gnome: Set GSETTINGS_SCHEMA_DIR in devenv

docs/markdown/Commands.md

@@ -302,5 +302,9 @@ These variables are set in environment in addition to those set using `meson.add
   `PATH` on Windows.
 - `GI_TYPELIB_PATH` includes every directory where a GObject Introspection
   typelib is built. This is automatically set when using `gnome.generate_gir()`.
+- `GSETTINGS_SCHEMA_DIR` *Since 0.59.0* includes every directory where a GSettings
+  schemas is compiled. This is automatically set when using `gnome.compile_schemas()`.
+  Note that this requires GLib >= 2.64 when `gnome.compile_schemas()` is used in
+  more than one directory.
 
 {{ devenv_arguments.inc }}

docs/markdown/snippets/gnome.md

@@ -0,0 +1,5 @@
+## `gnome.compile_schemas()` sets `GSETTINGS_SCHEMA_DIR` into devenv
+
+When using `gnome.compile_schemas()` the location of the compiled schema is
+added to `GSETTINGS_SCHEMA_DIR` environment variable when using
+[`meson devenv`](Commands.md#devenv) command.

mesonbuild/modules/gnome.py

@@ -932,6 +932,7 @@ class GnomeModule(ExtensionModule):
         else:
             targetname = 'gsettings-compile-' + state.subdir.replace('/', '_')
         target_g = build.CustomTarget(targetname, state.subdir, state.subproject, kwargs)
+        self._devenv_append('GSETTINGS_SCHEMA_DIR', os.path.join(state.environment.get_build_dir(), state.subdir))
         return ModuleReturnValue(target_g, [target_g])
 
     @permittedKwargs({'sources', 'media', 'symlink_media', 'languages'})