Rollup merge of #115011 - compiler-errors:warn-on-elided-assoc-ct-lt, r=cjgillot

Warn on elided lifetimes in associated constants (`ELIDED_LIFETIMES_IN_ASSOCIATED_CONSTANT`)

Elided lifetimes in associated constants (in impls) erroneously resolve to fresh lifetime parameters on the impl since #97313. This is not correct behavior (see #38831).

I originally opened #114716 to fix this, but given the time that has passed, the crater results seem pretty bad: https://github.com/rust-lang/rust/pull/114716#issuecomment-1682091952

This PR alternatively implements a lint against this behavior, and I'm hoping to bump this to deny in a few versions.

1 files changed, 8 insertions, 0 deletions

diff --git a/compiler/rustc_lint/src/context.rs b/compiler/rustc_lint/src/context.rs
index f73797415bc..aabefb729f3 100644
--- a/compiler/rustc_lint/src/context.rs
+++ b/compiler/rustc_lint/src/context.rs
@@ -966,6 +966,14 @@ pub trait LintContext: Sized {
                         Applicability::MachineApplicable
                     );
                 }
+                BuiltinLintDiagnostics::AssociatedConstElidedLifetime { elided, span } => {
+                    db.span_suggestion_verbose(
+                        if elided { span.shrink_to_hi() } else { span },
+                        "use the `'static` lifetime",
+                        if elided { "'static " } else { "'static" },
+                        Applicability::MachineApplicable
+                    );
+                }
             }
             // Rewrap `db`, and pass control to the user.
             decorate(db)