{initial_spec} cannot have multiple compilers"
@@ -353,7 +348,6 @@ def parse(self, initial_spec: Optional[spack.spec.Spec] = None) -> Optional[spac
                 initial_spec.compiler = spack.spec.CompilerSpec(compiler_name.strip(), ":")
                 self.has_compiler = True
             elif self.ctx.accept(TokenType.COMPILER_AND_VERSION):
-                self.hash_not_parsed_or_raise(initial_spec, self.ctx.current_token.value)
                 if self.has_compiler:
                     raise spack.spec.DuplicateCompilerSpecError(
                         f"{initial_spec} cannot have multiple compilers"
@@ -367,7 +361,6 @@ def parse(self, initial_spec: Optional[spack.spec.Spec] = None) -> Optional[spac
             elif self.ctx.accept(TokenType.VERSION) or self.ctx.accept(
                 TokenType.VERSION_HASH_PAIR
             ):
-                self.hash_not_parsed_or_raise(initial_spec, self.ctx.current_token.value)
                 if self.has_version:
                     raise spack.spec.MultipleVersionError(
                         f"{initial_spec} cannot have multiple versions"
@@ -378,25 +371,21 @@ def parse(self, initial_spec: Optional[spack.spec.Spec] = None) -> Optional[spac
                 initial_spec.attach_git_version_lookup()
                 self.has_version = True
             elif self.ctx.accept(TokenType.BOOL_VARIANT):
-                self.hash_not_parsed_or_raise(initial_spec, self.ctx.current_token.value)
                 variant_value = self.ctx.current_token.value[0] == "+"
                 initial_spec._add_flag(
                     self.ctx.current_token.value[1:].strip(), variant_value, propagate=False
                 )
             elif self.ctx.accept(TokenType.PROPAGATED_BOOL_VARIANT):
-                self.hash_not_parsed_or_raise(initial_spec, self.ctx.current_token.value)
                 variant_value = self.ctx.current_token.value[0:2] == "++"
                 initial_spec._add_flag(
                     self.ctx.current_token.value[2:].strip(), variant_value, propagate=True
                 )
             elif self.ctx.accept(TokenType.KEY_VALUE_PAIR):
-                self.hash_not_parsed_or_raise(initial_spec, self.ctx.current_token.value)
                 name, value = self.ctx.current_token.value.split("=", maxsplit=1)
                 name = name.strip("'\" ")
                 value = value.strip("'\" ")
                 initial_spec._add_flag(name, value, propagate=False)
             elif self.ctx.accept(TokenType.PROPAGATED_KEY_VALUE_PAIR):
-                self.hash_not_parsed_or_raise(initial_spec, self.ctx.current_token.value)
                 name, value = self.ctx.current_token.value.split("==", maxsplit=1)
                 name = name.strip("'\" ")
                 value = value.strip("'\" ")
@@ -411,12 +400,6 @@ def parse(self, initial_spec: Optional[spack.spec.Spec] = None) -> Optional[spac
 
         return initial_spec
 
-    def hash_not_parsed_or_raise(self, spec, addition):
-        if not self.has_hash:
-            return
-
-        raise spack.spec.RedundantSpecError(spec, addition)
-
 
 class FileParser:
     """Parse a single spec from a JSON or YAML file"""

lib/spack/spack/paths.py

@@ -10,11 +10,12 @@
 dependencies.
 """
 import os
+from pathlib import PurePath
 
 import llnl.util.filesystem
 
 #: This file lives in $prefix/lib/spack/spack/__file__
-prefix = llnl.util.filesystem.ancestor(__file__, 4)
+prefix = str(PurePath(llnl.util.filesystem.ancestor(__file__, 4)))
 
 #: synonym for prefix
 spack_root = prefix
@@ -88,7 +89,7 @@ def _get_user_cache_path():
     return os.path.expanduser(os.getenv("SPACK_USER_CACHE_PATH") or "~%s.spack" % os.sep)
 
 
-user_cache_path = _get_user_cache_path()
+user_cache_path = str(PurePath(_get_user_cache_path()))
 
 #: junit, cdash, etc. reports about builds
 reports_path = os.path.join(user_cache_path, "reports")

lib/spack/spack/platforms/__init__.py

@@ -64,7 +64,7 @@ def use_platform(new_platform):
         host = _PickleableCallable(new_platform)
 
         # Clear configuration and compiler caches
-        spack.config.config.clear_caches()
+        spack.config.CONFIG.clear_caches()
         spack.compilers._cache_config_files = []
 
         yield new_platform
@@ -73,5 +73,5 @@ def use_platform(new_platform):
         host = original_host_fn
 
         # Clear configuration and compiler caches
-        spack.config.config.clear_caches()
+        spack.config.CONFIG.clear_caches()
         spack.compilers._cache_config_files = []

lib/spack/spack/platforms/cray.py

@@ -139,6 +139,8 @@ def craype_type_and_version(cls):
         # If no default version, sort available versions and return latest
         versions_available = [spack.version.Version(v) for v in os.listdir(craype_dir)]
         versions_available.sort(reverse=True)
+        if not versions_available:
+            return (craype_type, None)
         return (craype_type, versions_available[0])
 
     @classmethod

lib/spack/spack/repo.py

@@ -387,7 +387,7 @@ def _create_new_cache(self) -> Dict[str, os.stat_result]:
 
             # Warn about invalid names that look like packages.
             if not nm.valid_module_name(pkg_name):
-                if not pkg_name.startswith("."):
+                if not pkg_name.startswith(".") and pkg_name != "repo.yaml":
                     tty.warn(
                         'Skipping package at {0}. "{1}" is not '
                         "a valid Spack module name.".format(pkg_dir, pkg_name)
@@ -647,7 +647,7 @@ class RepoPath:
     """
 
     def __init__(self, *repos, **kwargs):
-        cache = kwargs.get("cache", spack.caches.misc_cache)
+        cache = kwargs.get("cache", spack.caches.MISC_CACHE)
         self.repos = []
         self.by_namespace = nm.NamespaceTrie()
 
@@ -966,7 +966,7 @@ def check(condition, msg):
 
         # Indexes for this repository, computed lazily
         self._repo_index = None
-        self._cache = cache or spack.caches.misc_cache
+        self._cache = cache or spack.caches.MISC_CACHE
 
     def real_name(self, import_name):
         """Allow users to import Spack packages using Python identifiers.
@@ -1357,7 +1357,7 @@ def create_or_construct(path, namespace=None):
 
 def _path(configuration=None):
     """Get the singleton RepoPath instance for Spack."""
-    configuration = configuration or spack.config.config
+    configuration = configuration or spack.config.CONFIG
     return create(configuration=configuration)
 
