diff --git a/var/spack/repos/builtin/packages/acfl/package.py b/var/spack/repos/builtin/packages/acfl/package.py
index 84f7d7d3767..556f0d781cf 100644
--- a/var/spack/repos/builtin/packages/acfl/package.py
+++ b/var/spack/repos/builtin/packages/acfl/package.py
@@ -2,6 +2,7 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 import os
+import os.path
 
 import spack.platforms
 from spack.package import *
@@ -356,6 +357,11 @@ class Acfl(Package, CompilerPackage):
     provides("lapack")
     provides("fftw-api@3")
 
+    provides("c", "cxx")
+    provides("fortran")
+
+    requires("platform=linux", msg="acfl is only available for linux")
+
     depends_on("gmake", type="build")
 
     # Licensing - Not required from 22.0.1 on.
@@ -377,6 +383,23 @@ def install(self, spec, prefix):
         r"Arm C\/C\+\+\/Fortran Compiler version ([\d\.]+) \(build number \d+\) "
     )
 
+    opt_flags = ["-O", "-O0", "-O1", "-O2", "-O3", "-Ofast"]
+
+    link_paths = {
+        "c": os.path.join("arm", "armclang"),
+        "cxx": os.path.join("arm", "armclang++"),
+        "fortran": os.path.join("arm", "armflang"),
+    }
+
+    required_libs = ["libclang", "libflang"]
+
+    def _standard_flag(self, *, language, standard):
+        flags = {
+            "cxx": {"11": "-std=c++11", "14": "-std=c++14", "17": "-std=c++1z"},
+            "c": {"99": "-std=c99", "11": "-std=c11"},
+        }
+        return flags[language][standard]
+
     @property
     def cc(self):
         msg = "cannot retrieve C compiler [spec is not concrete]"
@@ -464,6 +487,9 @@ def setup_run_environment(self, env):
         env.prepend_path("LIBRARY_PATH", join_path(arm_dir, "lib"))
         env.prepend_path("MANPATH", join_path(arm_dir, "share", "man"))
 
+    def archspec_name(self):
+        return "arm"
+
     @run_after("install")
     def check_install(self):
         arm_dir = get_acfl_prefix(self.spec)
diff --git a/var/spack/repos/builtin/packages/aocc/package.py b/var/spack/repos/builtin/packages/aocc/package.py
index 242895a3cad..542cc723494 100644
--- a/var/spack/repos/builtin/packages/aocc/package.py
+++ b/var/spack/repos/builtin/packages/aocc/package.py
@@ -1,7 +1,7 @@
 # Copyright Spack Project Developers. See COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-
+import os.path
 
 from spack.package import *
 from spack.pkg.builtin.llvm import LlvmDetection
@@ -60,6 +60,9 @@ class Aocc(Package, LlvmDetection, CompilerPackage):
 
     depends_on("c", type="build")  # generated
 
+    provides("c", "cxx")
+    provides("fortran")
+
     # Licensing
     license_url = "https://www.amd.com/en/developer/aocc/aocc-compiler/eula.html"
 
@@ -114,3 +117,31 @@ def cfg_files(self):
 
     compiler_version_regex = r"AOCC_(\d+[._]\d+[._]\d+)"
     fortran_names = ["flang"]
+
+    debug_flags = [
+        "-gcodeview",
+        "-gdwarf-2",
+        "-gdwarf-3",
+        "-gdwarf-4",
+        "-gdwarf-5",
+        "-gline-tables-only",
+        "-gmodules",
+        "-g",
+    ]
+
+    opt_flags = ["-O0", "-O1", "-O2", "-O3", "-Ofast", "-Os", "-Oz", "-Og", "-O", "-O4"]
+
+    link_paths = {
+        "c": os.path.join("aocc", "clang"),
+        "cxx": os.path.join("aocc", "clang++"),
+        "fortran": os.path.join("aocc", "flang"),
+    }
+
+    required_libs = ["libclang"]
+
+    def _standard_flag(self, *, language: str, standard: str) -> str:
+        flags = {
+            "cxx": {"11": "-std=c++11", "14": "-std=c++14", "17": "-std=c++17"},
+            "c": {"99": "-std=c99", "11": "-std=c11"},
+        }
+        return flags[language][standard]
diff --git a/var/spack/repos/builtin/packages/apple-clang/package.py b/var/spack/repos/builtin/packages/apple-clang/package.py
index a4636a9ee0e..17293d6672b 100644
--- a/var/spack/repos/builtin/packages/apple-clang/package.py
+++ b/var/spack/repos/builtin/packages/apple-clang/package.py
@@ -1,6 +1,8 @@
 # Copyright Spack Project Developers. See COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
+import os
+
 from spack.package import *
 from spack.pkg.builtin.llvm import LlvmDetection
 
@@ -16,6 +18,14 @@ class AppleClang(BundlePackage, LlvmDetection, CompilerPackage):
     compiler_languages = ["c", "cxx"]
     compiler_version_regex = r"^Apple (?:LLVM|clang) version ([^ )]+)"
 
+    openmp_flag = "-Xpreprocessor -fopenmp"
+
+    link_paths = {"c": os.path.join("clang", "clang"), "cxx": os.path.join("clang", "clang++")}
+
+    required_libs = ["libclang"]
+
+    provides("c", "cxx")
+
     requires("platform=darwin")
 
     @classmethod
@@ -38,3 +48,28 @@ def cxx(self):
         msg = "apple-clang is expected to be an external spec"
         assert self.spec.concrete and self.spec.external, msg
         return self.spec.extra_attributes["compilers"].get("cxx", None)
+
+    def _standard_flag(self, *, language, standard):
+        flags = {
+            "cxx": {
+                "11": [("@4.0:", "-std=c++11")],
+                "14": [("@6.1:", "-std=c++14")],
+                "17": [("@6.1:10.0", "-std=c++1z"), ("10.1:", "-std=c++17")],
+                "20": [("@10.0:13.0", "-std=c++2a"), ("13.1:", "-std=c++20")],
+                "23": [("13.0:", "-std=c++2b")],
+            },
+            "c": {
+                "99": [("@4.0:", "-std=c99")],
+                "11": [("@4.0:", "-std=c11")],
+                "17": [("@11.1:", "-std=c17")],
+                "23": [("@11.1:", "-std=c2x")],
+            },
+        }
+        for condition, flag in flags[language][standard]:
+            if self.spec.satisfies(condition):
+                return flag
+        else:
+            raise RuntimeError(
+                f"{self.spec} does not support the '{standard}' standard "
+                f"for the '{language}' language"
+            )
diff --git a/var/spack/repos/builtin/packages/armpl-gcc/package.py b/var/spack/repos/builtin/packages/armpl-gcc/package.py
index b758f0dbb58..77cf566d72a 100644
--- a/var/spack/repos/builtin/packages/armpl-gcc/package.py
+++ b/var/spack/repos/builtin/packages/armpl-gcc/package.py
@@ -4,7 +4,6 @@
 
 import os
 
-import spack.error
 import spack.platforms
 from spack.package import *
 
@@ -406,6 +405,10 @@ class ArmplGcc(Package):
     provides("lapack")
     provides("fftw-api@3")
 
+    depends_on("c", type="build")
+    depends_on("fortran", type="build")
+    requires("^[virtuals=c,fortran] gcc", msg="armpl-gcc is only compatible with the GCC compiler")
+
     depends_on("gmake", type="build")
 
     # Run the installer with the desired install directory
@@ -431,8 +434,6 @@ def install(self, spec, prefix):
                 # Unmount image
                 hdiutil("detach", mountpoint)
             return
-        if self.compiler.name != "gcc":
-            raise spack.error.SpackError(("Only compatible with GCC.\n"))
 
         with when("@:22"):
             armpl_version = spec.version.up_to(3).string.split("_")[0]
diff --git a/var/spack/repos/builtin/packages/blt/package.py b/var/spack/repos/builtin/packages/blt/package.py
index 358ae60f7cc..ce2a66a0ed9 100644
--- a/var/spack/repos/builtin/packages/blt/package.py
+++ b/var/spack/repos/builtin/packages/blt/package.py
@@ -22,7 +22,7 @@ def spec_uses_gccname(spec):
 
 def llnl_link_helpers(options, spec, compiler):
     # From local package:
-    if compiler.fc:
+    if "fortran" in spec:
         fortran_compilers = ["gfortran", "xlf"]
         if any(f_comp in compiler.fc for f_comp in fortran_compilers) and (
             "clang" in compiler.cxx
@@ -37,7 +37,7 @@ def llnl_link_helpers(options, spec, compiler):
             if flags:
                 options.append(cmake_cache_string("BLT_EXE_LINKER_FLAGS", flags, description))
 
-    if "cce" in compiler.cxx:
+    if "cxx" in spec and spec["cxx"].name == "cce":
         description = "Adds a missing rpath for libraries " "associated with the fortran compiler"
         # Here is where to find libs that work for fortran
         libdir = "/opt/cray/pe/cce/{0}/cce-clang/x86_64/lib".format(compiler.version)
diff --git a/var/spack/repos/builtin/packages/cce/package.py b/var/spack/repos/builtin/packages/cce/package.py
index 23323803005..86105b8ce95 100644
--- a/var/spack/repos/builtin/packages/cce/package.py
+++ b/var/spack/repos/builtin/packages/cce/package.py
@@ -1,6 +1,8 @@
 # Copyright Spack Project Developers. See COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
+import os.path
+
 from spack.package import *
 
 
@@ -20,10 +22,29 @@ class Cce(Package, CompilerPackage):
         r"[Cc]ray (?:clang|C :|C\+\+ :|Fortran :) [Vv]ersion.*?(\d+(?:\.\d+)+)"
     )
 
-    # notify when the package is updated.
+    debug_flags = ["-g", "-G0", "-G1", "-G2", "-Gfast"]
+
+    liink_paths = {
+        "c": os.path.join("cce", "craycc"),
+        "cxx": os.path.join("cce", "case-insensitive", "crayCC"),
+        "fortran": os.path.join("cce", "crayftn"),
+    }
+
     maintainers("becker33")
 
     version("16.0.0")
 
+    provides("c", "cxx")
+    provides("fortran")
+
+    requires("platform=linux")
+
+    def _standard_flag(self, *, language, standard):
+        flags = {
+            "cxx": {"11": "-std=c++11", "14": "-std=c++14", "17": "-std=c++17"},
+            "c": {"99": "-std=c99", "11": "-std=c11"},
+        }
+        return flags[language][standard]
+
     def install(self, spec, prefix):
         raise NotImplementedError("cray compiler must be configured as external")
diff --git a/var/spack/repos/builtin/packages/claw/package.py b/var/spack/repos/builtin/packages/claw/package.py
index 32b3933fb41..de167f08539 100644
--- a/var/spack/repos/builtin/packages/claw/package.py
+++ b/var/spack/repos/builtin/packages/claw/package.py
@@ -1,11 +1,6 @@
 # Copyright Spack Project Developers. See COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-
-import os
-
-import spack.compilers
-import spack.spec
 from spack.package import *
 
