Merge branch 'pr/Akuli/12096' into paramspec-concatenate

Author: cdce8p

mypy/subtypes.py

@@ -289,6 +289,9 @@ def visit_instance(self, left: Instance) -> bool:
                     if isinstance(tvar, TypeVarType):
                         if not self.check_type_parameter(lefta, righta, tvar.variance):
                             nominal = False
+                    elif isinstance(tvar, ParamSpecType):
+                        if not self.check_type_parameter(lefta, righta, COVARIANT):
+                            nominal = False
                     else:
                         if not self.check_type_parameter(lefta, righta, COVARIANT):
                             nominal = False

test-data/unit/check-parameter-specification.test

@@ -1026,3 +1026,26 @@ P = ParamSpec("P")
 
 def x(f: Callable[Concatenate[int, Concatenate[int, P]], None]) -> None: ...  # E: Nested Concatenates are invalid
 [builtins fixtures/tuple.pyi]
+
+[case testDecoratingClassesThatUseParamSpec]
+from typing import Generic, TypeVar, Callable, Any
+from typing_extensions import ParamSpec
+
+_P = ParamSpec("_P")
+_T = TypeVar("_T")
+_F = TypeVar("_F", bound=Callable[..., Any])
+
+def f(x: _F) -> _F: ...
+
+@f  # Should be ok
+class OnlyParamSpec(Generic[_P]):
+    pass
+
+@f  # Should be ok
+class MixedWithTypeVar1(Generic[_P, _T]):
+    pass
+
+@f  # Should be ok
+class MixedWithTypeVar2(Generic[_T, _P]):
+    pass
+[builtins fixtures/dict.pyi]