port #[pattern_complexity_limit] to the new attribute parsing infrastructure

compiler/rustc_attr_parsing/src/attributes/crate_level.rs

@@ -147,3 +147,30 @@ impl<S: Stage> SingleAttributeParser<S> for TypeLengthLimitParser {
         })
     }
 }
+
+pub(crate) struct PatternComplexityLimitParser;
+
+impl<S: Stage> SingleAttributeParser<S> for PatternComplexityLimitParser {
+    const PATH: &[Symbol] = &[sym::pattern_complexity_limit];
+    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const TEMPLATE: AttributeTemplate = template!(NameValueStr: "N");
+    const TYPE: AttributeType = AttributeType::CrateLevel;
+
+    // FIXME: recursion limit is allowed on all targets and ignored,
+    //        even though it should only be valid on crates of course
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Crate)]);
+
+    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
+        let ArgParser::NameValue(nv) = args else {
+            cx.expected_name_value(cx.attr_span, None);
+            return None;
+        };
+
+        Some(AttributeKind::PatternComplexityLimit {
+            limit: cx.parse_limit_int(nv)?,
+            attr_span: cx.attr_span,
+            limit_span: nv.value_span,
+        })
+    }
+}

compiler/rustc_attr_parsing/src/context.rs

@@ -25,7 +25,8 @@ use crate::attributes::codegen_attrs::{
 };
 use crate::attributes::confusables::ConfusablesParser;
 use crate::attributes::crate_level::{
-    CrateNameParser, MoveSizeLimitParser, RecursionLimitParser, TypeLengthLimitParser,
+    CrateNameParser, MoveSizeLimitParser, PatternComplexityLimitParser, RecursionLimitParser,
+    TypeLengthLimitParser,
 };
 use crate::attributes::deprecation::DeprecationParser;
 use crate::attributes::dummy::DummyParser;
@@ -187,6 +188,7 @@ attribute_parsers!(
         Single<MustUseParser>,
         Single<OptimizeParser>,
         Single<PathAttributeParser>,
+        Single<PatternComplexityLimitParser>,
         Single<ProcMacroDeriveParser>,
         Single<RecursionLimitParser>,
         Single<RustcBuiltinMacroParser>,

compiler/rustc_hir/src/attrs/data_structures.rs

@@ -599,6 +599,9 @@ pub enum AttributeKind {
     /// Represents `#[path]`
     Path(Symbol, Span),
 
+    /// Represents `#[pattern_complexity_limit]`
+    PatternComplexityLimit { attr_span: Span, limit_span: Span, limit: usize },
+
     /// Represents `#[pointee]`
     Pointee(Span),
 

compiler/rustc_hir/src/attrs/encode_cross_crate.rs

@@ -71,6 +71,7 @@ impl AttributeKind {
             ParenSugar(..) => No,
             PassByValue(..) => Yes,
             Path(..) => No,
+            PatternComplexityLimit { .. } => No,
             Pointee(..) => No,
             ProcMacro(..) => No,
             ProcMacroAttribute(..) => No,

compiler/rustc_passes/src/check_attr.rs

@@ -273,6 +273,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                     | AttributeKind::RecursionLimit { .. }
                     | AttributeKind::MoveSizeLimit { .. }
                     | AttributeKind::TypeLengthLimit { .. }
+                    | AttributeKind::PatternComplexityLimit { .. }
                 ) => { /* do nothing  */ }
                 Attribute::Unparsed(attr_item) => {
                     style = Some(attr_item.style);