Allow assigning literals to Exact[int]

Reviewed By: carljm, wmeehan

Differential Revision: D37863615

fbshipit-source-id: e75ef58c4738d8e10e73fd25685eaf5837381beb

Author: tekknolagi

Lib/compiler/static/types.py

@@ -657,6 +657,8 @@ def get_generic_type(
         return concrete
 
     def get_literal_type(self, base_type: Value, literal_value: object) -> Value:
+        # Literals are always exact
+        base_type = base_type.exact()
         key = (base_type, literal_value)
         if key not in self._literal_types:
             self._literal_types[key] = literal_type = base_type.make_literal(

Lib/test/test_compiler/test_static/annotated.py

@@ -192,11 +192,9 @@ def test_exact_does_not_allow_literals(self) -> None:
             from typing import Annotated
 
             x: Annotated[int, "Exact"] = 3
+            reveal_type(x)
         """
-        # TODO(T113108364): This should be allowed.
-        self.type_error(
-            codestr, r"type mismatch: Literal\[3\] cannot be assigned to Exact\[int\]"
-        )
+        self.revealed_type(codestr, "Exact[int]")
 
     def test_exact_final_type_error_on_subclass_assignment(self) -> None:
         codestr = """