Auto merge of #143607 - JonathanBrouwer:proc_macro_attrs, r=<try>

Port the proc macro attributes to the new attribute parsing infrastructure

Ports `#[proc_macro]`, `#[proc_macro_attribute]`, `#[proc_macro_derive]` and `#[rustc_builtin_macro]` to the new attribute parsing infrastructure for #131229 (comment)

I've split this PR into commits for reviewability, and left some comments to clarify things
I did 4 related attributes in one PR because they share a lot of their code and logic, and doing them separately is kind of annoying as I need to leave both the old and new parsing in place then.

r? `@oli-obk`
cc `@jdonszelmann`

Author: bors

compiler/rustc_attr_data_structures/src/attributes.rs

@@ -313,12 +313,24 @@ pub enum AttributeKind {
     /// Represents `#[path]`
     Path(Symbol, Span),
 
+    /// Represents `#[proc_macro]`
+    ProcMacro(Span),
+
+    /// Represents `#[proc_macro_attribute]`
+    ProcMacroAttribute(Span),
+
+    /// Represents `#[proc_macro_derive]`
+    ProcMacroDerive { trait_name: Symbol, helper_attrs: ThinVec<Symbol>, span: Span },
+
     /// Represents `#[rustc_pub_transparent]` (used by the `repr_transparent_external_private_fields` lint).
     PubTransparent(Span),
 
     /// Represents [`#[repr]`](https://doc.rust-lang.org/stable/reference/type-layout.html#representations).
     Repr { reprs: ThinVec<(ReprAttr, Span)>, first_span: Span },
 
+    /// Represents `#[rustc_builtin_macro]`.
+    RustcBuiltinMacro { builtin_name: Option<Symbol>, helper_attrs: ThinVec<Symbol>, span: Span },
+
     /// Represents `#[rustc_layout_scalar_valid_range_end]`.
     RustcLayoutScalarValidRangeEnd(Box<u128>, Span),
 

compiler/rustc_attr_data_structures/src/encode_cross_crate.rs

@@ -45,8 +45,12 @@ impl AttributeKind {
             Optimize(..) => No,
             PassByValue(..) => Yes,
             Path(..) => No,
+            ProcMacro(..) => No,
+            ProcMacroAttribute(..) => No,
+            ProcMacroDerive { .. } => No,
             PubTransparent(..) => Yes,
             Repr { .. } => No,
+            RustcBuiltinMacro { .. } => Yes,
             RustcLayoutScalarValidRangeEnd(..) => Yes,
             RustcLayoutScalarValidRangeStart(..) => Yes,
             RustcObjectLifetimeDefault => No,

compiler/rustc_attr_parsing/src/attributes/mod.rs

@@ -39,6 +39,7 @@ pub(crate) mod must_use;
 pub(crate) mod no_implicit_prelude;
 pub(crate) mod non_exhaustive;
 pub(crate) mod path;
+pub(crate) mod proc_macro_attrs;
 pub(crate) mod repr;
 pub(crate) mod rustc_internal;
 pub(crate) mod semantics;

