Rollup merge of #140539 - nnethercote:simplify-attribute_groups, r=jdonszelmann

Simplify `attribute_groups`

It's more complicated than it needs to be.

r? ``@jdonszelmann``

Author: jhpratt

compiler/rustc_attr_parsing/src/attributes/allow_unstable.rs

@@ -10,7 +10,7 @@ use crate::session_diagnostics;
 
 pub(crate) struct AllowInternalUnstableParser;
 impl CombineAttributeParser for AllowInternalUnstableParser {
-    const PATH: &'static [rustc_span::Symbol] = &[sym::allow_internal_unstable];
+    const PATH: &'static [Symbol] = &[sym::allow_internal_unstable];
     type Item = (Symbol, Span);
     const CONVERT: ConvertFn<Self::Item> = AttributeKind::AllowInternalUnstable;
 
@@ -24,7 +24,7 @@ impl CombineAttributeParser for AllowInternalUnstableParser {
 
 pub(crate) struct AllowConstFnUnstableParser;
 impl CombineAttributeParser for AllowConstFnUnstableParser {
-    const PATH: &'static [rustc_span::Symbol] = &[sym::rustc_allow_const_fn_unstable];
+    const PATH: &'static [Symbol] = &[sym::rustc_allow_const_fn_unstable];
     type Item = Symbol;
     const CONVERT: ConvertFn<Self::Item> = AttributeKind::AllowConstFnUnstable;
 

compiler/rustc_attr_parsing/src/attributes/deprecation.rs

@@ -42,9 +42,9 @@ fn get(
 }
 
 impl SingleAttributeParser for DeprecationParser {
-    const PATH: &'static [rustc_span::Symbol] = &[sym::deprecated];
+    const PATH: &'static [Symbol] = &[sym::deprecated];
 
-    fn on_duplicate(cx: &AcceptContext<'_>, first_span: rustc_span::Span) {
+    fn on_duplicate(cx: &AcceptContext<'_>, first_span: Span) {
         // FIXME(jdonszelmann): merge with errors from check_attrs.rs
         cx.emit_err(session_diagnostics::UnusedMultiple {
             this: cx.attr_span,

compiler/rustc_attr_parsing/src/attributes/mod.rs

@@ -17,7 +17,7 @@
 use std::marker::PhantomData;
 
 use rustc_attr_data_structures::AttributeKind;
-use rustc_span::Span;
+use rustc_span::{Span, Symbol};
 use thin_vec::ThinVec;
 
 use crate::context::{AcceptContext, FinalizeContext};
@@ -33,7 +33,7 @@ pub(crate) mod transparency;
 pub(crate) mod util;
 
 type AcceptFn<T> = fn(&mut T, &AcceptContext<'_>, &ArgParser<'_>);
-type AcceptMapping<T> = &'static [(&'static [rustc_span::Symbol], AcceptFn<T>)];
+type AcceptMapping<T> = &'static [(&'static [Symbol], AcceptFn<T>)];
 
 /// An [`AttributeParser`] is a type which searches for syntactic attributes.
 ///
@@ -72,7 +72,7 @@ pub(crate) trait AttributeParser: Default + 'static {
 /// [`SingleAttributeParser`] can only convert attributes one-to-one, and cannot combine multiple
 /// attributes together like is necessary for `#[stable()]` and `#[unstable()]` for example.
 pub(crate) trait SingleAttributeParser: 'static {
-    const PATH: &'static [rustc_span::Symbol];
+    const PATH: &'static [Symbol];
 
     /// Caled when a duplicate attribute is found.
     ///
@@ -119,7 +119,7 @@ type ConvertFn<E> = fn(ThinVec<E>) -> AttributeKind;
 /// [`CombineAttributeParser`] can only convert a single kind of attribute, and cannot combine multiple
 /// attributes together like is necessary for `#[stable()]` and `#[unstable()]` for example.
 pub(crate) trait CombineAttributeParser: 'static {
-    const PATH: &'static [rustc_span::Symbol];
+    const PATH: &'static [Symbol];
 
     type Item;
     const CONVERT: ConvertFn<Self::Item>;

compiler/rustc_attr_parsing/src/attributes/repr.rs

@@ -1,7 +1,7 @@
 use rustc_abi::Align;
 use rustc_ast::{IntTy, LitIntType, LitKind, UintTy};
 use rustc_attr_data_structures::{AttributeKind, IntType, ReprAttr};
-use rustc_span::{Span, Symbol, sym};
+use rustc_span::{DUMMY_SP, Span, Symbol, sym};
 
 use super::{CombineAttributeParser, ConvertFn};
 use crate::context::AcceptContext;
@@ -21,7 +21,7 @@ pub(crate) struct ReprParser;
 
