Port crate name to the new attribute system

Author: jdonszelmann

compiler/rustc_attr_parsing/src/attributes/crate_level.rs

@@ -0,0 +1,34 @@
+use rustc_feature::{AttributeTemplate, template};
+use rustc_hir::attrs::AttributeKind;
+use rustc_span::{Symbol, sym};
+
+use super::{AttributeOrder, OnDuplicate, SingleAttributeParser};
+use crate::context::{ALL_TARGETS, AcceptContext, AllowedTargets, Stage};
+use crate::parser::ArgParser;
+
+pub(crate) struct CrateNameParser;
+
+impl<S: Stage> SingleAttributeParser<S> for CrateNameParser {
+    const PATH: &[Symbol] = &[sym::crate_name];
+    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::WarnButFutureError;
+    const TEMPLATE: AttributeTemplate = template!(NameValueStr: "name");
+
+    // FIXME: crate name is allowed on all targets and ignored,
+    //        even though it should only be valid on crates of course
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(ALL_TARGETS);
+
+    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
+        let ArgParser::NameValue(n) = args else {
+            cx.expected_name_value(cx.attr_span, None);
+            return None;
+        };
+
+        let Some(name) = n.value_as_str() else {
+            cx.expected_string_literal(n.value_span, Some(n.value_as_lit()));
+            return None;
+        };
+
+        Some(AttributeKind::CrateName { name, name_span: n.value_span, style: cx.attr_style })
+    }
+}

compiler/rustc_attr_parsing/src/attributes/mod.rs

@@ -31,6 +31,7 @@ pub(crate) mod cfg;
 pub(crate) mod cfg_old;
 pub(crate) mod codegen_attrs;
 pub(crate) mod confusables;
+pub(crate) mod crate_level;
 pub(crate) mod deprecation;
 pub(crate) mod dummy;
 pub(crate) mod inline;

compiler/rustc_attr_parsing/src/attributes/util.rs

@@ -1,4 +1,4 @@
-use rustc_ast::attr::{AttributeExt, first_attr_value_str_by_name};
+use rustc_ast::attr::AttributeExt;
 use rustc_feature::is_builtin_attr_name;
 use rustc_hir::RustcVersion;
 use rustc_span::{Symbol, sym};
@@ -23,10 +23,6 @@ pub fn is_builtin_attr(attr: &impl AttributeExt) -> bool {
     attr.is_doc_comment() || attr.ident().is_some_and(|ident| is_builtin_attr_name(ident.name))
 }
 
-pub fn find_crate_name(attrs: &[impl AttributeExt]) -> Option<Symbol> {
-    first_attr_value_str_by_name(attrs, sym::crate_name)
-}
-
 pub fn is_doc_alias_attrs_contain_symbol<'tcx, T: AttributeExt + 'tcx>(
     attrs: impl Iterator<Item = &'tcx T>,
     symbol: Symbol,

compiler/rustc_attr_parsing/src/context.rs

@@ -14,6 +14,7 @@ use rustc_hir::{
     AttrArgs, AttrItem, AttrPath, Attribute, HashIgnoredAttrId, HirId, MethodKind, Target,
 };
 use rustc_session::Session;
+use rustc_session::lint::BuiltinLintDiag;
 use rustc_span::{DUMMY_SP, ErrorGuaranteed, Span, Symbol, sym};
 
 use crate::attributes::allow_unstable::{
@@ -25,6 +26,7 @@ use crate::attributes::codegen_attrs::{
     TargetFeatureParser, TrackCallerParser, UsedParser,
 };
 use crate::attributes::confusables::ConfusablesParser;
+use crate::attributes::crate_level::CrateNameParser;
 use crate::attributes::deprecation::DeprecationParser;
 use crate::attributes::dummy::DummyParser;
 use crate::attributes::inline::{InlineParser, RustcForceInlineParser};
@@ -65,6 +67,7 @@ use crate::attributes::traits::{
 use crate::attributes::transparency::TransparencyParser;
 use crate::attributes::{AttributeParser as _, Combine, Single, WithoutArgs};
 use crate::context::MaybeWarn::{Allow, Error, Warn};
+use crate::lints::lint_name;
 use crate::parser::{ArgParser, MetaItemParser, PathParser};
 use crate::session_diagnostics::{
     AttributeParseError, AttributeParseErrorReason, InvalidTarget, UnknownMetaItem,
@@ -167,6 +170,7 @@ attribute_parsers!(
 
         // tidy-alphabetical-start
         Single<CoverageParser>,
+        Single<CrateNameParser>,
         Single<DeprecationParser>,
         Single<DummyParser>,
         Single<ExportNameParser>,
@@ -313,7 +317,9 @@ pub struct AcceptContext<'f, 'sess, S: Stage> {
     /// The span of the attribute currently being parsed
     pub(crate) attr_span: Span,
 
