Stabilize #[diagnostic::do_not_recommend]

compiler/rustc_feature/src/accepted.rs

@@ -173,6 +173,8 @@ declare_features! (
     (accepted, destructuring_assignment, "1.59.0", Some(71126)),
     /// Allows using the `#[diagnostic]` attribute tool namespace
     (accepted, diagnostic_namespace, "1.78.0", Some(111996)),
+    /// Controls errors in trait implementations.
+    (accepted, do_not_recommend, "CURRENT_RUSTC_VERSION", Some(51992)),
     /// Allows `#[doc(alias = "...")]`.
     (accepted, doc_alias, "1.48.0", Some(50146)),
     /// Allows `..` in tuple (struct) patterns.

compiler/rustc_feature/src/builtin_attrs.rs

@@ -1188,10 +1188,9 @@ pub static BUILTIN_ATTRIBUTE_MAP: LazyLock<FxHashMap<Symbol, &BuiltinAttribute>>
         map
     });
 
-pub fn is_stable_diagnostic_attribute(sym: Symbol, features: &Features) -> bool {
+pub fn is_stable_diagnostic_attribute(sym: Symbol, _features: &Features) -> bool {
     match sym {
-        sym::on_unimplemented => true,
-        sym::do_not_recommend => features.do_not_recommend(),
+        sym::on_unimplemented | sym::do_not_recommend => true,
         _ => false,
     }
 }

compiler/rustc_feature/src/unstable.rs

@@ -450,8 +450,6 @@ declare_features! (
     (unstable, deprecated_suggestion, "1.61.0", Some(94785)),
     /// Allows deref patterns.
     (incomplete, deref_patterns, "1.79.0", Some(87121)),
-    /// Controls errors in trait implementations.
-    (unstable, do_not_recommend, "1.67.0", Some(51992)),
     /// Tells rustdoc to automatically generate `#[doc(cfg(...))]`.
     (unstable, doc_auto_cfg, "1.58.0", Some(43781)),
     /// Allows `#[doc(cfg(...))]`.

compiler/rustc_passes/messages.ftl

@@ -353,6 +353,9 @@ passes_ignored_derived_impls =
 passes_implied_feature_not_exist =
     feature `{$implied_by}` implying `{$feature}` does not exist
 
+passes_incorrect_do_not_recommend_args =
+    `#[diagnostic::do_not_recommend]` does not expect any arguments
+
 passes_incorrect_do_not_recommend_location =
     `#[diagnostic::do_not_recommend]` can only be placed on trait implementations
 

compiler/rustc_passes/src/check_attr.rs

@@ -117,7 +117,7 @@ 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, item)
                 }
                 [sym::diagnostic, sym::on_unimplemented, ..] => {
                     self.check_diagnostic_on_unimplemented(attr.span, hir_id, target)
@@ -352,15 +352,36 @@ 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) {
-        if !matches!(target, Target::Impl) {
+    fn check_do_not_recommend(
+        &self,
+        attr_span: Span,
+        hir_id: HirId,
+        target: Target,
+        attr: &Attribute,
+        item: Option<ItemLike<'_>>,
+    ) {
+        if !matches!(target, Target::Impl)
+            || matches!(
+                item,
+                Some(ItemLike::Item(hir::Item {  kind: hir::ItemKind::Impl(_impl),.. }))
+                    if _impl.of_trait.is_none()
+            )
+        {
             self.tcx.emit_node_span_lint(
                 UNKNOWN_OR_MALFORMED_DIAGNOSTIC_ATTRIBUTES,
                 hir_id,
                 attr_span,
                 errors::IncorrectDoNotRecommendLocation,
             );
         }
+        if !matches!(attr.meta_kind(), Some(MetaItemKind::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

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 {

compiler/rustc_resolve/src/macros.rs

@@ -689,8 +689,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             && let [namespace, attribute, ..] = &*path.segments
             && namespace.ident.name == sym::diagnostic
             && !(attribute.ident.name == sym::on_unimplemented
-                || (attribute.ident.name == sym::do_not_recommend
-                    && self.tcx.features().do_not_recommend()))
+                || attribute.ident.name == sym::do_not_recommend)
         {
             let distance =
                 edit_distance(attribute.ident.name.as_str(), sym::on_unimplemented.as_str(), 5);

