interpreter: use typed_kwargs for build_target.name_prefix

mesonbuild/build.py

@@ -1181,7 +1181,7 @@ def process_kwargs(self, kwargs):
             if not os.path.isfile(trial):
                 raise InvalidArguments(f'Tried to add non-existing resource {r}.')
         self.resources = resources
-        if 'name_prefix' in kwargs:
+        if kwargs.get('name_prefix') is not None:
             name_prefix = kwargs['name_prefix']
             if isinstance(name_prefix, list):
                 if name_prefix:

mesonbuild/interpreter/kwargs.py

@@ -335,6 +335,7 @@ class _BaseBuildTarget(TypedDict):
     implicit_include_directories: bool
     link_depends: T.List[T.Union[str, File, build.CustomTarget, build.CustomTargetIndex, build.BuildTarget]]
     link_language: T.Optional[str]
+    name_prefix: T.Optional[str]
     native: MachineChoice
     override_options: T.Dict[OptionKey, T.Union[str, int, bool, T.List[str]]]
     depend_files: NotRequired[T.List[File]]

mesonbuild/interpreter/type_checking.py

@@ -560,12 +560,27 @@ def link_whole_validator(values: T.List[T.Union[StaticLibrary, CustomTarget, Cus
     NATIVE_KW,
 ]
 
+
+def _name_validator(arg: T.Optional[T.Union[str, T.List]]) -> T.Optional[str]:
+    if isinstance(arg, list) and arg:
+        return 'must be empty when passed as an array to signify the default value.'
+    return None
+
+
+_NAME_PREFIX_KW: KwargInfo[T.Optional[T.Union[str, T.List]]] = KwargInfo(
+    'name_prefix',
+    (str, NoneType, list),
+    validator=_name_validator,
+    convertor=lambda x: None if isinstance(x, list) else x,
+)
+
 # Applies to all build_target classes except jar
 _BUILD_TARGET_KWS: T.List[KwargInfo] = [
     *_ALL_TARGET_KWS,
     *_LANGUAGE_KWS,
     BT_SOURCES_KW,
     INCLUDE_DIRECTORIES.evolve(name='d_import_dirs'),
+    _NAME_PREFIX_KW,
     RUST_CRATE_TYPE_KW,
     KwargInfo('d_debug', ContainerTypeInfo(list, (str, int)), default=[], listify=True),
     D_MODULE_VERSIONS_KW,