Resolve const lifetimes to static in trait too

compiler/rustc_resolve/src/late.rs

@@ -312,8 +312,8 @@ enum LifetimeRibKind {
 
     /// Resolves elided lifetimes to `'static` if there are no other lifetimes in scope,
     /// otherwise give a warning that the previous behavior of introducing a new early-bound
-    /// lifetime is a bug and will be removed.
-    StaticIfNoLifetimeInScope(NodeId),
+    /// lifetime is a bug and will be removed (if `emit_lint` is enabled).
+    StaticIfNoLifetimeInScope { lint_id: NodeId, emit_lint: bool },
 
     /// Signal we cannot find which should be the anonymous lifetime.
     ElisionFailure,
@@ -1213,7 +1213,7 @@ impl<'a: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast,
                             }
                             LifetimeRibKind::AnonymousCreateParameter { .. }
                             | LifetimeRibKind::AnonymousReportError
-                            | LifetimeRibKind::StaticIfNoLifetimeInScope(_)
+                            | LifetimeRibKind::StaticIfNoLifetimeInScope { .. }
                             | LifetimeRibKind::Elided(_)
                             | LifetimeRibKind::ElisionFailure
                             | LifetimeRibKind::ConcreteAnonConst(_)
@@ -1581,7 +1581,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
                                     // lifetime would be illegal.
                                     LifetimeRibKind::Item
                                     | LifetimeRibKind::AnonymousReportError
-                                    | LifetimeRibKind::StaticIfNoLifetimeInScope(_)
+                                    | LifetimeRibKind::StaticIfNoLifetimeInScope { .. }
                                     | LifetimeRibKind::ElisionFailure => Some(LifetimeUseSet::Many),
                                     // An anonymous lifetime is legal here, and bound to the right
                                     // place, go ahead.
@@ -1644,7 +1644,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
                 | LifetimeRibKind::Generics { .. }
                 | LifetimeRibKind::ElisionFailure
                 | LifetimeRibKind::AnonymousReportError
-                | LifetimeRibKind::StaticIfNoLifetimeInScope(_) => {}
+                | LifetimeRibKind::StaticIfNoLifetimeInScope { .. } => {}
             }
         }
 
@@ -1678,7 +1678,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
                     self.record_lifetime_res(lifetime.id, res, elision_candidate);
                     return;
                 }
-                LifetimeRibKind::StaticIfNoLifetimeInScope(node_id) => {
+                LifetimeRibKind::StaticIfNoLifetimeInScope { lint_id: node_id, emit_lint } => {
                     let mut lifetimes_in_scope = vec![];
                     for rib in &self.lifetime_ribs[..i] {
                         lifetimes_in_scope.extend(rib.bindings.iter().map(|(ident, _)| ident.span));
@@ -1696,7 +1696,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
                             elision_candidate,
                         );
                         return;
-                    } else {
+                    } else if emit_lint {
                         self.r.lint_buffer.buffer_lint(
                             lint::builtin::ELIDED_LIFETIMES_IN_ASSOCIATED_CONSTANT,
                             node_id,
@@ -1925,7 +1925,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
                     //     impl Foo for std::cell::Ref<u32> // note lack of '_
                     //     async fn foo(_: std::cell::Ref<u32>) { ... }
                     LifetimeRibKind::AnonymousCreateParameter { report_in_path: true, .. }
-                    | LifetimeRibKind::StaticIfNoLifetimeInScope(_) => {
+                    | LifetimeRibKind::StaticIfNoLifetimeInScope { .. } => {
                         let sess = self.r.tcx.sess;
                         let subdiag = rustc_errors::elided_lifetime_in_path_suggestion(
                             sess.source_map(),
@@ -2859,19 +2859,27 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
                             kind: LifetimeBinderKind::ConstItem,
                         },
                         |this| {
-                            this.visit_generics(generics);
-                            this.visit_ty(ty);
-
-                            // Only impose the restrictions of `ConstRibKind` for an
-                            // actual constant expression in a provided default.
-                            if let Some(expr) = expr {
-                                // We allow arbitrary const expressions inside of associated consts,
-                                // even if they are potentially not const evaluatable.
-                                //
-                                // Type parameters can already be used and as associated consts are
-                                // not used as part of the type system, this is far less surprising.
-                                this.resolve_const_body(expr, None);
-                            }
+                            this.with_lifetime_rib(
+                                LifetimeRibKind::StaticIfNoLifetimeInScope {
+                                    lint_id: item.id,
+                                    emit_lint: false,
+                                },
+                                |this| {
+                                    this.visit_generics(generics);
+                                    this.visit_ty(ty);
+
+                                    // Only impose the restrictions of `ConstRibKind` for an
+                                    // actual constant expression in a provided default.
+                                    if let Some(expr) = expr {
+                                        // We allow arbitrary const expressions inside of associated consts,
+                                        // even if they are potentially not const evaluatable.
+                                        //
+                                        // Type parameters can already be used and as associated consts are
+                                        // not used as part of the type system, this is far less surprising.
+                                        this.resolve_const_body(expr, None);
+                                    }
+                                },
+                            )
                         },
                     );
                 }
@@ -3052,7 +3060,11 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
                     },
                     |this| {
                         this.with_lifetime_rib(
-                            LifetimeRibKind::StaticIfNoLifetimeInScope(item.id),
+                            LifetimeRibKind::StaticIfNoLifetimeInScope {
+                                lint_id: item.id,
+                                // In impls, it's not a hard error yet due to backcompat.
+                                emit_lint: true,
+                            },
                             |this| {
                                 // If this is a trait impl, ensure the const
                                 // exists in trait