 
@@ -87,8 +82,6 @@ class Claw(CMakePackage):
     def flag_handler(self, name, flags):
         if name == "cflags":
             compiler_spec = self.spec.compiler
-            if spack.compilers.is_mixed_toolchain(self.compiler):
-                compiler_spec = self._get_real_compiler_spec("cc") or compiler_spec
             if any(
                 [
                     compiler_spec.satisfies(s)
@@ -105,25 +98,3 @@ def cmake_args(self):
         args = ["-DOMNI_CONF_OPTION=--with-libxml2=%s" % self.spec["libxml2"].prefix]
 
         return args
-
-    def _get_real_compiler_spec(self, language):
-        lang_compiler = getattr(self.compiler, language)
-
-        if not lang_compiler:
-            return None
-
-        for compiler_name in spack.compilers.supported_compilers():
-            compiler_cls = spack.compilers.class_for_compiler_name(compiler_name)
-            lang_version_fn = getattr(compiler_cls, "{0}_version".format(language))
-            for regexp in compiler_cls.search_regexps(language):
-                if regexp.match(os.path.basename(lang_compiler)):
-                    try:
-                        detected_version = lang_version_fn(lang_compiler)
-                        if detected_version:
-                            compiler_version = Version(detected_version)
-                            if compiler_version != Version("unknown"):
-                                return spack.spec.CompilerSpec(compiler_name, compiler_version)
-                    except Exception:
-                        continue
-
-        return None
diff --git a/var/spack/repos/builtin/packages/clingo/package.py b/var/spack/repos/builtin/packages/clingo/package.py
index 4c448043099..3b1ac8c8a4c 100644
--- a/var/spack/repos/builtin/packages/clingo/package.py
+++ b/var/spack/repos/builtin/packages/clingo/package.py
@@ -2,7 +2,7 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
-from spack.compiler import UnsupportedCompilerFlag
+from spack.compilers.error import UnsupportedCompilerFlag
 from spack.package import *
 
 
@@ -38,8 +38,8 @@ class Clingo(CMakePackage):
     version("5.3.0", sha256="b0d406d2809352caef7fccf69e8864d55e81ee84f4888b0744894977f703f976")
     version("5.2.2", sha256="da1ef8142e75c5a6f23c9403b90d4f40b9f862969ba71e2aaee9a257d058bfcf")
 
-    depends_on("c", type="build")  # generated
-    depends_on("cxx", type="build")  # generated
+    depends_on("c", type="build")
+    depends_on("cxx", type="build")
 
     variant("docs", default=False, description="build documentation with Doxygen")
     variant("python", default=True, description="build with python bindings")
@@ -100,7 +100,7 @@ def cmake_py_shared(self):
 
     def cmake_args(self):
         try:
-            self.compiler.cxx14_flag
+            self.spec["cxx"].package.standard_flag(language="cxx", standard="14")
         except UnsupportedCompilerFlag:
             InstallError("clingo requires a C++14-compliant C++ compiler")
 
diff --git a/var/spack/repos/builtin/packages/cmake/package.py b/var/spack/repos/builtin/packages/cmake/package.py
index a2b70d4eec3..6fc0ce5765f 100644
--- a/var/spack/repos/builtin/packages/cmake/package.py
+++ b/var/spack/repos/builtin/packages/cmake/package.py
@@ -243,16 +243,6 @@ def determine_version(cls, exe):
         match = re.search(r"cmake.*version\s+(\S+)", output)
         return match.group(1) if match else None
 
-    def flag_handler(self, name, flags):
-        if name == "cxxflags" and self.compiler.name == "fj":
-            cxx11plus_flags = (self.compiler.cxx11_flag, self.compiler.cxx14_flag)
-            cxxpre11_flags = self.compiler.cxx98_flag
-            if any(f in flags for f in cxxpre11_flags):
-                raise ValueError("cannot build cmake pre-c++11 standard")
-            elif not any(f in flags for f in cxx11plus_flags):
-                flags.append(self.compiler.cxx11_flag)
-        return (flags, None, None)
-
     def bootstrap_args(self):
         spec = self.spec
         args = []
diff --git a/var/spack/repos/builtin/packages/cray-mpich/package.py b/var/spack/repos/builtin/packages/cray-mpich/package.py
index 485ca4da6eb..af45cde0402 100644
--- a/var/spack/repos/builtin/packages/cray-mpich/package.py
+++ b/var/spack/repos/builtin/packages/cray-mpich/package.py
@@ -79,10 +79,15 @@ def setup_run_environment(self, env):
             self.setup_mpi_wrapper_variables(env)
             return
 
-        env.set("MPICC", self.compiler.cc)
-        env.set("MPICXX", self.compiler.cxx)
-        env.set("MPIFC", self.compiler.fc)
-        env.set("MPIF77", self.compiler.f77)
+        if self.spec.dependencies(virtuals=("c",)):
+            env.set("MPICC", self.spec["c"].package.cc)
+
+        if self.spec.dependencies(virtuals=("cxx",)):
+            env.set("MPICXX", self.spec["cxx"].package.cxx)
+
+        if self.spec.dependencies(virtuals=("fortran",)):
+            env.set("MPIFC", self.spec["fortran"].package.fc)
+            env.set("MPIF77", self.spec["fortran"].package.fc)
 
     def setup_dependent_package(self, module, dependent_spec):
         spec = self.spec
diff --git a/var/spack/repos/builtin/packages/cray-mvapich2/package.py b/var/spack/repos/builtin/packages/cray-mvapich2/package.py
index f362b89503c..5c2da4c7b7e 100644
--- a/var/spack/repos/builtin/packages/cray-mvapich2/package.py
+++ b/var/spack/repos/builtin/packages/cray-mvapich2/package.py
@@ -29,10 +29,15 @@ class CrayMvapich2(MpichEnvironmentModifications, Package):
     requires("platform=linux", msg="Cray MVAPICH2 is only available on Cray")
 
     def setup_run_environment(self, env):
-        env.set("MPICC", self.compiler.cc)
-        env.set("MPICXX", self.compiler.cxx)
-        env.set("MPIFC", self.compiler.fc)
-        env.set("MPIF77", self.compiler.f77)
+        if self.spec.dependencies(virtuals=("c",)):
+            env.set("MPICC", self.spec["c"].package.cc)
+
+        if self.spec.dependencies(virtuals=("cxx",)):
+            env.set("MPICXX", self.spec["cxx"].package.cxx)
+
+        if self.spec.dependencies(virtuals=("fortran",)):
+            env.set("MPIFC", self.spec["fortran"].package.fc)
+            env.set("MPIF77", self.spec["fortran"].package.fc)
 
     def install(self, spec, prefix):
         raise InstallError(
diff --git a/var/spack/repos/builtin/packages/cuda/package.py b/var/spack/repos/builtin/packages/cuda/package.py
index 72dd1cc5604..1743adcd82f 100644
--- a/var/spack/repos/builtin/packages/cuda/package.py
+++ b/var/spack/repos/builtin/packages/cuda/package.py
@@ -727,7 +727,8 @@ def setup_build_environment(self, env):
             env.append_path("LD_LIBRARY_PATH", libxml2_home.lib)
 
     def setup_dependent_build_environment(self, env, dependent_spec):
-        env.set("CUDAHOSTCXX", dependent_spec.package.compiler.cxx)
+        if "cxx" in dependent_spec:
+            env.set("CUDAHOSTCXX", dependent_spec["cxx"].package.cxx)
         env.set("CUDA_HOME", self.prefix)
         env.set("NVHPC_CUDA_HOME", self.prefix)
 
diff --git a/var/spack/repos/builtin/packages/cxx/package.py b/var/spack/repos/builtin/packages/cxx/package.py
index 000d345ceec..daf88e61041 100644
--- a/var/spack/repos/builtin/packages/cxx/package.py
+++ b/var/spack/repos/builtin/packages/cxx/package.py
@@ -4,8 +4,6 @@
 
 import os
 
-import spack.compilers
-import spack.spec
 from spack.package import *
 
 
@@ -17,25 +15,14 @@ class Cxx(Package):
 
     def test_cxx(self):
         """Compile and run 'Hello World'"""
-        cxx = which(os.environ["CXX"])
         expected = ["Hello world", "YES!"]
-
+        cxx = Executable(self.cxx)
         test_source = self.test_suite.current_test_data_dir
         for test in os.listdir(test_source):
             exe_name = f"{test}.exe"
-            filepath = test_source.join(test)
             with test_part(self, f"test_cxx_{test}", f"build and run {exe_name}"):
-                # standard options
-                # Hack to get compiler attributes
-                # TODO: remove this when compilers are dependencies
-                c_name = clang if self.spec.satisfies("llvm+clang") else self.name
-                c_spec = spack.spec.CompilerSpec(c_name, self.spec.version)
-                c_cls = spack.compilers.class_for_compiler_name(c_name)
-                compiler = c_cls(c_spec, None, None, ["fakecc", "fakecxx"])
-                cxx_opts = [compiler.cxx11_flag] if "c++11" in test else []
-                cxx_opts += ["-o", exe_name, filepath]
-
-                cxx(*cxx_opts)
+                filepath = join_path(test_source, test)
+                cxx("-o", exe_name, filepath)
                 exe = which(exe_name)
                 out = exe(output=str.split, error=str.split)
                 check_outputs(expected, out)
diff --git a/var/spack/repos/builtin/packages/dealii/package.py b/var/spack/repos/builtin/packages/dealii/package.py
index c75ccfe3de0..1f55d7e87e6 100644
--- a/var/spack/repos/builtin/packages/dealii/package.py
+++ b/var/spack/repos/builtin/packages/dealii/package.py
@@ -54,9 +54,9 @@ class Dealii(CMakePackage, CudaPackage):
     version("8.2.1", sha256="d75674e45fe63cd9fa294460fe45228904d51a68f744dbb99cd7b60720f3b2a0")
     version("8.1.0", sha256="d666bbda2a17b41b80221d7029468246f2658051b8c00d9c5907cd6434c4df99")
 
-    depends_on("c", type="build")  # generated
-    depends_on("cxx", type="build")  # generated
-    depends_on("fortran", type="build")  # generated
+    depends_on("c", type="build")
+    depends_on("cxx", type="build")
+    depends_on("fortran", type="build")
 
     # Configuration variants
     variant(
@@ -685,7 +685,7 @@ def cmake_args(self):
         # Add flags for machine vectorization, used when tutorials
         # and user code is built.
         # See https://github.com/dealii/dealii/issues/9164
-        options.append(self.define("DEAL_II_CXX_FLAGS", os.environ["SPACK_TARGET_ARGS"]))
+        options.append(self.define("DEAL_II_CXX_FLAGS", os.environ["SPACK_TARGET_ARGS_CXX"]))
 
         # platform introspection - needs to be disabled in some environments
         if spec.satisfies("+platform-introspection"):
diff --git a/var/spack/repos/builtin/packages/esmf/package.py b/var/spack/repos/builtin/packages/esmf/package.py
index 0b4da2bcaed..ea4257c94d5 100644
--- a/var/spack/repos/builtin/packages/esmf/package.py
+++ b/var/spack/repos/builtin/packages/esmf/package.py
@@ -7,7 +7,6 @@
 
 import spack.build_systems.makefile
 import spack.build_systems.python
-import spack.compiler
 from spack.build_environment import dso_suffix, stat_suffix
 from spack.package import *
 
@@ -259,29 +258,16 @@ def setup_build_environment(self, env):
         # ESMF_COMPILER must be set to select which Fortran and
         # C++ compilers are being used to build the ESMF library.
 
