Port #[rustc_skip_during_method_dispatch] to the new attribute system

Author: GrigorenkoPV

compiler/rustc_attr_data_structures/src/attributes.rs

@@ -243,6 +243,9 @@ pub enum AttributeKind {
     /// Represents [`#[repr]`](https://doc.rust-lang.org/stable/reference/type-layout.html#representations).
     Repr(ThinVec<(ReprAttr, Span)>),
 
+    /// Represents `#[rustc_skip_during_method_dispatch]`.
+    SkipDuringMethodDispatch { array: bool, boxed_slice: bool, span: Span },
+
     /// Represents `#[stable]`, `#[unstable]` and `#[rustc_allowed_through_unstable_modules]`.
     Stability {
         stability: Stability,

compiler/rustc_attr_parsing/src/attributes/codegen_attrs.rs

@@ -48,11 +48,7 @@ impl<S: Stage> SingleAttributeParser<S> for ColdParser {
     const TEMPLATE: AttributeTemplate = template!(Word);
 
     fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
-        if !args.no_args() {
-            cx.expected_no_args(args.span().unwrap_or(cx.attr_span));
-            return None;
-        };
-
+        cx.expect_no_args(args).ok()?;
         Some(AttributeKind::Cold(cx.attr_span))
     }
 }

compiler/rustc_attr_parsing/src/attributes/lint_helpers.rs

@@ -14,8 +14,8 @@ impl<S: Stage> SingleAttributeParser<S> for AsPtrParser {
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
     const TEMPLATE: AttributeTemplate = template!(Word);
 
-    fn convert(cx: &mut AcceptContext<'_, '_, S>, _args: &ArgParser<'_>) -> Option<AttributeKind> {
-        // FIXME: check that there's no args (this is currently checked elsewhere)
+    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
+        cx.expect_no_args(args).ok()?;
         Some(AttributeKind::AsPtr(cx.attr_span))
     }
 }

compiler/rustc_attr_parsing/src/attributes/mod.rs

@@ -34,6 +34,7 @@ pub(crate) mod deprecation;
 pub(crate) mod inline;
 pub(crate) mod lint_helpers;
 pub(crate) mod repr;
+pub(crate) mod resolution;
 pub(crate) mod semantics;
 pub(crate) mod stability;
 pub(crate) mod transparency;

compiler/rustc_attr_parsing/src/attributes/resolution.rs

@@ -0,0 +1,52 @@
+use core::mem;
+
+use rustc_attr_data_structures::AttributeKind;
+use rustc_feature::{AttributeTemplate, template};
+use rustc_span::{ErrorGuaranteed, Symbol, sym};
+
+use crate::attributes::{AttributeOrder, OnDuplicate, SingleAttributeParser};
+use crate::context::{AcceptContext, Stage};
+use crate::parser::ArgParser;
+
+pub(crate) struct SkipDuringMethodDispatchParser;
+
+impl<S: Stage> SingleAttributeParser<S> for SkipDuringMethodDispatchParser {
+    const PATH: &[Symbol] = &[sym::rustc_skip_during_method_dispatch];
+    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepFirst;
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+
+    const TEMPLATE: AttributeTemplate = template!(List: "array, boxed_slice");
+
+    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
+        let mut array = false;
+        let mut boxed_slice = false;
+        let Some(args) = args.list() else {
+            cx.expected_list(cx.attr_span);
+            return None;
+        };
+        if args.is_empty() {
+            cx.expected_at_least_one_argument(args.span);
+            return None;
+        }
+        for arg in args.mixed() {
+            let Some(arg) = arg.meta_item() else {
+                cx.unexpected_literal(arg.span());
+                continue;
+            };
+            let _: Result<(), ErrorGuaranteed> = cx.expect_no_args(arg.args());
+            let path = arg.path();
+            let (key, skip): (Symbol, &mut bool) = match path.word_sym() {
+                Some(key @ sym::array) => (key, &mut array),
+                Some(key @ sym::boxed_slice) => (key, &mut boxed_slice),
+                _ => {
+                    cx.expected_specific_argument(path.span(), vec!["array", "boxed_slice"]);
+                    continue;
+                }
+            };
+            if mem::replace(skip, true) {
+                cx.duplicate_key(arg.span(), key);
+            }
+        }
+        Some(AttributeKind::SkipDuringMethodDispatch { array, boxed_slice, span: cx.attr_span })
+    }
+}

compiler/rustc_attr_parsing/src/attributes/stability.rs

@@ -139,7 +139,8 @@ impl<S: Stage> SingleAttributeParser<S> for ConstStabilityIndirectParser {
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Ignore;
     const TEMPLATE: AttributeTemplate = template!(Word);
 
-    fn convert(_cx: &mut AcceptContext<'_, '_, S>, _args: &ArgParser<'_>) -> Option<AttributeKind> {
+    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
+        cx.expect_no_args(args).ok()?;
         Some(AttributeKind::ConstStabilityIndirect)
     }
 }

compiler/rustc_attr_parsing/src/context.rs

@@ -21,6 +21,7 @@ use crate::attributes::deprecation::DeprecationParser;
 use crate::attributes::inline::{InlineParser, RustcForceInlineParser};
 use crate::attributes::lint_helpers::AsPtrParser;
 use crate::attributes::repr::{AlignParser, ReprParser};
+use crate::attributes::resolution::SkipDuringMethodDispatchParser;
 use crate::attributes::semantics::MayDangleParser;
 use crate::attributes::stability::{
     BodyStabilityParser, ConstStabilityIndirectParser, ConstStabilityParser, StabilityParser,
@@ -114,6 +115,7 @@ attribute_parsers!(
         Single<MayDangleParser>,
         Single<OptimizeParser>,
         Single<RustcForceInlineParser>,
+        Single<SkipDuringMethodDispatchParser>,
         Single<TransparencyParser>,
         // tidy-alphabetical-end
     ];
@@ -237,14 +239,22 @@ impl<'f, 'sess: 'f, S: Stage> AcceptContext<'f, 'sess, S> {
         })
     }
 