tests/ui/consts/static-default-lifetime/elided-lifetime.rs

@@ -9,8 +9,7 @@ impl Foo<'_> {
 }
 
 trait Bar {
-    const STATIC: &'static str;
-    // TODO^
+    const STATIC: &str;
 }
 
 impl Bar for Foo<'_> {

tests/ui/consts/static-default-lifetime/elided-lifetime.stderr

@@ -22,15 +22,15 @@ LL |     const STATIC: &'static str = "";
    |                    +++++++
 
 error: `&` without an explicit lifetime name cannot be used here
-  --> $DIR/elided-lifetime.rs:17:19
+  --> $DIR/elided-lifetime.rs:16:19
    |
 LL |     const STATIC: &str = "";
    |                   ^
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #115010 </~https://github.com/rust-lang/rust/issues/115010>
 note: cannot automatically infer `'static` because of other lifetimes in scope
-  --> $DIR/elided-lifetime.rs:16:18
+  --> $DIR/elided-lifetime.rs:15:18
    |
 LL | impl Bar for Foo<'_> {
    |                  ^^
@@ -40,15 +40,15 @@ LL |     const STATIC: &'static str = "";
    |                    +++++++
 
 error[E0308]: const not compatible with trait
-  --> $DIR/elided-lifetime.rs:17:5
+  --> $DIR/elided-lifetime.rs:16:5
    |
 LL |     const STATIC: &str = "";
    |     ^^^^^^^^^^^^^^^^^^ lifetime mismatch
    |
    = note: expected reference `&'static _`
               found reference `&_`
 note: the anonymous lifetime as defined here...
-  --> $DIR/elided-lifetime.rs:16:18
+  --> $DIR/elided-lifetime.rs:15:18
    |
 LL | impl Bar for Foo<'_> {
    |                  ^^

tests/ui/consts/static-default-lifetime/generic-associated-const.rs

@@ -12,7 +12,6 @@ impl A {
 
 trait Trait {
     const GAC_TYPE<T>: &str = "";
-    //~^ ERROR missing lifetime specifier
     const GAC_LIFETIME<'a>: &str = "";
     //~^ ERROR missing lifetime specifier
 }

tests/ui/consts/static-default-lifetime/generic-associated-const.stderr

@@ -1,16 +1,5 @@
 error[E0106]: missing lifetime specifier
-  --> $DIR/generic-associated-const.rs:14:24
-   |
-LL |     const GAC_TYPE<T>: &str = "";
-   |                        ^ expected named lifetime parameter
-   |
-help: consider introducing a named lifetime parameter
-   |
-LL |     const GAC_TYPE<'a, T>: &'a str = "";
-   |                    +++      ++
-
-error[E0106]: missing lifetime specifier
-  --> $DIR/generic-associated-const.rs:16:29
+  --> $DIR/generic-associated-const.rs:15:29
    |
 LL |     const GAC_LIFETIME<'a>: &str = "";
    |                             ^ expected named lifetime parameter
@@ -52,6 +41,6 @@ help: use the `'static` lifetime
 LL |     const GAC_LIFETIME<'a>: &'static str = "";
    |                              +++++++
 
-error: aborting due to 3 previous errors; 1 warning emitted
+error: aborting due to 2 previous errors; 1 warning emitted
 
 For more information about this error, try `rustc --explain E0106`.