-        if self.pkg.compiler.name == "gcc":
+        if spec["fortran"].name == "gcc" and spec["c"].name == "gcc":
+            gfortran_major_version = int(spec["fortran"].version[0])
             env.set("ESMF_COMPILER", "gfortran")
-            with self.pkg.compiler.compiler_environment():
-                gfortran_major_version = int(
-                    spack.compiler.get_compiler_version_output(
-                        self.pkg.compiler.fc, "-dumpversion"
-                    ).split(".")[0]
-                )
         elif self.pkg.compiler.name == "intel" or self.pkg.compiler.name == "oneapi":
             env.set("ESMF_COMPILER", "intel")
-        elif self.pkg.compiler.name in ["clang", "apple-clang"]:
-            if "flang" in self.pkg.compiler.fc:
-                env.set("ESMF_COMPILER", "llvm")
-            elif "gfortran" in self.pkg.compiler.fc:
-                env.set("ESMF_COMPILER", "gfortranclang")
-                with self.pkg.compiler.compiler_environment():
-                    gfortran_major_version = int(
-                        spack.compiler.get_compiler_version_output(
-                            self.pkg.compiler.fc, "-dumpversion"
-                        ).split(".")[0]
-                    )
-            else:
-                raise InstallError("Unsupported C/C++/Fortran compiler combination")
+        elif spec["fortran"].name == "gcc" and spec["c"].name in ["clang", "apple-clang"]:
+            gfortran_major_version = int(spec["fortran"].version[0])
+            env.set("ESMF_COMPILER", "gfortranclang")
+        elif spec["fortran"].name == "llvm":
+            env.set("ESMF_COMPILER", "llvm")
         elif self.pkg.compiler.name == "nag":
             env.set("ESMF_COMPILER", "nag")
         elif self.pkg.compiler.name == "nvhpc":
diff --git a/var/spack/repos/builtin/packages/fj/package.py b/var/spack/repos/builtin/packages/fj/package.py
index 3f0898330f0..56b874e7112 100644
--- a/var/spack/repos/builtin/packages/fj/package.py
+++ b/var/spack/repos/builtin/packages/fj/package.py
@@ -1,6 +1,8 @@
 # Copyright Spack Project Developers. See COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
+import os.path
+
 from spack.package import *
 
 
@@ -14,6 +16,9 @@ class Fj(Package, CompilerPackage):
 
     maintainers("t-karatsu")
 
+    provides("c", "cxx")
+    provides("fortran")
+
     def install(self, spec, prefix):
         raise InstallError(
             "Fujitsu compilers are not installable yet, but can be "
@@ -26,3 +31,29 @@ def install(self, spec, prefix):
     fortran_names = ["frt"]
     compiler_version_regex = r"\((?:FCC|FRT)\) ([a-z\d.]+)"
     compiler_version_argument = "--version"
+
+    debug_flags = ["-g"]
+    opt_flags = ["-O0", "-O1", "-O2", "-O3", "-Ofast"]
+
+    pic_flag = "-KPIC"
+    openmp_flag = "-Kopenmp"
+
+    link_paths = {
+        "c": os.path.join("fj", "fcc"),
+        "cxx": os.path.join("fj", "case-insensitive", "FCC"),
+        "fortran": os.path.join("fj", "frt"),
+    }
+
+    required_libs = ["libfj90i", "libfj90f", "libfjsrcinfo"]
+
+    def _standard_flag(self, *, language, standard):
+        flags = {
+            "cxx": {
+                "98": "-std=c++98",
+                "11": "-std=c++11",
+                "14": "-std=c++14",
+                "17": "-std=c++17",
+            },
+            "c": {"99": "-std=c99", "11": "-std=c11"},
+        }
+        return flags[language][standard]
diff --git a/var/spack/repos/builtin/packages/gcc-runtime/package.py b/var/spack/repos/builtin/packages/gcc-runtime/package.py
index 95680003b7a..8edc4ae35e4 100644
--- a/var/spack/repos/builtin/packages/gcc-runtime/package.py
+++ b/var/spack/repos/builtin/packages/gcc-runtime/package.py
@@ -27,8 +27,6 @@ class GccRuntime(Package):
 
     license("GPL-3.0-or-later WITH GCC-exception-3.1")
 
-    requires("%gcc")
-
     LIBRARIES = [
         "asan",
         "atomic",
@@ -47,15 +45,18 @@ class GccRuntime(Package):
 
     # libgfortran ABI
     provides("fortran-rt", "libgfortran")
-    provides("libgfortran@3", when="%gcc@:6")
-    provides("libgfortran@4", when="%gcc@7")
-    provides("libgfortran@5", when="%gcc@8:")
+    provides("libgfortran@3", when="@:6")
+    provides("libgfortran@4", when="@7")
+    provides("libgfortran@5", when="@8:")
 
     depends_on("libc", type="link", when="platform=linux")
 
+    depends_on("gcc", type="build")
+
     def install(self, spec, prefix):
+        gcc_pkg = self["gcc"]
         if spec.platform in ["linux", "freebsd"]:
-            libraries = get_elf_libraries(compiler=self.compiler, libraries=self.LIBRARIES)
+            libraries = get_elf_libraries(compiler=gcc_pkg, libraries=self.LIBRARIES)
         elif spec.platform == "darwin":
             libraries = self._get_libraries_macho()
         else:
@@ -75,7 +76,7 @@ def install(self, spec, prefix):
 
     def _get_libraries_macho(self):
         """Same as _get_libraries_elf but for Mach-O binaries"""
-        cc = Executable(self.compiler.cc)
+        cc = Executable(self.spec["gcc"].package.cc)
         path_and_install_name = []
 
         for name in self.LIBRARIES:
diff --git a/var/spack/repos/builtin/packages/gcc/package.py b/var/spack/repos/builtin/packages/gcc/package.py
index f220d8f5f3d..dfb929d8723 100644
--- a/var/spack/repos/builtin/packages/gcc/package.py
+++ b/var/spack/repos/builtin/packages/gcc/package.py
@@ -9,7 +9,7 @@
 
 from llnl.util.symlink import readlink
 
-import spack.compiler
+import spack.build_systems.compiler
 import spack.platforms
 import spack.repo
 import spack.util.libc
@@ -32,9 +32,9 @@ class Gcc(AutotoolsPackage, GNUMirrorPackage, CompilerPackage):
 
     license("GPL-2.0-or-later AND LGPL-2.1-or-later")
 
-    provides("c")
-    provides("cxx")
-    provides("fortran")
+    provides("c", when="languages=c")
+    provides("cxx", when="languages=c++")
+    provides("fortran", when="languages=fortran")
 
     version("master", branch="master")
 
@@ -594,7 +594,12 @@ def supported_languages(self):
         # This weirdness is because it could be called on an abstract spec
         if "languages" not in self.spec.variants:
             return self.compiler_languages
-        return [x for x in self.compiler_languages if x in self.spec.variants["languages"].value]
+        variant_value = {"cxx": "c++"}
+        return [
+            x
+            for x in self.compiler_languages
+            if self.spec.satisfies(f"languages={variant_value.get(x, x)}")
+        ]
 
     c_names = ["gcc"]
     cxx_names = ["g++"]
@@ -605,6 +610,40 @@ def supported_languages(self):
     compiler_version_regex = r"([0-9.]+)"
     compiler_version_argument = ("-dumpfullversion", "-dumpversion")
 
+    link_paths = {
+        "c": os.path.join("gcc", "gcc"),
+        "cxx": os.path.join("gcc", "g++"),
+        "fortran": os.path.join("gcc", "gfortran"),
+    }
+
+    debug_flags = ["-g", "-gstabs+", "-gstabs", "-gxcoff+", "-gxcoff", "-gvms"]
+    opt_flags = ["-O", "-O0", "-O1", "-O2", "-O3", "-Os", "-Ofast", "-Og"]
+
+    required_libs = ["libgcc", "libgfortran"]
+    stdcxx_libs = "-lstdc++"
+
+    def _standard_flag(self, *, language, standard):
+        flags = {
+            "cxx": {
+                "98": [("@6:", "-std=c++98"), ("@:5", "")],
+                "11": [("@4.3:4.6", "-std=c++0x"), ("@4.7:", "-std=c++11")],
+                "14": [("@4.8", "-std=c++1y"), ("@4.9:", "-std=c++14")],
+                "17": [("@5", "-std=c++1z"), ("@6:", "-std=c++17")],
+                "20": [("@8:10", "-std=c++2a"), ("@11:", "-std=c++20")],
+                "23": [("@11:13", "-std=c++2b"), ("@14:", "-std=c++23")],
+            },
+            "c": {"99": [("@4.5:", "-std=c99")], "11": [("@4.7:", "-std=c11")]},
+        }
+        for condition, flag in flags[language][standard]:
+            if self.spec.satisfies(condition):
+                return flag
+
+        else:
+            raise RuntimeError(
+                f"{self.spec} does not support the '{standard}' standard "
+                f"for the '{language}' language"
+            )
+
     @classmethod
     def filter_detected_exes(cls, prefix, exes_in_prefix):
         # Apple's gcc is actually apple clang, so skip it.
@@ -612,7 +651,9 @@ def filter_detected_exes(cls, prefix, exes_in_prefix):
             not_apple_clang = []
             for exe in exes_in_prefix:
                 try:
-                    output = spack.compiler.get_compiler_version_output(exe, "--version")
+                    output = spack.build_systems.compiler.compiler_output(
+                        exe, version_argument="--version"
+                    )
                 except Exception:
                     output = ""
                 if "clang version" in output:
@@ -1157,7 +1198,7 @@ def runtime_constraints(cls, *, spec, pkg):
         )
         pkg("*").depends_on(
             f"gcc-runtime@{str(spec.version)}:",
-            when=f"%{str(spec)}",
+            when=f"^[deptypes=build] {spec.name}@{spec.versions}",
             type="link",
             description=f"If any package uses %{str(spec)}, "
             f"it depends on gcc-runtime@{str(spec.version)}:",
@@ -1172,18 +1213,21 @@ def runtime_constraints(cls, *, spec, pkg):
         for fortran_virtual in ("fortran-rt", gfortran_str):
             pkg("*").depends_on(
                 fortran_virtual,
-                when=f"%{str(spec)}",
-                languages=["fortran"],
+                when=f"^[virtuals=fortran deptypes=build] {spec.name}@{spec.versions}",
                 type="link",
                 description=f"Add a dependency on '{gfortran_str}' for nodes compiled with "
                 f"{str(spec)} and using the 'fortran' language",
             )
         # The version of gcc-runtime is the same as the %gcc used to "compile" it
-        pkg("gcc-runtime").requires(f"@={str(spec.version)}", when=f"%{str(spec)}")
+        pkg("gcc-runtime").requires(
+            f"@{str(spec.versions)}", when=f"^[deptypes=build] {spec.name}@{spec.versions}"
+        )
 
         # If a node used %gcc@X.Y its dependencies must use gcc-runtime@:X.Y
         # (technically @:X is broader than ... <= @=X but this should work in practice)
-        pkg("*").propagate(f"%gcc@:{str(spec.version)}", when=f"%{str(spec)}")
+        pkg("*").propagate(
+            f"gcc@:{str(spec.version)}", when=f"^[deptypes=build] {spec.name}@{spec.versions}"
+        )
 
     def _post_buildcache_install_hook(self):
         if not self.spec.satisfies("platform=linux"):
diff --git a/var/spack/repos/builtin/packages/glibc/package.py b/var/spack/repos/builtin/packages/glibc/package.py
index 3e2130a217e..46d851c5d5f 100644
--- a/var/spack/repos/builtin/packages/glibc/package.py
+++ b/var/spack/repos/builtin/packages/glibc/package.py
@@ -111,6 +111,8 @@ class Glibc(AutotoolsPackage, GNUMirrorPackage):
     # include_next <limits.h> not working
     patch("67fbfa5.patch", when="@:2.7")
 
+    conflicts("musl")
+
     def setup_build_environment(self, env):
         if self.spec.satisfies("@:2.21"):
             env.append_flags("LDFLAGS", "-no-pie")
diff --git a/var/spack/repos/builtin/packages/go/package.py b/var/spack/repos/builtin/packages/go/package.py
index db4f7ca2482..3d3a2bf64ac 100644
--- a/var/spack/repos/builtin/packages/go/package.py
+++ b/var/spack/repos/builtin/packages/go/package.py
@@ -83,6 +83,9 @@ class Go(Package):
 
     phases = ["build", "install"]
 
+    depends_on("c", type="build")
+    depends_on("cxx", type="build")
+
     def url_for_version(self, version):
         return f"https://go.dev/dl/go{version}.src.tar.gz"
 
