Avoid gobject-introspection dependency except if g-ir-scanner is from subproject

mesonbuild/modules/gnome.py

@@ -254,8 +254,8 @@ class GnomeModule(ExtensionModule):
 
     def __init__(self, interpreter: 'Interpreter') -> None:
         super().__init__(interpreter)
-        self.gir_dep: T.Optional[Dependency] = None
         self.giscanner: T.Optional[ToolType] = None
+        self.giscanner_extra: T.List[Dependency] = []
         self.gicompiler: T.Optional[ToolType] = None
         self.install_glib_compile_schemas = False
         self.install_gio_querymodules: T.List[str] = []
@@ -788,20 +788,26 @@ def postconf_hook(self, b: build.Build) -> None:
         if self.devenv is not None:
             b.devenv.append(self.devenv)
 
-    def _get_gir_dep(self, state: 'ModuleState') -> T.Tuple[Dependency, T.Union[Executable, 'ExternalProgram', 'OverrideProgram'],
-                                                            T.Union[Executable, 'ExternalProgram', 'OverrideProgram']]:
-        if not self.gir_dep:
-            self.gir_dep = state.dependency('gobject-introspection-1.0')
+    def _get_gi(self, state: 'ModuleState') -> T.Tuple[ToolType, T.List[Dependency], ToolType]:
+        if not self.giscanner:
             self.giscanner = self._find_tool(state, 'g-ir-scanner')
-            self.gicompiler = self._find_tool(state, 'g-ir-compiler')
-        return self.gir_dep, self.giscanner, self.gicompiler
+            if isinstance(self.giscanner, OverrideProgram):
+                # The gobject-introspection subproject just registers g-ir-scanner
+                # as a python script, with meson unaware of the native module the
+                # script depends upton that has to be built first. If g-i was
+                # configured with the right option, the gobject-introspection-1.0
+                # dependency itself indirectly depends on the native module; so if
+                # g-ir-scanner originates from a subproject, also add the g-i dep.
+                self.giscanner_extra.append(state.dependency('gobject-introspection-1.0'))
+            self.gicompiler = self._find_tool(state, 'g-ir-compiler', for_machine=MachineChoice.HOST)
+        return self.giscanner, self.giscanner_extra, self.gicompiler
 
     def _giscanner_version_compare(self, state: 'ModuleState', cmp: str) -> bool:
         # Support for --version was introduced in g-i 1.58, but Ubuntu
         # Bionic shipped 1.56.1. As all our version checks are greater
         # than 1.58, we can just return False if get_version fails.
         try:
-            giscanner, _, _ = self._get_gir_dep(state)
+            giscanner, _, _ = self._get_gi(state)
             return mesonlib.version_compare(giscanner.get_version(), cmp)
         except MesonException:
             return False
@@ -997,6 +1003,8 @@ def _make_gir_target(
         run_env.set('CFLAGS', [quote_arg(x) for x in env_flags], ' ')
         run_env.merge(kwargs['env'])
 
+        giscanner, _, _ = self._get_gi(state)
+
         # response file supported?
         rspable = self._giscanner_version_compare(state, '>= 1.85.0')
 
@@ -1150,7 +1158,7 @@ def generate_gir(self, state: 'ModuleState', args: T.Tuple[T.List[T.Union[Execut
         if len(girtargets) > 1 and any(isinstance(el, Executable) for el in girtargets):
             raise MesonException('generate_gir only accepts a single argument when one of the arguments is an executable')
 
-        gir_dep, giscanner, gicompiler = self._get_gir_dep(state)
+        giscanner, giscanner_extra, gicompiler = self._get_gi(state)
 
         ns = kwargs['namespace']
         nsversion = kwargs['nsversion']
@@ -1161,14 +1169,16 @@ def generate_gir(self, state: 'ModuleState', args: T.Tuple[T.List[T.Union[Execut
         builddir = os.path.join(state.environment.get_build_dir(), state.subdir)
 
         depends: T.List[T.Union['FileOrString', 'build.GeneratedTypes', build.BuildTarget, build.StructuredSources]] = []
-        depends.extend(gir_dep.sources)
+        for extra in giscanner_extra:
+            depends.extend(extra.sources)
         depends.extend(girtargets)
 
         langs_compilers = self._get_girtargets_langs_compilers(girtargets)
         cflags, internal_ldflags, external_ldflags = self._get_langs_compilers_flags(state, langs_compilers)
         deps = self._get_gir_targets_deps(girtargets)
         deps += kwargs['dependencies']
-        deps += [gir_dep]
+        deps += giscanner_extra # probably not necessary
+        deps += [state.dependency('glib-2.0'), state.dependency('gobject-2.0'), state.dependency('gmodule-2.0'), state.dependency('gio-2.0')]
         typelib_includes, depends = self._gather_typelib_includes_and_update_depends(state, deps, depends)
         # ldflags will be misinterpreted by gir scanner (showing
         # spurious dependencies) but building GStreamer fails if they