spack build-env: error when deps are not installed (#35533)

Currently we attempt to setup the build environment even when
dependencies are not installed, which typically results in error while
searching for libraries or executables in a dependency's prefix.

With this change, we get a more user friendly error:

```
$ spack build-env perl
==> Error: Not all dependencies of perl are installed, cannot setup build environment:
 -   qpj6dw5  perl@5.36.0%apple-clang@14.0.0+cpanm+open+shared+threads build_system=generic arch=darwin-ventura-m1
 -   jq2plbe      ^berkeley-db@18.1.40%apple-clang@14.0.0+cxx~docs+stl build_system=autotools patches=26090f4,b231fcc arch=darwin-ventura-m1
...
$ echo $?
1
```

lib/spack/spack/cmd/build_env.py

@@ -5,7 +5,7 @@
 import spack.cmd.common.env_utility as env_utility
 
 description = (
-    "run a command in a spec's install environment, " "or dump its environment to screen or file"
+    "run a command in a spec's install environment, or dump its environment to screen or file"
 )
 section = "build"
 level = "long"

lib/spack/spack/cmd/common/env_utility.py

@@ -12,7 +12,11 @@
 import spack.build_environment as build_environment
 import spack.cmd
 import spack.cmd.common.arguments as arguments
+import spack.error
 import spack.paths
+import spack.spec
+import spack.store
+from spack import traverse
 from spack.util.environment import dump_environment, pickle_environment
 
 
@@ -38,6 +42,41 @@ def setup_parser(subparser):
     )
 
 
+class AreDepsInstalledVisitor:
+    def __init__(self, context="build"):
+        if context not in ("build", "test"):
+            raise ValueError("context can only be build or test")
+
+        if context == "build":
+            self.direct_deps = ("build", "link", "run")
+        else:
+            self.direct_deps = ("build", "test", "link", "run")
+
+        self.has_uninstalled_deps = False
+
+    def accept(self, item):
+        # The root may be installed or uninstalled.
+        if item.depth == 0:
+            return True
+
+        # Early exit after we've seen an uninstalled dep.
+        if self.has_uninstalled_deps:
+            return False
+
+        spec = item.edge.spec
+        if not spec.external and not spec.installed:
+            self.has_uninstalled_deps = True
+            return False
+
+        return True
+
+    def neighbors(self, item):
+        # Direct deps: follow build & test edges.
+        # Transitive deps: follow link / run.
+        deptypes = self.direct_deps if item.depth == 0 else ("link", "run")
+        return item.edge.spec.edges_to_dependencies(deptype=deptypes)
+
+
 def emulate_env_utility(cmd_name, context, args):
     if not args.spec:
         tty.die("spack %s requires a spec." % cmd_name)
@@ -65,6 +104,27 @@ def emulate_env_utility(cmd_name, context, args):
 
     spec = spack.cmd.matching_spec_from_env(spec)
 
+    # Require that dependencies are installed.
+    visitor = AreDepsInstalledVisitor(context=context)
+
+    # Mass install check needs read transaction.
+    with spack.store.db.read_transaction():
+        traverse.traverse_breadth_first_with_visitor([spec], traverse.CoverNodesVisitor(visitor))
+
+    if visitor.has_uninstalled_deps:
+        raise spack.error.SpackError(
+            f"Not all dependencies of {spec.name} are installed. "
+            f"Cannot setup {context} environment:",
+            spec.tree(
+                status_fn=spack.spec.Spec.install_status,
+                hashlen=7,
+                hashes=True,
+                # This shows more than necessary, but we cannot dynamically change deptypes
+                # in Spec.tree(...).
+                deptypes="all" if context == "build" else ("build", "test", "link", "run"),
+            ),
+        )
+
     build_environment.setup_package(spec.package, args.dirty, context)
 
     if args.dump:

lib/spack/spack/cmd/test_env.py

@@ -5,7 +5,7 @@
 import spack.cmd.common.env_utility as env_utility
 
 description = (
-    "run a command in a spec's test environment, " "or dump its environment to screen or file"
+    "run a command in a spec's test environment, or dump its environment to screen or file"
 )
 section = "admin"
 level = "long"

lib/spack/spack/test/cmd/build_env.py

@@ -6,6 +6,7 @@
 
 import pytest
 
+import spack.error
 from spack.main import SpackCommand
 
 build_env = SpackCommand("build-env")
@@ -48,3 +49,10 @@ def test_pickle(tmpdir):
         environment = pickle.load(open(_out_file, "rb"))
         assert type(environment) == dict
         assert "PATH" in environment
+
+
+def test_failure_when_uninstalled_deps(config, mock_packages):
+    with pytest.raises(
+        spack.error.SpackError, match="Not all dependencies of dttop are installed"
+    ):
+        build_env("dttop")