 
@@ -1404,14 +1404,14 @@ def use_repositories(*paths_and_repos, **kwargs):
     paths = [getattr(x, "root", x) for x in paths_and_repos]
     scope_name = "use-repo-{}".format(uuid.uuid4())
     repos_key = "repos:" if override else "repos"
-    spack.config.config.push_scope(
+    spack.config.CONFIG.push_scope(
         spack.config.InternalConfigScope(name=scope_name, data={repos_key: paths})
     )
-    PATH, saved = create(configuration=spack.config.config), PATH
+    PATH, saved = create(configuration=spack.config.CONFIG), PATH
     try:
         yield PATH
     finally:
-        spack.config.config.remove_scope(scope_name=scope_name)
+        spack.config.CONFIG.remove_scope(scope_name=scope_name)
         PATH = saved
 
 

lib/spack/spack/schema/concretizer.py

@@ -28,6 +28,12 @@
             "unify": {
                 "oneOf": [{"type": "boolean"}, {"type": "string", "enum": ["when_possible"]}]
             },
+            "duplicates": {
+                "type": "object",
+                "properties": {
+                    "strategy": {"type": "string", "enum": ["none", "minimal", "full"]}
+                },
+            },
         },
     }
 }

lib/spack/spack/solver/counter.py

@@ -0,0 +1,159 @@
+# Copyright 2013-2023 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+import collections
+from typing import List, Set, Tuple
+
+import spack.dependency
+import spack.package_base
+
+PossibleDependencies = Set[str]
+
+
+class Counter:
+    """Computes the possible packages and the maximum number of duplicates
+    allowed for each of them.
+
+    Args:
+        specs: abstract specs to concretize
+        tests: if True, add test dependencies to the list of possible packages
+    """
+
+    def __init__(self, specs: List["spack.spec.Spec"], tests: bool) -> None:
+        self.specs = specs
+
+        self.link_run_types: Tuple[str, ...] = ("link", "run", "test")
+        self.all_types: Tuple[str, ...] = spack.dependency.all_deptypes
+        if not tests:
+            self.link_run_types = ("link", "run")
+            self.all_types = ("link", "run", "build")
+
+        self._possible_dependencies: PossibleDependencies = set()
+        self._possible_virtuals: Set[str] = set(x.name for x in specs if x.virtual)
+
+    def possible_dependencies(self) -> PossibleDependencies:
+        """Returns the list of possible dependencies"""
+        self.ensure_cache_values()
+        return self._possible_dependencies
+
+    def possible_virtuals(self) -> Set[str]:
+        """Returns the list of possible virtuals"""
+        self.ensure_cache_values()
+        return self._possible_virtuals
+
+    def ensure_cache_values(self) -> None:
+        """Ensure the cache values have been computed"""
+        if self._possible_dependencies:
+            return
+        self._compute_cache_values()
+
+    def possible_packages_facts(self, gen: "spack.solver.asp.PyclingoDriver", fn) -> None:
+        """Emit facts associated with the possible packages"""
+        raise NotImplementedError("must be implemented by derived classes")
+
+    def _compute_cache_values(self):
+        raise NotImplementedError("must be implemented by derived classes")
+
+
+class NoDuplicatesCounter(Counter):
+    def _compute_cache_values(self):
+        result = spack.package_base.possible_dependencies(
+            *self.specs, virtuals=self._possible_virtuals, deptype=self.all_types
+        )
+        self._possible_dependencies = set(result)
+
+    def possible_packages_facts(self, gen, fn):
+        gen.h2("Maximum number of nodes (packages)")
+        for package_name in sorted(self.possible_dependencies()):
+            gen.fact(fn.max_dupes(package_name, 1))
+        gen.newline()
+        gen.h2("Maximum number of nodes (virtual packages)")
+        for package_name in sorted(self.possible_virtuals()):
+            gen.fact(fn.max_dupes(package_name, 1))
+        gen.newline()
+        gen.h2("Possible package in link-run subDAG")
+        for name in sorted(self.possible_dependencies()):
+            gen.fact(fn.possible_in_link_run(name))
+        gen.newline()
+
+
+class MinimalDuplicatesCounter(NoDuplicatesCounter):
+    def __init__(self, specs, tests):
+        super().__init__(specs, tests)
+        self._link_run: PossibleDependencies = set()
+        self._direct_build: PossibleDependencies = set()
+        self._total_build: PossibleDependencies = set()
+        self._link_run_virtuals: Set[str] = set()
+
+    def _compute_cache_values(self):
+        self._link_run = set(
+            spack.package_base.possible_dependencies(
+                *self.specs, virtuals=self._possible_virtuals, deptype=self.link_run_types
+            )
+        )
+        self._link_run_virtuals.update(self._possible_virtuals)
+        for x in self._link_run:
+            current = spack.repo.PATH.get_pkg_class(x).dependencies_of_type("build")
+            self._direct_build.update(current)
+
+        self._total_build = set(
+            spack.package_base.possible_dependencies(
+                *self._direct_build, virtuals=self._possible_virtuals, deptype=self.all_types
+            )
+        )
+        self._possible_dependencies = set(self._link_run) | set(self._total_build)
+
+    def possible_packages_facts(self, gen, fn):
+        build_tools = set(spack.repo.PATH.packages_with_tags("build-tools"))
+        gen.h2("Packages with at most a single node")
+        for package_name in sorted(self.possible_dependencies() - build_tools):
+            gen.fact(fn.max_dupes(package_name, 1))
+        gen.newline()
+
+        gen.h2("Packages with at multiple possible nodes (build-tools)")
+        for package_name in sorted(self.possible_dependencies() & build_tools):
+            gen.fact(fn.max_dupes(package_name, 2))
+            gen.fact(fn.multiple_unification_sets(package_name))
+        gen.newline()
+
+        gen.h2("Maximum number of nodes (virtual packages)")
+        for package_name in sorted(self.possible_virtuals()):
+            gen.fact(fn.max_dupes(package_name, 1))
+        gen.newline()
+
+        gen.h2("Possible package in link-run subDAG")
+        for name in sorted(self._link_run):
+            gen.fact(fn.possible_in_link_run(name))
+        gen.newline()
+
+
+class FullDuplicatesCounter(MinimalDuplicatesCounter):
+    def possible_packages_facts(self, gen, fn):
+        build_tools = set(spack.repo.PATH.packages_with_tags("build-tools"))
+        counter = collections.Counter(
+            list(self._link_run) + list(self._total_build) + list(self._direct_build)
+        )
+        gen.h2("Maximum number of nodes")
+        for pkg, count in sorted(counter.items(), key=lambda x: (x[1], x[0])):
+            count = min(count, 2)
+            gen.fact(fn.max_dupes(pkg, count))
+        gen.newline()
+
+        gen.h2("Build unification sets ")
+        for name in sorted(self.possible_dependencies() & build_tools):
+            gen.fact(fn.multiple_unification_sets(name))
+        gen.newline()
+
+        gen.h2("Possible package in link-run subDAG")
+        for name in sorted(self._link_run):
+            gen.fact(fn.possible_in_link_run(name))
+        gen.newline()
+
+        counter = collections.Counter(
+            list(self._link_run_virtuals) + list(self._possible_virtuals)
+        )
+        gen.h2("Maximum number of virtual nodes")
+        for pkg, count in sorted(counter.items(), key=lambda x: (x[1], x[0])):
+            gen.fact(fn.max_dupes(pkg, count))
+        gen.newline()

