Rollup merge of rust-lang#138985 - oli-obk:push-mvlqmtmyozro, r=compiler-errors

Use the correct binder scope for elided lifetimes in assoc consts

Beyond diagnostics this has no real effect, and it's also just about a future incompat lint. But it causes ICEs in some refactorings that I'm doing, so trying to get it out of the way

Author: TaKO8Ki

compiler/rustc_resolve/src/late.rs

@@ -3329,34 +3329,44 @@ impl<'a, 'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
                     },
                     |this| {
                         this.with_lifetime_rib(
-                            LifetimeRibKind::StaticIfNoLifetimeInScope {
-                                lint_id: item.id,
-                                // In impls, it's not a hard error yet due to backcompat.
-                                emit_lint: true,
+                            // Until these are a hard error, we need to create them within the correct binder,
+                            // Otherwise the lifetimes of this assoc const think they are lifetimes of the trait.
+                            LifetimeRibKind::AnonymousCreateParameter {
+                                binder: item.id,
+                                report_in_path: true,
                             },
                             |this| {
-                                // If this is a trait impl, ensure the const
-                                // exists in trait
-                                this.check_trait_item(
-                                    item.id,
-                                    item.ident,
-                                    &item.kind,
-                                    ValueNS,
-                                    item.span,
-                                    seen_trait_items,
-                                    |i, s, c| ConstNotMemberOfTrait(i, s, c),
-                                );
+                                this.with_lifetime_rib(
+                                    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
+                                        this.check_trait_item(
+                                            item.id,
+                                            item.ident,
+                                            &item.kind,
+                                            ValueNS,
+                                            item.span,
+                                            seen_trait_items,
+                                            |i, s, c| ConstNotMemberOfTrait(i, s, c),
+                                        );
 
-                                this.visit_generics(generics);
-                                this.visit_ty(ty);
-                                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.visit_generics(generics);
+                                        this.visit_ty(ty);
+                                        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);
+                                        }
+                                    },
+                                )
                             },
                         );
                     },

tests/ui/consts/assoc-const-elided-lifetime.stderr

@@ -35,8 +35,6 @@ note: cannot automatically infer `'static` because of other lifetimes in scope
    |
 LL | impl<'a> Foo<'a> {
    |      ^^
-LL |     const FOO: Foo<'_> = Foo { x: PhantomData::<&()> };
-   |                    ^^
 help: use the `'static` lifetime
    |
 LL |     const BAR: &'static () = &();

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

@@ -16,7 +16,7 @@ impl Bar for Foo<'_> {
     const STATIC: &str = "";
     //~^ ERROR `&` without an explicit lifetime name cannot be used here
     //~| WARN this was previously accepted by the compiler but is being phased out
-    //~| ERROR const not compatible with trait
+    //~| ERROR lifetime parameters or bounds on const `STATIC` do not match the trait declaration
 }
 
 fn main() {}

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

@@ -39,21 +39,15 @@ help: use the `'static` lifetime
 LL |     const STATIC: &'static str = "";
    |                    +++++++
 
-error[E0308]: const not compatible with trait
-  --> $DIR/elided-lifetime.rs:16:5
+error[E0195]: lifetime parameters or bounds on const `STATIC` do not match the trait declaration
+  --> $DIR/elided-lifetime.rs:16:17
    |
+LL |     const STATIC: &str;
+   |                 - lifetimes in impl do not match this const in trait
+...
 LL |     const STATIC: &str = "";
-   |     ^^^^^^^^^^^^^^^^^^ lifetime mismatch
-   |
-   = note: expected reference `&'static _`
-              found reference `&_`
-note: the anonymous lifetime as defined here...
-  --> $DIR/elided-lifetime.rs:16:19
-   |
-LL |     const STATIC: &str = "";
-   |                   ^
-   = note: ...does not necessarily outlive the static lifetime
+   |                 ^ lifetimes do not match const in trait
 
 error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0308`.
+For more information about this error, try `rustc --explain E0195`.

tests/ui/consts/static-default-lifetime/static-trait-impl.rs

@@ -9,7 +9,7 @@ impl Bar<'_> for A {
     const STATIC: &str = "";
     //~^ ERROR `&` without an explicit lifetime name cannot be used here
     //~| WARN this was previously accepted by the compiler but is being phased out
-    //~| ERROR const not compatible with trait
+    //~| ERROR lifetime parameters or bounds on const `STATIC` do not match the trait declaration
 }
 
 struct B;

tests/ui/consts/static-default-lifetime/static-trait-impl.stderr

@@ -21,25 +21,15 @@ help: use the `'static` lifetime
 LL |     const STATIC: &'static str = "";
    |                    +++++++
 
-error[E0308]: const not compatible with trait
-  --> $DIR/static-trait-impl.rs:9:5
+error[E0195]: lifetime parameters or bounds on const `STATIC` do not match the trait declaration
+  --> $DIR/static-trait-impl.rs:9:17
    |
+LL |     const STATIC: &'a str;
+   |                 - lifetimes in impl do not match this const in trait
+...
 LL |     const STATIC: &str = "";
-   |     ^^^^^^^^^^^^^^^^^^ lifetime mismatch
-   |
-   = note: expected reference `&_`
-              found reference `&_`
-note: the anonymous lifetime as defined here...
-  --> $DIR/static-trait-impl.rs:9:19
-   |
-LL |     const STATIC: &str = "";
-   |                   ^
-note: ...does not necessarily outlive the anonymous lifetime as defined here
-  --> $DIR/static-trait-impl.rs:8:10
-   |
-LL | impl Bar<'_> for A {
-   |          ^^
+   |                 ^ lifetimes do not match const in trait
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0308`.
+For more information about this error, try `rustc --explain E0195`.