rust/tests/ui/impl-trait/stashed-diag-issue-121504.rs

//@ edition: 2021

trait MyTrait {
    async fn foo(self) -> (Self, i32);
}

impl MyTrait for xyz::T { //~ ERROR failed to resolve: use of undeclared crate or module `xyz`
    async fn foo(self, key: i32) -> (u32, i32) {
        (self, key)
    }
}

fn main() {}
Overhaul how stashed diagnostics work, again. Stashed errors used to be counted as errors, but could then be cancelled, leading to `ErrorGuaranteed` soundness holes. #120828 changed that, closing the soundness hole. But it introduced other difficulties because you sometimes have to account for pending stashed errors when making decisions about whether errors have occured/will occur and it's easy to overlook these. This commit aims for a middle ground. - Stashed errors (not warnings) are counted immediately as emitted errors, avoiding the possibility of forgetting to consider them. - The ability to cancel (or downgrade) stashed errors is eliminated, by disallowing the use of `steal_diagnostic` with errors, and introducing the more restrictive methods `try_steal_{modify,replace}_and_emit_err` that can be used instead. Other things: - `DiagnosticBuilder::stash` and `DiagCtxt::stash_diagnostic` now both return `Option<ErrorGuaranteed>`, which enables the removal of two `delayed_bug` calls and one `Ty::new_error_with_message` call. This is possible because we store error guarantees in `DiagCtxt::stashed_diagnostics`. - Storing the guarantees also saves us having to maintain a counter. - Calls to the `stashed_err_count` method are no longer necessary alongside calls to `has_errors`, which is a nice simplification, and eliminates two more `span_delayed_bug` calls and one FIXME comment. - Tests are added for three of the four fixed PRs mentioned below. - `issue-121108.rs`'s output improved slightly, omitting a non-useful error message. Fixes #121451. Fixes #121477. Fixes #121504. Fixes #121508. 2024-02-25 22:21:01 -06:00			`//@ edition: 2021`

			`trait MyTrait {`
			`async fn foo(self) -> (Self, i32);`
			`}`

			impl MyTrait for xyz::T { //~ ERROR failed to resolve: use of undeclared crate or module `xyz`
			`async fn foo(self, key: i32) -> (u32, i32) {`
			`(self, key)`
			`}`
			`}`

			`fn main() {}`