Port #![compiler_builtins] to the attribute parser.

compiler/rustc_attr_parsing/src/attributes/link_attrs.rs

@@ -665,3 +665,12 @@ impl<S: Stage> NoArgsAttributeParser<S> for NeedsAllocatorParser {
     const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Crate)]);
     const CREATE: fn(Span) -> AttributeKind = |_| AttributeKind::NeedsAllocator;
 }
+
+pub(crate) struct CompilerBuiltinsParser;
+
+impl<S: Stage> NoArgsAttributeParser<S> for CompilerBuiltinsParser {
+    const PATH: &[Symbol] = &[sym::compiler_builtins];
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Crate)]);
+    const CREATE: fn(Span) -> AttributeKind = |_| AttributeKind::CompilerBuiltins;
+}

compiler/rustc_attr_parsing/src/context.rs

@@ -40,8 +40,9 @@ use crate::attributes::dummy::DummyParser;
 use crate::attributes::inline::{InlineParser, RustcForceInlineParser};
 use crate::attributes::instruction_set::InstructionSetParser;
 use crate::attributes::link_attrs::{
-    ExportStableParser, FfiConstParser, FfiPureParser, LinkNameParser, LinkOrdinalParser,
-    LinkParser, LinkSectionParser, LinkageParser, NeedsAllocatorParser, StdInternalSymbolParser,
+    CompilerBuiltinsParser, ExportStableParser, FfiConstParser, FfiPureParser, LinkNameParser,
+    LinkOrdinalParser, LinkParser, LinkSectionParser, LinkageParser, NeedsAllocatorParser,
+    StdInternalSymbolParser,
 };
 use crate::attributes::lint_helpers::{
     AsPtrParser, AutomaticallyDerivedParser, PassByValueParser, PubTransparentParser,
@@ -251,6 +252,7 @@ attribute_parsers!(
         Single<WithoutArgs<AutomaticallyDerivedParser>>,
         Single<WithoutArgs<CoinductiveParser>>,
         Single<WithoutArgs<ColdParser>>,
+        Single<WithoutArgs<CompilerBuiltinsParser>>,
         Single<WithoutArgs<ConstContinueParser>>,
         Single<WithoutArgs<ConstStabilityIndirectParser>>,
         Single<WithoutArgs<CoroutineParser>>,

compiler/rustc_hir/src/attrs/data_structures.rs

@@ -687,6 +687,9 @@ pub enum AttributeKind {
     /// Represents `#[collapse_debuginfo]`.
     CollapseDebugInfo(CollapseMacroDebuginfo),
 
+    /// Represents `#[compiler_builtins]`.
+    CompilerBuiltins,
+
     /// Represents `#[rustc_confusables]`.
     Confusables {
         symbols: ThinVec<Symbol>,

compiler/rustc_hir/src/attrs/encode_cross_crate.rs

@@ -32,6 +32,7 @@ impl AttributeKind {
             Coinductive(..) => No,
             Cold(..) => No,
             CollapseDebugInfo(..) => Yes,
+            CompilerBuiltins => No,
             Confusables { .. } => Yes,
             ConstContinue(..) => No,
             ConstStability { .. } => Yes,

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -741,7 +741,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                 externally_implementable_items,
                 proc_macro_data,
                 debugger_visualizers,
-                compiler_builtins: ast::attr::contains_name(attrs, sym::compiler_builtins),
+                compiler_builtins: find_attr!(attrs, AttributeKind::CompilerBuiltins),
                 needs_allocator: find_attr!(attrs, AttributeKind::NeedsAllocator),
                 needs_panic_runtime: ast::attr::contains_name(attrs, sym::needs_panic_runtime),
                 no_builtins: ast::attr::contains_name(attrs, sym::no_builtins),

compiler/rustc_middle/src/ty/context.rs

@@ -3562,7 +3562,7 @@ pub fn provide(providers: &mut Providers) {
     providers.is_panic_runtime =
         |tcx, LocalCrate| contains_name(tcx.hir_krate_attrs(), sym::panic_runtime);
     providers.is_compiler_builtins =
-        |tcx, LocalCrate| contains_name(tcx.hir_krate_attrs(), sym::compiler_builtins);
+        |tcx, LocalCrate| find_attr!(tcx.hir_krate_attrs(), AttributeKind::CompilerBuiltins);
     providers.has_panic_handler = |tcx, LocalCrate| {
         // We want to check if the panic handler was defined in this crate
         tcx.lang_items().panic_impl().is_some_and(|did| did.is_local())

compiler/rustc_passes/src/check_attr.rs

@@ -299,6 +299,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                     | AttributeKind::NoCore { .. }
                     | AttributeKind::NoStd { .. }
                     | AttributeKind::NoMain
+                    | AttributeKind::CompilerBuiltins
                     | AttributeKind::ObjcClass { .. }
                     | AttributeKind::ObjcSelector { .. }
                     | AttributeKind::RustcCoherenceIsCore(..)
@@ -397,10 +398,8 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                             | sym::rustc_no_implicit_bounds
                             | sym::test_runner
                             | sym::reexport_test_harness_main
-                            | sym::no_main
                             | sym::no_builtins
                             | sym::crate_type
-                            | sym::compiler_builtins
                             | sym::profiler_runtime
                             | sym::needs_panic_runtime
                             | sym::panic_runtime