From bd538f90fe127a8896935c03d6be8a336edc0780 Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume1.gomez@gmail.com>
Date: Tue, 3 Mar 2026 17:21:41 +0100
Subject: [PATCH] Remove unused `rustc_errors::LintDiagnosticBox` trait

---
 compiler/rustc_errors/src/diagnostic.rs | 10 ----------
 compiler/rustc_errors/src/lib.rs        |  2 +-
 2 files changed, 1 insertion(+), 11 deletions(-)

diff --git a/compiler/rustc_errors/src/diagnostic.rs b/compiler/rustc_errors/src/diagnostic.rs
index 27a70534c5bc..4dec167b982b 100644
--- a/compiler/rustc_errors/src/diagnostic.rs
+++ b/compiler/rustc_errors/src/diagnostic.rs
@@ -137,16 +137,6 @@ pub trait LintDiagnostic<'a, G: EmissionGuarantee> {
     fn decorate_lint<'b>(self, diag: &'b mut Diag<'a, G>);
 }
 
-pub trait LintDiagnosticBox<'a, G: EmissionGuarantee> {
-    fn decorate_lint_box<'b>(self: Box<Self>, diag: &'b mut Diag<'a, G>);
-}
-
-impl<'a, G: EmissionGuarantee, D: LintDiagnostic<'a, G>> LintDiagnosticBox<'a, G> for D {
-    fn decorate_lint_box<'b>(self: Box<Self>, diag: &'b mut Diag<'a, G>) {
-        self.decorate_lint(diag);
-    }
-}
-
 #[derive(Clone, Debug, Encodable, Decodable)]
 pub(crate) struct DiagLocation {
     file: Cow<'static, str>,
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index eab919f08ab5..4ef4d5807463 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -40,7 +40,7 @@
 pub use decorate_diag::{BufferedEarlyLint, DecorateDiagCompat, LintBuffer};
 pub use diagnostic::{
     BugAbort, Diag, DiagInner, DiagStyledString, Diagnostic, EmissionGuarantee, FatalAbort,
-    LintDiagnostic, LintDiagnosticBox, StringPart, Subdiag, Subdiagnostic,
+    LintDiagnostic, StringPart, Subdiag, Subdiagnostic,
 };
 pub use diagnostic_impls::{
     DiagSymbolList, ElidedLifetimeInPathSubdiag, ExpectedLifetimeParameter,