lib/spack/spack/solver/cycle_detection.lp

@@ -0,0 +1,21 @@
+% Copyright 2013-2023 Lawrence Livermore National Security, LLC and other
+% Spack Project Developers. See the top-level COPYRIGHT file for details.
+%
+% SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+%=============================================================================
+% Avoid cycles in the DAG
+%
+% Some combinations of conditional dependencies can result in cycles;
+% this ensures that we solve around them. Note that these rules are quite
+% demanding on both grounding and solving, since they need to compute and
+% consider all possible paths between pair of nodes.
+%=============================================================================
+
+
+#program no_cycle.
+path(Parent, Child) :- depends_on(Parent, Child).
+path(Parent, Descendant) :- path(Parent, A), depends_on(A, Descendant).
+:- path(A, A).
+
+#defined depends_on/2.

lib/spack/spack/solver/heuristic.lp

@@ -0,0 +1,29 @@
+% Copyright 2013-2023 Lawrence Livermore National Security, LLC and other
+% Spack Project Developers. See the top-level COPYRIGHT file for details.
+%
+% SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+%=============================================================================
+% Heuristic to speed-up solves (node with ID 0)
+%=============================================================================
+
+
+%-----------------
+% Domain heuristic
+%-----------------
+#heuristic attr("hash", node(0, Package), Hash) : literal(_, "root", Package). [45, init]
+#heuristic attr("root", node(0, Package)) : literal(_, "root", Package). [45, true]
+#heuristic attr("node", node(0, Package)) : literal(_, "root", Package). [45, true]
+#heuristic attr("node", node(0, Package)) : literal(_, "node", Package). [45, true]
+
+% Root node
+#heuristic attr("version", node(0, Package), Version) : pkg_fact(Package, version_declared(Version, 0)), attr("root", node(0, Package)). [35, true]
+#heuristic version_weight(node(0, Package), 0) : pkg_fact(Package, version_declared(Version, 0)), attr("root", node(0, Package)). [35, true]
+#heuristic attr("variant_value", node(0, Package), Variant, Value) : variant_default_value(Package, Variant, Value), attr("root", node(0, Package)). [35, true]
+#heuristic attr("node_target", node(0, Package), Target) : pkg_fact(Package, target_weight(Target, 0)), attr("root", node(0, Package)). [35, true]
+#heuristic node_target_weight(node(0, Package), 0) : attr("root", node(0, Package)). [35, true]
+#heuristic node_compiler(node(0, Package), CompilerID) : default_compiler_preference(ID, 0), compiler_id(ID), attr("root", node(0, Package)). [35, true]
+
+% Providers
+#heuristic attr("node", node(0, Package)) : default_provider_preference(Virtual, Package, 0), possible_in_link_run(Package). [30, true]
+

lib/spack/spack/solver/heuristic_separate.lp

@@ -0,0 +1,24 @@
+% Copyright 2013-2023 Lawrence Livermore National Security, LLC and other
+% Spack Project Developers. See the top-level COPYRIGHT file for details.
+%
+% SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+%=============================================================================
+% Heuristic to speed-up solves (node with ID > 0)
+%=============================================================================
+
+% node(ID, _)
+#heuristic attr("version", node(ID, Package), Version) : pkg_fact(Package, version_declared(Version, 0)), attr("node", node(ID, Package)), ID > 0. [25-5*ID, true]
+#heuristic version_weight(node(ID, Package), 0) : pkg_fact(Package, version_declared(Version, 0)), attr("node", node(ID, Package)), ID > 0. [25-5*ID, true]
+#heuristic attr("variant_value", node(ID, Package), Variant, Value) : variant_default_value(Package, Variant, Value), attr("node", node(ID, Package)), ID > 0. [25-5*ID, true]
+#heuristic attr("node_target", node(ID, Package), Target) : pkg_fact(Package, target_weight(Target, 0)), attr("node", node(ID, Package)), ID > 0. [25-5*ID, true]
+#heuristic node_target_weight(node(ID, Package), 0) : attr("node", node(ID, Package)), ID > 0. [25-5*ID, true]
+#heuristic node_compiler(node(ID, Package), CompilerID) : default_compiler_preference(CompilerID, 0), compiler_id(CompilerID), attr("node", node(ID, Package)), ID > 0. [25-5*ID, true]
+
+% node(ID, _), split build dependencies
+#heuristic attr("version", node(ID, Package), Version) : pkg_fact(Package, version_declared(Version, 0)), attr("node", node(ID, Package)), multiple_unification_sets(Package), ID > 0. [25, true]
+#heuristic version_weight(node(ID, Package), 0) : pkg_fact(Package, version_declared(Version, 0)), attr("node", node(ID, Package)), multiple_unification_sets(Package), ID > 0. [25, true]
+#heuristic attr("variant_value", node(ID, Package), Variant, Value) : variant_default_value(Package, Variant, Value), attr("node", node(ID, Package)), multiple_unification_sets(Package), ID > 0. [25, true]
+#heuristic attr("node_target", node(ID, Package), Target) : pkg_fact(Package, target_weight(Target, 0)), attr("node", node(ID, Package)), multiple_unification_sets(Package), ID > 0. [25, true]
+#heuristic node_target_weight(node(ID, Package), 0) : attr("node", node(ID, Package)), multiple_unification_sets(Package), ID > 0. [25, true]
+#heuristic node_compiler(node(ID, Package), CompilerID) : default_compiler_preference(CompilerID, 0), compiler_id(CompilerID), attr("node", node(ID, Package)), multiple_unification_sets(Package), ID > 0. [25, true]

lib/spack/spack/solver/os_compatibility.lp

@@ -3,9 +3,11 @@
 %
 % SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
+%=============================================================================
 % OS compatibility rules for reusing solves.
 % os_compatible(RecentOS, OlderOS)
 % OlderOS binaries can be used on RecentOS
+%=============================================================================
 
 % macOS
 os_compatible("monterey", "bigsur").

