Port #[marker] to the new attribute system

Author: GrigorenkoPV

compiler/rustc_attr_data_structures/src/attributes.rs

@@ -255,6 +255,9 @@ pub enum AttributeKind {
     /// Represents `#[rustc_macro_transparency]`.
     MacroTransparency(Transparency),
 
+    /// Represents `#[marker]`.
+    Marker(Span),
+
     /// Represents [`#[may_dangle]`](https://std-dev-guide.rust-lang.org/tricky/may-dangle.html).
     MayDangle(Span),
 

compiler/rustc_attr_parsing/src/attributes/traits.rs

@@ -124,3 +124,13 @@ impl<S: Stage> NoArgsAttributeParser<S> for UnsafeSpecializationMarkerParser {
         AttributeKind::UnsafeSpecializationMarker(span)
     }
 }
+
+pub(crate) struct MarkerParser;
+impl<S: Stage> NoArgsAttributeParser<S> for MarkerParser {
+    const PATH: &[Symbol] = &[sym::marker];
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+
+    fn create(span: Span) -> AttributeKind {
+        AttributeKind::Marker(span)
+    }
+}

compiler/rustc_attr_parsing/src/context.rs

@@ -29,7 +29,7 @@ use crate::attributes::stability::{
 };
 use crate::attributes::traits::{
     CoinductiveParser, ConstTraitParser, DenyExplicitImplParser, DoNotImplementViaObjectParser,
-    SkipDuringMethodDispatchParser, SpecializationTraitParser, TypeConstParser,
+    MarkerParser, SkipDuringMethodDispatchParser, SpecializationTraitParser, TypeConstParser,
     UnsafeSpecializationMarkerParser,
 };
 use crate::attributes::transparency::TransparencyParser;
@@ -133,6 +133,7 @@ attribute_parsers!(
         Single<WithoutArgs<ExportStableParser>>,
         Single<WithoutArgs<FfiConstParser>>,
         Single<WithoutArgs<FfiPureParser>>,
+        Single<WithoutArgs<MarkerParser>>,
         Single<WithoutArgs<MayDangleParser>>,
         Single<WithoutArgs<NoMangleParser>>,
         Single<WithoutArgs<PassByValueParser>>,

compiler/rustc_hir_analysis/src/collect.rs

@@ -1148,7 +1148,7 @@ fn trait_def(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::TraitDef {
     }
 
     // Only regular traits can be marker.
-    let is_marker = !is_alias && attrs.iter().any(|attr| attr.has_name(sym::marker));
+    let is_marker = !is_alias && find_attr!(attrs, AttributeKind::Marker(_));
 
     let rustc_coinductive = find_attr!(attrs, AttributeKind::Coinductive(_));
     let is_fundamental = attrs.iter().any(|attr| attr.has_name(sym::fundamental));

compiler/rustc_parse/src/validate_attr.rs

@@ -302,6 +302,7 @@ fn emit_malformed_attribute(
             | sym::const_trait
             | sym::rustc_specialization_trait
             | sym::rustc_unsafe_specialization_marker
+            | sym::marker
             | sym::type_const
             | sym::rustc_pass_by_value
             | sym::repr

compiler/rustc_passes/src/check_attr.rs

@@ -137,6 +137,9 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 &Attribute::Parsed(AttributeKind::TypeConst(attr_span)) => {
                     self.check_type_const(hir_id, attr_span, target)
                 }
+                &Attribute::Parsed(AttributeKind::Marker(attr_span)) => {
+                    self.check_marker(hir_id, attr_span, span, target)
+                }
                 Attribute::Parsed(AttributeKind::Confusables { first_span, .. }) => {
                     self.check_confusables(*first_span, target);
                 }
@@ -225,7 +228,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                             self.check_no_sanitize(attr, span, target)
                         }
                         [sym::non_exhaustive, ..] => self.check_non_exhaustive(hir_id, attr, span, target, item),
-                        [sym::marker, ..] => self.check_marker(hir_id, attr, span, target),
                         [sym::target_feature, ..] => {
                             self.check_target_feature(hir_id, attr, span, target, attrs)
                         }
@@ -792,21 +794,19 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
     }
 
     /// Checks if the `#[marker]` attribute on an `item` is valid.
-    fn check_marker(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
+    fn check_marker(&self, hir_id: HirId, attr_span: Span, span: Span, target: Target) {
         match target {
             Target::Trait => {}
             // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
             // `#[marker]` attribute with just a lint, because we previously
             // erroneously allowed it and some crates used it accidentally, to be compatible
             // with crates depending on them, we can't throw an error here.
             Target::Field | Target::Arm | Target::MacroDef => {
-                self.inline_attr_str_error_with_macro_def(hir_id, attr.span(), "marker");
+                self.inline_attr_str_error_with_macro_def(hir_id, attr_span, "marker");
             }
             _ => {
-                self.dcx().emit_err(errors::AttrShouldBeAppliedToTrait {
-                    attr_span: attr.span(),
-                    defn_span: span,
-                });
+                self.dcx()
+                    .emit_err(errors::AttrShouldBeAppliedToTrait { attr_span, defn_span: span });
             }
         }
     }

tests/ui/marker_trait_attr/marker-attribute-with-values.stderr

@@ -1,20 +1,30 @@
-error: malformed `marker` attribute input
+error[E0565]: malformed `marker` attribute input
   --> $DIR/marker-attribute-with-values.rs:3:1
    |
 LL | #[marker(always)]
-   | ^^^^^^^^^^^^^^^^^ help: must be of the form: `#[marker]`
+   | ^^^^^^^^--------^
+   | |       |
+   | |       didn't expect any arguments here
+   | help: must be of the form: `#[marker]`
 
-error: malformed `marker` attribute input
+error[E0565]: malformed `marker` attribute input
   --> $DIR/marker-attribute-with-values.rs:6:1
    |
 LL | #[marker("never")]
-   | ^^^^^^^^^^^^^^^^^^ help: must be of the form: `#[marker]`
+   | ^^^^^^^^---------^
+   | |       |
+   | |       didn't expect any arguments here
+   | help: must be of the form: `#[marker]`
 
-error: malformed `marker` attribute input
+error[E0565]: malformed `marker` attribute input
   --> $DIR/marker-attribute-with-values.rs:9:1
    |
 LL | #[marker(key = "value")]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^ help: must be of the form: `#[marker]`
+   | ^^^^^^^^---------------^
+   | |       |
+   | |       didn't expect any arguments here
+   | help: must be of the form: `#[marker]`
 
 error: aborting due to 3 previous errors
 
+For more information about this error, try `rustc --explain E0565`.