Rollup merge of #111444 - cjgillot:issue-111400, r=oli-obk

Only warn single-use lifetime when the binders match. Fixes #111400
rust-lang · May 12, 2023 · 7c31df9 · 7c31df9
2 parents d4d15e8 + a2fe993
commit 7c31df9
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diff --git a/compiler/rustc_resolve/src/late.rs b/compiler/rustc_resolve/src/late.rs
@@ -1482,7 +1482,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
             if let Some(&(_, res)) = rib.bindings.get(&normalized_ident) {
                 self.record_lifetime_res(lifetime.id, res, LifetimeElisionCandidate::Named);
 
-                if let LifetimeRes::Param { param, .. } = res {
+                if let LifetimeRes::Param { param, binder } = res {
                     match self.lifetime_uses.entry(param) {
                         Entry::Vacant(v) => {
                             debug!("First use of {:?} at {:?}", res, ident.span);
@@ -1496,10 +1496,16 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
                                     LifetimeRibKind::Item
                                     | LifetimeRibKind::AnonymousReportError
                                     | LifetimeRibKind::ElisionFailure => Some(LifetimeUseSet::Many),
-                                    // An anonymous lifetime is legal here, go ahead.
-                                    LifetimeRibKind::AnonymousCreateParameter { .. } => {
-                                        Some(LifetimeUseSet::One { use_span: ident.span, use_ctxt })
-                                    }
+                                    // An anonymous lifetime is legal here, and bound to the right
+                                    // place, go ahead.
+                                    LifetimeRibKind::AnonymousCreateParameter {
+                                        binder: anon_binder,
+                                        ..
+                                    } => Some(if binder == anon_binder {
+                                        LifetimeUseSet::One { use_span: ident.span, use_ctxt }
+                                    } else {
+                                        LifetimeUseSet::Many
+                                    }),
                                     // Only report if eliding the lifetime would have the same
                                     // semantics.
                                     LifetimeRibKind::Elided(r) => Some(if res == r {

diff --git a/tests/ui/associated-inherent-types/issue-109790.rs b/tests/ui/associated-inherent-types/issue-109790.rs
@@ -2,6 +2,7 @@
 
 #![feature(inherent_associated_types)]
 #![allow(incomplete_features)]
+#![deny(single_use_lifetimes)]
 
 struct Foo<T>(T);