Add subscript notation to packages (spack#48467)

This PR allows using the subscript notation directly on packages. The
intent is to reduce the boilerplate needed to retrieve package
properties from nodes other than root.

Author: alalazo

lib/spack/spack/package_base.py

@@ -767,6 +767,9 @@ def __init__(self, spec):
         self.win_rpath = fsys.WindowsSimulatedRPath(self)
         super().__init__()
 
+    def __getitem__(self, key: str) -> "PackageBase":
+        return self.spec[key].package
+
     @classmethod
     def dependency_names(cls):
         return _subkeys(cls.dependencies)

lib/spack/spack/test/package_class.py

@@ -285,3 +285,16 @@ def compilers(compiler, arch_spec):
     error = capfd.readouterr()[1]
     assert "Skipping tests for package" in error
     assert "test requires missing compiler" in error
+
+
+def test_package_subscript(default_mock_concretization):
+    """Tests that we can use the subscript notation on packages, and that it returns a package"""
+    root = default_mock_concretization("mpileaks")
+    root_pkg = root.package
+
+    # Subscript of a virtual
+    assert isinstance(root_pkg["mpi"], spack.package_base.PackageBase)
+
+    # Subscript on concrete
+    for d in root.traverse():
+        assert isinstance(root_pkg[d.name], spack.package_base.PackageBase)

var/spack/repos/builtin/packages/cp2k/package.py

@@ -790,7 +790,7 @@ def edit(self, pkg, spec, prefix):
                     "# include Plumed.inc as recommended by"
                     "PLUMED to include libraries and flags"
                 )
-                mkf.write("include {0}\n".format(spec["plumed"].package.plumed_inc))
+                mkf.write("include {0}\n".format(self.pkg["plumed"].plumed_inc))
 
             mkf.write("\n# COMPILER, LINKER, TOOLS\n\n")
             mkf.write(

var/spack/repos/builtin/packages/glvis/package.py

@@ -153,7 +153,7 @@ def common_args(self):
             "CC={0}".format(env["CC"]),
             "PREFIX={0}".format(self.spec.prefix.bin),
             "MFEM_DIR={0}".format(self.spec["mfem"].prefix),
-            "CONFIG_MK={0}".format(self.spec["mfem"].package.config_mk),
+            "CONFIG_MK={0}".format(self.pkg["mfem"].config_mk),
         ]
 
         # https://github.com/spack/spack/issues/42839

var/spack/repos/builtin/packages/gromacs/package.py

@@ -585,7 +585,7 @@ def patch(self):
             )
 
         if self.spec.satisfies("+plumed"):
-            self.spec["plumed"].package.apply_patch(self)
+            self["plumed"].apply_patch(self)
 
         if self.spec.satisfies("%nvhpc"):
             # Disable obsolete workaround

var/spack/repos/builtin/packages/laghos/package.py

@@ -58,8 +58,8 @@ def build_targets(self):
         spec = self.spec
 
         targets.append("MFEM_DIR=%s" % spec["mfem"].prefix)
-        targets.append("CONFIG_MK=%s" % spec["mfem"].package.config_mk)
-        targets.append("TEST_MK=%s" % spec["mfem"].package.test_mk)
+        targets.append("CONFIG_MK=%s" % self["mfem"].config_mk)
+        targets.append("TEST_MK=%s" % self["mfem"].test_mk)
         if spec.satisfies("@:2.0"):
             targets.append("CXX=%s" % spec["mpi"].mpicxx)
         if self.spec.satisfies("+ofast %gcc"):

var/spack/repos/builtin/packages/mfem/package.py

@@ -1309,7 +1309,7 @@ def libs(self):
     @property
     def config_mk(self):
         """Export the location of the config.mk file.
-        This property can be accessed using spec["mfem"].package.config_mk
+        This property can be accessed using pkg["mfem"].config_mk
         """
         dirs = [self.prefix, self.prefix.share.mfem]
         for d in dirs:
@@ -1321,7 +1321,7 @@ def config_mk(self):
     @property
     def test_mk(self):
         """Export the location of the test.mk file.
-        This property can be accessed using spec["mfem"].package.test_mk.
+        This property can be accessed using pkg["mfem"].test_mk.
         In version 3.3.2 and newer, the location of test.mk is also defined
         inside config.mk, variable MFEM_TEST_MK.
         """

var/spack/repos/builtin/packages/namd/package.py

@@ -147,11 +147,9 @@ def _copy_arch_file(self, lib):
     def _append_option(self, opts, lib):
         if lib != "python":
             self._copy_arch_file(lib)
-        spec = self.spec
+        lib_pkg = self[lib]
         lib_prefix = (
-            spec[lib].package.component_prefix
-            if spec[lib].name == "intel-oneapi-mkl"
-            else spec[lib].prefix
+            lib_pkg.component_prefix if lib_pkg.name == "intel-oneapi-mkl" else lib_pkg.prefix
         )
         opts.extend(["--with-{0}".format(lib), "--{0}-prefix".format(lib), lib_prefix])
 

var/spack/repos/builtin/packages/nfft/package.py

@@ -35,7 +35,7 @@ class Nfft(AutotoolsPackage):
     @property
     def fftw_selected_precisions(self):
         if not self._fftw_precisions:
-            self._fftw_precisions = self.spec["fftw"].package.selected_precisions
+            self._fftw_precisions = self["fftw"].selected_precisions
         return self._fftw_precisions
 
     def configure(self, spec, prefix):

var/spack/repos/builtin/packages/openvdb/package.py

@@ -84,10 +84,10 @@ def post_install(self):
                 pyso = "pyopenvdb.dylib"
             else:
                 pyso = "pyopenvdb.so"
-            pyver = "python{0}".format(spec["python"].package.version.up_to(2))
+            pyver = f"python{self['python'].version.up_to(2)}"
 
-            src = prefix.lib.join(pyver).join(pyso)
+            src = self.prefix.lib.join(pyver).join(pyso)
             if not os.path.isfile(src):
-                src = prefix.lib64.join(pyver).join(pyso)
+                src = self.prefix.lib64.join(pyver).join(pyso)
             assert os.path.isfile(src)
             os.rename(src, os.path.join(python_platlib, pyso))