@@ -95,8 +98,8 @@ def determine_version(cls, exe):
     def setup_build_environment(self, env):
         # We need to set CC/CXX_FOR_TARGET, otherwise cgo will use the
         # internal Spack wrappers and fail.
-        env.set("CC_FOR_TARGET", self.compiler.cc)
-        env.set("CXX_FOR_TARGET", self.compiler.cxx)
+        env.set("CC_FOR_TARGET", self.spec["c"].package.cc)
+        env.set("CXX_FOR_TARGET", self.spec["cxx"].package.cxx)
         env.set("GOMAXPROCS", make_jobs)
 
     def build(self, spec, prefix):
diff --git a/var/spack/repos/builtin/packages/intel-oneapi-compilers-classic/package.py b/var/spack/repos/builtin/packages/intel-oneapi-compilers-classic/package.py
index f6dcbec83ec..60727f3ace4 100644
--- a/var/spack/repos/builtin/packages/intel-oneapi-compilers-classic/package.py
+++ b/var/spack/repos/builtin/packages/intel-oneapi-compilers-classic/package.py
@@ -108,3 +108,30 @@ def symlink_dir(self, src, dest):
                 link_tree.merge(dest_path)
             else:
                 os.symlink(src_path, dest_path)
+
+    @property
+    def cc(self):
+        msg = "cannot retrieve C compiler [spec is not concrete]"
+        assert self.spec.concrete, msg
+        if self.spec.external:
+            return self.spec.extra_attributes["compilers"].get("c", None)
+        return str(self.prefix.bin.icc)
+
+    @property
+    def cxx(self):
+        msg = "cannot retrieve C++ compiler [spec is not concrete]"
+        assert self.spec.concrete, msg
+        if self.spec.external:
+            return self.spec.extra_attributes["compilers"].get("cxx", None)
+        return str(self.prefix.bin.icpc)
+
+    @property
+    def fortran(self):
+        msg = "cannot retrieve Fortran compiler [spec is not concrete]"
+        assert self.spec.concrete, msg
+        if self.spec.external:
+            return self.spec.extra_attributes["compilers"].get("fortran", None)
+        return str(self.prefix.bin.ifort)
+
+    def archspec_name(self):
+        return "intel"
diff --git a/var/spack/repos/builtin/packages/intel-oneapi-compilers/package.py b/var/spack/repos/builtin/packages/intel-oneapi-compilers/package.py
index 4e7dfdf634e..e55a39afa32 100644
--- a/var/spack/repos/builtin/packages/intel-oneapi-compilers/package.py
+++ b/var/spack/repos/builtin/packages/intel-oneapi-compilers/package.py
@@ -1,9 +1,11 @@
 # Copyright Spack Project Developers. See COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-
 import os
+import os.path
+import pathlib
 import platform
+import warnings
 
 from spack.build_environment import dso_suffix
 from spack.package import *
@@ -329,6 +331,47 @@ class IntelOneapiCompilers(IntelOneApiPackage, CompilerPackage):
         r"(?:(?:oneAPI DPC\+\+(?:\/C\+\+)? Compiler)|(?:\(IFORT\))|(?:\(IFX\))) (\S+)"
     )
 
+    debug_flags = ["-debug", "-g", "-g0", "-g1", "-g2", "-g3"]
+    opt_flags = ["-O", "-O0", "-O1", "-O2", "-O3", "-Ofast", "-Os"]
+
+    openmp_flag = "-fiopenmp"
+
+    link_paths = {
+        "c": os.path.join("oneapi", "icx"),
+        "cxx": os.path.join("oneapi", "icpx"),
+        "fortran": os.path.join("oneapi", "ifx"),
+    }
+
+    required_libs = [
+        "libirc",
+        "libifcore",
+        "libifcoremt",
+        "libirng",
+        "libsvml",
+        "libintlc",
+        "libimf",
+        "libsycl",
+        "libOpenCL",
+    ]
+
+    stdcxx_libs = ("-cxxlib",)
+
+    provides("c")
+    provides("cxx")
+    provides("fortran")
+
+    def _standard_flag(self, *, language, standard):
+        flags = {
+            "cxx": {
+                "11": "-std=c++11",
+                "14": "-std=c++14",
+                "17": "-std=c++17",
+                "20": "-std=c++20",
+            },
+            "c": {"99": "-std=c99", "11": "-std=c1x"},
+        }
+        return flags[language][standard]
+
     # See https://github.com/spack/spack/issues/39252
     depends_on("patchelf@:0.17", type="build", when="@:2024.1")
     # Add the nvidia variant
@@ -337,10 +380,8 @@ class IntelOneapiCompilers(IntelOneApiPackage, CompilerPackage):
     # Add the amd variant
     variant("amd", default=False, description="Install AMD plugin for OneAPI")
     conflicts("@:2022.2.1", when="+amd", msg="Codeplay AMD plugin requires newer release")
-    # TODO: effectively gcc is a direct dependency of intel-oneapi-compilers, but we
-    # cannot express that properly. For now, add conflicts for non-gcc compilers
-    # instead.
-    requires("%gcc", msg="intel-oneapi-compilers must be installed with %gcc")
+
+    depends_on("gcc languages=c,c++", type="run")
 
     for v in versions:
         version(v["version"], expand=False, **v["cpp"])
@@ -419,6 +460,31 @@ def setup_run_environment(self, env):
         env.set("F77", self._llvm_bin.ifx)
         env.set("FC", self._llvm_bin.ifx)
 
+    def setup_dependent_build_environment(self, env, dependent_spec):
+        super().setup_dependent_build_environment(env, dependent_spec)
+        # workaround bug in icpx driver where it requires sycl-post-link is on the PATH
+        # It is located in the same directory as the driver. Error message:
+        #   clang++: error: unable to execute command:
+        #   Executable "sycl-post-link" doesn't exist!
+        # also ensures that shared objects and libraries required by the compiler,
+        # e.g. libonnx, can be found succesfully
+        # due to a fix, this is no longer required for OneAPI versions >= 2024.2
+        bin_dir = os.path.dirname(self.cxx)
+        lib_dir = os.path.join(os.path.dirname(bin_dir), "lib")
+        if self.cxx and self.spec.satisfies("%oneapi@:2024.1"):
+            env.prepend_path("PATH", bin_dir)
+            env.prepend_path("LD_LIBRARY_PATH", lib_dir)
+
+        # 2024 release bumped the libsycl version because of an ABI
+        # change, 2024 compilers are required.  You will see this
+        # error:
+        #
+        # /usr/bin/ld: warning: libsycl.so.7, needed by ...., not found
+        if self.spec.satisfies("%oneapi@:2023"):
+            for c in ["dnn"]:
+                if self.spec.satisfies(f"^intel-oneapi-{c}@2024:"):
+                    warnings.warn(f"intel-oneapi-{c}@2024 SYCL APIs requires %oneapi@2024:")
+
     def install(self, spec, prefix):
         # Copy instead of install to speed up debugging
         # install_tree("/opt/intel/oneapi/compiler", self.prefix)
@@ -514,9 +580,9 @@ def extend_config_flags(self):
             common_flags = ["-Wl,-rpath,{}".format(d) for d in self._ld_library_path()]
 
         # Make sure that underlying clang gets the right GCC toolchain by default
-        llvm_flags = ["--gcc-toolchain={}".format(self.compiler.prefix)]
-        classic_flags = ["-gcc-name={}".format(self.compiler.cc)]
-        classic_flags.append("-gxx-name={}".format(self.compiler.cxx))
+        gcc = self.spec["gcc"].package
+        llvm_flags = [f"--gcc-toolchain={gcc.prefix}"]
+        classic_flags = [f"-gcc-name={gcc.cc}", f"-gxx-name={gcc.cxx}"]
 
         # Older versions trigger -Wunused-command-line-argument warnings whenever
         # linker flags are passed in preprocessor (-E) or compilation mode (-c).
@@ -551,6 +617,24 @@ def _ld_library_path(self):
             if find(p, "*." + dso_suffix, recursive=False):
                 yield p
 
+    def archspec_name(self):
+        return "oneapi"
+
+    @classmethod
+    def determine_variants(cls, exes, version_str):
+        variant, extra_attributes = super().determine_variants(exes, version_str)
+
+        bin_dirs = {pathlib.Path(x).parent for x in exes}
+        if len(bin_dirs) != 1:
+            dirs = ", ".join([str(x) for x in sorted(bin_dirs)])
+            raise RuntimeError(f"executables found in multiple dirs: {dirs}")
+        bin_dir = bin_dirs.pop()
+        prefix_parts = bin_dir.parts[: bin_dir.parts.index("compiler")]
+        computed_prefix = pathlib.Path(*prefix_parts)
+        extra_attributes["prefix"] = str(computed_prefix)
+
+        return variant, extra_attributes
+
     @classmethod
     def runtime_constraints(cls, *, spec, pkg):
         pkg("*").depends_on(
@@ -561,7 +645,7 @@ def runtime_constraints(cls, *, spec, pkg):
         )
         pkg("*").depends_on(
             f"intel-oneapi-runtime@{str(spec.version)}:",
-            when=f"%{str(spec)}",
+            when=f"^[deptypes=build] {spec.name}@{spec.versions}",
             type="link",
             description=f"If any package uses %{str(spec)}, "
             f"it depends on intel-oneapi-runtime@{str(spec.version)}:",
@@ -570,11 +654,43 @@ def runtime_constraints(cls, *, spec, pkg):
         for fortran_virtual in ("fortran-rt", "libifcore@5"):
             pkg("*").depends_on(
                 fortran_virtual,
-                when=f"%{str(spec)}",
-                languages=["fortran"],
+                when=f"^[virtuals=fortran deptypes=build] {spec.name}@{spec.versions}",
                 type="link",
                 description=f"Add a dependency on 'libifcore' for nodes compiled with "
                 f"{str(spec)} and using the 'fortran' language",
             )
         # The version of intel-oneapi-runtime is the same as the %oneapi used to "compile" it
-        pkg("intel-oneapi-runtime").requires(f"@={str(spec.version)}", when=f"%{str(spec)}")
+        pkg("intel-oneapi-runtime").requires(
+            f"@{str(spec.versions)}", when=f"^[deptypes=build] {spec.name}@{spec.versions}"
+        )
+
+        # If a node used %intel-oneapi=runtime@X.Y its dependencies must use @:X.Y
+        # (technically @:X is broader than ... <= @=X but this should work in practice)
+        pkg("*").propagate(
+            f"intel-oneapi-compilers@:{str(spec.version)}",
+            when=f"^[deptypes=build] {spec.name}@{spec.versions}",
+        )
+
+    @property
+    def cc(self):
+        msg = "cannot retrieve C compiler [spec is not concrete]"
+        assert self.spec.concrete, msg
+        if self.spec.external:
+            return self.spec.extra_attributes["compilers"].get("c", None)
+        return str(self._llvm_bin.icx)
+
+    @property
+    def cxx(self):
+        msg = "cannot retrieve C++ compiler [spec is not concrete]"
+        assert self.spec.concrete, msg
+        if self.spec.external:
+            return self.spec.extra_attributes["compilers"].get("cxx", None)
+        return str(self._llvm_bin.icpx)
+
+    @property
+    def fortran(self):
+        msg = "cannot retrieve Fortran compiler [spec is not concrete]"
+        assert self.spec.concrete, msg
+        if self.spec.external:
+            return self.spec.extra_attributes["compilers"].get("fortran", None)
+        return str(self._llvm_bin.ifx)
diff --git a/var/spack/repos/builtin/packages/intel-oneapi-mpi/package.py b/var/spack/repos/builtin/packages/intel-oneapi-mpi/package.py
index 609ba05c167..29c1d0ce303 100644
--- a/var/spack/repos/builtin/packages/intel-oneapi-mpi/package.py
+++ b/var/spack/repos/builtin/packages/intel-oneapi-mpi/package.py
@@ -200,11 +200,17 @@ def setup_dependent_package(self, module, dep_spec):
 
     def setup_dependent_build_environment(self, env, dependent_spec):
         dependent_module = dependent_spec.package.module
-        env.set("I_MPI_CC", dependent_module.spack_cc)
-        env.set("I_MPI_CXX", dependent_module.spack_cxx)
-        env.set("I_MPI_F77", dependent_module.spack_f77)
-        env.set("I_MPI_F90", dependent_module.spack_fc)
-        env.set("I_MPI_FC", dependent_module.spack_fc)
+        for var_name, attr_name in (
+            ("I_MPI_CC", "spack_cc"),
+            ("I_MPI_CXX", "spack_cxx"),
+            ("I_MPI_FC", "spack_fc"),
+            ("I_MPI_F90", "spack_fc"),
+            ("I_MPI_F77", "spack_f77"),
+        ):
+            if not hasattr(dependent_module, attr_name):
+                continue
+
+            env.set(var_name, getattr(dependent_module, attr_name))
 