 impl CombineAttributeParser for ReprParser {
     type Item = (ReprAttr, Span);
-    const PATH: &'static [rustc_span::Symbol] = &[sym::repr];
+    const PATH: &'static [Symbol] = &[sym::repr];
     const CONVERT: ConvertFn<Self::Item> = AttributeKind::Repr;
 
     fn extend<'a>(
@@ -99,7 +99,7 @@ fn parse_repr(cx: &AcceptContext<'_>, param: &MetaItemParser<'_>) -> Option<Repr
     let (name, ident_span) = if let Some(ident) = param.path_without_args().word() {
         (Some(ident.name), ident.span)
     } else {
-        (None, rustc_span::DUMMY_SP)
+        (None, DUMMY_SP)
     };
 
     let args = param.args();

compiler/rustc_attr_parsing/src/attributes/stability.rs

@@ -117,7 +117,7 @@ impl AttributeParser for BodyStabilityParser {
 pub(crate) struct ConstStabilityIndirectParser;
 // FIXME(jdonszelmann): single word attribute group when we have these
 impl SingleAttributeParser for ConstStabilityIndirectParser {
-    const PATH: &'static [rustc_span::Symbol] = &[sym::rustc_const_stable_indirect];
+    const PATH: &'static [Symbol] = &[sym::rustc_const_stable_indirect];
 
     // ignore
     fn on_duplicate(_cx: &AcceptContext<'_>, _first_span: Span) {}

compiler/rustc_attr_parsing/src/attributes/transparency.rs

@@ -1,6 +1,6 @@
 use rustc_attr_data_structures::AttributeKind;
 use rustc_span::hygiene::Transparency;
-use rustc_span::sym;
+use rustc_span::{Span, Symbol, sym};
 
 use super::{AcceptContext, SingleAttributeParser};
 use crate::parser::ArgParser;
@@ -11,9 +11,9 @@ pub(crate) struct TransparencyParser;
 #[allow(rustc::untranslatable_diagnostic)]
 #[allow(rustc::diagnostic_outside_of_impl)]
 impl SingleAttributeParser for TransparencyParser {
-    const PATH: &'static [rustc_span::Symbol] = &[sym::rustc_macro_transparency];
+    const PATH: &'static [Symbol] = &[sym::rustc_macro_transparency];
 
-    fn on_duplicate(cx: &crate::context::AcceptContext<'_>, first_span: rustc_span::Span) {
+    fn on_duplicate(cx: &crate::context::AcceptContext<'_>, first_span: Span) {
         cx.dcx().span_err(vec![first_span, cx.attr_span], "multiple macro transparency attributes");
     }
 

compiler/rustc_attr_parsing/src/context.rs

@@ -26,24 +26,29 @@ macro_rules! attribute_groups {
     (
         pub(crate) static $name: ident = [$($names: ty),* $(,)?];
     ) => {
-        pub(crate) static $name: LazyLock<(
-            BTreeMap<&'static [Symbol], Vec<Box<dyn Fn(&AcceptContext<'_>, &ArgParser<'_>) + Send + Sync>>>,
-            Vec<Box<dyn Send + Sync + Fn(&FinalizeContext<'_>) -> Option<AttributeKind>>>
-        )> = LazyLock::new(|| {
-            let mut accepts = BTreeMap::<_, Vec<Box<dyn Fn(&AcceptContext<'_>, &ArgParser<'_>) + Send + Sync>>>::new();
-            let mut finalizes = Vec::<Box<dyn Send + Sync + Fn(&FinalizeContext<'_>) -> Option<AttributeKind>>>::new();
+        type Accepts = BTreeMap<
+            &'static [Symbol],
+            Box<dyn Send + Sync + Fn(&AcceptContext<'_>, &ArgParser<'_>)>
+        >;
+        type Finalizes = Vec<
+            Box<dyn Send + Sync + Fn(&FinalizeContext<'_>) -> Option<AttributeKind>>
+        >;
+        pub(crate) static $name: LazyLock<(Accepts, Finalizes)> = LazyLock::new(|| {
+            let mut accepts = Accepts::new();
+            let mut finalizes = Finalizes::new();
             $(
                 {
                     thread_local! {
                         static STATE_OBJECT: RefCell<$names> = RefCell::new(<$names>::default());
                     };
 
                     for (k, v) in <$names>::ATTRIBUTES {
-                        accepts.entry(*k).or_default().push(Box::new(|cx, args| {
+                        let old = accepts.insert(*k, Box::new(|cx, args| {
                             STATE_OBJECT.with_borrow_mut(|s| {
                                 v(s, cx, args)
                             })
                         }));
+                        assert!(old.is_none());
                     }
 
                     finalizes.push(Box::new(|cx| {
@@ -110,7 +115,8 @@ impl<'a> Deref for AcceptContext<'a> {
 