-    pub(crate) fn expected_no_args(&self, args_span: Span) -> ErrorGuaranteed {
-        self.emit_err(AttributeParseError {
-            span: args_span,
-            attr_span: self.attr_span,
-            template: self.template.clone(),
-            attribute: self.attr_path.clone(),
-            reason: AttributeParseErrorReason::ExpectedNoArgs,
-        })
+    pub(crate) fn expect_no_args(&self, args: &ArgParser<'_>) -> Result<(), ErrorGuaranteed> {
+        if let Some(span) = match args {
+            ArgParser::NoArgs => None,
+            ArgParser::List(args) => Some(args.span),
+            ArgParser::NameValue(args) => Some(args.eq_span.to(args.value_span)),
+        } {
+            Err(self.emit_err(AttributeParseError {
+                span,
+                attr_span: self.attr_span,
+                template: self.template.clone(),
+                attribute: self.attr_path.clone(),
+                reason: AttributeParseErrorReason::ExpectedNoArgs,
+            }))
+        } else {
+            Ok(())
+        }
     }
 
     /// emit an error that a `name = value` pair was expected at this span. The symbol can be given for
@@ -292,6 +302,16 @@ impl<'f, 'sess: 'f, S: Stage> AcceptContext<'f, 'sess, S> {
         })
     }
 
+    pub(crate) fn expected_at_least_one_argument(&self, span: Span) -> ErrorGuaranteed {
+        self.emit_err(AttributeParseError {
+            span,
+            attr_span: self.attr_span,
+            template: self.template.clone(),
+            attribute: self.attr_path.clone(),
+            reason: AttributeParseErrorReason::ExpectedAtLeastOneArgument,
+        })
+    }
+
     pub(crate) fn expected_specific_argument(
         &self,
         span: Span,

compiler/rustc_attr_parsing/src/session_diagnostics.rs

@@ -476,6 +476,7 @@ pub(crate) struct UnrecognizedReprHint {
 pub(crate) enum AttributeParseErrorReason {
     ExpectedNoArgs,
     ExpectedStringLiteral { byte_string: Option<Span> },
+    ExpectedAtLeastOneArgument,
     ExpectedSingleArgument,
     ExpectedList,
     UnexpectedLiteral,
@@ -519,6 +520,9 @@ impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for AttributeParseError {
                 diag.span_label(self.span, "expected a single argument here");
                 diag.code(E0805);
             }
+            AttributeParseErrorReason::ExpectedAtLeastOneArgument => {
+                diag.span_label(self.span, "expected at least 1 argument here");
+            }
             AttributeParseErrorReason::ExpectedList => {
                 diag.span_label(self.span, "expected this to be a list");
             }

compiler/rustc_feature/src/builtin_attrs.rs

@@ -1083,7 +1083,7 @@ pub static BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
         "the `#[rustc_main]` attribute is used internally to specify test entry point function",
     ),
     rustc_attr!(
-        rustc_skip_during_method_dispatch, Normal, template!(List: "array, boxed_slice"), WarnFollowing,
+        rustc_skip_during_method_dispatch, Normal, template!(List: "array, boxed_slice"), ErrorFollowing,
         EncodeCrossCrate::No,
         "the `#[rustc_skip_during_method_dispatch]` attribute is used to exclude a trait \
         from method dispatch when the receiver is of the following type, for compatibility in \

compiler/rustc_hir_analysis/src/collect.rs

@@ -21,6 +21,7 @@ use std::ops::Bound;
 
 use rustc_abi::ExternAbi;
 use rustc_ast::Recovered;
+use rustc_attr_data_structures::{AttributeKind, find_attr};
 use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
 use rustc_data_structures::unord::UnordMap;
 use rustc_errors::{
@@ -1151,22 +1152,11 @@ fn trait_def(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::TraitDef {
     let rustc_coinductive = tcx.has_attr(def_id, sym::rustc_coinductive);
     let is_fundamental = tcx.has_attr(def_id, sym::fundamental);
 
-    // FIXME: We could probably do way better attribute validation here.
-    let mut skip_array_during_method_dispatch = false;
-    let mut skip_boxed_slice_during_method_dispatch = false;
-    for attr in tcx.get_attrs(def_id, sym::rustc_skip_during_method_dispatch) {
-        if let Some(lst) = attr.meta_item_list() {
-            for item in lst {
-                if let Some(ident) = item.ident() {
-                    match ident.as_str() {
-                        "array" => skip_array_during_method_dispatch = true,
-                        "boxed_slice" => skip_boxed_slice_during_method_dispatch = true,
-                        _ => (),
-                    }
-                }
-            }
-        }
-    }
+    let [skip_array_during_method_dispatch, skip_boxed_slice_during_method_dispatch] = find_attr!(
+        tcx.get_all_attrs(def_id),
+        AttributeKind::SkipDuringMethodDispatch { array, boxed_slice, span:_ } => [*array, *boxed_slice]
+    )
+    .unwrap_or([false; 2]);
 
     let specialization_kind = if tcx.has_attr(def_id, sym::rustc_unsafe_specialization_marker) {
         ty::trait_def::TraitSpecializationKind::Marker