lib/spack/spack/solver/when_possible.lp

@@ -0,0 +1,27 @@
+% Copyright 2013-2023 Lawrence Livermore National Security, LLC and other
+% Spack Project Developers. See the top-level COPYRIGHT file for details.
+%
+% SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+%=============================================================================
+% Minimize the number of literals that are not solved
+%
+% This minimization is used for the "when_possible" concretization mode,
+% otherwise we assume that all literals must be solved.
+%=============================================================================
+
+% Give clingo the choice to solve an input spec or not
+{ solve_literal(ID) } :- literal(ID).
+literal_not_solved(ID) :- not solve_literal(ID), literal(ID).
+
+% Make a problem with "zero literals solved" unsat. This is to trigger
+% looking for solutions to the ASP problem with "errors", which results
+% in better reporting for users. See #30669 for details.
+1 { solve_literal(ID) : literal(ID) }.
+
+opt_criterion(300, "number of input specs not concretized").
+#minimize{ 0@300: #true }.
+#minimize { 1@300,ID : literal_not_solved(ID) }.
+
+#heuristic literal_solved(ID) : literal(ID). [1, sign]
+#heuristic literal_solved(ID) : literal(ID). [50, init]

lib/spack/spack/spec.py

@@ -112,50 +112,49 @@
     "UnsatisfiableDependencySpecError",
     "AmbiguousHashError",
     "InvalidHashError",
-    "RedundantSpecError",
     "SpecDeprecatedError",
 ]
 
 #: Valid pattern for an identifier in Spack
 
-identifier_re = r"\w[\w-]*"
+IDENTIFIER_RE = r"\w[\w-]*"
 
-compiler_color = "@g"  #: color for highlighting compilers
-version_color = "@c"  #: color for highlighting versions
-architecture_color = "@m"  #: color for highlighting architectures
-enabled_variant_color = "@B"  #: color for highlighting enabled variants
-disabled_variant_color = "r"  #: color for highlighting disabled varaints
-dependency_color = "@."  #: color for highlighting dependencies
-hash_color = "@K"  #: color for highlighting package hashes
+COMPILER_COLOR = "@g"  #: color for highlighting compilers
+VERSION_COLOR = "@c"  #: color for highlighting versions
+ARCHITECTURE_COLOR = "@m"  #: color for highlighting architectures
+ENABLED_VARIANT_COLOR = "@B"  #: color for highlighting enabled variants
+DISABLED_VARIANT_COLOR = "r"  #: color for highlighting disabled varaints
+DEPENDENCY_COLOR = "@."  #: color for highlighting dependencies
+HASH_COLOR = "@K"  #: color for highlighting package hashes
 
 #: This map determines the coloring of specs when using color output.
 #: We make the fields different colors to enhance readability.
 #: See llnl.util.tty.color for descriptions of the color codes.
-color_formats = {
-    "%": compiler_color,
-    "@": version_color,
-    "=": architecture_color,
-    "+": enabled_variant_color,
-    "~": disabled_variant_color,
-    "^": dependency_color,
-    "#": hash_color,
+COLOR_FORMATS = {
+    "%": COMPILER_COLOR,
+    "@": VERSION_COLOR,
+    "=": ARCHITECTURE_COLOR,
+    "+": ENABLED_VARIANT_COLOR,
+    "~": DISABLED_VARIANT_COLOR,
+    "^": DEPENDENCY_COLOR,
+    "#": HASH_COLOR,
 }
 
 #: Regex used for splitting by spec field separators.
 #: These need to be escaped to avoid metacharacters in
-#: ``color_formats.keys()``.
-_separators = "[\\%s]" % "\\".join(color_formats.keys())
+#: ``COLOR_FORMATS.keys()``.
+_SEPARATORS = "[\\%s]" % "\\".join(COLOR_FORMATS.keys())
 
 #: Default format for Spec.format(). This format can be round-tripped, so that:
 #:     Spec(Spec("string").format()) == Spec("string)"
-default_format = (
+DEFAULT_FORMAT = (
     "{name}{@versions}"
     "{%compiler.name}{@compiler.versions}{compiler_flags}"
     "{variants}{arch=architecture}{/abstract_hash}"
 )
 
 #: Display format, which eliminates extra `@=` in the output, for readability.
-display_format = (
+DISPLAY_FORMAT = (
     "{name}{@version}"
     "{%compiler.name}{@compiler.version}{compiler_flags}"
     "{variants}{arch=architecture}{/abstract_hash}"
@@ -187,7 +186,7 @@ class InstallStatus(enum.Enum):
 
 def colorize_spec(spec):
     """Returns a spec colorized according to the colors specified in
-    color_formats."""
+    COLOR_FORMATS."""
 
     class insert_color:
         def __init__(self):
@@ -200,9 +199,9 @@ def __call__(self, match):
                 return clr.cescape(sep)
             self.last = sep
 
-            return "%s%s" % (color_formats[sep], clr.cescape(sep))
+            return "%s%s" % (COLOR_FORMATS[sep], clr.cescape(sep))
 
-    return clr.colorize(re.sub(_separators, insert_color(), str(spec)) + "@.")
+    return clr.colorize(re.sub(_SEPARATORS, insert_color(), str(spec)) + "@.")
 
 
 @lang.lazy_lexicographic_ordering
@@ -985,16 +984,14 @@ def __iter__(self):
     def __len__(self):
         return len(self.edges)
 
-    def add(self, edge):
-        """Adds a new edge to this object.
-
-        Args:
-            edge (DependencySpec): edge to be added
-        """
+    def add(self, edge: DependencySpec):
         key = edge.spec.name if self.store_by_child else edge.parent.name
-        current_list = self.edges.setdefault(key, [])
-        current_list.append(edge)
-        current_list.sort(key=_sort_by_dep_types)
+        if key in self.edges:
+            lst = self.edges[key]
+            lst.append(edge)
+            lst.sort(key=_sort_by_dep_types)
+        else:
+            self.edges[key] = [edge]
 
     def __str__(self):
         return "{deps: %s}" % ", ".join(str(d) for d in sorted(self.values()))
@@ -1927,19 +1924,15 @@ def _lookup_hash(self):
         store, or finally, binary caches."""
         import spack.environment
 
-        matches = []
         active_env = spack.environment.active_environment()
 
-        if active_env:
-            env_matches = active_env.get_by_hash(self.abstract_hash) or []
-            matches = [m for m in env_matches if m._satisfies(self)]
-        if not matches:
-            db_matches = spack.store.STORE.db.get_by_hash(self.abstract_hash) or []
-            matches = [m for m in db_matches if m._satisfies(self)]
-        if not matches:
-            query = spack.binary_distribution.BinaryCacheQuery(True)
-            remote_matches = query("/" + self.abstract_hash) or []
-            matches = [m for m in remote_matches if m._satisfies(self)]
+        # First env, then store, then binary cache
+        matches = (
+            (active_env.all_matching_specs(self) if active_env else [])
+            or spack.store.STORE.db.query(self, installed=any)
+            or spack.binary_distribution.BinaryCacheQuery(True)(self)
+        )
+
         if not matches:
             raise InvalidHashError(self, self.abstract_hash)
 
