rust/tests/ui/return-disjoint-regions.stderr

error[E0515]: cannot return value referencing function parameter `x`
  --> $DIR/return-disjoint-regions.rs:4:5
   |
LL |     let y = &x;
   |             -- `x` is borrowed here
LL |     (y, y)
   |     ^^^^^^ returns a value referencing data owned by the current function

error: aborting due to previous error

For more information about this error, try `rustc --explain E0515`.
Use an 'approximate' universal upper bound when reporting region errors Fixes #67765 When reporting errors during MIR region inference, we sometimes use `universal_upper_bound` to obtain a named universal region that we can display to the user. However, this is not always possible - in a case like `fn foo<'a, 'b>() { .. }`, the only upper bound for a region containing `'a` and `'b` is `'static`. When displaying diagnostics, it's usually better to display some named region (even if there are multiple involved) rather than fall back to a generic error involving `'static`. This commit adds a new `approx_universal_upper_bound` method, which uses the lowest-numbered universal region if the only alternative is to return `'static`. 2020-06-27 17:54:56 +00:00			error[E0515]: cannot return value referencing function parameter `x`
			`--> $DIR/return-disjoint-regions.rs:4:5`
			`\|`
			`LL \| let y = &x;`
			\| -- `x` is borrowed here
			`LL \| (y, y)`
			`\| ^^^^^^ returns a value referencing data owned by the current function`

			`error: aborting due to previous error`

			For more information about this error, try `rustc --explain E0515`.