interpreter: store correct files for project regeneration

Right now sub-sub projects are not correctly registered, because we
don't have a way to pass up past the first level of subproject. This
patch changes that by making the build_Def_files as defined in the
Interpreter initializer accurate for translated dependencies, ie, cmake
dependencies won't define a dependency on a non-existent meson.build.
This means that it can always add the subi.build_def_files because they
are always accurate.

mesonbuild/interpreter.py

@@ -2383,6 +2383,7 @@ class Interpreter(InterpreterBase):
                 default_project_options: T.Optional[T.Dict[str, str]] = None,
                 mock: bool = False,
                 ast: T.Optional[mparser.CodeBlockNode] = None,
+                is_translated: bool = False,
             ) -> None:
         super().__init__(build.environment.get_source_dir(), subdir, subproject)
         self.an_unpicklable_object = mesonlib.an_unpicklable_object
@@ -2421,8 +2422,16 @@ class Interpreter(InterpreterBase):
             self.default_project_options = {}
         self.project_default_options = {}
         self.build_func_dict()
+
         # build_def_files needs to be defined before parse_project is called
-        self.build_def_files = [os.path.join(self.subdir, environment.build_filename)]
+        #
+        # For non-meson subprojects, we'll be using the ast. Even if it does
+        # exist we don't want to add a dependency on it, it's autogenerated
+        # from the actual build files, and is just for reference.
+        self.build_def_files = []
+        build_filename = os.path.join(self.subdir, environment.build_filename)
+        if not is_translated:
+            self.build_def_files.append(build_filename)
         if not mock:
             self.parse_project()
         self._redetect_machines()
@@ -2941,11 +2950,14 @@ external dependencies (including libraries) must go to "dependencies".''')
                 return self.disabled_subproject(subp_name, exception=e)
             raise e
 
-    def _do_subproject_meson(self, subp_name, subdir, default_options, kwargs, ast=None, build_def_files=None):
+    def _do_subproject_meson(self, subp_name: str, subdir: str, default_options, kwargs,
+                             ast: T.Optional[mparser.CodeBlockNode] = None,
+                             build_def_files: T.Optional[T.List[str]] = None,
+                             is_translated: bool = False) -> SubprojectHolder:
         with mlog.nested():
             new_build = self.build.copy()
             subi = Interpreter(new_build, self.backend, subp_name, subdir, self.subproject_dir,
-                               self.modules, default_options, ast=ast)
+                               self.modules, default_options, ast=ast, is_translated=is_translated)
             subi.subprojects = self.subprojects
 
             subi.subproject_stack = self.subproject_stack + [subp_name]
@@ -2971,7 +2983,7 @@ external dependencies (including libraries) must go to "dependencies".''')
         # Duplicates are possible when subproject uses files from project root
         if build_def_files:
             self.build_def_files = list(set(self.build_def_files + build_def_files))
-        else:
+        # We always need the subi.build_def_files, to propgate sub-sub-projects
         self.build_def_files = list(set(self.build_def_files + subi.build_def_files))
         self.build.merge(subi.build)
         self.build.subprojects[subp_name] = subi.project_version
@@ -3016,7 +3028,7 @@ external dependencies (including libraries) must go to "dependencies".''')
                 mlog.cmd_ci_include(meson_filename)
                 mlog.log()
 
-            result = self._do_subproject_meson(subp_name, subdir, default_options, kwargs, ast, cm_int.bs_files)
+            result = self._do_subproject_meson(subp_name, subdir, default_options, kwargs, ast, cm_int.bs_files, is_translated=True)
             result.cm_interpreter = cm_int
 
         mlog.log()

run_unittests.py

@@ -5247,6 +5247,20 @@ recommended as it is not supported on some platforms''')
         wrap = PackageDefinition(redirect_wrap)
         self.assertEqual(wrap.get('url'), 'http://invalid')
 
+    @skip_if_no_cmake
+    def test_nested_cmake_rebuild(self) -> None:
+        # This checks a bug where if a non-meson project is used as a third
+        # level (or deeper) subproject it doesn't cause a rebuild if the build
+        # files for that project are changed
+        testdir = os.path.join(self.unit_test_dir, '85 nested subproject regenerate depends')
+        cmakefile = Path(testdir) / 'subprojects' / 'sub2' / 'CMakeLists.txt'
+        self.init(testdir)
+        self.build()
+        with cmakefile.open('a') as f:
+            os.utime(str(cmakefile))
+        self.assertReconfiguredBuildIsNoop()
+
+
 class FailureTests(BasePlatformTests):
     '''
     Tests that test failure conditions. Build files here should be dynamically

test cases/unit/85 nested subproject regenerate depends/main.c

@@ -0,0 +1,3 @@
+int main(void) {
+    return 0;
+}

test cases/unit/85 nested subproject regenerate depends/meson.build

@@ -0,0 +1,6 @@
+project('nested subproject regenerate depends', 'c')
+
+s = subproject('sub1')
+
+# This is needed to make msbuild noop check work correctly
+executable('exe', 'main.c')

test cases/unit/85 nested subproject regenerate depends/subprojects/sub1/meson.build

@@ -0,0 +1,4 @@
+project('sub1')
+
+cmake = import('cmake')
+cmake.subproject('sub2')

test cases/unit/85 nested subproject regenerate depends/subprojects/sub2/CMakeLists.txt

@@ -0,0 +1 @@
+project(sub2)