i18n: merge_file() deprecate positional arguments

They always have been ignored but it became an hard error with no
deprecation period in 0.60.0. Since it breaks some GNOME projects,
deprecate for now and keep it removed for 0.61.0.

Fixes: #9441

mesonbuild/modules/i18n.py

@@ -22,7 +22,7 @@
 from .. import mlog
 from ..interpreter.type_checking import CT_BUILD_BY_DEFAULT, CT_INPUT_KW, CT_INSTALL_DIR_KW, CT_INSTALL_TAG_KW, CT_OUTPUT_KW, INSTALL_KW, NoneType, in_set_validator
 from ..interpreterbase import FeatureNew
-from ..interpreterbase.decorators import ContainerTypeInfo, KwargInfo, noPosargs, typed_kwargs, typed_pos_args
+from ..interpreterbase.decorators import ContainerTypeInfo, KwargInfo, typed_kwargs, typed_pos_args
 from ..scripts.gettext import read_linguas
 
 if T.TYPE_CHECKING:
@@ -128,7 +128,6 @@ def _get_data_dirs(state: 'ModuleState', dirs: T.Iterable[str]) -> T.List[str]:
         return [path.join(src_dir, d) for d in dirs]
 
     @FeatureNew('i18n.merge_file', '0.37.0')
-    @noPosargs
     @typed_kwargs(
         'i18n.merge_file',
         CT_BUILD_BY_DEFAULT,
@@ -143,6 +142,9 @@ def _get_data_dirs(state: 'ModuleState', dirs: T.Iterable[str]) -> T.List[str]:
         KwargInfo('type', str, default='xml', validator=in_set_validator({'xml', 'desktop'})),
     )
     def merge_file(self, state: 'ModuleState', args: T.List['TYPE_var'], kwargs: 'MergeFile') -> ModuleReturnValue:
+        if args:
+            mlog.deprecation('i18n.merge_file does not take any positional arguments. ' +
+                             'This will become an hard error in next Meson release.')
         if not shutil.which('xgettext'):
             self.nogettext_warning()
             return ModuleReturnValue(None, [])