rust/tests/ui/macros/vec-macro-in-pattern.rs

// This is a regression test for #61933
// Verify that the vec![] macro may not be used in patterns
// and that the resulting diagnostic is actually helpful.

fn main() {
    match Some(vec![42]) {
        Some(vec![43]) => {} //~ ERROR expected pattern, found `#`
        _ => {}
    }
}
Force vec! to expressions only 2021-01-16 09:32:51 -06:00			`// This is a regression test for #61933`
			`// Verify that the vec![] macro may not be used in patterns`
			`// and that the resulting diagnostic is actually helpful.`

			`fn main() {`
			`match Some(vec![42]) {`
Remove `__rust_force_expr`. This was added (with a different name) to improve an error message. It is no longer needed -- removing it changes the error message, but overall I think the new message is no worse: - the mention of `#` in the first line is a little worse, - but the extra context makes it very clear what the problem is, perhaps even clearer than the old message, - and the removal of the note about the `expr` fragment (an internal detail of `__rust_force_expr`) is an improvement. Overall I think the error is quite clear and still far better than the old message that prompted #61933, which didn't even mention patterns. The motivation for this is #124141, which will cause pasted metavariables to be tokenized and reparsed instead of the AST node being cached. This change in behaviour occasionally has a non-zero perf cost, and `__rust_force_expr` causes the tokenize/reparse step to occur twice. Removing `__rust_force_expr` greatly reduces the extra overhead for the `deep-vector` benchmark. 2024-06-23 01:12:39 -05:00			Some(vec![43]) => {} //~ ERROR expected pattern, found `#`
Force vec! to expressions only 2021-01-16 09:32:51 -06:00			`_ => {}`
			`}`
			`}`