         # Set compiler wrappers for dependent build stage
         wrappers = self.wrapper_paths()
diff --git a/var/spack/repos/builtin/packages/intel-oneapi-runtime/package.py b/var/spack/repos/builtin/packages/intel-oneapi-runtime/package.py
index 2ff2e5b1889..d4548efc48e 100644
--- a/var/spack/repos/builtin/packages/intel-oneapi-runtime/package.py
+++ b/var/spack/repos/builtin/packages/intel-oneapi-runtime/package.py
@@ -19,8 +19,7 @@ class IntelOneapiRuntime(Package):
 
     tags = ["runtime"]
 
-    requires("%oneapi")
-
+    depends_on("intel-oneapi-compilers", type="build")
     depends_on("gcc-runtime", type="link")
 
     LIBRARIES = [
@@ -46,7 +45,8 @@ class IntelOneapiRuntime(Package):
     depends_on("libc", type="link", when="platform=linux")
 
     def install(self, spec, prefix):
-        libraries = get_elf_libraries(compiler=self.compiler, libraries=self.LIBRARIES)
+        oneapi_pkg = self.spec["intel-oneapi-compilers"].package
+        libraries = get_elf_libraries(compiler=oneapi_pkg, libraries=self.LIBRARIES)
         mkdir(prefix.lib)
 
         if not libraries:
diff --git a/var/spack/repos/builtin/packages/intel/package.py b/var/spack/repos/builtin/packages/intel/package.py
index 5e4159d8f99..67c3dddfaf2 100644
--- a/var/spack/repos/builtin/packages/intel/package.py
+++ b/var/spack/repos/builtin/packages/intel/package.py
@@ -3,7 +3,9 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 import re
 
-import spack.compiler
+import llnl.util.tty as tty
+
+import spack.build_systems.compiler
 from spack.package import *
 
 
@@ -234,7 +236,9 @@ class Intel(IntelPackage):
     def determine_version(cls, exe):
         version_regex = re.compile(r"\((?:IFORT|ICC)\) ([^ ]+)")
         try:
-            output = spack.compiler.get_compiler_version_output(exe, "--version")
+            output = spack.build_systems.compiler.compiler_output(
+                exe, version_argument="--version"
+            )
             match = version_regex.search(output)
             if match:
                 return match.group(1)
diff --git a/var/spack/repos/builtin/packages/libxml2/package.py b/var/spack/repos/builtin/packages/libxml2/package.py
index baf0672cd80..724236b2705 100644
--- a/var/spack/repos/builtin/packages/libxml2/package.py
+++ b/var/spack/repos/builtin/packages/libxml2/package.py
@@ -110,7 +110,7 @@ def url_for_version(self, version):
 
     def flag_handler(self, name, flags):
         if name == "cflags" and self.spec.satisfies("+pic"):
-            flags.append(self.compiler.cc_pic_flag)
+            flags.append(self.spec["c"].package.pic_flag)
             flags.append("-DPIC")
         return (flags, None, None)
 
diff --git a/var/spack/repos/builtin/packages/llvm-amdgpu/package.py b/var/spack/repos/builtin/packages/llvm-amdgpu/package.py
index 1b887702295..c93ba1890c2 100644
--- a/var/spack/repos/builtin/packages/llvm-amdgpu/package.py
+++ b/var/spack/repos/builtin/packages/llvm-amdgpu/package.py
@@ -6,17 +6,23 @@
 import shutil
 
 from spack.package import *
+from spack.pkg.builtin.llvm import LlvmDetection
 
 
-class LlvmAmdgpu(CMakePackage, CompilerPackage):
+class LlvmAmdgpu(CMakePackage, LlvmDetection, CompilerPackage):
     """Toolkit for the construction of highly optimized compilers,
     optimizers, and run-time environments."""
 
     homepage = "https://github.com/ROCm/llvm-project"
     git = "https://github.com/ROCm/llvm-project.git"
     url = "https://github.com/ROCm/llvm-project/archive/rocm-6.2.4.tar.gz"
-    tags = ["rocm"]
+    tags = ["rocm", "compiler"]
     executables = [r"amdclang", r"amdclang\+\+", r"amdflang", r"clang.*", r"flang.*", "llvm-.*"]
+
+    link_paths = {"c": "rocmcc/amdclang", "cxx": "rocmcc/amdclang++", "fortran": "rocmcc/amdflang"}
+
+    stdcxx_libs = ("-lstdc++",)
+
     generator("ninja")
 
     maintainers("srekolam", "renjithravindrankannath", "haampie", "afzpatel")
@@ -215,6 +221,15 @@ class LlvmAmdgpu(CMakePackage, CompilerPackage):
         when="@master",
     )
 
+    stdcxx_libs = ("-lstdc++",)
+
+    def _standard_flag(self, *, language, standard):
+        flags = {
+            "cxx": {"11": "-std=c++11", "14": "-std=c++14", "17": "-std=c++17"},
+            "c": {"99": "-std=c99", "11": "-std=c1x"},
+        }
+        return flags[language][standard]
+
     def cmake_args(self):
         llvm_projects = ["clang", "lld", "clang-tools-extra", "compiler-rt"]
         llvm_runtimes = ["libcxx", "libcxxabi"]
@@ -338,3 +353,27 @@ def setup_dependent_build_environment(self, env, dependent_spec):
             if "libclang_rt.asan-x86_64.so" in files:
                 env.prepend_path("LD_LIBRARY_PATH", root)
         env.prune_duplicate_paths("LD_LIBRARY_PATH")
+
+    @property
+    def cc(self):
+        msg = "cannot retrieve C compiler [spec is not concrete]"
+        assert self.spec.concrete, msg
+        if self.spec.external:
+            return self.spec.extra_attributes["compilers"].get("c", None)
+        return os.path.join(self.spec.prefix.bin, "amdclang")
+
+    @property
+    def cxx(self):
+        msg = "cannot retrieve C++ compiler [spec is not concrete]"
+        assert self.spec.concrete, msg
+        if self.spec.external:
+            return self.spec.extra_attributes["compilers"].get("cxx", None)
+        return os.path.join(self.spec.prefix.bin, "amdclang++")
+
+    @property
+    def fc(self):
+        msg = "cannot retrieve Fortran compiler [spec is not concrete]"
+        assert self.spec.concrete, msg
+        if self.spec.external:
+            return self.spec.extra_attributes["compilers"].get("fc", None)
+        return os.path.join(self.spec.prefix.bin, "amdflang")
diff --git a/var/spack/repos/builtin/packages/llvm/package.py b/var/spack/repos/builtin/packages/llvm/package.py
index ba6606d9d1c..5f81c4d0525 100644
--- a/var/spack/repos/builtin/packages/llvm/package.py
+++ b/var/spack/repos/builtin/packages/llvm/package.py
@@ -7,7 +7,6 @@
 
 from llnl.util.lang import classproperty
 
-import spack.compilers
 from spack.build_systems.cmake import get_cmake_prefix_path
 from spack.operating_systems.mac_os import macos_sdk_path
 from spack.package import *
@@ -394,6 +393,9 @@ class Llvm(CMakePackage, CudaPackage, LlvmDetection, CompilerPackage):
     provides("libllvm@4", when="@4.0.0:4")
     provides("libllvm@3", when="@3.0.0:3")
 
+    provides("c", "cxx", when="+clang")
+    provides("fortran", when="+flang")
+
     extends("python", when="+python")
 
     # Build dependency
@@ -495,9 +497,9 @@ class Llvm(CMakePackage, CudaPackage, LlvmDetection, CompilerPackage):
             },
         }.items():
             with when(v):
-                for comp in spack.compilers.supported_compilers():
-                    conflicts("%{0}{1}".format(comp, compiler_conflicts.get(comp, "")))
-        del v, compiler_conflicts, comp
+                for _name, _constraint in compiler_conflicts.items():
+                    conflicts(f"%{_name}{_constraint}")
+        del v, compiler_conflicts, _name, _constraint
 
     # libomptarget
     conflicts("+cuda", when="@15:")  # +cuda variant is obselete since LLVM 15
@@ -875,6 +877,55 @@ def f77(self):
             result = os.path.join(self.spec.prefix.bin, "flang")
         return result
 
+    debug_flags = [
+        "-gcodeview",
+        "-gdwarf-2",
+        "-gdwarf-3",
+        "-gdwarf-4",
+        "-gdwarf-5",
+        "-gline-tables-only",
+        "-gmodules",
+        "-g",
+    ]
+
+    opt_flags = ["-O0", "-O1", "-O2", "-O3", "-Ofast", "-Os", "-Oz", "-Og", "-O", "-O4"]
+
+    link_paths = {
+        "c": os.path.join("clang", "clang"),
+        "cxx": os.path.join("clang", "clang++"),
+        "fortran": os.path.join("clang", "flang"),
+    }
+
+    required_libs = ["libclang"]
+
+    def _standard_flag(self, *, language, standard):
+        flags = {
+            "cxx": {
+                "11": [("@3.3:", "-std=c++11")],
+                "14": [("@3.5:", "-std=c++14")],
+                "17": [("@3.5:4", "-std=c++1z"), ("@5:", "-std=c++17")],
+                "20": [("@5:10", "-std=c++2a"), ("@11:", "-std=c++20")],
+                "23": [("@12:16", "-std=c++2b"), ("@17:", "-std=c++23")],
+            },
+            "c": {
+                "99": [("@:", "-std=c99")],
+                "11": [("@3.1:", "-std=c11")],
+                "17": [("@6:", "-std=c17")],
+                "23": [("@9:17", "-std=c2x"), ("@18:", "-std=c23")],
+            },
+        }
+        for condition, flag in flags[language][standard]:
+            if self.spec.satisfies(condition):
+                return flag
+        else:
+            raise RuntimeError(
+                f"{self.spec} does not support the '{standard}' standard "
+                f"for the '{language}' language"
+            )
+
+    def archspec_name(self):
+        return "clang"
+
     @property
     def libs(self):
         return LibraryList(self.llvm_config("--libfiles", "all", result="list"))
diff --git a/var/spack/repos/builtin/packages/mapl/package.py b/var/spack/repos/builtin/packages/mapl/package.py
index bfe8e3f1eb6..8393aad514c 100644
--- a/var/spack/repos/builtin/packages/mapl/package.py
+++ b/var/spack/repos/builtin/packages/mapl/package.py
@@ -4,7 +4,6 @@
 
 import subprocess
 
-import spack.compiler
 from spack.package import *
 
 
@@ -256,9 +255,7 @@ class Mapl(CMakePackage):
     # MAPL can use ifx only from MAPL 2.51 onwards and only supports
     # ifx 2025.0 and newer due to bugs in ifx.
     conflicts("%oneapi@2025:", when="@:2.50")
-    # NOTE there is a further check on oneapi in the cmake_args below
-    # that is hard to conflict since we don't know the fortran compiler
-    # at this point
+    conflicts("^[virtuals=fortran] intel-oneapi-compilers")
 
     variant("flap", default=False, description="Build with FLAP support", when="@:2.39")
     variant("pflogger", default=True, description="Build with pFlogger support")
@@ -381,33 +378,14 @@ def cmake_args(self):
         fflags = []
         if self.compiler.name in ["gcc", "clang", "apple-clang"]:
             fflags.append("-ffree-line-length-none")
-            gfortran_major_ver = int(
-                spack.compiler.get_compiler_version_output(self.compiler.fc, "-dumpversion").split(
-                    "."
-                )[0]
-            )
+
+            gfortran_major_ver = int(self.spec["fortran"].version[0])
             if gfortran_major_ver >= 10:
                 fflags.append("-fallow-invalid-boz")
                 fflags.append("-fallow-argument-mismatch")
         if fflags:
             args.append(self.define("CMAKE_Fortran_FLAGS", " ".join(fflags)))
 
