rust/tests/ui/rfcs/rfc-1937-termination-trait/termination-trait-impl-trait.rs

// Tests that an `impl Trait` that is not `impl Termination` will not work.
fn main() -> impl Copy { }
//~^ ERROR `main` has invalid return type `impl Copy`
Fix `fn main() -> impl Trait` for non-`Termination` trait Fixes #50595. This bug currently affects stable. Why I think we can go for hard error: - It will in stable for at most one cycle and there is no legitimate reason to abuse it, nor any known uses in the wild. - It only affects `bin` crates (which have a `main`), so there is little practical difference between a hard error or a deny lint, both are a one line fix. The fix was to just unshadow a variable. Thanks @nikomatsakis for the mentoring! r? @nikomatsakis 2018-05-11 11:29:04 -03:00			// Tests that an `impl Trait` that is not `impl Termination` will not work.
			`fn main() -> impl Copy { }`
pretty: trim paths of unique symbols If a symbol name can only be imported from one place for a type, and as long as it was not glob-imported anywhere in the current crate, we can trim its printed path and print only the name. This has wide implications on error messages with types, for example, shortening `std::vec::Vec` to just `Vec`, as long as there is no other `Vec` importable anywhere. This adds a new '-Z trim-diagnostic-paths=false' option to control this feature. On the good path, with no diagnosis printed, we should try to avoid issuing this query, so we need to prevent trimmed_def_paths query on several cases. This change also relies on a previous commit that differentiates between `Debug` and `Display` on various rustc types, where the latter is trimmed and presented to the user and the former is not. 2020-09-02 10:40:56 +03:00			//~^ ERROR `main` has invalid return type `impl Copy`