[syntax-errors] type alias statements before Python 3.12 (#16478)

Summary
--
Another simple one, just detect standalone `type` statements. I limited
the diagnostic to `type` itself like [pyright]. That probably makes the
most sense for more complicated examples.

Test Plan
--
Inline tests.

[pyright]:
https://pyright-play.net/?pythonVersion=3.8&strict=true&code=C4TwDgpgBAHlC8UCWA7YQ
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Brent Westbrook 2025-03-04 12:20:10 -05:00 committed by GitHub
parent 087d92cbf4
commit 32c66ec4b7
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@ -888,8 +888,22 @@ impl<'src> Parser<'src> {
/// See: <https://docs.python.org/3/reference/simple_stmts.html#the-type-statement>
fn parse_type_alias_statement(&mut self) -> ast::StmtTypeAlias {
let start = self.node_start();
let type_range = self.current_token_range();
self.bump(TokenKind::Type);
// test_ok type_stmt_py312
// # parse_options: {"target-version": "3.12"}
// type x = int
// test_err type_stmt_py311
// # parse_options: {"target-version": "3.11"}
// type x = int
self.add_unsupported_syntax_error(
UnsupportedSyntaxErrorKind::TypeAliasStatement,
type_range,
);
let mut name = Expr::Name(self.parse_name());
helpers::set_expr_ctx(&mut name, ExprContext::Store);