-        # If oneapi@:2024 is used and it gets past the conflict above, we might be
-        # using ifx or ifort. If we are using ifx and the MAPL version is 2.50 or older
-        # we need to raise an error
-
-        if self.spec.satisfies("@:2.50 %oneapi@:2024"):
-            # We now need to get which Fortran compiler is used here but there
-            # isn't an easy way like:
-            #   if self.spec["fortran"].name == "ifx":
-            # yet (see https://github.com/spack/spack/pull/45189)
-            # So we need to parse the output of $FC --version
-            output = spack.compiler.get_compiler_version_output(
-                self.compiler.fc, "-diag-disable=10448 --version", ignore_errors=True
-            )
-            if "ifx" in output:
-                raise InstallError("MAPL versions 2.50 and older do not support ifx")
-
         # Scripts often need to know the MPI stack used to setup the environment.
         # Normally, we can autodetect this, but building with Spack does not
         # seem to work. We need to pass in the MPI stack used to CMake
diff --git a/var/spack/repos/builtin/packages/mpich/package.py b/var/spack/repos/builtin/packages/mpich/package.py
index 817d6fb6267..baac23c1616 100644
--- a/var/spack/repos/builtin/packages/mpich/package.py
+++ b/var/spack/repos/builtin/packages/mpich/package.py
@@ -6,7 +6,7 @@
 import re
 import sys
 
-import spack.compilers
+import spack.compilers.config
 import spack.package_base
 from spack.package import *
 
@@ -383,7 +383,7 @@ def determine_version(cls, exe):
     @classmethod
     def determine_variants(cls, exes, version):
         def get_spack_compiler_spec(compiler):
-            spack_compilers = spack.compilers.find_compilers([os.path.dirname(compiler)])
+            spack_compilers = spack.compilers.config.find_compilers([os.path.dirname(compiler)])
             actual_compiler = None
             # check if the compiler actually matches the one we want
             for spack_compiler in spack_compilers:
@@ -509,25 +509,6 @@ def autoreconf(self, spec, prefix):
         bash = which("bash")
         bash("./autogen.sh")
 
-    @run_before("autoreconf")
-    def die_without_fortran(self):
-        # Until we can pass variants such as +fortran through virtual
-        # dependencies depends_on('mpi'), require Fortran compiler to
-        # avoid delayed build errors in dependents.
-        # The user can work around this by disabling Fortran explicitly
-        # with ~fortran
-
-        f77 = self.compiler.f77
-        fc = self.compiler.fc
-
-        fortran_missing = f77 is None or fc is None
-
-        if "+fortran" in self.spec and fortran_missing:
-            raise InstallError(
-                "mpich +fortran requires Fortran compilers. Configure "
-                "Fortran compiler or disable Fortran support with ~fortran"
-            )
-
     def configure_args(self):
         spec = self.spec
         config_args = [
diff --git a/var/spack/repos/builtin/packages/msvc/package.py b/var/spack/repos/builtin/packages/msvc/package.py
index ec365721b1e..f6677829627 100644
--- a/var/spack/repos/builtin/packages/msvc/package.py
+++ b/var/spack/repos/builtin/packages/msvc/package.py
@@ -1,9 +1,15 @@
 # Copyright Spack Project Developers. See COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
+import os.path
 import re
+import subprocess
 
-import spack.compiler
+import archspec.cpu
+
+import spack.build_systems.compiler
+import spack.platforms
+import spack.version
 from spack.package import *
 
 
@@ -26,13 +32,26 @@ def install(self, spec, prefix):
     compiler_version_argument = ""
     compiler_version_regex = r"([1-9][0-9]*\.[0-9]*\.[0-9]*)"
 
+    # Named wrapper links within build_env_path
+    # Due to the challenges of supporting compiler wrappers
+    # in Windows, we leave these blank, and dynamically compute
+    # based on proper versions of MSVC from there
+    # pending acceptance of #28117 for full support using
+    # compiler wrappers
+    link_paths = {"c": "", "cxx": "", "fortran": ""}
+
+    provides("c", "cxx")
+    requires("platform=windows", msg="MSVC is only supported on Windows")
+
     @classmethod
     def determine_version(cls, exe):
         # MSVC compiler does not have a proper version argument
         # Errors out and prints version info with no args
         match = re.search(
             cls.compiler_version_regex,
-            spack.compiler.get_compiler_version_output(exe, version_arg=None, ignore_errors=True),
+            spack.build_systems.compiler.compiler_output(
+                exe, version_argument=None, ignore_errors=1
+            ),
         )
         if match:
             return match.group(1)
@@ -58,9 +77,164 @@ def cxx(self):
         msg = "cannot retrieve C++ compiler [spec is not concrete]"
         assert self.spec.concrete, msg
 
+    def setup_dependent_build_environment(self, env, dependent_spec):
+        self.init_msvc()
+        # Set the build environment variables for spack. Just using
+        # subprocess.call() doesn't work since that operates in its own
+        # environment which is destroyed (along with the adjusted variables)
+        # once the process terminates. So go the long way around: examine
+        # output, sort into dictionary, use that to make the build
+        # environment.
+
+        # vcvars can target specific sdk versions, force it to pick up concretized sdk
+        # version, if needed by spec
+        if dependent_spec.name != "win-sdk" and "win-sdk" in dependent_spec:
+            self.vcvars_call.sdk_ver = dependent_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())
+            if key and value
+        )
+
+        for env_var in int_env:
+            if os.pathsep not in int_env[env_var]:
+                env.set(env_var, int_env[env_var])
+            else:
+                env.set_path(env_var, int_env[env_var].split(os.pathsep))
+
+        env.set("CC", self.cc)
+        env.set("CXX", self.cxx)
+
+    def init_msvc(self):
+        # 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(os.path.dirname(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("-", "_")
+        if str(archspec.cpu.host().family) == "x86_64":
+            arch = "amd64"
+
+        msvc_version = spack.version.Version(
+            re.search(Msvc.compiler_version_regex, self.cc).group(1)
+        )
+        self.vcvars_call = VCVarsInvocation(vcvars_script_path, arch, msvc_version)
+        env_cmds.append(self.vcvars_call)
+        self.msvc_compiler_environment = CmdCall(*env_cmds)
+
+    def _standard_flag(self, *, language: str, standard: str) -> str:
+        flags = {
+            "cxx": {
+                "11": "/std:c++11",
+                "14": "/std:c++14",
+                "17": "/std:c++17",
+                "20": "/std:c++20",
+            },
+            "c": {"11": "/std:c11", "17": "/std:c17"},
+        }
+        return flags[language][standard]
+
+
+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 fortran(self):
-        if self.spec.external:
-            return self.spec.extra_attributes["compilers"]["fortran"]
-        msg = "cannot retrieve Fortran compiler [spec is not concrete]"
-        assert self.spec.concrete, msg
+    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}"
+
+
+FC_PATH = {}
+
+
+def get_valid_fortran_pth():
+    """Assign maximum available fortran compiler version"""
+    # TODO (johnwparent): validate compatibility w/ try compiler
+    # functionality when added
+    sort_fn = lambda fc_ver: spack.version.Version(fc_ver)
+    sort_fc_ver = sorted(list(FC_PATH.keys()), key=sort_fn)
+    return FC_PATH[sort_fc_ver[-1]] if sort_fc_ver else None
diff --git a/var/spack/repos/builtin/packages/musl/package.py b/var/spack/repos/builtin/packages/musl/package.py
index 516f538b16e..9ec77c895b0 100644
--- a/var/spack/repos/builtin/packages/musl/package.py
+++ b/var/spack/repos/builtin/packages/musl/package.py
@@ -48,6 +48,8 @@ class Musl(MakefilePackage):
 
     depends_on("c", type="build")  # generated
 
+    conflicts("glibc")
+
     def patch(self):
         config = FileFilter("configure")
         if self.compiler.name == "gcc":
diff --git a/var/spack/repos/builtin/packages/mvapich2/package.py b/var/spack/repos/builtin/packages/mvapich2/package.py
index f4f242965b3..2c704891966 100644
--- a/var/spack/repos/builtin/packages/mvapich2/package.py
+++ b/var/spack/repos/builtin/packages/mvapich2/package.py
@@ -6,7 +6,7 @@
 import re
 import sys
 
-import spack.compilers
+import spack.compilers.config
 from spack.package import *
 from spack.pkg.builtin.mpich import MpichEnvironmentModifications
 
@@ -172,7 +172,7 @@ def determine_version(cls, exe):
     @classmethod
     def determine_variants(cls, exes, version):
         def get_spack_compiler_spec(path):
-            spack_compilers = spack.compilers.find_compilers([path])
+            spack_compilers = spack.compilers.config.find_compilers([path])
             for spack_compiler in spack_compilers:
                 if os.path.dirname(spack_compiler.cc) == path:
                     return spack_compiler.spec
diff --git a/var/spack/repos/builtin/packages/nag/package.py b/var/spack/repos/builtin/packages/nag/package.py
index 74482793320..cca7669e363 100644
--- a/var/spack/repos/builtin/packages/nag/package.py
+++ b/var/spack/repos/builtin/packages/nag/package.py
@@ -2,6 +2,7 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 import os
+import os.path
 
 from spack.package import *
 
@@ -72,6 +73,48 @@ def setup_run_environment(self, env):
     compiler_version_regex = r"NAG Fortran Compiler Release (\d+).(\d+)\(.*\) Build (\d+)"
     compiler_version_argument = "-V"
 
