add xfail test for unsupported enum nonmember

test-data/unit/check-python311.test

@@ -1,3 +1,39 @@
+[case testMatchLiteralPatternEnumWithNonMember-xfail]
+from enum import Enum, nonmember
+from typing import NoReturn
+def assert_never(x: NoReturn) -> None: ...
+
+class int:
+    def __new__(cls, value: int): pass
+
+class Medal(int, Enum):
+    prize: str = nonmember("nothing")
+
+    def __new__(cls, value: int, prize: str | None) -> Medal:
+        enum = int.__new__(cls, value)
+        enum._value_ = value
+        if prize is not None:
+            enum.prize = prize
+        return enum
+
+    gold = (1, 'cash prize')
+    silver = (2, 'sponsorship')
+    bronze = (3, 'nothing')
+
+m: Medal
+
+match m:
+    case Medal.gold:
+        reveal_type(m)  # N: Revealed type is "Literal[__main__.Medal.gold]"
+    case Medal.silver:
+        reveal_type(m)  # N: Revealed type is "Literal[__main__.Medal.silver]"
+    case Medal.bronze:
+        reveal_type(m)  # N: Revealed type is "Literal[__main__.Medal.bronze]"
+    case _ as unreachable:
+        assert_never(unreachable)
+
+[builtins fixtures/tuple.pyi]
+
 [case testTryStarSimple]
 try:
     pass

test-data/unit/lib-stub/enum.pyi

@@ -48,3 +48,6 @@ class auto(IntFlag):
 # It is python-3.11+ only:
 class StrEnum(str, Enum):
     def __new__(cls: Type[_T], value: str | _T) -> _T: ...
+
+
+def nonmember(value: _T) -> _T: pass