From d50d1db7e539ee53c329afd18f4f77050a42beb3 Mon Sep 17 00:00:00 2001
From: Jonathan Brouwer <jonathantbrouwer@gmail.com>
Date: Wed, 17 Jun 2026 13:46:30 +0200
Subject: [PATCH] Move `UnusedDuplicate` diag struct to `rustc_attr_parsing`

---
 compiler/rustc_attr_parsing/src/attributes/doc.rs |  8 ++------
 compiler/rustc_attr_parsing/src/context.rs        | 14 +++-----------
 .../rustc_attr_parsing/src/session_diagnostics.rs | 13 +++++++++++++
 compiler/rustc_errors/src/lib.rs                  |  1 -
 compiler/rustc_errors/src/lints.rs                | 15 ---------------
 5 files changed, 18 insertions(+), 33 deletions(-)
 delete mode 100644 compiler/rustc_errors/src/lints.rs

diff --git a/compiler/rustc_attr_parsing/src/attributes/doc.rs b/compiler/rustc_attr_parsing/src/attributes/doc.rs
index 382f0539f7678..e91ab584bcf47 100644
--- a/compiler/rustc_attr_parsing/src/attributes/doc.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/doc.rs
@@ -22,7 +22,7 @@ use crate::diagnostics::{
 use crate::parser::{ArgParser, MetaItemOrLitParser, MetaItemParser, OwnedPathParser};
 use crate::session_diagnostics::{
     DocAliasBadChar, DocAliasEmpty, DocAliasMalformed, DocAliasStartEnd, DocAttrNotCrateLevel,
-    DocAttributeNotAttribute, DocKeywordNotKeyword,
+    DocAttributeNotAttribute, DocKeywordNotKeyword, UnusedDuplicate,
 };
 
 fn check_keyword(cx: &mut AcceptContext<'_, '_>, keyword: Symbol, span: Span) -> bool {
@@ -159,11 +159,7 @@ impl DocParser {
                     let unused_span = path.span();
                     cx.emit_lint(
                         rustc_session::lint::builtin::INVALID_DOC_ATTRIBUTES,
-                        rustc_errors::lints::UnusedDuplicate {
-                            this: unused_span,
-                            other: used_span,
-                            warning: true,
-                        },
+                        UnusedDuplicate { this: unused_span, other: used_span, warning: true },
                         unused_span,
                     );
                     return;
diff --git a/compiler/rustc_attr_parsing/src/context.rs b/compiler/rustc_attr_parsing/src/context.rs
index fb5ca0375900a..2811bc8ff5683 100644
--- a/compiler/rustc_attr_parsing/src/context.rs
+++ b/compiler/rustc_attr_parsing/src/context.rs
@@ -71,7 +71,7 @@ use crate::parser::{
 };
 use crate::session_diagnostics::{
     AttributeParseError, AttributeParseErrorReason, AttributeParseErrorSuggestions,
-    ParsedDescription,
+    ParsedDescription, UnusedDuplicate,
 };
 use crate::target_checking::AllowedTargets;
 use crate::{AttrSuggestionStyle, AttributeParser, AttributeTemplate, EmitAttribute};
@@ -436,11 +436,7 @@ impl<'f, 'sess: 'f> SharedContext<'f, 'sess> {
     pub(crate) fn warn_unused_duplicate(&mut self, used_span: Span, unused_span: Span) {
         self.emit_lint(
             rustc_session::lint::builtin::UNUSED_ATTRIBUTES,
-            rustc_errors::lints::UnusedDuplicate {
-                this: unused_span,
-                other: used_span,
-                warning: false,
-            },
+            UnusedDuplicate { this: unused_span, other: used_span, warning: false },
             unused_span,
         )
     }
@@ -452,11 +448,7 @@ impl<'f, 'sess: 'f> SharedContext<'f, 'sess> {
     ) {
         self.emit_lint(
             rustc_session::lint::builtin::UNUSED_ATTRIBUTES,
-            rustc_errors::lints::UnusedDuplicate {
-                this: unused_span,
-                other: used_span,
-                warning: true,
-            },
+            UnusedDuplicate { this: unused_span, other: used_span, warning: true },
             unused_span,
         )
     }
diff --git a/compiler/rustc_attr_parsing/src/session_diagnostics.rs b/compiler/rustc_attr_parsing/src/session_diagnostics.rs
index 193ffe195fb6c..d1470d870d130 100644
--- a/compiler/rustc_attr_parsing/src/session_diagnostics.rs
+++ b/compiler/rustc_attr_parsing/src/session_diagnostics.rs
@@ -1045,3 +1045,16 @@ pub(crate) struct AdditionalCommaSuggestion {
     #[primary_span]
     pub span: Span,
 }
+
+#[derive(Diagnostic)]
+#[diag("unused attribute")]
+pub(crate) struct UnusedDuplicate {
+    #[suggestion("remove this attribute", code = "", applicability = "machine-applicable")]
+    pub this: Span,
+    #[note("attribute also specified here")]
+    pub other: Span,
+    #[warning(
+        "this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!"
+    )]
+    pub warning: bool,
+}
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index 76cdb10f429c7..e9bb6701c38f1 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -79,7 +79,6 @@ mod diagnostic_impls;
 pub mod emitter;
 pub mod formatting;
 pub mod json;
-pub mod lints;
 mod lock;
 pub mod markdown;
 pub mod timings;
diff --git a/compiler/rustc_errors/src/lints.rs b/compiler/rustc_errors/src/lints.rs
deleted file mode 100644
index 9c93a09bf764c..0000000000000
--- a/compiler/rustc_errors/src/lints.rs
+++ /dev/null
@@ -1,15 +0,0 @@
-use rustc_macros::Diagnostic;
-use rustc_span::Span;
-
-#[derive(Diagnostic)]
-#[diag("unused attribute")]
-pub struct UnusedDuplicate {
-    #[suggestion("remove this attribute", code = "", applicability = "machine-applicable")]
-    pub this: Span,
-    #[note("attribute also specified here")]
-    pub other: Span,
-    #[warning(
-        "this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!"
-    )]
-    pub warning: bool,
-}