@@ -1960,19 +1953,17 @@ def lookup_hash(self):
         spec = self.copy(deps=False)
         # root spec is replaced
         if spec.abstract_hash:
-            new = self._lookup_hash()
-            spec._dup(new)
+            spec._dup(self._lookup_hash())
             return spec
 
         # Get dependencies that need to be replaced
         for node in self.traverse(root=False):
             if node.abstract_hash:
-                new = node._lookup_hash()
-                spec._add_dependency(new, deptypes=(), virtuals=())
+                spec._add_dependency(node._lookup_hash(), deptypes=(), virtuals=())
 
         # reattach nodes that were not otherwise satisfied by new dependencies
         for node in self.traverse(root=False):
-            if not any(n._satisfies(node) for n in spec.traverse()):
+            if not any(n.satisfies(node) for n in spec.traverse()):
                 spec._add_dependency(node.copy(), deptypes=(), virtuals=())
 
         return spec
@@ -1985,9 +1976,7 @@ def replace_hash(self):
         if not any(node for node in self.traverse(order="post") if node.abstract_hash):
             return
 
-        spec_by_hash = self.lookup_hash()
-
-        self._dup(spec_by_hash)
+        self._dup(self.lookup_hash())
 
     def to_node_dict(self, hash=ht.dag_hash):
         """Create a dictionary representing the state of this Spec.
@@ -2983,9 +2972,12 @@ def _new_concretize(self, tests=False):
             providers = [spec.name for spec in answer.values() if spec.package.provides(name)]
             name = providers[0]
 
-        assert name in answer
+        node = spack.solver.asp.SpecBuilder.make_node(pkg=name)
+        assert (
+            node in answer
+        ), f"cannot find {name} in the list of specs {','.join([n.pkg for n in answer.keys()])}"
 
-        concretized = answer[name]
+        concretized = answer[node]
         self._dup(concretized)
 
     def concretize(self, tests=False):
@@ -3519,7 +3511,8 @@ def update_variant_validate(self, variant_name, values):
         for value in values:
             if self.variants.get(variant_name):
                 msg = (
-                    "Cannot append a value to a single-valued " "variant with an already set value"
+                    f"cannot append the new value '{value}' to the single-valued "
+                    f"variant '{self.variants[variant_name]}'"
                 )
                 assert pkg_variant.multi, msg
                 self.variants[variant_name].append(value)
@@ -3719,15 +3712,19 @@ def intersects(self, other: "Spec", deps: bool = True) -> bool:
         """
         other = self._autospec(other)
 
-        lhs = self.lookup_hash() or self
-        rhs = other.lookup_hash() or other
-
-        return lhs._intersects(rhs, deps)
-
-    def _intersects(self, other: "Spec", deps: bool = True) -> bool:
         if other.concrete and self.concrete:
             return self.dag_hash() == other.dag_hash()
 
+        self_hash = self.dag_hash() if self.concrete else self.abstract_hash
+        other_hash = other.dag_hash() if other.concrete else other.abstract_hash
+
+        if (
+            self_hash
+            and other_hash
+            and not (self_hash.startswith(other_hash) or other_hash.startswith(self_hash))
+        ):
+            return False
+
         # If the names are different, we need to consider virtuals
         if self.name != other.name and self.name and other.name:
             if self.virtual and other.virtual:
@@ -3787,19 +3784,8 @@ def _intersects(self, other: "Spec", deps: bool = True) -> bool:
         # If we need to descend into dependencies, do it, otherwise we're done.
         if deps:
             return self._intersects_dependencies(other)
-        else:
-            return True
 
-    def satisfies(self, other, deps=True):
-        """
-        This checks constraints on common dependencies against each other.
-        """
-        other = self._autospec(other)
-
-        lhs = self.lookup_hash() or self
-        rhs = other.lookup_hash() or other
-
-        return lhs._satisfies(rhs, deps=deps)
+        return True
 
     def _intersects_dependencies(self, other):
         if not other._dependencies or not self._dependencies:
@@ -3836,7 +3822,7 @@ def _intersects_dependencies(self, other):
 
         return True
 
-    def _satisfies(self, other: "Spec", deps: bool = True) -> bool:
+    def satisfies(self, other: "Spec", deps: bool = True) -> bool:
         """Return True if all concrete specs matching self also match other, otherwise False.
 
         Args:
@@ -3851,6 +3837,13 @@ def _satisfies(self, other: "Spec", deps: bool = True) -> bool:
             # objects.
             return self.concrete and self.dag_hash() == other.dag_hash()
 
+        # If the right-hand side has an abstract hash, make sure it's a prefix of the
+        # left-hand side's (abstract) hash.
+        if other.abstract_hash:
+            compare_hash = self.dag_hash() if self.concrete else self.abstract_hash
+            if not compare_hash or not compare_hash.startswith(other.abstract_hash):
+                return False
+
         # If the names are different, we need to consider virtuals
         if self.name != other.name and self.name and other.name:
             # A concrete provider can satisfy a virtual dependency.
@@ -4227,9 +4220,7 @@ def eq_node(self, other):
     def _cmp_iter(self):
         """Lazily yield components of self for comparison."""
 
-        cmp_spec = self.lookup_hash() or self
-
-        for item in cmp_spec._cmp_node():
+        for item in self._cmp_node():
             yield item
 
         # This needs to be in _cmp_iter so that no specs with different process hashes
@@ -4240,10 +4231,10 @@ def _cmp_iter(self):
         # TODO: they exist for speed.  We should benchmark whether it's really worth
         # TODO: having two types of hashing now that we use `json` instead of `yaml` for
         # TODO: spec hashing.
-        yield cmp_spec.process_hash() if cmp_spec.concrete else None
+        yield self.process_hash() if self.concrete else None
 
         def deps():
-            for dep in sorted(itertools.chain.from_iterable(cmp_spec._dependencies.values())):
+            for dep in sorted(itertools.chain.from_iterable(self._dependencies.values())):
                 yield dep.spec.name
                 yield tuple(sorted(dep.deptypes))
                 yield hash(dep.spec)
@@ -4253,7 +4244,7 @@ def deps():
     def colorized(self):
         return colorize_spec(self)
 
-    def format(self, format_string=default_format, **kwargs):
+    def format(self, format_string=DEFAULT_FORMAT, **kwargs):
         r"""Prints out particular pieces of a spec, depending on what is
         in the format string.
 
