Rollup merge of #84316 - teymour-aldridge:improve-defaulted-never-not…

…e, r=petrochenkov Improve an error message.
rust-lang · Apr 18, 2021 · 8eb1f5c · 8eb1f5c
2 parents 7f20b6f + 567de4a
commit 8eb1f5c
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Showing 3 changed files with 12 additions and 8 deletions.
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
@@ -503,14 +503,14 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
  let unit_obligation =
  obligation.with(predicate.without_const().to_predicate(tcx));
  if self.predicate_may_hold(&unit_obligation) {
+ err.note("this trait is implemented for `()`.");
  err.note(
- "the trait is implemented for `()`. \
- Possibly this error has been caused by changes to \
- Rust's type-inference algorithm (see issue #48950 \
- <https://github.com/rust-lang/rust/issues/48950> \
- for more information). Consider whether you meant to use \
- the type `()` here instead.",
+ "this error might have been caused by changes to \
+ Rust's type-inference algorithm (see issue #48950 \
+ <https://github.com/rust-lang/rust/issues/48950> \
+ for more information).",
  );
+ err.help("did you intend to use the type `()` here instead?");
  }
  }
 

diff --git a/src/test/ui/never_type/defaulted-never-note.rs b/src/test/ui/never_type/defaulted-never-note.rs
@@ -26,7 +26,9 @@ fn smeg() {
  foo(_x);
  //~^ ERROR the trait bound
  //~| NOTE the trait `ImplementedForUnitButNotNever` is not implemented
- //~| NOTE the trait is implemented for `()`
+ //~| NOTE this trait is implemented for `()`
+ //~| NOTE this error might have been caused
+ //~| HELP did you intend
 }
 
 fn main() {

diff --git a/src/test/ui/never_type/defaulted-never-note.stderr b/src/test/ui/never_type/defaulted-never-note.stderr
@@ -7,7 +7,9 @@ LL | fn foo<T: ImplementedForUnitButNotNever>(_t: T) {}
 LL | foo(_x);
  | ^^^ the trait `ImplementedForUnitButNotNever` is not implemented for `!`
  |
- = note: the trait is implemented for `()`. Possibly this error has been caused by changes to Rust's type-inference algorithm (see issue #48950 <https://github.com/rust-lang/rust/issues/48950> for more information). Consider whether you meant to use the type `()` here instead.
+ = note: this trait is implemented for `()`.
+ = note: this error might have been caused by changes to Rust's type-inference algorithm (see issue #48950 <https://github.com/rust-lang/rust/issues/48950> for more information).
+ = help: did you intend to use the type `()` here instead?
 
 error: aborting due to previous error