Fix crash on ParamSpec in incremental mode (#14885)

Fixes #14687
Fixes #14353

Author: ilevkivskyi

mypy/fixup.py

@@ -170,7 +170,7 @@ def visit_class_def(self, c: ClassDef) -> None:
             if isinstance(v, TypeVarType):
                 for value in v.values:
                     value.accept(self.type_fixer)
-                v.upper_bound.accept(self.type_fixer)
+            v.upper_bound.accept(self.type_fixer)
 
     def visit_type_var_expr(self, tv: TypeVarExpr) -> None:
         for value in tv.values:

test-data/unit/check-incremental.test

@@ -6403,3 +6403,29 @@ def g(d: Dict[TValue]) -> TValue:
 tmp/b.py:6: error: TypedDict "a.Dict[TValue]" has no key "x"
 [out2]
 tmp/b.py:6: error: TypedDict "a.Dict[TValue]" has no key "y"
+
+[case testParamSpecNoCrash]
+import m
+[file m.py]
+from typing import Callable, TypeVar
+from lib import C
+
+T = TypeVar("T")
+def test(x: Callable[..., T]) -> T: ...
+test(C)  # type: ignore
+
+[file m.py.2]
+from typing import Callable, TypeVar
+from lib import C
+
+T = TypeVar("T")
+def test(x: Callable[..., T]) -> T: ...
+test(C)  # type: ignore
+# touch
+[file lib.py]
+from typing import ParamSpec, Generic, Callable
+
+P = ParamSpec("P")
+class C(Generic[P]):
+    def __init__(self, fn: Callable[P, int]) -> None: ...
+[builtins fixtures/dict.pyi]