compiler/rustc_attr_parsing/src/attributes/proc_macro_attrs.rs

@@ -0,0 +1,139 @@
+use rustc_attr_data_structures::AttributeKind;
+use rustc_feature::{AttributeTemplate, template};
+use rustc_span::{Span, Symbol, sym};
+use thin_vec::ThinVec;
+
+use crate::attributes::{
+    AttributeOrder, NoArgsAttributeParser, OnDuplicate, SingleAttributeParser,
+};
+use crate::context::{AcceptContext, Stage};
+use crate::parser::ArgParser;
+
+pub(crate) struct ProcMacroParser;
+impl<S: Stage> NoArgsAttributeParser<S> for ProcMacroParser {
+    const PATH: &[Symbol] = &[sym::proc_macro];
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const CREATE: fn(Span) -> AttributeKind = AttributeKind::ProcMacro;
+}
+
+pub(crate) struct ProcMacroAttributeParser;
+impl<S: Stage> NoArgsAttributeParser<S> for ProcMacroAttributeParser {
+    const PATH: &[Symbol] = &[sym::proc_macro_attribute];
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const CREATE: fn(Span) -> AttributeKind = AttributeKind::ProcMacroAttribute;
+}
+
+pub(crate) struct ProcMacroDeriveParser;
+impl<S: Stage> SingleAttributeParser<S> for ProcMacroDeriveParser {
+    const PATH: &[Symbol] = &[sym::proc_macro_derive];
+    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const TEMPLATE: AttributeTemplate =
+        template!(List: "TraitName, /*opt*/ attributes(name1, name2, ...)");
+
+    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
+        let (trait_name, helper_attrs) = parse_derive_like(cx, args, true)?;
+        Some(AttributeKind::ProcMacroDerive {
+            trait_name: trait_name.expect("Trait name is mandatory, so it is present"),
+            helper_attrs,
+            span: cx.attr_span,
+        })
+    }
+}
+
+pub(crate) struct RustcBuiltinMacroParser;
+impl<S: Stage> SingleAttributeParser<S> for RustcBuiltinMacroParser {
+    const PATH: &[Symbol] = &[sym::rustc_builtin_macro];
+    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const TEMPLATE: AttributeTemplate =
+        template!(List: "TraitName, /*opt*/ attributes(name1, name2, ...)");
+
+    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
+        let (builtin_name, helper_attrs) = parse_derive_like(cx, args, false)?;
+        Some(AttributeKind::RustcBuiltinMacro { builtin_name, helper_attrs, span: cx.attr_span })
+    }
+}
+
+fn parse_derive_like<S: Stage>(
+    cx: &mut AcceptContext<'_, '_, S>,
+    args: &ArgParser<'_>,
+    trait_name_mandatory: bool,
+) -> Option<(Option<Symbol>, ThinVec<Symbol>)> {
+    let Some(list) = args.list() else {
+        // For #[rustc_builtin_macro], it is permitted to leave out the trait name
+        if args.no_args().is_ok() && !trait_name_mandatory {
+            return Some((None, ThinVec::new()));
+        }
+        cx.expected_list(cx.attr_span);
+        return None;
+    };
+    let mut items = list.mixed();
+
+    // Parse the name of the trait that is derived.
+    let Some(trait_attr) = items.next() else {
+        cx.expected_at_least_one_argument(list.span);
+        return None;
+    };
+    let Some(trait_attr) = trait_attr.meta_item() else {
+        cx.unexpected_literal(trait_attr.span());
+        return None;
+    };
+    let Some(trait_ident) = trait_attr.path().word() else {
+        cx.expected_identifier(trait_attr.path().span());
+        return None;
+    };
+    if !trait_ident.name.can_be_raw() {
+        cx.expected_identifier(trait_ident.span);
+        return None;
+    }
+    if let Err(e) = trait_attr.args().no_args() {
+        cx.expected_no_args(e);
+        return None;
+    };
+
+    // Parse optional attributes
+    let mut attributes = ThinVec::new();
+    if let Some(attrs) = items.next() {
+        let Some(attr_list) = attrs.meta_item() else {
+            cx.expected_list(attrs.span());
+            return None;
+        };
+        if !attr_list.path().word_is(sym::attributes) {
+            cx.expected_specific_argument(attrs.span(), vec!["attributes"]);
+            return None;
+        }
+        let Some(attr_list) = attr_list.args().list() else {
+            cx.expected_list(attrs.span());
+            return None;
+        };
+
+        // Parse item in `attributes(...)` argument
+        for attr in attr_list.mixed() {
+            let Some(attr) = attr.meta_item() else {
+                cx.expected_identifier(attr.span());
+                return None;
+            };
+            if let Err(e) = attr.args().no_args() {
+                cx.expected_no_args(e);
+                return None;
+            };
+            let Some(ident) = attr.path().word() else {
+                cx.expected_identifier(attr.path().span());
+                return None;
+            };
+            if !ident.name.can_be_raw() {
+                cx.expected_identifier(ident.span);
+                return None;
+            }
+            attributes.push(ident.name);
+        }
+    }
+
+    // If anything else is specified, we should reject it
+    if let Some(next) = items.next() {
+        cx.expected_no_args(next.span());
+    }
+
+    Some((Some(trait_ident.name), attributes))
+}

