interpreterbase: Add a new field to KwargInfo for extra types

We have some cases where we want to have an extra set of validators that
run on specific types, and give detailed answers. However, we don't want
those types to show up in the list of accepted types. This new keyword
allows for that.

1 files changed, 24 insertions, 2 deletions

diff --git a/mesonbuild/interpreterbase/decorators.py b/mesonbuild/interpreterbase/decorators.py
index 486a58573..591586523 100644
--- a/mesonbuild/interpreterbase/decorators.py
+++ b/mesonbuild/interpreterbase/decorators.py
@@ -353,6 +353,10 @@ class KwargInfo(T.Generic[_T]):
     :param not_set_warning: A warning message that is logged if the kwarg is not
         set by the user.
     :param feature_validator: A callable returning an iterable of FeatureNew | FeatureDeprecated objects.
+    :param extra_types:
+        A mapping of types to a callable that is passed that type and returns an
+        error message. These types are specifically *not* added to the general
+        error message
     """
     def __init__(self, name: str,
                  types: T.Union[T.Type[_T], T.Tuple[T.Union[T.Type[_T], ContainerTypeInfo], ...], ContainerTypeInfo],
@@ -367,7 +371,8 @@ class KwargInfo(T.Generic[_T]):
                  feature_validator: T.Optional[T.Callable[[_T], T.Iterable[FeatureCheckBase]]] = None,
                  validator: T.Optional[T.Callable[[T.Any], T.Optional[str]]] = None,
                  convertor: T.Optional[T.Callable[[_T], object]] = None,
-                 not_set_warning: T.Optional[str] = None):
+                 not_set_warning: T.Optional[str] = None,
+                 extra_types: T.Optional[T.Mapping[T.Type, T.Callable[[object], str]]] = None):
         self.name = name
         self.types = types
         self.required = required
@@ -383,6 +388,7 @@ class KwargInfo(T.Generic[_T]):
         self.validator = validator
         self.convertor = convertor
         self.not_set_warning = not_set_warning
+        self.extra_types = extra_types if extra_types is not None else {}
 
     def evolve(self, *,
                name: T.Union[str, _NULL_T] = _NULL,
@@ -397,7 +403,9 @@ class KwargInfo(T.Generic[_T]):
                deprecated_values: T.Union[T.Dict[T.Union[_T, ContainerTypeInfo, type], T.Union[str, T.Tuple[str, str]]], None, _NULL_T] = _NULL,
                feature_validator: T.Union[T.Callable[[_T], T.Iterable[FeatureCheckBase]], None, _NULL_T] = _NULL,
                validator: T.Union[T.Callable[[_T], T.Optional[str]], None, _NULL_T] = _NULL,
-               convertor: T.Union[T.Callable[[_T], object], None, _NULL_T] = _NULL) -> 'KwargInfo':
+               convertor: T.Union[T.Callable[[_T], object], None, _NULL_T] = _NULL,
+               extra_types: T.Union[T.Mapping[T.Type, T.Callable[[object], str]], None, _NULL_T] = _NULL,
+               ) -> 'KwargInfo':
         """Create a shallow copy of this KwargInfo, with modifications.
 
         This allows us to create a new copy of a KwargInfo with modifications.
@@ -424,6 +432,7 @@ class KwargInfo(T.Generic[_T]):
             feature_validator=feature_validator if not isinstance(feature_validator, _NULL_T) else self.feature_validator,
             validator=validator if not isinstance(validator, _NULL_T) else self.validator,
             convertor=convertor if not isinstance(convertor, _NULL_T) else self.convertor,
+            extra_types=extra_types if not isinstance(extra_types, _NULL_T) else self.extra_types,
         )
 
 
@@ -529,7 +538,20 @@ def typed_kwargs(name: str, *types: KwargInfo, allow_unknown: bool = False) -> T
                     if info.listify:
                         kwargs[info.name] = value = mesonlib.listify(value)
                     if not check_value_type(types_tuple, value):
+                        extra_desc: T.List[str] = []
+                        if info.extra_types:
+                            if isinstance(value, list):
+                                for (t, cb), v in itertools.product(info.extra_types.items(), value):
+                                    if isinstance(v, t):
+                                        extra_desc.append(cb(v))
+                            else:
+                                for t, cb in info.extra_types.items():
+                                    if isinstance(value, t):
+                                        extra_desc.append(cb(value))
+
                         shouldbe = types_description(types_tuple)
+                        if extra_desc:
+                            shouldbe = '{}. {}'.format(shouldbe, '. '.join(extra_desc))
                         raise InvalidArguments(f'{name} keyword argument {info.name!r} was of type {raw_description(value)} but should have been {shouldbe}')
 
                     if info.validator is not None: