Auto merge of #125410 - fmease:adj-lint-diag-api, r=nnethercote

[perf] Delay the construction of early lint diag structs

Attacks some of the perf regressions from https://github.com/rust-lang/rust/pull/124417#issuecomment-2123700666.

See individual commits for details. The first three commits are not strictly necessary.
However, the 2nd one (06bc4fc67145e3a7be9b5a2cf2b5968cef36e587, *Remove `LintDiagnostic::msg`*) makes the main change way nicer to implement.
It's also pretty sweet on its own if I may say so myself.

1 files changed, 3 insertions, 3 deletions

diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index 3b884ff864a..4dc5d84b318 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -39,7 +39,7 @@ pub use diagnostic_impls::{
 };
 pub use emitter::ColorConfig;
 pub use rustc_error_messages::{
-    fallback_fluent_bundle, fluent_bundle, DelayDm, DiagMessage, FluentBundle, LanguageIdentifier,
+    fallback_fluent_bundle, fluent_bundle, DiagMessage, FluentBundle, LanguageIdentifier,
     LazyFallbackBundle, MultiSpan, SpanLabel, SubdiagMessage,
 };
 pub use rustc_lint_defs::{pluralize, Applicability};
@@ -572,8 +572,8 @@ impl Drop for DiagCtxtInner {
             if let Some(backtrace) = &self.must_produce_diag {
                 panic!(
                     "must_produce_diag: `trimmed_def_paths` called but no diagnostics emitted; \
-                       use `DelayDm` for lints or `with_no_trimmed_paths` for debugging. \
-                       called at: {backtrace}"
+                     `with_no_trimmed_paths` for debugging. \
+                     called at: {backtrace}"
                 );
             }
         }