Parsers for the attributes

Signed-off-by: Jonathan Brouwer <jonathantbrouwer@gmail.com>

Author: JonathanBrouwer

compiler/rustc_attr_parsing/src/attributes/mod.rs

@@ -38,6 +38,7 @@ 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::KeepLast;
+    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::KeepLast;
+    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 {
+        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 {
+        // For #[rustc_builtin_macro], it is permitted to leave out the trait name
+        if !trait_name_mandatory {
+            return None;
+        }
+        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

@@ -29,6 +29,9 @@ 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,
@@ -135,6 +138,8 @@ attribute_parsers!(
         Single<MustUseParser>,
         Single<OptimizeParser>,
         Single<PathAttributeParser>,
+        Single<ProcMacroDeriveParser>,
+        Single<RustcBuiltinMacroParser>,
         Single<RustcForceInlineParser>,
         Single<RustcLayoutScalarValidRangeEnd>,
         Single<RustcLayoutScalarValidRangeStart>,
@@ -151,6 +156,8 @@ attribute_parsers!(
         Single<WithoutArgs<NoMangleParser>>,
         Single<WithoutArgs<NonExhaustiveParser>>,
         Single<WithoutArgs<PassByValueParser>>,
+        Single<WithoutArgs<ProcMacroAttributeParser>>,
+        Single<WithoutArgs<ProcMacroParser>>,
         Single<WithoutArgs<PubTransparentParser>>,
         Single<WithoutArgs<TrackCallerParser>>,
         // tidy-alphabetical-end
@@ -418,6 +425,16 @@ 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);