fix handling of Enum default value

atom/meta/annotation_utils.py

@@ -67,6 +67,14 @@ def generate_member_from_type_or_generic(
     # We are dealing with a Literal, so use an Enum member
     elif not types:
         m_cls = Enum
+        if default is not _NO_DEFAULT:
+            if default not in parameters:
+                raise ValueError("Default value does not appear in Literal")
+            # Make the default value the first in the enum arguments.
+            p = list(parameters)
+            p.pop(p.index(default))
+            parameters = (default, *p)
+            default = _NO_DEFAULT
     # Int, Float, Str, Bytes, List, Dict, Set, Tuple, Bool, Callable
     elif len(types) == 1 and types[0] in _TYPE_TO_MEMBER:
         t = types[0]

tests/test_atom_from_annotations.py

@@ -312,6 +312,8 @@ class A(Atom, use_annotations=True):
     assert isinstance(A.a, member)
     if member is Subclass:
         assert A.a.default_value_mode == member(int, default=default).default_value_mode
+    elif member is Enum:
+        assert A.a.default_value_mode[1] == default
     elif member is not Instance:
         assert A.a.default_value_mode == member(default=default).default_value_mode