@@ -4332,7 +4323,7 @@ def format(self, format_string=default_format, **kwargs):
         def write(s, c=None):
             f = clr.cescape(s)
             if c is not None:
-                f = color_formats[c] + f + "@."
+                f = COLOR_FORMATS[c] + f + "@."
             clr.cwrite(f, stream=out, color=color)
 
         def write_attribute(spec, attribute, color):
@@ -4531,7 +4522,7 @@ def tree(self, **kwargs):
         status_fn = kwargs.pop("status_fn", False)
         cover = kwargs.pop("cover", "nodes")
         indent = kwargs.pop("indent", 0)
-        fmt = kwargs.pop("format", default_format)
+        fmt = kwargs.pop("format", DEFAULT_FORMAT)
         prefix = kwargs.pop("prefix", None)
         show_types = kwargs.pop("show_types", False)
         deptypes = kwargs.pop("deptypes", "all")
@@ -5339,14 +5330,6 @@ class NoSuchSpecFileError(SpecFilenameError):
     """Raised when a spec file doesn't exist."""
 
 
-class RedundantSpecError(spack.error.SpecError):
-    def __init__(self, spec, addition):
-        super().__init__(
-            "Attempting to add %s to spec %s which is already concrete."
-            " This is likely the result of adding to a spec specified by hash." % (addition, spec)
-        )
-
-
 class SpecFormatStringError(spack.error.SpecError):
     """Called for errors in Spec format strings."""
 

lib/spack/spack/spec_list.py

@@ -97,8 +97,10 @@ def remove(self, spec):
             msg += "Either %s is not in %s or %s is " % (spec, self.name, spec)
             msg += "expanded from a matrix and cannot be removed directly."
             raise SpecListError(msg)
-        assert len(remove) == 1
-        self.yaml_list.remove(remove[0])
+
+        # Remove may contain more than one string representation of the same spec
+        for item in remove:
+            self.yaml_list.remove(item)
 
         # invalidate cache variables when we change the list
         self._expanded_list = None
@@ -197,7 +199,9 @@ def _expand_matrix_constraints(matrix_config):
     for combo in itertools.product(*expanded_rows):
         # Construct a combined spec to test against excludes
         flat_combo = [constraint for constraint_list in combo for constraint in constraint_list]
-        flat_combo = [Spec(x) for x in flat_combo]
+
+        # Resolve abstract hashes so we can exclude by their concrete properties
+        flat_combo = [Spec(x).lookup_hash() for x in flat_combo]
 
         test_spec = flat_combo[0].copy()
         for constraint in flat_combo[1:]:

lib/spack/spack/stage.py

@@ -484,7 +484,7 @@ def fetch(self, mirror_only=False, err_msg=None):
 
             if self.default_fetcher.cachable:
                 for rel_path in reversed(list(self.mirror_paths)):
-                    cache_fetcher = spack.caches.fetch_cache.fetcher(
+                    cache_fetcher = spack.caches.FETCH_CACHE.fetcher(
                         rel_path, digest, expand=expand, extension=extension
                     )
                     fetchers.insert(0, cache_fetcher)
@@ -577,7 +577,7 @@ def check(self):
             self.fetcher.check()
 
     def cache_local(self):
-        spack.caches.fetch_cache.store(self.fetcher, self.mirror_paths.storage_path)
+        spack.caches.FETCH_CACHE.store(self.fetcher, self.mirror_paths.storage_path)
 
     def cache_mirror(self, mirror, stats):
         """Perform a fetch if the resource is not already cached

lib/spack/spack/store.py

@@ -212,7 +212,7 @@ def create(configuration: ConfigurationType) -> Store:
     Args:
         configuration: configuration to create a store.
     """
-    configuration = configuration or spack.config.config
+    configuration = configuration or spack.config.CONFIG
     config_dict = configuration.get("config")
     root, unpadded_root, projections = parse_install_tree(config_dict)
     hash_length = configuration.get("config:install_hash_length")
@@ -234,7 +234,7 @@ def create(configuration: ConfigurationType) -> Store:
 
 
 def _create_global() -> Store:
-    result = create(configuration=spack.config.config)
+    result = create(configuration=spack.config.CONFIG)
     return result
 
 
@@ -372,10 +372,10 @@ def use_store(
 
     # Swap the store with the one just constructed and return it
     ensure_singleton_created()
-    spack.config.config.push_scope(
+    spack.config.CONFIG.push_scope(
         spack.config.InternalConfigScope(name=scope_name, data={"config": {"install_tree": data}})
     )
-    temporary_store = create(configuration=spack.config.config)
+    temporary_store = create(configuration=spack.config.CONFIG)
     original_store, STORE = STORE, temporary_store
 
     try:
@@ -383,7 +383,7 @@ def use_store(
     finally:
         # Restore the original store
         STORE = original_store
-        spack.config.config.remove_scope(scope_name=scope_name)
+        spack.config.CONFIG.remove_scope(scope_name=scope_name)
 
 
 class MatchError(spack.error.SpackError):

lib/spack/spack/subprocess_context.py

@@ -94,14 +94,14 @@ class TestState:
 
     def __init__(self):
         if _SERIALIZE:
-            self.config = spack.config.config
+            self.config = spack.config.CONFIG
             self.platform = spack.platforms.host
             self.test_patches = store_patches()
             self.store = spack.store.STORE
 
     def restore(self):
         if _SERIALIZE:
-            spack.config.config = self.config
+            spack.config.CONFIG = self.config
             spack.repo.PATH = spack.repo.create(self.config)
             spack.platforms.host = self.platform
             spack.store.STORE = self.store

lib/spack/spack/test/architecture.py

@@ -4,6 +4,7 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 import os
 import platform
+import sys
 
 import pytest
 
@@ -199,15 +200,11 @@ def test_satisfy_strict_constraint_when_not_concrete(architecture_tuple, constra
     ],
 )
 @pytest.mark.usefixtures("mock_packages", "config")
+@pytest.mark.only_clingo("Fixing the parser broke this test for the original concretizer.")
 def test_concretize_target_ranges(root_target_range, dep_target_range, result, monkeypatch):
     # Monkeypatch so that all concretization is done as if the machine is core2
     monkeypatch.setattr(spack.platforms.test.Test, "default", "core2")
 
-    # use foobar=bar to make the problem simpler for the old concretizer
-    # the new concretizer should not need that help
-    if spack.config.get("config:concretizer") == "original":
-        pytest.skip("Fixing the parser broke this test for the original concretizer.")
-
     spec_str = "a %%gcc@10 foobar=bar target=%s ^b target=%s" % (
         root_target_range,
         dep_target_range,
@@ -227,6 +224,7 @@ def test_concretize_target_ranges(root_target_range, dep_target_range, result, m
         (["21.11", "21.9"], None, False),
     ],
 )
+@pytest.mark.skipif(sys.platform == "win32", reason="Cray does not use windows")
 def test_cray_platform_detection(versions, default, expected, tmpdir, monkeypatch, working_env):
     ex_path = str(tmpdir.join("fake_craype_dir"))
     fs.mkdirp(ex_path)

lib/spack/spack/test/bindist.py

@@ -37,7 +37,7 @@
 from spack.paths import test_path
 from spack.spec import Spec
 
