Allow enum members in Literals.

We still allow unsolvables, because enum members will continue to show up as those until the overlay is enabled.

PiperOrigin-RevId: 400070986

pytype/overlays/typing_overlay.py

@@ -687,7 +687,7 @@ def _build_value(self, node, inner, ellipses):
     values = []
     errors = []
     for i, param in enumerate(inner):
-      # TODO(b/173742489): Once pytype has proper support for enums, we should
+      # TODO(b/173742489): Once the enum overlay is enabled, we should
       # stop allowing unsolvable and handle enums here.
       if (param == self.vm.convert.none or
           isinstance(param, abstract.LiteralClass) or
@@ -696,6 +696,8 @@ def _build_value(self, node, inner, ellipses):
       elif (isinstance(param, abstract.ConcreteValue) and
             isinstance(param.pyval, (int, str, bytes))):
         value = abstract.LiteralClass(param, self.vm)
+      elif isinstance(param, abstract.Instance) and param.cls.is_enum:
+        value = abstract.LiteralClass(param, self.vm)
       else:
         if i in ellipses:
           invalid_param = "..."

pytype/tests/test_typing2.py

@@ -900,6 +900,15 @@ def f(x: Literal["x", "y"]):
         f(x)
     """)
 
+  def test_enum(self):
+    # Requires the enum overlay
+    self.Check("""
+      import enum
+      from typing import Literal
+      class M(enum.Enum):
+        A = 1
+      x: Literal[M.A]
+    """)
 
 if __name__ == "__main__":
   test_base.main()