build: Add IncludeDirs.rel_string_list

This allows us to clean up many instances of the same pattern
implemented elsewhere, by consolidating into one.

Author: dcbaker

mesonbuild/build.py

@@ -510,6 +510,26 @@ def abs_string_list(self, sourcedir: str, builddir: str) -> T.List[str]:
             strlist.append(os.path.join(builddir, self.curdir, idir))
         return strlist
 
+    def rel_string_list(self, build_to_src: str) -> T.List[str]:
+        """Convert IncludeDirs object to a list of relative string paths.
+
+        :param build_to_src: The relative path from the build dir to source dir
+        :return: A list if strings (without compiler argument)
+        """
+        strlist: T.List[str] = []
+        for idirs, add_src in [(self.incdirs, True), (self.extra_build_dirs, False)]:
+            for idir in idirs:
+                bld_dir = os.path.normpath(os.path.join(self.curdir, idir))
+                if idir not in {'', '.'}:
+                    expdir = bld_dir
+                else:
+                    expdir = self.curdir
+                strlist.append(bld_dir)
+                if add_src:
+                    strlist.append(os.path.normpath(os.path.join(build_to_src, expdir)))
+        return strlist
+
+
 @dataclass(eq=False)
 class ExtractedObjects(HoldableObject):
     '''

mesonbuild/compilers/d.py

@@ -513,20 +513,8 @@ def get_feature_args(self, kwargs: DFeatures, build_to_src: str) -> T.List[str]:
         import_dir_arg = d_feature_args[self.id]['import_dir']
         if not import_dir_arg:
             raise EnvironmentException('D compiler %s does not support the "string import directories" feature.' % self.name_string())
-        # TODO: ImportDirs.to_string_list(), but we need both the project source
-        # root and project build root for that.
         for idir_obj in kwargs['import_dirs']:
-            basedir = idir_obj.curdir
-            for idir in idir_obj.incdirs:
-                bldtreedir = os.path.join(basedir, idir)
-                # Avoid superfluous '/.' at the end of paths when d is '.'
-                if idir not in ('', '.'):
-                    expdir = bldtreedir
-                else:
-                    expdir = basedir
-                srctreedir = os.path.join(build_to_src, expdir)
-                res.append(f'{import_dir_arg}{srctreedir}')
-                res.append(f'{import_dir_arg}{bldtreedir}')
+            res.extend(f'{import_dir_arg}{i}' for i in idir_obj.rel_string_list(build_to_src))
 
         return res