rust/tests/ui/rust-2018/issue-51008.rs

// Regression test for #51008 -- the anonymous lifetime in `&i32` was
// being incorrectly considered part of the "elided lifetimes" from
// the impl.
//
// run-pass

#![feature(rust_2018_preview)]

trait A {

}

impl<F> A for F where F: FnOnce(&i32) {}

fn main() {}
reset the "anonymous lifetime mode" for parenthesized where clauses Background: The anonymous lifetime mode is used to prohibit elided lifetimes where they didn't used to be permitted, and instead require that `'_` be used. For example: ```rust impl Trait for Ref<T> { .. } // ^^^^^^ ERROR: should be `Ref<'_, T>` ``` When we are parsing the parts of the impl header, we enter into an alternate mode called `CreateParameter`. In this mode, we give an error for things like `Ref<T>`, but for elided lifetimes in a reference type like `&T` we make the elided lifetime into an in-band lifetime: https://github.com/rust-lang/rust/blob/4f99f37b7e213d69a489884f651adfc6d217cef5/src/librustc/hir/lowering.rs#L4017-L4035 This was not intended to change behavior because we only enter into that mode in contexts where elision was not historically permitted. However, the problem is that we fail to reset the mode when we enter into bounds like `Fn(&u32)`, where elision was allowed -- the same occurs for fn types like `fn(&u32`). This PR restores the original mode in those contexts. 2018-05-30 14:27:53 +00:00			// Regression test for #51008 -- the anonymous lifetime in `&i32` was
			`// being incorrectly considered part of the "elided lifetimes" from`
			`// the impl.`
			`//`
			`// run-pass`

			`#![feature(rust_2018_preview)]`

			`trait A {`

			`}`

			`impl<F> A for F where F: FnOnce(&i32) {}`

			`fn main() {}`