library/core/src/lib.rs

@@ -108,6 +108,7 @@
 // Library features:
 // tidy-alphabetical-start
 #![cfg_attr(bootstrap, feature(const_fmt_arguments_new))]
+#![cfg_attr(bootstrap, feature(do_not_recommend))]
 #![feature(array_ptr_get)]
 #![feature(asm_experimental_arch)]
 #![feature(const_align_of_val)]
@@ -145,7 +146,6 @@
 #![feature(const_unicode_case_lookup)]
 #![feature(core_intrinsics)]
 #![feature(coverage_attribute)]
-#![feature(do_not_recommend)]
 #![feature(internal_impls_macro)]
 #![feature(ip)]
 #![feature(is_ascii_octdigit)]

tests/ui/diagnostic_namespace/do_not_recommend/as_expression.current.stderr

@@ -1,5 +1,5 @@
 error[E0277]: the trait bound `&str: AsExpression<Integer>` is not satisfied
-  --> $DIR/as_expression.rs:57:15
+  --> $DIR/as_expression.rs:55:15
    |
 LL |     SelectInt.check("bar");
    |               ^^^^^ the trait `AsExpression<Integer>` is not implemented for `&str`

tests/ui/diagnostic_namespace/do_not_recommend/as_expression.next.stderr

@@ -1,5 +1,5 @@
 error[E0277]: the trait bound `&str: AsExpression<<SelectInt as Expression>::SqlType>` is not satisfied
-  --> $DIR/as_expression.rs:57:21
+  --> $DIR/as_expression.rs:55:21
    |
 LL |     SelectInt.check("bar");
    |               ----- ^^^^^ the trait `AsExpression<<SelectInt as Expression>::SqlType>` is not implemented for `&str`
@@ -8,7 +8,7 @@ LL |     SelectInt.check("bar");
    |
    = help: the trait `AsExpression<Text>` is implemented for `&str`
 note: required by a bound in `Foo::check`
-  --> $DIR/as_expression.rs:48:12
+  --> $DIR/as_expression.rs:46:12
    |
 LL |     fn check<T>(&self, _: T) -> <T as AsExpression<<Self as Expression>::SqlType>>::Expression
    |        ----- required by a bound in this associated function
@@ -17,7 +17,7 @@ LL |         T: AsExpression<Self::SqlType>,
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `Foo::check`
 
 error[E0277]: the trait bound `&str: AsExpression<Integer>` is not satisfied
-  --> $DIR/as_expression.rs:57:15
+  --> $DIR/as_expression.rs:55:15
    |
 LL |     SelectInt.check("bar");
    |               ^^^^^ the trait `AsExpression<Integer>` is not implemented for `&str`
@@ -26,7 +26,7 @@ LL |     SelectInt.check("bar");
    = help: for that trait implementation, expected `Text`, found `Integer`
 
 error[E0271]: type mismatch resolving `<SelectInt as Expression>::SqlType == Text`
-  --> $DIR/as_expression.rs:57:5
+  --> $DIR/as_expression.rs:55:5
    |
 LL |     SelectInt.check("bar");
    |     ^^^^^^^^^^^^^^^^^^^^^^ expected `Text`, found `Integer`

tests/ui/diagnostic_namespace/do_not_recommend/as_expression.rs

@@ -2,8 +2,6 @@
 //@ ignore-compare-mode-next-solver (explicit revisions)
 //@[next] compile-flags: -Znext-solver
 
-#![feature(do_not_recommend)]
-
 pub trait Expression {
     type SqlType;
 }

tests/ui/diagnostic_namespace/do_not_recommend/does_not_acccept_args.current.stderr

@@ -0,0 +1,22 @@
+warning: `#[diagnostic::do_not_recommend]` does not expect any arguments
+  --> $DIR/does_not_acccept_args.rs:10:1
+   |
+LL | #[diagnostic::do_not_recommend(not_accepted)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(unknown_or_malformed_diagnostic_attributes)]` on by default
+
+warning: `#[diagnostic::do_not_recommend]` does not expect any arguments
+  --> $DIR/does_not_acccept_args.rs:14:1
+   |
+LL | #[diagnostic::do_not_recommend(not_accepted = "foo")]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: `#[diagnostic::do_not_recommend]` does not expect any arguments
+  --> $DIR/does_not_acccept_args.rs:18:1
+   |
+LL | #[diagnostic::do_not_recommend(not_accepted(42))]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: 3 warnings emitted
+