+    # Unlike other compilers, the NAG compiler passes options to GCC, which
+    # then passes them to the linker. Therefore, we need to doubly wrap the
+    # options with '-Wl,-Wl,,'
+    rpath_arg = "-Wl,-Wl,,-rpath,,"
+    linker_arg = "-Wl,-Wl,,"
+    disable_new_dtags = ""
+    enable_new_dtags = ""
+    debug_flags = ["-g", "-gline", "-g90"]
+    opt_flags = ["-O", "-O0", "-O1", "-O2", "-O3", "-O4"]
+
+    link_paths = {"fortran": os.path.join("nag", "nagfor")}
+
+    # NAG does not support a flag that would enable verbose output and
+    # compilation/linking at the same time (with either '-#' or '-dryrun'
+    # the compiler only prints the commands but does not run them).
+    # Therefore, the only thing we can do is to pass the '-v' argument to
+    # the underlying GCC. In order to get verbose output from the latter
+    # at both compile and linking stages, we need to call NAG with two
+    # additional flags: '-Wc,-v' and '-Wl,-v'. However, we return only
+    # '-Wl,-v' for the following reasons:
+    #   1) the interface of this method does not support multiple flags in
+    #      the return value and, at least currently, verbose output at the
+    #      linking stage has a higher priority for us;
+    #   2) NAG is usually mixed with GCC compiler, which also accepts
+    #      '-Wl,-v' and produces meaningful result with it: '-v' is passed
+    #      to the linker and the latter produces verbose output for the
+    #      linking stage ('-Wc,-v', however, would break the compilation
+    #      with a message from GCC that the flag is not recognized).
+    #
+    # This way, we at least enable the implicit rpath detection, which is
+    # based on compilation of a C file (see method
+    # spack.compiler._compile_dummy_c_source): in the case of a mixed
+    # NAG/GCC toolchain, the flag will be passed to g++ (e.g.
+    # 'g++ -Wl,-v ./main.c'), otherwise, the flag will be passed to nagfor
+    # (e.g. 'nagfor -Wl,-v ./main.c' - note that nagfor recognizes '.c'
+    # extension and treats the file accordingly). The list of detected
+    # rpaths will contain only GCC-related directories and rpaths to
+    # NAG-related directories are injected by nagfor anyway.
+    verbose_flag = "-Wl,-v"
+
+    openmp_flag = "-openmp"
+
     @property
     def fortran(self):
         msg = "cannot retrieve Fortran compiler [spec is not concrete]"
diff --git a/var/spack/repos/builtin/packages/ncurses/package.py b/var/spack/repos/builtin/packages/ncurses/package.py
index 6a800f41f6b..451d1cc73fc 100644
--- a/var/spack/repos/builtin/packages/ncurses/package.py
+++ b/var/spack/repos/builtin/packages/ncurses/package.py
@@ -106,9 +106,9 @@ def setup_build_environment(self, env):
 
     def flag_handler(self, name, flags):
         if name == "cflags":
-            flags.append(self.compiler.cc_pic_flag)
+            flags.append(self.spec["c"].package.pic_flag)
         elif name == "cxxflags":
-            flags.append(self.compiler.cxx_pic_flag)
+            flags.append(self.spec["cxx"].package.pic_flag)
 
         # ncurses@:6.0 fails in definition of macro 'mouse_trafo' without -P
         if self.spec.satisfies("@:6.0 %gcc@5.0:"):
@@ -118,7 +118,7 @@ def flag_handler(self, name, flags):
         # ncurses@:6.0 uses dynamic exception specifications not allowed in c++17
         if self.spec.satisfies("@:5"):
             if name == "cxxflags":
-                flags.append(self.compiler.cxx14_flag)
+                flags.append(self.spec["cxx"].package.standard_flag(language="cxx", standard="14"))
 
         return (flags, None, None)
 
diff --git a/var/spack/repos/builtin/packages/nvhpc/package.py b/var/spack/repos/builtin/packages/nvhpc/package.py
index fe530a289ae..e7b53da0b6e 100644
--- a/var/spack/repos/builtin/packages/nvhpc/package.py
+++ b/var/spack/repos/builtin/packages/nvhpc/package.py
@@ -3,7 +3,7 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 #
 # Copyright (c) 2020, NVIDIA CORPORATION. All rights reserved.
-
+import os.path
 import platform
 
 from spack.package import *
@@ -446,9 +446,7 @@ class Nvhpc(Package, CompilerPackage):
         if pkg:
             version(ver, sha256=pkg[0], url=pkg[1])
 
-    depends_on("c", type="build")  # generated
-    depends_on("cxx", type="build")  # generated
-    depends_on("fortran", type="build")  # generated
+    depends_on("gcc languages=c,c++,fortran", type="run")
 
     variant("blas", default=True, description="Enable BLAS")
     variant(
@@ -469,7 +467,8 @@ class Nvhpc(Package, CompilerPackage):
     provides("lapack", when="+lapack")
     provides("mpi", when="+mpi")
 
-    requires("%gcc", msg="nvhpc must be installed with %gcc")
+    provides("c", "cxx")
+    provides("fortran")
 
     # For now we only detect compiler components
     # It will require additional work to detect mpi/lapack/blas components
@@ -480,6 +479,28 @@ class Nvhpc(Package, CompilerPackage):
     compiler_version_argument = "--version"
     compiler_version_regex = r"nv[^ ]* (?:[^ ]+ Dev-r)?([0-9.]+)(?:-[0-9]+)?"
 
+    debug_flags = ["-g", "-gopt"]
+    opt_flags = ["-O", "-O0", "-O1", "-O2", "-O3", "-O4"]
+
+    pic_flag = "-fpic"
+    openmp_flag = "-mp"
+
+    link_paths = {
+        "c": os.path.join("nvhpc", "nvc"),
+        "cxx": os.path.join("nvhpc", "nvc++"),
+        "fortran": os.path.join("nvhpc", "nvfortran"),
+    }
+
+    required_libs = ["libnvc", "libnvf"]
+    stdcxx_libs = ("-c++libs",)
+
+    def _standard_flag(self, *, language, standard):
+        flags = {
+            "cxx": {"11": "--c++11", "14": "--c++14", "17": "--c++17"},
+            "c": {"99": "-c99", "11": "-c11"},
+        }
+        return flags[language][standard]
+
     @classmethod
     def determine_variants(cls, exes, version_str):
         # TODO: use other exes to determine default_cuda/install_type/blas/lapack/mpi variants
@@ -509,11 +530,11 @@ def install(self, spec, prefix):
 
         makelocalrc_args = [
             "-gcc",
-            self.compiler.cc,
+            spec["gcc"].package.cc,
             "-gpp",
-            self.compiler.cxx,
+            spec["gcc"].package.cxx,
             "-g77",
-            self.compiler.f77,
+            spec["gcc"].package.fortran,
             "-x",
             compilers_bin,
         ]
diff --git a/var/spack/repos/builtin/packages/openfoam/package.py b/var/spack/repos/builtin/packages/openfoam/package.py
index 90cb3c784ff..2eb1770cdd5 100644
--- a/var/spack/repos/builtin/packages/openfoam/package.py
+++ b/var/spack/repos/builtin/packages/openfoam/package.py
@@ -918,7 +918,12 @@ class OpenfoamArch:
 
     #: Map spack compiler names to OpenFOAM compiler names
     #  By default, simply capitalize the first letter
-    compiler_mapping = {"aocc": "Amd", "fj": "Fujitsu", "intel": "Icc", "oneapi": "Icx"}
+    compiler_mapping = {
+        "aocc": "Amd",
+        "fj": "Fujitsu",
+        "intel": "Icc",
+        "intel-oneapi-compilers": "Icx",
+    }
 
     def __init__(self, spec, **kwargs):
         # Some user settings, to be adjusted manually or via variants
diff --git a/var/spack/repos/builtin/packages/openmpi/package.py b/var/spack/repos/builtin/packages/openmpi/package.py
index 6591f04bae5..14836bd1fb6 100644
--- a/var/spack/repos/builtin/packages/openmpi/package.py
+++ b/var/spack/repos/builtin/packages/openmpi/package.py
@@ -7,7 +7,9 @@
 import re
 import sys
 
-import spack.compilers
+import llnl.util.tty as tty
+
+import spack.compilers.config
 from spack.package import *
 
 
@@ -898,10 +900,16 @@ def setup_run_environment(self, env):
     def setup_dependent_build_environment(self, env, dependent_spec):
         # Use the spack compiler wrappers under MPI
         dependent_module = dependent_spec.package.module
-        env.set("OMPI_CC", dependent_module.spack_cc)
-        env.set("OMPI_CXX", dependent_module.spack_cxx)
-        env.set("OMPI_FC", dependent_module.spack_fc)
-        env.set("OMPI_F77", dependent_module.spack_f77)
+        for var_name, attr_name in (
+            ("OMPI_CC", "spack_cc"),
+            ("OMPI_CXX", "spack_cxx"),
+            ("OMPI_FC", "spack_fc"),
+            ("OMPI_F77", "spack_f77"),
+        ):
+            if not hasattr(dependent_module, attr_name):
+                continue
+
+            env.set(var_name, getattr(dependent_module, attr_name))
 
         # See https://www.open-mpi.org/faq/?category=building#installdirs
         for suffix in [
@@ -1351,7 +1359,7 @@ def test_example(self):
 
 
 def get_spack_compiler_spec(compiler):
-    spack_compilers = spack.compilers.find_compilers([os.path.dirname(compiler)])
+    spack_compilers = spack.compilers.config.find_compilers([os.path.dirname(compiler)])
     actual_compiler = None
     # check if the compiler actually matches the one we want
     for spack_compiler in spack_compilers:
diff --git a/var/spack/repos/builtin/packages/openssl/package.py b/var/spack/repos/builtin/packages/openssl/package.py
index 27cddb8d36f..f08ebbadb0e 100644
--- a/var/spack/repos/builtin/packages/openssl/package.py
+++ b/var/spack/repos/builtin/packages/openssl/package.py
@@ -154,7 +154,7 @@ def install(self, spec, prefix):
         if spec.satisfies("@1.0"):
             options.append("no-krb5")
         # clang does not support the .arch directive in assembly files.
-        if "clang" in self.compiler.cc and spec.target.family == "aarch64":
+        if "clang" in self.spec["c"].package.cc and spec.target.family == "aarch64":
             options.append("no-asm")
         elif "%nvhpc" in spec:
             # Last tested on nvidia@22.3 for x86_64:
diff --git a/var/spack/repos/builtin/packages/perl/package.py b/var/spack/repos/builtin/packages/perl/package.py
index 3f8e1605826..835b5ae89bd 100644
--- a/var/spack/repos/builtin/packages/perl/package.py
+++ b/var/spack/repos/builtin/packages/perl/package.py
@@ -337,7 +337,7 @@ def do_stage(self, mirror_only=False):
     def nmake_arguments(self):
         args = []
         if self.spec.satisfies("%msvc"):
-            args.append("CCTYPE=%s" % self.compiler.short_msvc_version)
+            args.append("CCTYPE=%s" % self.spec["msvc"].package.short_msvc_version)
         else:
             raise RuntimeError("Perl unsupported for non MSVC compilers on Windows")
         args.append("INST_TOP=%s" % windows_sfn(self.prefix.replace("/", "\\")))
@@ -384,7 +384,7 @@ def configure_args(self):
         # https://github.com/spack/spack/pull/3081 and
         # https://github.com/spack/spack/pull/4416
         if spec.satisfies("%intel"):
-            config_args.append("-Accflags={0}".format(self.compiler.cc_pic_flag))
+            config_args.append("-Accflags={0}".format(self.spec["cc"].package.pic_flag))
 
         if "+shared" in spec:
             config_args.append("-Duseshrplib")
@@ -546,9 +546,10 @@ def filter_config_dot_pm(self):
             "-MModule::Loaded", "-MConfig", "-e", "print is_loaded(Config)", output=str
         )
 
+        c_compiler = self.spec["c"].package.cc
         with self.make_briefly_writable(config_dot_pm):
             match = "cc *=>.*"
-            substitute = "cc => '{cc}',".format(cc=self.compiler.cc)
+            substitute = "cc => '{cc}',".format(cc=c_compiler)
             filter_file(match, substitute, config_dot_pm, **kwargs)
 
         # And the path Config_heavy.pl
@@ -557,11 +558,11 @@ def filter_config_dot_pm(self):
 
         with self.make_briefly_writable(config_heavy):
             match = "^cc=.*"
-            substitute = "cc='{cc}'".format(cc=self.compiler.cc)
+            substitute = "cc='{cc}'".format(cc=c_compiler)
             filter_file(match, substitute, config_heavy, **kwargs)
 
             match = "^ld=.*"
-            substitute = "ld='{ld}'".format(ld=self.compiler.cc)
+            substitute = "ld='{ld}'".format(ld=c_compiler)
             filter_file(match, substitute, config_heavy, **kwargs)
 
             match = "^ccflags='"
diff --git a/var/spack/repos/builtin/packages/python/package.py b/var/spack/repos/builtin/packages/python/package.py
index c380f24b57a..143b094f7bc 100644
--- a/var/spack/repos/builtin/packages/python/package.py
+++ b/var/spack/repos/builtin/packages/python/package.py
@@ -692,7 +692,7 @@ def configure_args(self):
         config_args.append("--without-ensurepip")
 
         if "+pic" in spec:
-            cflags.append(self.compiler.cc_pic_flag)
+            cflags.append(self.spec["c"].package.pic_flag)
 
         if "+ssl" in spec:
             config_args.append("--with-openssl={0}".format(spec["openssl"].prefix))
@@ -810,9 +810,9 @@ def filter_compilers(self):
 
         filenames = [self.get_sysconfigdata_name(), self.config_vars["makefile_filename"]]
 
-        filter_file(spack_cc, self.compiler.cc, *filenames, **kwargs)
-        if spack_cxx and self.compiler.cxx:
-            filter_file(spack_cxx, self.compiler.cxx, *filenames, **kwargs)
+        filter_file(spack_cc, self.spec["c"].package.cc, *filenames, **kwargs)
+        if spack_cxx:
+            filter_file(spack_cxx, self.spec["cxx"].package.cxx, *filenames, **kwargs)
 
     @run_after("install")
     def symlink(self):
@@ -1288,7 +1288,13 @@ def setup_dependent_build_environment(self, env, dependent_spec):
         # try to modify LDSHARED (LDCXXSHARED), the second variable, which is
         # used for linking, in a consistent manner.
 
