Fix missing error for "str" | None union with string literals

pyrefly/lib/alt/solve.rs

@@ -2253,6 +2253,9 @@ impl<'a, Ans: LookupAnswer> AnswersSolver<'a, Ans> {
                     match t {
                         Type::ClassDef(_) => true,
                         Type::Type(box Type::ClassType(cls)) => cls.targs().is_empty(),
+                        // `None` is `NoneType` at runtime, which is a plain type that
+                        // doesn't support `__or__` with string literals.
+                        Type::None => true,
                         Type::TypeAlias(ta) => {
                             let ta = me.get_type_alias(&ta);
                             let t = if ta.style == TypeAliasStyle::Scoped {

pyrefly/lib/test/annotation.rs

@@ -27,20 +27,27 @@ testcase!(
     test_union_operator_with_bare_string_literal,
     TestEnv::new_with_version(PythonVersion::new(3, 13, 0)),
     r#"
-from typing import assert_type, TypeVar, Generic
+from typing import assert_type, Any, TypeVar, Generic, Literal, Callable, LiteralString
 T = TypeVar("T")
 class C(Generic[T]): ...
 bad1: int | "str" = "foo"  # E: `|` union syntax does not work with string literals
 bad2: int | "str" | T = "foo"  # E: `|` union syntax does not work with string literals  # E: Type variable `T` is not in scope
 bad3: "str" | int = "foo"  # E: `|` union syntax does not work with string literals
 bad4: "str" | int | T = "foo"  # E: `|` union syntax does not work with string literals  # E: Type variable `T` is not in scope
 bad5: C | "str" = "foo"  # E: `|` union syntax does not work with string literals
+bad6: "str" | None = "foo"  # E: `|` union syntax does not work with string literals
+bad7: None | "str" = "foo"  # E: `|` union syntax does not work with string literals
+bad8: "str" | Any = "foo"  # E: `|` union syntax does not work with string literals
+bad9: Any | "str" = "foo"  # E: `|` union syntax does not work with string literals
 ok1: T | "str" = "foo"  # E: Type variable `T` is not in scope
 ok2: "str" | T = "foo"  # E: Type variable `T` is not in scope
 ok3 = list["str" | T]
 ok4 = (int) | (str)
 ok5: "str" | C[int] = "foo"
 ok6: C[int] | "str" = "foo"
+ok7: "str" | Literal[1] = "foo"
+ok8: "str" | Callable[[int], str] = "foo"
+ok9: "str" | LiteralString = "foo"
 "#,
 );
 
@@ -59,6 +66,58 @@ bad: "int" | "list[str]" = 1  # E: `|` union syntax does not work with string li
     "#,
 );
 
+testcase!(
+    test_union_forward_ref_with_special_classes,
+    TestEnv::new_with_version(PythonVersion::new(3, 13, 0)),
+    r#"
+from typing import TypedDict, NamedTuple, Protocol
+
+class TD(TypedDict):
+    x: int
+
+class NT(NamedTuple):
+    x: int
+
+class P(Protocol):
+    def f(self) -> None: ...
+
+bad1: "str" | TD = "foo"  # E: `|` union syntax does not work with string literals
+bad2: "str" | NT = NT(x=1)  # E: `|` union syntax does not work with string literals
+bad3: "str" | P = "foo"  # E: `|` union syntax does not work with string literals
+"#,
+);
+
+testcase!(
+    test_union_forward_ref_with_none,
+    TestEnv::new_with_version(PythonVersion::new(3, 13, 0)),
+    r#"
+from dataclasses import dataclass
+
+def test() -> "Foo" | None:  # E: `|` union syntax does not work with string literals
+    return Foo(bar=1)
+
+@dataclass
+class Foo:
+    bar: int
+"#,
+);
+
+testcase!(
+    bug = "list[int] (types.GenericAlias) errors at runtime but List[int] (typing._GenericAlias) does not; pyrefly can't distinguish them",
+    test_union_forward_ref_with_builtin_generics,
+    TestEnv::new_with_version(PythonVersion::new(3, 13, 0)),
+    r#"
+from typing import List, Dict, Type, Any
+ok_but_runtime_error1: "str" | list[int] = "foo"
+ok_but_runtime_error2: "str" | dict[str, int] = "foo"
+ok_but_runtime_error3: "str" | tuple[int, ...] = "foo"
+ok_but_runtime_error4: "str" | type[int] = "foo"
+ok1: "str" | List[int] = "foo"
+ok2: "str" | Dict[str, int] = "foo"
+ok3: "str" | Type[Any] = "foo"
+"#,
+);
+
 // Test that the error is NOT raised for Python 3.14+
 // In Python 3.14+, annotations are not evaluated at runtime by default (PEP 649)
 testcase!(