Check `#[diagnostic::do_not_recommend]` for arguments

This commit adds a check that verifies that no arguments are passed to
`#[diagnostic::do_not_recommend]`. If we detect arguments we emit a warning.

2 files changed, 20 insertions, 2 deletions

diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index ce7947ad3ec..9879dfa9720 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -115,7 +115,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         for attr in attrs {
             match attr.path().as_slice() {
                 [sym::diagnostic, sym::do_not_recommend, ..] => {
-                    self.check_do_not_recommend(attr.span, hir_id, target)
+                    self.check_do_not_recommend(attr.span, hir_id, target, attr)
                 }
                 [sym::diagnostic, sym::on_unimplemented, ..] => {
                     self.check_diagnostic_on_unimplemented(attr.span, hir_id, target)
@@ -348,7 +348,13 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
     }
 
     /// Checks if `#[diagnostic::do_not_recommend]` is applied on a trait impl.
-    fn check_do_not_recommend(&self, attr_span: Span, hir_id: HirId, target: Target) {
+    fn check_do_not_recommend(
+        &self,
+        attr_span: Span,
+        hir_id: HirId,
+        target: Target,
+        attr: &Attribute,
+    ) {
         if !matches!(target, Target::Impl) {
             self.tcx.emit_node_span_lint(
                 UNKNOWN_OR_MALFORMED_DIAGNOSTIC_ATTRIBUTES,
@@ -357,6 +363,14 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 errors::IncorrectDoNotRecommendLocation,
             );
         }
+        if !attr.is_word() {
+            self.tcx.emit_node_span_lint(
+                UNKNOWN_OR_MALFORMED_DIAGNOSTIC_ATTRIBUTES,
+                hir_id,
+                attr_span,
+                errors::DoNotRecommendDoesNotExpectArgs,
+            );
+        }
     }
 
     /// Checks if `#[diagnostic::on_unimplemented]` is applied to a trait definition
diff --git a/compiler/rustc_passes/src/errors.rs b/compiler/rustc_passes/src/errors.rs
index f71d5284052..5e7bfa5e3bb 100644
--- a/compiler/rustc_passes/src/errors.rs
+++ b/compiler/rustc_passes/src/errors.rs
@@ -20,6 +20,10 @@ use crate::lang_items::Duplicate;
 #[diag(passes_incorrect_do_not_recommend_location)]
 pub(crate) struct IncorrectDoNotRecommendLocation;
 
+#[derive(LintDiagnostic)]
+#[diag(passes_incorrect_do_not_recommend_args)]
+pub(crate) struct DoNotRecommendDoesNotExpectArgs;
+
 #[derive(Diagnostic)]
 #[diag(passes_autodiff_attr)]
 pub(crate) struct AutoDiffAttr {