tests/ui/diagnostic_namespace/do_not_recommend/does_not_acccept_args.next.stderr

@@ -0,0 +1,22 @@
+warning: `#[diagnostic::do_not_recommend]` does not expect any arguments
+  --> $DIR/does_not_acccept_args.rs:10:1
+   |
+LL | #[diagnostic::do_not_recommend(not_accepted)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(unknown_or_malformed_diagnostic_attributes)]` on by default
+
+warning: `#[diagnostic::do_not_recommend]` does not expect any arguments
+  --> $DIR/does_not_acccept_args.rs:14:1
+   |
+LL | #[diagnostic::do_not_recommend(not_accepted = "foo")]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: `#[diagnostic::do_not_recommend]` does not expect any arguments
+  --> $DIR/does_not_acccept_args.rs:18:1
+   |
+LL | #[diagnostic::do_not_recommend(not_accepted(42))]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: 3 warnings emitted
+

tests/ui/diagnostic_namespace/do_not_recommend/does_not_acccept_args.rs

@@ -0,0 +1,22 @@
+//@ check-pass
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
+
+trait Foo {}
+trait Bar {}
+trait Baz {}
+
+#[diagnostic::do_not_recommend(not_accepted)]
+//~^ WARNING `#[diagnostic::do_not_recommend]` does not expect any arguments
+impl<T> Foo for T where T: Send {}
+
+#[diagnostic::do_not_recommend(not_accepted = "foo")]
+//~^ WARNING `#[diagnostic::do_not_recommend]` does not expect any arguments
+impl<T> Bar for T where T: Send {}
+
+#[diagnostic::do_not_recommend(not_accepted(42))]
+//~^ WARNING `#[diagnostic::do_not_recommend]` does not expect any arguments
+impl<T> Baz for T where T: Send {}
+
+fn main() {}

tests/ui/diagnostic_namespace/do_not_recommend/incorrect-locations.stderr → tests/ui/diagnostic_namespace/do_not_recommend/incorrect-locations.current.stderr

@@ -1,52 +1,58 @@
 warning: `#[diagnostic::do_not_recommend]` can only be placed on trait implementations
-  --> $DIR/incorrect-locations.rs:4:1
+  --> $DIR/incorrect-locations.rs:6:1
    |
 LL | #[diagnostic::do_not_recommend]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `#[warn(unknown_or_malformed_diagnostic_attributes)]` on by default
 
 warning: `#[diagnostic::do_not_recommend]` can only be placed on trait implementations
-  --> $DIR/incorrect-locations.rs:8:1
+  --> $DIR/incorrect-locations.rs:10:1
    |
 LL | #[diagnostic::do_not_recommend]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: `#[diagnostic::do_not_recommend]` can only be placed on trait implementations
-  --> $DIR/incorrect-locations.rs:12:1
+  --> $DIR/incorrect-locations.rs:14:1
    |
 LL | #[diagnostic::do_not_recommend]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: `#[diagnostic::do_not_recommend]` can only be placed on trait implementations
-  --> $DIR/incorrect-locations.rs:16:1
+  --> $DIR/incorrect-locations.rs:18:1
    |
 LL | #[diagnostic::do_not_recommend]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: `#[diagnostic::do_not_recommend]` can only be placed on trait implementations
-  --> $DIR/incorrect-locations.rs:20:1
+  --> $DIR/incorrect-locations.rs:22:1
    |
 LL | #[diagnostic::do_not_recommend]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: `#[diagnostic::do_not_recommend]` can only be placed on trait implementations
-  --> $DIR/incorrect-locations.rs:24:1
+  --> $DIR/incorrect-locations.rs:26:1
    |
 LL | #[diagnostic::do_not_recommend]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: `#[diagnostic::do_not_recommend]` can only be placed on trait implementations
-  --> $DIR/incorrect-locations.rs:28:1
+  --> $DIR/incorrect-locations.rs:30:1
    |
 LL | #[diagnostic::do_not_recommend]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: `#[diagnostic::do_not_recommend]` can only be placed on trait implementations
-  --> $DIR/incorrect-locations.rs:32:1
+  --> $DIR/incorrect-locations.rs:34:1
    |
 LL | #[diagnostic::do_not_recommend]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-warning: 8 warnings emitted
+warning: `#[diagnostic::do_not_recommend]` can only be placed on trait implementations
+  --> $DIR/incorrect-locations.rs:38:1
+   |
+LL | #[diagnostic::do_not_recommend]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: 9 warnings emitted