 /// Context given to every attribute parser during finalization.
 ///
-/// Gives [`AttributeParser`](crate::attributes::AttributeParser)s enough information to create errors, for example.
+/// Gives [`AttributeParser`](crate::attributes::AttributeParser)s enough information to create
+/// errors, for example.
 pub(crate) struct FinalizeContext<'a> {
     /// The parse context, gives access to the session and the
     /// diagnostics context.
@@ -141,10 +147,9 @@ pub struct AttributeParser<'sess> {
     sess: &'sess Session,
     features: Option<&'sess Features>,
 
-    /// *only* parse attributes with this symbol.
+    /// *Only* parse attributes with this symbol.
     ///
-    /// Used in cases where we want the lowering infrastructure for
-    /// parse just a single attribute.
+    /// Used in cases where we want the lowering infrastructure for parse just a single attribute.
     parse_only: Option<Symbol>,
 
     /// Can be used to instruct parsers to reduce the number of diagnostics it emits.
@@ -157,9 +162,9 @@ impl<'sess> AttributeParser<'sess> {
     /// One example where this is necessary, is to parse `feature` attributes themselves for
     /// example.
     ///
-    /// Try to use this as little as possible. Attributes *should* be lowered during `rustc_ast_lowering`.
-    /// Some attributes require access to features to parse, which would crash if you tried to do so
-    /// through [`parse_limited`](Self::parse_limited).
+    /// Try to use this as little as possible. Attributes *should* be lowered during
+    /// `rustc_ast_lowering`. Some attributes require access to features to parse, which would
+    /// crash if you tried to do so through [`parse_limited`](Self::parse_limited).
     ///
     /// To make sure use is limited, supply a `Symbol` you'd like to parse. Only attributes with
     /// that symbol are picked out of the list of instructions and parsed. Those are returned.
@@ -217,19 +222,18 @@ impl<'sess> AttributeParser<'sess> {
         let group_cx = FinalizeContext { cx: self, target_span };
 
         for attr in attrs {
-            // if we're only looking for a single attribute,
-            // skip all the ones we don't care about
+            // If we're only looking for a single attribute, skip all the ones we don't care about.
             if let Some(expected) = self.parse_only {
                 if !attr.has_name(expected) {
                     continue;
                 }
             }
 
-            // sometimes, for example for `#![doc = include_str!("readme.md")]`,
+            // Sometimes, for example for `#![doc = include_str!("readme.md")]`,
             // doc still contains a non-literal. You might say, when we're lowering attributes
             // that's expanded right? But no, sometimes, when parsing attributes on macros,
             // we already use the lowering logic and these are still there. So, when `omit_doc`
-            // is set we *also* want to ignore these
+            // is set we *also* want to ignore these.
             if omit_doc == OmitDoc::Skip && attr.has_name(sym::doc) {
                 continue;
             }
@@ -263,21 +267,17 @@ impl<'sess> AttributeParser<'sess> {
                     let (path, args) = parser.deconstruct();
                     let parts = path.segments().map(|i| i.name).collect::<Vec<_>>();
 
-                    if let Some(accepts) = ATTRIBUTE_MAPPING.0.get(parts.as_slice()) {
-                        for f in accepts {
-                            let cx = AcceptContext {
-                                group_cx: &group_cx,
-                                attr_span: lower_span(attr.span),
-                            };
+                    if let Some(accept) = ATTRIBUTE_MAPPING.0.get(parts.as_slice()) {
+                        let cx =
+                            AcceptContext { group_cx: &group_cx, attr_span: lower_span(attr.span) };
 
-                            f(&cx, &args)
-                        }
+                        accept(&cx, &args)
                     } else {
-                        // if we're here, we must be compiling a tool attribute... Or someone forgot to
-                        // parse their fancy new attribute. Let's warn them in any case. If you are that
-                        // person, and you really your attribute should remain unparsed, carefully read the
-                        // documentation in this module and if you still think so you can add an exception
-                        // to this assertion.
+                        // If we're here, we must be compiling a tool attribute... Or someone
+                        // forgot to parse their fancy new attribute. Let's warn them in any case.
+                        // If you are that person, and you really think your attribute should
+                        // remain unparsed, carefully read the documentation in this module and if
+                        // you still think so you can add an exception to this assertion.
 
                         // FIXME(jdonszelmann): convert other attributes, and check with this that
                         // we caught em all

compiler/rustc_attr_parsing/src/parser.rs

@@ -12,8 +12,7 @@ use rustc_ast::{AttrArgs, DelimArgs, Expr, ExprKind, LitKind, MetaItemLit, Norma
 use rustc_ast_pretty::pprust;
 use rustc_errors::DiagCtxtHandle;
 use rustc_hir::{self as hir, AttrPath};
-use rustc_span::symbol::{Ident, kw, sym};
-use rustc_span::{ErrorGuaranteed, Span, Symbol};
+use rustc_span::{ErrorGuaranteed, Ident, Span, Symbol, kw, sym};
 
 pub struct SegmentIterator<'a> {
     offset: usize,