-pytestmark = pytest.mark.skipif(sys.platform == "win32", reason="does not run on windows")
+pytestmark = pytest.mark.not_on_windows("does not run on windows")
 
 mirror_cmd = spack.main.SpackCommand("mirror")
 install_cmd = spack.main.SpackCommand("install")
@@ -51,7 +51,7 @@
 def cache_directory(tmpdir):
     fetch_cache_dir = tmpdir.ensure("fetch_cache", dir=True)
     fsc = spack.fetch_strategy.FsCache(str(fetch_cache_dir))
-    spack.config.caches, old_cache_path = fsc, spack.caches.fetch_cache
+    spack.config.caches, old_cache_path = fsc, spack.caches.FETCH_CACHE
 
     yield spack.config.caches
 
@@ -115,8 +115,8 @@ def default_config(tmpdir, config_directory, monkeypatch, install_mockery_mutabl
         ]
     )
 
-    spack.config.config, old_config = cfg, spack.config.config
-    spack.config.config.set("repos", [spack.paths.mock_packages_path])
+    spack.config.CONFIG, old_config = cfg, spack.config.CONFIG
+    spack.config.CONFIG.set("repos", [spack.paths.mock_packages_path])
     njobs = spack.config.get("config:build_jobs")
     if not njobs:
         spack.config.set("config:build_jobs", 4, scope="user")
@@ -138,9 +138,9 @@ def default_config(tmpdir, config_directory, monkeypatch, install_mockery_mutabl
     if not timeout:
         spack.config.set("config:connect_timeout", 10, scope="user")
 
-    yield spack.config.config
+    yield spack.config.CONFIG
 
-    spack.config.config = old_config
+    spack.config.CONFIG = old_config
     mutable_dir.remove()
 
 

lib/spack/spack/test/bootstrap.py

@@ -26,11 +26,11 @@ def test_store_is_restored_correctly_after_bootstrap(mutable_config, tmpdir):
     user_path = str(tmpdir.join("store"))
     with spack.store.use_store(user_path):
         assert spack.store.STORE.root == user_path
-        assert spack.config.config.get("config:install_tree:root") == user_path
+        assert spack.config.CONFIG.get("config:install_tree:root") == user_path
         with spack.bootstrap.ensure_bootstrap_configuration():
             assert spack.store.STORE.root == spack.bootstrap.config.store_path()
         assert spack.store.STORE.root == user_path
-        assert spack.config.config.get("config:install_tree:root") == user_path
+        assert spack.config.CONFIG.get("config:install_tree:root") == user_path
 
 
 @pytest.mark.regression("38963")
@@ -40,11 +40,11 @@ def test_store_padding_length_is_zero_during_bootstrapping(mutable_config, tmpdi
     """
     user_path = str(tmpdir.join("store"))
     with spack.store.use_store(user_path, extra_data={"padded_length": 512}):
-        assert spack.config.config.get("config:install_tree:padded_length") == 512
+        assert spack.config.CONFIG.get("config:install_tree:padded_length") == 512
         with spack.bootstrap.ensure_bootstrap_configuration():
             assert spack.store.STORE.root == spack.bootstrap.config.store_path()
-            assert spack.config.config.get("config:install_tree:padded_length") == 0
-        assert spack.config.config.get("config:install_tree:padded_length") == 512
+            assert spack.config.CONFIG.get("config:install_tree:padded_length") == 0
+        assert spack.config.CONFIG.get("config:install_tree:padded_length") == 512
 
 
 @pytest.mark.regression("38963")
@@ -54,15 +54,15 @@ def test_install_tree_customization_is_respected(mutable_config, tmp_path):
     """
     spack.store.reinitialize()
     store_dir = tmp_path / "store"
-    spack.config.config.set("config:install_tree:root", str(store_dir))
+    spack.config.CONFIG.set("config:install_tree:root", str(store_dir))
     with spack.bootstrap.ensure_bootstrap_configuration():
         assert spack.store.STORE.root == spack.bootstrap.config.store_path()
         assert (
-            spack.config.config.get("config:install_tree:root")
+            spack.config.CONFIG.get("config:install_tree:root")
             == spack.bootstrap.config.store_path()
         )
-        assert spack.config.config.get("config:install_tree:padded_length") == 0
-    assert spack.config.config.get("config:install_tree:root") == str(store_dir)
+        assert spack.config.CONFIG.get("config:install_tree:padded_length") == 0
+    assert spack.config.CONFIG.get("config:install_tree:root") == str(store_dir)
     assert spack.store.STORE.root == str(store_dir)
 
 
@@ -185,12 +185,12 @@ def test_bootstrap_custom_store_in_environment(mutable_config, tmpdir):
 
 def test_nested_use_of_context_manager(mutable_config):
     """Test nested use of the context manager"""
-    user_config = spack.config.config
+    user_config = spack.config.CONFIG
     with spack.bootstrap.ensure_bootstrap_configuration():
-        assert spack.config.config != user_config
+        assert spack.config.CONFIG != user_config
         with spack.bootstrap.ensure_bootstrap_configuration():
-            assert spack.config.config != user_config
-    assert spack.config.config == user_config
+            assert spack.config.CONFIG != user_config
+    assert spack.config.CONFIG == user_config
 
 
 @pytest.mark.parametrize("expected_missing", [False, True])

lib/spack/spack/test/build_distribution.py

@@ -5,7 +5,6 @@
 
 import os
 import os.path
-import sys
 
 import pytest
 
@@ -16,7 +15,7 @@
 
 install = spack.main.SpackCommand("install")
 
-pytestmark = pytest.mark.skipif(sys.platform == "win32", reason="does not run on windows")
+pytestmark = pytest.mark.not_on_windows("does not run on windows")
 
 
 def test_build_tarball_overwrite(install_mockery, mock_fetch, monkeypatch, tmpdir):

lib/spack/spack/test/build_environment.py

@@ -6,7 +6,6 @@
 import os
 import platform
 import posixpath
-import sys
 
 import pytest
 
@@ -17,8 +16,9 @@
 import spack.package_base
 import spack.spec
 import spack.util.spack_yaml as syaml
-from spack.build_environment import _static_to_shared_library, determine_number_of_jobs, dso_suffix
+from spack.build_environment import _static_to_shared_library, dso_suffix
 from spack.paths import build_env_path
+from spack.util.cpus import determine_number_of_jobs
 from spack.util.environment import EnvironmentModifications
 from spack.util.executable import Executable
 from spack.util.path import Path, convert_to_platform_path
@@ -119,7 +119,7 @@ def __call__(self, *args, **kwargs):
     return mock_module_cmd
 