tests/ui/suggestions/missing-lifetime-in-assoc-const-type.default.stderr

@@ -1,57 +1,25 @@
-error[E0106]: missing lifetime specifier
-  --> $DIR/missing-lifetime-in-assoc-const-type.rs:6:14
-   |
-LL |     const A: &str = "";
-   |              ^ expected named lifetime parameter
-   |
-help: consider introducing a named lifetime parameter
-   |
-LL ~ trait ZstAssert<'a>: Sized {
-LL ~     const A: &'a str = "";
-   |
-
-error[E0106]: missing lifetime specifier
+error[E0726]: implicit elided lifetime not allowed here
   --> $DIR/missing-lifetime-in-assoc-const-type.rs:7:14
    |
 LL |     const B: S = S { s: &() };
-   |              ^ expected named lifetime parameter
-   |
-help: consider introducing a named lifetime parameter
-   |
-LL ~ trait ZstAssert<'a>: Sized {
-LL |     const A: &str = "";
-LL ~     const B: S<'a> = S { s: &() };
+   |              ^ expected lifetime parameter
    |
-
-error[E0106]: missing lifetime specifier
-  --> $DIR/missing-lifetime-in-assoc-const-type.rs:8:15
-   |
-LL |     const C: &'_ str = "";
-   |               ^^ expected named lifetime parameter
-   |
-help: consider introducing a named lifetime parameter
-   |
-LL ~ trait ZstAssert<'a>: Sized {
-LL |     const A: &str = "";
-LL |     const B: S = S { s: &() };
-LL ~     const C: &'a str = "";
+help: indicate the anonymous lifetime
    |
+LL |     const B: S<'_> = S { s: &() };
+   |               ++++
 
-error[E0106]: missing lifetime specifiers
+error[E0726]: implicit elided lifetime not allowed here
   --> $DIR/missing-lifetime-in-assoc-const-type.rs:9:14
    |
 LL |     const D: T = T { a: &(), b: &() };
-   |              ^ expected 2 lifetime parameters
-   |
-help: consider introducing a named lifetime parameter
+   |              ^ expected lifetime parameters
    |
-LL ~ trait ZstAssert<'a>: Sized {
-LL |     const A: &str = "";
-LL |     const B: S = S { s: &() };
-LL |     const C: &'_ str = "";
-LL ~     const D: T<'a, 'a> = T { a: &(), b: &() };
+help: indicate the anonymous lifetimes
    |
+LL |     const D: T<'_, '_> = T { a: &(), b: &() };
+   |               ++++++++
 
-error: aborting due to 4 previous errors
+error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0106`.
+For more information about this error, try `rustc --explain E0726`.

tests/ui/suggestions/missing-lifetime-in-assoc-const-type.generic_const_items.stderr

@@ -1,47 +1,25 @@
-error[E0106]: missing lifetime specifier
-  --> $DIR/missing-lifetime-in-assoc-const-type.rs:6:14
-   |
-LL |     const A: &str = "";
-   |              ^ expected named lifetime parameter
-   |
-help: consider introducing a named lifetime parameter
-   |
-LL |     const A<'a>: &'a str = "";
-   |            ++++   ++
-
-error[E0106]: missing lifetime specifier
+error[E0726]: implicit elided lifetime not allowed here
   --> $DIR/missing-lifetime-in-assoc-const-type.rs:7:14
    |
 LL |     const B: S = S { s: &() };
-   |              ^ expected named lifetime parameter
-   |
-help: consider introducing a named lifetime parameter
-   |
-LL |     const B<'a>: S<'a> = S { s: &() };
-   |            ++++   ++++
-
-error[E0106]: missing lifetime specifier
-  --> $DIR/missing-lifetime-in-assoc-const-type.rs:8:15
-   |
-LL |     const C: &'_ str = "";
-   |               ^^ expected named lifetime parameter
+   |              ^ expected lifetime parameter
    |
-help: consider introducing a named lifetime parameter
+help: indicate the anonymous lifetime
    |
-LL |     const C<'a>: &'a str = "";
-   |            ++++   ~~
+LL |     const B: S<'_> = S { s: &() };
+   |               ++++
 
-error[E0106]: missing lifetime specifiers
+error[E0726]: implicit elided lifetime not allowed here
   --> $DIR/missing-lifetime-in-assoc-const-type.rs:9:14
    |
 LL |     const D: T = T { a: &(), b: &() };
-   |              ^ expected 2 lifetime parameters
+   |              ^ expected lifetime parameters
    |
-help: consider introducing a named lifetime parameter
+help: indicate the anonymous lifetimes
    |
-LL |     const D<'a>: T<'a, 'a> = T { a: &(), b: &() };
-   |            ++++   ++++++++
+LL |     const D: T<'_, '_> = T { a: &(), b: &() };
+   |               ++++++++
 
-error: aborting due to 4 previous errors
+error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0106`.
+For more information about this error, try `rustc --explain E0726`.

tests/ui/suggestions/missing-lifetime-in-assoc-const-type.rs

@@ -3,10 +3,10 @@
 #![cfg_attr(generic_const_items, feature(generic_const_items), allow(incomplete_features))]
 
 trait ZstAssert: Sized {
-    const A: &str = ""; //~ ERROR missing lifetime specifier
-    const B: S = S { s: &() }; //~ ERROR missing lifetime specifier
-    const C: &'_ str = ""; //~ ERROR missing lifetime specifier
-    const D: T = T { a: &(), b: &() }; //~ ERROR missing lifetime specifier
+    const A: &str = "";
+    const B: S = S { s: &() }; //~ ERROR implicit elided lifetime not allowed here
+    const C: &'_ str = "";
+    const D: T = T { a: &(), b: &() }; //~ ERROR implicit elided lifetime not allowed here
 }
 
 struct S<'a> {