Fix crash on invalid enum in method (#16511)

Fixes #16163

Fix is straightforward: I simply copy the logic we have for invalid
TypedDicts/NamedTuples.

mypy/semanal_enum.py

@@ -106,16 +106,19 @@ class A(enum.Enum):
         items, values, ok = self.parse_enum_call_args(call, fullname.split(".")[-1])
         if not ok:
             # Error. Construct dummy return value.
-            info = self.build_enum_call_typeinfo(var_name, [], fullname, node.line)
+            name = var_name
+            if is_func_scope:
+                name += "@" + str(call.line)
+            info = self.build_enum_call_typeinfo(name, [], fullname, node.line)
         else:
             name = cast(StrExpr, call.args[0]).value
             if name != var_name or is_func_scope:
                 # Give it a unique name derived from the line number.
                 name += "@" + str(call.line)
             info = self.build_enum_call_typeinfo(name, items, fullname, call.line)
-            # Store generated TypeInfo under both names, see semanal_namedtuple for more details.
-            if name != var_name or is_func_scope:
-                self.api.add_symbol_skip_local(name, info)
+        # Store generated TypeInfo under both names, see semanal_namedtuple for more details.
+        if name != var_name or is_func_scope:
+            self.api.add_symbol_skip_local(name, info)
         call.analyzed = EnumCallExpr(info, items, values)
         call.analyzed.set_line(call)
         info.line = node.line

test-data/unit/check-incremental.test

@@ -6560,3 +6560,26 @@ class C:
 [out]
 [out2]
 tmp/a.py:3: note: Revealed type is "TypedDict('b.C.Hidden@5', {'x': builtins.int})"
+
+[case testNoIncrementalCrashOnInvalidEnumMethod]
+import a
+[file a.py]
+from lib import TheClass
+[file a.py.2]
+from lib import TheClass
+x: TheClass
+reveal_type(x.enum_type)
+[file lib.py]
+import enum
+
+class TheClass:
+    def __init__(self) -> None:
+        names = ["foo"]
+        pyenum = enum.Enum('Blah', {  # type: ignore[misc]
+            x.upper(): x
+            for x in names
+        })
+        self.enum_type = pyenum
+[out]
+[out2]
+tmp/a.py:3: note: Revealed type is "def (value: builtins.object) -> lib.TheClass.pyenum@6"