From ee855c02aff1dfc5e609f2ff307885e8842f454c Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume1.gomez@gmail.com>
Date: Wed, 4 Mar 2026 11:32:19 +0100
Subject: [PATCH] Migrate `rustc_pattern_analysis` lint to `Diagnostic`

---
 compiler/rustc_pattern_analysis/src/errors.rs |  6 ++++--
 compiler/rustc_pattern_analysis/src/lints.rs  | 10 +++-------
 2 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/compiler/rustc_pattern_analysis/src/errors.rs b/compiler/rustc_pattern_analysis/src/errors.rs
index b27e52f32bf2..25432d6ea5cd 100644
--- a/compiler/rustc_pattern_analysis/src/errors.rs
+++ b/compiler/rustc_pattern_analysis/src/errors.rs
@@ -1,5 +1,5 @@
 use rustc_errors::{Diag, EmissionGuarantee, Subdiagnostic};
-use rustc_macros::{Diagnostic, LintDiagnostic, Subdiagnostic};
+use rustc_macros::{Diagnostic, Subdiagnostic};
 use rustc_middle::ty::Ty;
 use rustc_span::Span;
 
@@ -131,10 +131,12 @@ pub(crate) struct NonExhaustiveOmittedPattern<'tcx> {
     pub uncovered: Uncovered,
 }
 
-#[derive(LintDiagnostic)]
+#[derive(Diagnostic)]
 #[diag("the lint level must be set on the whole match")]
 #[help("it no longer has any effect to set the lint level on an individual match arm")]
 pub(crate) struct NonExhaustiveOmittedPatternLintOnArm {
+    #[primary_span]
+    pub span: Span,
     #[label("remove this attribute")]
     pub lint_span: Span,
     #[suggestion(
diff --git a/compiler/rustc_pattern_analysis/src/lints.rs b/compiler/rustc_pattern_analysis/src/lints.rs
index 3da744dc8c02..5a8adf4841c4 100644
--- a/compiler/rustc_pattern_analysis/src/lints.rs
+++ b/compiler/rustc_pattern_analysis/src/lints.rs
@@ -92,17 +92,13 @@ pub(crate) fn lint_nonexhaustive_missing_variants<'p, 'tcx>(
             let LevelAndSource { level, src, .. } =
                 rcx.tcx.lint_level_at_node(NON_EXHAUSTIVE_OMITTED_PATTERNS, arm.arm_data);
             if !matches!(level, rustc_session::lint::Level::Allow) {
-                let decorator = NonExhaustiveOmittedPatternLintOnArm {
+                rcx.tcx.dcx().emit_warn(NonExhaustiveOmittedPatternLintOnArm {
+                    span: arm.pat.data().span,
                     lint_span: src.span(),
                     suggest_lint_on_match: rcx.whole_match_span.map(|span| span.shrink_to_lo()),
                     lint_level: level.as_str(),
                     lint_name: "non_exhaustive_omitted_patterns",
-                };
-
-                use rustc_errors::LintDiagnostic;
-                let mut err = rcx.tcx.dcx().struct_span_warn(arm.pat.data().span, "");
-                decorator.decorate_lint(&mut err);
-                err.emit();
+                });
             }
         }
     }