 
-@pytest.mark.skipif(sys.platform == "win32", reason="Static to Shared not supported on Win (yet)")
+@pytest.mark.not_on_windows("Static to Shared not supported on Win (yet)")
 def test_static_to_shared_library(build_environment):
     os.environ["SPACK_TEST_COMMAND"] = "dump-args"
 
@@ -443,7 +443,7 @@ def test_parallel_false_is_not_propagating(default_mock_concretization):
 
     spack.build_environment.set_module_variables_for_package(s["b"].package)
     assert s["b"].package.module.make_jobs == spack.build_environment.determine_number_of_jobs(
-        s["b"].package.parallel
+        parallel=s["b"].package.parallel
     )
 
 
@@ -475,28 +475,62 @@ def test_setting_dtags_based_on_config(config_setting, expected_flag, config, mo
 
 def test_build_jobs_sequential_is_sequential():
     assert (
-        determine_number_of_jobs(parallel=False, command_line=8, config_default=8, max_cpus=8) == 1
+        determine_number_of_jobs(
+            parallel=False,
+            max_cpus=8,
+            config=spack.config.Configuration(
+                spack.config.InternalConfigScope("command_line", {"config": {"build_jobs": 8}}),
+                spack.config.InternalConfigScope("defaults", {"config": {"build_jobs": 8}}),
+            ),
+        )
+        == 1
     )
 
 
 def test_build_jobs_command_line_overrides():
     assert (
-        determine_number_of_jobs(parallel=True, command_line=10, config_default=1, max_cpus=1)
+        determine_number_of_jobs(
+            parallel=True,
+            max_cpus=1,
+            config=spack.config.Configuration(
+                spack.config.InternalConfigScope("command_line", {"config": {"build_jobs": 10}}),
+                spack.config.InternalConfigScope("defaults", {"config": {"build_jobs": 1}}),
+            ),
+        )
         == 10
     )
     assert (
-        determine_number_of_jobs(parallel=True, command_line=10, config_default=100, max_cpus=100)
+        determine_number_of_jobs(
+            parallel=True,
+            max_cpus=100,
+            config=spack.config.Configuration(
+                spack.config.InternalConfigScope("command_line", {"config": {"build_jobs": 10}}),
+                spack.config.InternalConfigScope("defaults", {"config": {"build_jobs": 100}}),
+            ),
+        )
         == 10
     )
 
 
 def test_build_jobs_defaults():
     assert (
-        determine_number_of_jobs(parallel=True, command_line=None, config_default=1, max_cpus=10)
+        determine_number_of_jobs(
+            parallel=True,
+            max_cpus=10,
+            config=spack.config.Configuration(
+                spack.config.InternalConfigScope("defaults", {"config": {"build_jobs": 1}})
+            ),
+        )
         == 1
     )
     assert (
-        determine_number_of_jobs(parallel=True, command_line=None, config_default=100, max_cpus=10)
+        determine_number_of_jobs(
+            parallel=True,
+            max_cpus=10,
+            config=spack.config.Configuration(
+                spack.config.InternalConfigScope("defaults", {"config": {"build_jobs": 100}})
+            ),
+        )
         == 10
     )
 

lib/spack/spack/test/build_systems.py

@@ -5,7 +5,6 @@
 
 import glob
 import os
-import sys
 
 import py.path
 import pytest
@@ -43,7 +42,7 @@ def _func(dir_str):
     return _func
 
 
-@pytest.mark.skipif(sys.platform == "win32", reason="make not available on Windows")
+@pytest.mark.not_on_windows("make not available on Windows")
 @pytest.mark.usefixtures("config", "mock_packages", "working_env")
 class TestTargets:
     @pytest.mark.parametrize(
@@ -92,7 +91,7 @@ def test_negative_ninja_check(self, input_dir, test_dir, concretize_and_setup):
             s.package._if_ninja_target_execute("check")
 
 
-@pytest.mark.skipif(sys.platform == "win32", reason="autotools not available on windows")
+@pytest.mark.not_on_windows("autotools not available on windows")
 @pytest.mark.usefixtures("config", "mock_packages")
 class TestAutotoolsPackage:
     def test_with_or_without(self, default_mock_concretization):

lib/spack/spack/test/builder.py

@@ -3,7 +3,6 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 import os.path
-import sys
 
 import pytest
 
@@ -106,10 +105,7 @@ def test_old_style_compatibility_with_super(spec_str, method_name, expected):
     assert value == expected
 
 
-@pytest.mark.skipif(
-    sys.platform == "win32",
-    reason="log_ouput cannot currently be used outside of subprocess on Windows",
-)
+@pytest.mark.not_on_windows("log_ouput cannot currently be used outside of subprocess on Windows")
 @pytest.mark.regression("33928")
 @pytest.mark.usefixtures("builder_test_repository", "config", "working_env")
 @pytest.mark.disable_clean_stage_check
@@ -153,7 +149,7 @@ def test_monkey_patching_test_log_file():
 
 # Windows context manager's __exit__ fails with ValueError ("I/O operation
 # on closed file").
-@pytest.mark.skipif(sys.platform == "win32", reason="Does not run on windows")
+@pytest.mark.not_on_windows("Does not run on windows")
 def test_install_time_test_callback(tmpdir, config, mock_packages, mock_stage):
     """Confirm able to run stand-alone test as a post-install callback."""
     s = spack.spec.Spec("py-test-callback").concretized()

lib/spack/spack/test/cache_fetch.py

@@ -31,13 +31,16 @@ def test_fetch_missing_cache(tmpdir, _fetch_method):
 @pytest.mark.parametrize("_fetch_method", ["curl", "urllib"])
 def test_fetch(tmpdir, _fetch_method):
     """Ensure a fetch after expanding is effectively a no-op."""
-    testpath = str(tmpdir)
-    cache = os.path.join(testpath, "cache.tar.gz")
+    cache_dir = tmpdir.join("cache")
+    stage_dir = tmpdir.join("stage")
+    mkdirp(cache_dir)
+    mkdirp(stage_dir)
+    cache = os.path.join(cache_dir, "cache.tar.gz")
     touch(cache)
     url = url_util.path_to_file_url(cache)
     with spack.config.override("config:url_fetch_method", _fetch_method):
         fetcher = CacheURLFetchStrategy(url=url)
-        with Stage(fetcher, path=testpath) as stage:
+        with Stage(fetcher, path=str(stage_dir)) as stage:
             source_path = stage.source_path
             mkdirp(source_path)
             fetcher.fetch()

lib/spack/spack/test/cc.py

@@ -8,7 +8,6 @@
 arguments correctly.
 """
 import os
-import sys
 
 import pytest
 
@@ -145,7 +144,7 @@
     + test_args_without_paths
 )
 
-pytestmark = pytest.mark.skipif(sys.platform == "win32", reason="does not run on windows")
+pytestmark = pytest.mark.not_on_windows("does not run on windows")
 
 
 @pytest.fixture(scope="function")