compiler/rustc_attr_parsing/src/context.rs

@@ -33,6 +33,9 @@ use crate::attributes::must_use::MustUseParser;
 use crate::attributes::no_implicit_prelude::NoImplicitPreludeParser;
 use crate::attributes::non_exhaustive::NonExhaustiveParser;
 use crate::attributes::path::PathParser as PathAttributeParser;
+use crate::attributes::proc_macro_attrs::{
+    ProcMacroAttributeParser, ProcMacroDeriveParser, ProcMacroParser, RustcBuiltinMacroParser,
+};
 use crate::attributes::repr::{AlignParser, ReprParser};
 use crate::attributes::rustc_internal::{
     RustcLayoutScalarValidRangeEnd, RustcLayoutScalarValidRangeStart,
@@ -140,6 +143,8 @@ attribute_parsers!(
         Single<MustUseParser>,
         Single<OptimizeParser>,
         Single<PathAttributeParser>,
+        Single<ProcMacroDeriveParser>,
+        Single<RustcBuiltinMacroParser>,
         Single<RustcForceInlineParser>,
         Single<RustcLayoutScalarValidRangeEnd>,
         Single<RustcLayoutScalarValidRangeStart>,
@@ -159,6 +164,8 @@ attribute_parsers!(
         Single<WithoutArgs<NoMangleParser>>,
         Single<WithoutArgs<NonExhaustiveParser>>,
         Single<WithoutArgs<PassByValueParser>>,
+        Single<WithoutArgs<ProcMacroAttributeParser>>,
+        Single<WithoutArgs<ProcMacroParser>>,
         Single<WithoutArgs<PubTransparentParser>>,
         Single<WithoutArgs<StdInternalSymbolParser>>,
         Single<WithoutArgs<TrackCallerParser>>,
@@ -427,6 +434,16 @@ impl<'f, 'sess: 'f, S: Stage> AcceptContext<'f, 'sess, S> {
         })
     }
 
+    pub(crate) fn expected_identifier(&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::ExpectedIdentifier,
+        })
+    }
+
     pub(crate) fn warn_empty_attribute(&mut self, span: Span) {
         self.emit_lint(AttributeLintKind::EmptyAttribute { first_span: span }, span);
     }

compiler/rustc_attr_parsing/src/session_diagnostics.rs

@@ -525,6 +525,7 @@ pub(crate) enum AttributeParseErrorReason {
     ExpectedNameValue(Option<Symbol>),
     DuplicateKey(Symbol),
     ExpectedSpecificArgument { possibilities: Vec<&'static str>, strings: bool },
+    ExpectedIdentifier,
 }
 
 pub(crate) struct AttributeParseError {
@@ -618,6 +619,9 @@ impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for AttributeParseError {
                     }
                 }
             }
+            AttributeParseErrorReason::ExpectedIdentifier => {
+                diag.span_label(self.span, format!("expected a valid identifier here"));
+            }
         }
 
         let suggestions = self.template.suggestions(false, &name);

compiler/rustc_builtin_macros/src/proc_macro_harness.rs

@@ -1,11 +1,13 @@
-use std::mem;
+use std::{mem, slice};
 
 use rustc_ast::ptr::P;
 use rustc_ast::visit::{self, Visitor};
-use rustc_ast::{self as ast, NodeId, attr};
+use rustc_ast::{self as ast, HasNodeId, NodeId, attr};
 use rustc_ast_pretty::pprust;
+use rustc_attr_data_structures::AttributeKind;
+use rustc_attr_parsing::AttributeParser;
 use rustc_errors::DiagCtxtHandle;
-use rustc_expand::base::{ExtCtxt, ResolverExpand, parse_macro_name_and_helper_attrs};
+use rustc_expand::base::{ExtCtxt, ResolverExpand};
 use rustc_expand::expand::{AstFragment, ExpansionConfig};
 use rustc_feature::Features;
 use rustc_session::Session;
@@ -22,7 +24,7 @@ struct ProcMacroDerive {
     trait_name: Symbol,
     function_ident: Ident,
     span: Span,
-    attrs: Vec<Symbol>,
+    attrs: ThinVec<Symbol>,
 }
 
