Make BaseConfiguration pickleable (#47545)

Signed-off-by: Massimiliano Culpo <massimiliano.culpo@gmail.com>

lib/spack/spack/modules/common.py

@@ -330,18 +330,17 @@ class BaseConfiguration:
     default_projections = {"all": "{name}/{version}-{compiler.name}-{compiler.version}"}
 
     def __init__(self, spec: spack.spec.Spec, module_set_name: str, explicit: bool) -> None:
-        # Module where type(self) is defined
-        m = inspect.getmodule(self)
-        assert m is not None  # make mypy happy
-        self.module = m
         # Spec for which we want to generate a module file
         self.spec = spec
         self.name = module_set_name
         self.explicit = explicit
-        # Dictionary of configuration options that should be applied
-        # to the spec
+        # Dictionary of configuration options that should be applied to the spec
         self.conf = merge_config_rules(self.module.configuration(self.name), self.spec)
 
+    @property
+    def module(self):
+        return inspect.getmodule(self)
+
     @property
     def projections(self):
         """Projection from specs to module names"""
@@ -775,10 +774,6 @@ def __init__(
     ) -> None:
         self.spec = spec
 
-        # This class is meant to be derived. Get the module of the
-        # actual writer.
-        self.module = inspect.getmodule(self)
-        assert self.module is not None  # make mypy happy
         m = self.module
 
         # Create the triplet of configuration/layout/context
@@ -816,6 +811,10 @@ def __init__(
             name = type(self).__name__
             raise ModulercHeaderNotDefined(msg.format(name))
 
+    @property
+    def module(self):
+        return inspect.getmodule(self)
+
     def _get_template(self):
         """Gets the template that will be rendered for this spec."""
         # Get templates and put them in the order of importance:

lib/spack/spack/test/modules/common.py

@@ -2,6 +2,7 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 import os
+import pickle
 import stat
 
 import pytest
@@ -223,3 +224,10 @@ def test_check_module_set_name(mutable_config):
 
     with pytest.raises(spack.error.ConfigError, match=msg):
         spack.cmd.modules.check_module_set_name("third")
+
+
+@pytest.mark.parametrize("module_type", ["tcl", "lmod"])
+def test_module_writers_are_pickleable(default_mock_concretization, module_type):
+    s = default_mock_concretization("mpileaks")
+    writer = spack.modules.module_types[module_type](s, "default")
+    assert pickle.loads(pickle.dumps(writer)).spec == s