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Do not consider repeated lifetime params for elision.

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This commit is contained in:
Camille GILLOT 2022-10-23 19:35:47 +00:00
parent 6c9c2d862d
commit 47704bbcc0
3 changed files with 21 additions and 6 deletions
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10
compiler/rustc_resolve/src/late.rs
View file

@ -565,7 +565,7 @@ struct LateResolutionVisitor<'a, 'b, 'ast> {
/// They will be used to determine the correct lifetime for the fn return type.
/// The `LifetimeElisionCandidate` is used for diagnostics, to suggest introducing named
/// lifetimes.
lifetime_elision_candidates: Option<FxIndexMap<LifetimeRes, LifetimeElisionCandidate>>,
lifetime_elision_candidates: Option<Vec<(LifetimeRes, LifetimeElisionCandidate)>>,
/// The trait that the current context can refer to.
current_trait_ref: Option<(Module<'a>, TraitRef)>,
@ -1799,7 +1799,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
match res {
LifetimeRes::Param { .. } | LifetimeRes::Fresh { .. } | LifetimeRes::Static => {
if let Some(ref mut candidates) = self.lifetime_elision_candidates {
candidates.insert(res, candidate);
candidates.push((res, candidate));
}
}
LifetimeRes::Infer | LifetimeRes::Error | LifetimeRes::ElidedAnchor { .. } => {}
@ -1910,8 +1910,8 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
// We do not have a `self` candidate, look at the full list.
let all_candidates = all_candidates.unwrap();
if all_candidates.len() == 1 {
Ok(*all_candidates.first().unwrap().0)
if let [(res, _)] = &all_candidates[..] {
Ok(*res)
} else {
let all_candidates = all_candidates
.into_iter()
@ -2391,7 +2391,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
// Do not account for the parameters we just bound for function lifetime elision.
if let Some(ref mut candidates) = self.lifetime_elision_candidates {
for (_, res) in function_lifetime_rib.bindings.values() {
candidates.remove(res);
candidates.retain(|(r, _)| r != res);
}
}

3
src/test/ui/lifetimes/lifetime-elision-return-type-requires-explicit-lifetime.rs
View file

@ -42,4 +42,7 @@ fn k<'a, T: WithLifetime<'a>>(_x: T::Output) -> &isize {
panic!()
}
fn l<'a>(_: &'a str, _: &'a str) -> &str { "" }
//~^ ERROR missing lifetime specifier
fn main() {}

14
src/test/ui/lifetimes/lifetime-elision-return-type-requires-explicit-lifetime.stderr
View file

@ -70,6 +70,18 @@ help: consider using the `'a` lifetime
LL | fn k<'a, T: WithLifetime<'a>>(_x: T::Output) -> &'a isize {
| ++
error: aborting due to 6 previous errors
error[E0106]: missing lifetime specifier
--> $DIR/lifetime-elision-return-type-requires-explicit-lifetime.rs:45:37
|
LL | fn l<'a>(_: &'a str, _: &'a str) -> &str { "" }
| ------- ------- ^ expected named lifetime parameter
|
= help: this function's return type contains a borrowed value with an elided lifetime, but the lifetime cannot be derived from the arguments
help: consider using the `'a` lifetime
|
LL | fn l<'a>(_: &'a str, _: &'a str) -> &'a str { "" }
| ++
error: aborting due to 7 previous errors
For more information about this error, try `rustc --explain E0106`.