 struct ProcMacroDef {
@@ -41,6 +43,7 @@ struct CollectProcMacros<'a> {
     macros: Vec<ProcMacro>,
     in_root: bool,
     dcx: DiagCtxtHandle<'a>,
+    session: &'a Session,
     source_map: &'a SourceMap,
     is_proc_macro_crate: bool,
     is_test_crate: bool,
@@ -63,6 +66,7 @@ pub fn inject(
         macros: Vec::new(),
         in_root: true,
         dcx,
+        session: sess,
         source_map: sess.source_map(),
         is_proc_macro_crate,
         is_test_crate,
@@ -98,8 +102,17 @@ impl<'a> CollectProcMacros<'a> {
         function_ident: Ident,
         attr: &'a ast::Attribute,
     ) {
-        let Some((trait_name, proc_attrs)) =
-            parse_macro_name_and_helper_attrs(self.dcx, attr, "derive")
+        let Some(rustc_hir::Attribute::Parsed(AttributeKind::ProcMacroDerive {
+            trait_name,
+            helper_attrs,
+            ..
+        })) = AttributeParser::parse_limited(
+            self.session,
+            slice::from_ref(attr),
+            sym::proc_macro_derive,
+            item.span,
+            item.node_id(),
+        )
         else {
             return;
         };
@@ -110,7 +123,7 @@ impl<'a> CollectProcMacros<'a> {
                 span: item.span,
                 trait_name,
                 function_ident,
-                attrs: proc_attrs,
+                attrs: helper_attrs,
             }));
         } else {
             let msg = if !self.in_root {

compiler/rustc_expand/messages.ftl

@@ -1,26 +1,8 @@
-expand_arg_not_attributes =
-    second argument must be `attributes`
-
-expand_attr_no_arguments =
-    attribute must have either one or two arguments
-
-expand_attribute_meta_item =
-    attribute must be a meta item, not a literal
-
-expand_attribute_single_word =
-    attribute must only be a single word
-
 expand_attributes_on_expressions_experimental =
     attributes on expressions are experimental
     .help_outer_doc = `///` is used for outer documentation comments; for a plain comment, use `//`
     .help_inner_doc = `//!` is used for inner documentation comments; for a plain comment, use `//` by removing the `!` or inserting a space in between them: `// !`
 
-expand_attributes_wrong_form =
-    attribute must be of form: `attributes(foo, bar)`
-
-expand_cannot_be_name_of_macro =
-    `{$trait_ident}` cannot be a name of {$macro_type} macro
-
 expand_collapse_debuginfo_illegal =
     illegal value for attribute #[collapse_debuginfo(no|external|yes)]
 
@@ -71,9 +53,6 @@ expand_glob_delegation_outside_impls =
 expand_glob_delegation_traitless_qpath =
     qualified path without a trait in glob delegation
 
-expand_helper_attribute_name_invalid =
-    `{$name}` cannot be a name of derive helper attribute
-
 expand_incomplete_parse =
     macro expansion ignores {$descr} and any tokens following
     .label = caused by the macro expansion here
@@ -165,12 +144,6 @@ expand_mve_unrecognized_var =
 expand_non_inline_modules_in_proc_macro_input_are_unstable =
     non-inline modules in proc macro input are unstable
 
-expand_not_a_meta_item =
-    not a meta item
-
-expand_only_one_word =
-    must only be one word
-
 expand_proc_macro_back_compat = using an old version of `{$crate_name}`
     .note = older versions of the `{$crate_name}` crate no longer compile; please update to `{$crate_name}` v{$fixed_version}, or switch to one of the `{$crate_name}` alternatives