update the devenv module hooks to support generic modifications to Build

We may want to do things like update install scripts as well, which have
to happen before generating the backend. Instead of adding one module
method per thing to do, use a single function that allows for modifying
the Build object directly.

mesonbuild/modules/__init__.py

@@ -31,7 +31,7 @@ if T.TYPE_CHECKING:
     from ..interpreterbase import TYPE_var, TYPE_kwargs
     from ..programs import OverrideProgram
     from ..wrap import WrapMode
-    from ..build import EnvironmentVariables, Executable
+    from ..build import Executable
     from ..dependencies import Dependency
 
 class ModuleState:
@@ -219,8 +219,8 @@ class NewExtensionModule(ModuleObject):
     def found() -> bool:
         return True
 
-    def get_devenv(self) -> T.Optional['EnvironmentVariables']:
+    def postconf_hook(self, b: build.Build) -> None:
-        return None
+        pass
 
 # FIXME: Port all modules to stop using self.interpreter and use API on
 # ModuleState instead. Modules should stop using this class and instead use

mesonbuild/modules/gnome.py

@@ -784,8 +784,9 @@ class GnomeModule(ExtensionModule):
             self.devenv = build.EnvironmentVariables()
         self.devenv.prepend(varname, [value])
 
-    def get_devenv(self) -> T.Optional[build.EnvironmentVariables]:
+    def postconf_hook(self, b: build.Build) -> None:
-        return self.devenv
+        if self.devenv is not None:
+            b.devenv.append(self.devenv)
 
     def _get_gir_dep(self, state: 'ModuleState') -> T.Tuple[Dependency, T.Union[build.Executable, 'ExternalProgram', 'OverrideProgram'],
                                                             T.Union[build.Executable, 'ExternalProgram', 'OverrideProgram']]:

mesonbuild/msetup.py

@@ -251,13 +251,14 @@ class MesonApp:
             # sync with the time that gets applied to any files. Thus, we dump this file as late as
             # possible, but before build files, and if any error occurs, delete it.
             cdf = env.dump_coredata()
+
+            self.finalize_postconf_hooks(b, intr)
             if self.options.profile:
                 fname = f'profile-{intr.backend.name}-backend.log'
                 fname = os.path.join(self.build_dir, 'meson-private', fname)
                 profile.runctx('intr.backend.generate()', globals(), locals(), filename=fname)
             else:
                 intr.backend.generate()
-            self._finalize_devenv(b, intr)
             build.save(b, dumpfile)
             if env.first_invocation:
                 # Use path resolved by coredata because they could have been
@@ -300,13 +301,11 @@ class MesonApp:
                     os.unlink(cdf)
             raise
 
-    def _finalize_devenv(self, b: build.Build, intr: interpreter.Interpreter) -> None:
+    def finalize_postconf_hooks(self, b: build.Build, intr: interpreter.Interpreter) -> None:
         b.devenv.append(intr.backend.get_devenv())
         b.devenv.append(PkgConfigDependency.get_env(intr.environment, MachineChoice.HOST, uninstalled=True))
         for mod in intr.modules.values():
-            devenv = mod.get_devenv()
+            mod.postconf_hook(b)
-            if devenv:
-                b.devenv.append(devenv)
 
 def run(options: T.Union[argparse.Namespace, T.List[str]]) -> int:
     if not isinstance(options, argparse.Namespace):