Port #[rustc_proc_macro_decls] to the new attribute parser.

compiler/rustc_attr_parsing/src/attributes/macro_attrs.rs

@@ -206,3 +206,12 @@ impl<S: Stage> SingleAttributeParser<S> for CollapseDebugInfoParser {
         Some(AttributeKind::CollapseDebugInfo(info))
     }
 }
+
+pub(crate) struct RustcProcMacroDeclsParser;
+
+impl<S: Stage> NoArgsAttributeParser<S> for RustcProcMacroDeclsParser {
+    const PATH: &[Symbol] = &[sym::rustc_proc_macro_decls];
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Static)]);
+    const CREATE: fn(Span) -> AttributeKind = |_| AttributeKind::RustcProcMacroDecls;
+}

compiler/rustc_attr_parsing/src/context.rs

@@ -297,6 +297,7 @@ attribute_parsers!(
         Single<WithoutArgs<RustcOutlivesParser>>,
         Single<WithoutArgs<RustcPassIndirectlyInNonRusticAbisParser>>,
         Single<WithoutArgs<RustcPreserveUbChecksParser>>,
+        Single<WithoutArgs<RustcProcMacroDeclsParser>>,
         Single<WithoutArgs<RustcReallocatorParser>>,
         Single<WithoutArgs<RustcRegionsParser>>,
         Single<WithoutArgs<RustcShouldNotBeCalledOnConstItems>>,

compiler/rustc_hir/src/attrs/data_structures.rs

@@ -1288,6 +1288,9 @@ pub enum AttributeKind {
     /// Represents `#[rustc_preserve_ub_checks]`
     RustcPreserveUbChecks,
 
+    /// Represents `#[rustc_proc_macro_decls]`
+    RustcProcMacroDecls,
+
     /// Represents `#[rustc_pub_transparent]` (used by the `repr_transparent_external_private_fields` lint).
     RustcPubTransparent(Span),
 

compiler/rustc_hir/src/attrs/encode_cross_crate.rs

@@ -156,6 +156,7 @@ impl AttributeKind {
             RustcPassByValue(..) => Yes,
             RustcPassIndirectlyInNonRusticAbis(..) => No,
             RustcPreserveUbChecks => No,
+            RustcProcMacroDecls => No,
             RustcPubTransparent(..) => Yes,
             RustcReallocator => No,
             RustcRegions => No,

compiler/rustc_interface/src/proc_macro_decls.rs

@@ -1,15 +1,14 @@
-use rustc_ast::attr;
+use rustc_hir::attrs::AttributeKind;
 use rustc_hir::def_id::LocalDefId;
+use rustc_hir::find_attr;
 use rustc_middle::query::Providers;
 use rustc_middle::ty::TyCtxt;
-use rustc_span::sym;
 
 fn proc_macro_decls_static(tcx: TyCtxt<'_>, (): ()) -> Option<LocalDefId> {
     let mut decls = None;
 
     for id in tcx.hir_free_items() {
-        let attrs = tcx.hir_attrs(id.hir_id());
-        if attr::contains_name(attrs, sym::rustc_proc_macro_decls) {
+        if find_attr!(tcx.hir_attrs(id.hir_id()), AttributeKind::RustcProcMacroDecls) {
             decls = Some(id.owner_id.def_id);
         }
     }

compiler/rustc_passes/src/check_attr.rs

@@ -348,6 +348,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                     | AttributeKind::RustcPassByValue (..)
                     | AttributeKind::RustcPassIndirectlyInNonRusticAbis(..)
                     | AttributeKind::RustcPreserveUbChecks
+                    | AttributeKind::RustcProcMacroDecls
                     | AttributeKind::RustcReallocator
                     | AttributeKind::RustcRegions
                     | AttributeKind::RustcReservationImpl(..)
@@ -406,7 +407,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                             | sym::rustc_doc_primitive
                             | sym::rustc_test_marker
                             | sym::rustc_layout
-                            | sym::rustc_proc_macro_decls
                             | sym::rustc_autodiff
                             | sym::rustc_capture_analysis
                             | sym::rustc_mir