-        for compile_var, link_var in [("CC", "LDSHARED"), ("CXX", "LDCXXSHARED")]:
+        for language, compile_var, link_var in [
+            ("c", "CC", "LDSHARED"),
+            ("cxx", "CXX", "LDCXXSHARED"),
+        ]:
+            if not dependent_spec.dependencies(virtuals=(language,)):
+                continue
+
             # First, we get the values from the sysconfigdata:
             config_compile = self.config_vars[compile_var]
             config_link = self.config_vars[link_var]
@@ -1296,8 +1302,7 @@ def setup_dependent_build_environment(self, env, dependent_spec):
             # The dependent environment will have the compilation command set to
             # the following:
             new_compile = join_path(
-                spack.paths.build_env_path,
-                dependent_spec.package.compiler.link_paths[compile_var.lower()],
+                spack.paths.build_env_path, dependent_spec[language].package.link_paths[language]
             )
 
             # Normally, the link command starts with the compilation command:
diff --git a/var/spack/repos/builtin/packages/spectrum-mpi/package.py b/var/spack/repos/builtin/packages/spectrum-mpi/package.py
index 13a4be26c6b..a5b0871684f 100644
--- a/var/spack/repos/builtin/packages/spectrum-mpi/package.py
+++ b/var/spack/repos/builtin/packages/spectrum-mpi/package.py
@@ -4,7 +4,7 @@
 import os
 import re
 
-import spack.compilers
+import spack.compilers.config
 from spack.package import *
 
 
@@ -48,7 +48,7 @@ def get_host_compiler(exe):
         def get_spack_compiler_spec(compilers_found):
             # check using cc for now, as everyone should have that defined.
             path = os.path.dirname(compilers_found["cc"])
-            spack_compilers = spack.compilers.find_compilers([path])
+            spack_compilers = spack.compilers.config.find_compilers([path])
             actual_compiler = None
             # check if the compiler actually matches the one we want
             for spack_compiler in spack_compilers:
diff --git a/var/spack/repos/builtin/packages/taskflow/package.py b/var/spack/repos/builtin/packages/taskflow/package.py
index 44e76d98587..331cc2dcc2d 100644
--- a/var/spack/repos/builtin/packages/taskflow/package.py
+++ b/var/spack/repos/builtin/packages/taskflow/package.py
@@ -2,7 +2,7 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
-from spack.compiler import UnsupportedCompilerFlag
+from spack.compilers.error import UnsupportedCompilerFlag
 from spack.package import *
 
 
diff --git a/var/spack/repos/builtin/packages/vasp/package.py b/var/spack/repos/builtin/packages/vasp/package.py
index 8744f076066..d682a02ede1 100644
--- a/var/spack/repos/builtin/packages/vasp/package.py
+++ b/var/spack/repos/builtin/packages/vasp/package.py
@@ -86,7 +86,7 @@ class Vasp(MakefilePackage, CudaPackage):
     depends_on("nccl", when="@6.3: +cuda")
     depends_on("hdf5+fortran+mpi", when="+hdf5")
     # at the very least the nvhpc mpi seems required
-    depends_on("nvhpc+mpi+lapack+blas", when="%nvhpc")
+    requires("^nvhpc+mpi+lapack+blas", when="%nvhpc")
 
     conflicts(
         "%gcc@:8", msg="GFortran before 9.x does not support all features needed to build VASP"
diff --git a/var/spack/repos/builtin/packages/win-file/package.py b/var/spack/repos/builtin/packages/win-file/package.py
index 29624b31693..0f66363b6e8 100644
--- a/var/spack/repos/builtin/packages/win-file/package.py
+++ b/var/spack/repos/builtin/packages/win-file/package.py
@@ -22,6 +22,8 @@ class WinFile(Package):
 
     version("5.45", sha256="11b8f3abf647c711bc50ef8451c8d6e955f11c4afd8b0a98f2ac65e9b6e10d5e")
 
+    depends_on("c", type="build")
+
     @classmethod
     def determine_version(cls, exe):
         output = Executable(exe)("--version", output=str, error=str)
diff --git a/var/spack/repos/builtin/packages/win-gpg/package.py b/var/spack/repos/builtin/packages/win-gpg/package.py
index 501668703fc..8c0876f8e79 100644
--- a/var/spack/repos/builtin/packages/win-gpg/package.py
+++ b/var/spack/repos/builtin/packages/win-gpg/package.py
@@ -23,6 +23,8 @@ class WinGpg(Package):
 
     version("2.4.5", sha256="249ab87bd06abea3140054089bad44d9a5d1531413590576da609142db2673ec")
 
+    depends_on("c", type="build")
+
     @classmethod
     def determine_version(cls, exe):
         output = Executable(exe)("--version", output=str, error=str)
diff --git a/var/spack/repos/builtin/packages/xl/package.py b/var/spack/repos/builtin/packages/xl/package.py
index 438ac4c214d..c63bcd54fdb 100644
--- a/var/spack/repos/builtin/packages/xl/package.py
+++ b/var/spack/repos/builtin/packages/xl/package.py
@@ -1,6 +1,8 @@
 # Copyright Spack Project Developers. See COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
+import os.path
+
 from spack.package import *
 
 
@@ -14,6 +16,9 @@ class Xl(Package, CompilerPackage):
 
     variant("r", default=True, description="The _r version of compilers")
 
+    provides("c", "cxx")
+    provides("fortran")
+
     def install(self, spec, prefix):
         raise InstallError(
             "XL compilers are not installable yet, but can be "
@@ -27,6 +32,48 @@ def install(self, spec, prefix):
     compiler_version_argument = "-qversion"
     compiler_version_regex = r"([0-9]?[0-9]\.[0-9])"
 
+    pic_flag = "-qpic"
+    openmp_flag = "-qsmp=omp"
+
+    debug_flags = ["-g", "-g0", "-g1", "-g2", "-g8", "-g9"]
+    opt_flags = ["-O", "-O0", "-O1", "-O2", "-O3", "-O4", "-O5", "-Ofast"]
+    verbose_flag = "-V"
+
+    @property
+    def link_paths(self):
+        if self.spec.satisfies("~r"):
+            return {
+                "c": os.path.join("xl", "xlc"),
+                "cxx": os.path.join("xl", "xlc++"),
+                "fortran": os.path.join("xl", "xlf"),
+            }
+
+        return {
+            "c": os.path.join("xl", "xlc_r"),
+            "cxx": os.path.join("xl", "xlc++_r"),
+            "fortran": os.path.join("xl", "xlf_r"),
+        }
+
+    def _standard_flag(self, *, language, standard):
+        flags = {
+            "cxx": {
+                "11": [("@13.1:", "-qlanglvl=extended0x")],
+                "14": [("@16.1.1.8:", "-std=c++14")],
+            },
+            "c": {
+                "99": [("@10.1:13.0", "-qlanglvl=extc99"), ("@13.1:", "-std=gnu99")],
+                "11": [("@12.1:13.1.1", "-qlanglvl=extc1x"), ("@13.1.2:", "-std=gnu11")],
+            },
+        }
+        for condition, flag in flags[language][standard]:
+            if self.spec.satisfies(condition):
+                return flag
+        else:
+            raise RuntimeError(
+                f"{self.spec} does not support the '{standard}' standard "
+                f"for the '{language}' language"
+            )
+
     @classmethod
     def determine_variants(cls, exes, version_str):
         _r_exes = [e for e in exes if e.endswith("_r")]
diff --git a/var/spack/repos/builtin/packages/yafyaml/package.py b/var/spack/repos/builtin/packages/yafyaml/package.py
index f1e4f699fee..ac2975d168a 100644
--- a/var/spack/repos/builtin/packages/yafyaml/package.py
+++ b/var/spack/repos/builtin/packages/yafyaml/package.py
@@ -3,9 +3,7 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
 import os
-import re
 
-import spack.compiler
 from spack.package import *
 
 
@@ -65,35 +63,8 @@ class Yafyaml(CMakePackage):
         msg="yaFyaml only works with the Fujitsu compiler from 1.3.0 onwards",
     )
 
-    # GCC 13.3 and higher only work with yafyaml 1.4.0 onwards
-    # First we can check if the spec is gcc@13.3...
     conflicts("%gcc@13.3:", when="@:1.3.0", msg="GCC 13.3+ only works with yafyaml 1.4.0 onwards")
 
-    # ...but if it is not (say apple-clang with gfortran as a fc), there is
-    # no easy way to check this. So we hijack flag_handler to raise an
-    # exception if we detect gfortran 13.3 or 14.
-    # NOTE: This will only error out at install time, so `spack spec` will
-    # not catch this.
-    def flag_handler(self, name, flags):
-        # We need to match any compiler that has a name of gfortran or gfortran-*
-        pattern = re.compile(r"gfortran(-\d+)?$")
-
-        if pattern.search(self.compiler.fc):
-            gfortran_version = spack.compiler.get_compiler_version_output(
-                self.compiler.fc, "-dumpfullversion"
-            ).strip()
-
-            # gfortran_version is now a string like "13.3.0". We now need to just capture
-            # the major and minor version numbers
-            gfortran_version = ".".join(gfortran_version.split(".")[:2])
-
-            if self.spec.satisfies("@:1.3.0") and (float(gfortran_version) >= 13.3):
-                raise InstallError(
-                    f"Your gfortran version {gfortran_version} is not compatible with "
-                    f"yafyaml 1.3.0 and below. Use yafyaml 1.4.0 or higher."
-                )
-        return None, None, None
-
     variant(
         "build_type",
         default="Release",
diff --git a/var/spack/repos/builtin/packages/zlib-ng/package.py b/var/spack/repos/builtin/packages/zlib-ng/package.py
index f0618245160..ffd10edb706 100644
--- a/var/spack/repos/builtin/packages/zlib-ng/package.py
+++ b/var/spack/repos/builtin/packages/zlib-ng/package.py
@@ -71,7 +71,7 @@ def libs(self):
 
     def flag_handler(self, name, flags):
         if name == "cflags" and self.spec.satisfies("+pic build_system=autotools"):
-            flags.append(self.compiler.cc_pic_flag)
+            flags.append(self.spec["c"].package.pic_flag)
         return (flags, None, None)