Do not strip away generic parameters explicitly set to Any (#467)

Author: JelleZijlstra

docs/changelog.md

@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- Do not strip away generic parameters explicitly set to
+  `Any` (#467)
 - Fix bug that led to some overloaded calls incorrectly
   resolving to `Any` (#462)
 - Support `__init__` and `__new__` signatures from typeshed (#429)

pyanalyze/annotations.py

@@ -1069,8 +1069,6 @@ def _value_of_origin_args(
         origin = _maybe_get_extra(origin)
         if args:
             args_vals = [_type_from_runtime(val, ctx) for val in args]
-            if all(isinstance(val, AnyValue) for val in args_vals):
-                return _maybe_typed_value(origin)
             return GenericValue(origin, args_vals)
         else:
             return _maybe_typed_value(origin)

pyanalyze/test_annotations.py

@@ -75,11 +75,12 @@ def rgx(m: Match[str], p: Pattern[bytes]) -> None:
 
     @assert_passes()
     def test_generic(self):
-        from typing import List
+        from typing import List, Any
 
-        def capybara(x: List[int], y: List) -> None:
+        def capybara(x: List[int], y: List, z: List[Any]) -> None:
             assert_is_value(x, GenericValue(list, [TypedValue(int)]))
             assert_is_value(y, TypedValue(list))
+            assert_is_value(z, GenericValue(list, [AnyValue(AnySource.explicit)]))
 
     @assert_passes()
     def test_supports_int(self):