Fix crash on ParamSpec

docs/changelog.md

@@ -2,6 +2,7 @@
 
 ## Unreleased
 
+- Fix crash on some occurrences of `ParamSpec` in stub files (#797)
 - Fix crash when Pydantic 1 is installed (#793)
 - Fix error on use of TypeVar defaults in stubs (PEP 696). The
   default is still ignored, but now the TypeVar is treated as

pyanalyze/annotations.py

@@ -557,12 +557,14 @@ def _type_from_runtime(
 def make_type_var_value(tv: TypeVarLike, ctx: Context) -> TypeVarValue:
     if (
         isinstance(tv, (TypeVar, typing_extensions.TypeVar))
-        and tv.__bound__ is not None
+        and getattr(tv, "__bound__", None) is not None
     ):
         bound = _type_from_runtime(tv.__bound__, ctx)
     else:
         bound = None
-    if isinstance(tv, (TypeVar, typing_extensions.TypeVar)) and tv.__constraints__:
+    if isinstance(tv, (TypeVar, typing_extensions.TypeVar)) and getattr(
+        tv, "__constraints__", ()
+    ):
         constraints = tuple(
             _type_from_runtime(constraint, ctx) for constraint in tv.__constraints__
         )
@@ -1083,7 +1085,7 @@ def visit_Call(self, node: ast.Call) -> Optional[Value]:
                     else:
                         return None
             return KnownValue(func.val(*args, **kwargs))
-        elif func.val == TypeVar:
+        elif is_typing_name(func.val, "TypeVar"):
             arg_values = [self.visit(arg) for arg in node.args]
             kwarg_values = [(kw.arg, self.visit(kw.value)) for kw in node.keywords]
             if not arg_values:

pyanalyze/stubs/_pyanalyze_tests-stubs/paramspec.pyi

@@ -0,0 +1,7 @@
+from typing_extensions import Callable, ParamSpec, TypeVar
+
+T = TypeVar("T")
+P = ParamSpec("P")
+
+def f(x: T) -> T: ...
+def g(x: Callable[P, T], *args: P.args, **kwargs: P.kwargs) -> T: ...

pyanalyze/test_typeshed.py

@@ -281,6 +281,19 @@ def capybara(x: int):
 
             assert_type(f(x), int)
 
+    @assert_passes()
+    def test_typing_extensions_paramspec(self):
+        def some_func(x: int) -> str:
+            return str(x)
+
+        def capybara(x: int):
+            from _pyanalyze_tests.paramspec import f, g
+            from typing_extensions import assert_type
+
+            assert_type(f(x), int)
+            assert_type(g(some_func, x), str)
+            g(some_func, "not an int")  # TODO should error
+
     def test_typeddict(self):
         tsf = TypeshedFinder.make(Checker(), TEST_OPTIONS, verbose=True)
         mod = "_pyanalyze_tests.typeddict"