+    /// Whether it is an inner or outer attribute
     pub(crate) attr_style: AttrStyle,
+
     /// The expected structure of the attribute.
     ///
     /// Used in reporting errors to give a hint to users what the attribute *should* look like.
@@ -759,13 +765,34 @@ impl<'sess> AttributeParser<'sess, Early> {
         target_span: Span,
         target_node_id: NodeId,
         features: Option<&'sess Features>,
+    ) -> Option<Attribute> {
+        Self::parse_limited_should_emit(
+            sess,
+            attrs,
+            sym,
+            target_span,
+            target_node_id,
+            features,
+            ShouldEmit::Nothing,
+        )
+    }
+
+    /// Usually you want `parse_limited`, which defaults to no errors.
+    pub fn parse_limited_should_emit(
+        sess: &'sess Session,
+        attrs: &[ast::Attribute],
+        sym: Symbol,
+        target_span: Span,
+        target_node_id: NodeId,
+        features: Option<&'sess Features>,
+        should_emit: ShouldEmit,
     ) -> Option<Attribute> {
         let mut p = Self {
             features,
             tools: Vec::new(),
             parse_only: Some(sym),
             sess,
-            stage: Early { emit_errors: ShouldEmit::Nothing },
+            stage: Early { emit_errors: should_emit },
         };
         let mut parsed = p.parse_attribute_list(
             attrs,
@@ -774,8 +801,13 @@ impl<'sess> AttributeParser<'sess, Early> {
             Target::Crate, // Does not matter, we're not going to emit errors anyways
             OmitDoc::Skip,
             std::convert::identity,
-            |_lint| {
-                panic!("can't emit lints here for now (nothing uses this atm)");
+            |AttributeLint { id, span, kind }| {
+                sess.psess.buffer_lint(
+                    lint_name(&kind),
+                    span,
+                    id,
+                    BuiltinLintDiag::AttributeLint(kind),
+                );
             },
         );
         assert!(parsed.len() <= 1);

compiler/rustc_attr_parsing/src/lib.rs

@@ -92,10 +92,8 @@ mod session_diagnostics;
 
 pub use attributes::cfg::{CFG_TEMPLATE, EvalConfigResult, eval_config_entry, parse_cfg_attr};
 pub use attributes::cfg_old::*;
-pub use attributes::util::{
-    find_crate_name, is_builtin_attr, is_doc_alias_attrs_contain_symbol, parse_version,
-};
+pub use attributes::util::{is_builtin_attr, is_doc_alias_attrs_contain_symbol, parse_version};
 pub use context::{AttributeParser, Early, Late, OmitDoc, ShouldEmit};
-pub use lints::emit_attribute_lint;
+pub use lints::{decorate_attribute_lint_kind, emit_attribute_lint};
 
 rustc_fluent_macro::fluent_messages! { "../messages.ftl" }

compiler/rustc_attr_parsing/src/lints.rs

@@ -1,59 +1,68 @@
-use rustc_errors::{DiagArgValue, LintEmitter};
+use rustc_errors::{AttributeLintDecorator, DeferedAttributeLintDecorator, DiagArgValue};
 use rustc_hir::lints::{AttributeLint, AttributeLintKind};
 use rustc_hir::{HirId, Target};
+use rustc_session::lint::Lint;
 use rustc_span::sym;
 
 use crate::session_diagnostics;
 
-pub fn emit_attribute_lint<L: LintEmitter>(lint: &AttributeLint<HirId>, lint_emitter: L) {
-    let AttributeLint { id, span, kind } = lint;
+pub(crate) fn lint_name(kind: &AttributeLintKind) -> &'static Lint {
+    use rustc_session::lint::builtin::*;
+    match kind {
+        AttributeLintKind::UnusedDuplicate { .. } => UNUSED_ATTRIBUTES,
+        AttributeLintKind::IllFormedAttributeInput { .. } => ILL_FORMED_ATTRIBUTE_INPUT,
+        AttributeLintKind::EmptyAttribute { .. } => UNUSED_ATTRIBUTES,
+        AttributeLintKind::InvalidTarget { name, target, .. } => {
+            // This check is here because `deprecated` had its own lint group and removing this would be a breaking change
+            if *name == sym::deprecated
+                && ![Target::Closure, Target::Expression, Target::Statement, Target::Arm]
+                    .contains(target)
+            {
+                rustc_session::lint::builtin::USELESS_DEPRECATED
+            } else {
+                rustc_session::lint::builtin::UNUSED_ATTRIBUTES
+            }
+        }
+    }
+}
 
+pub fn decorate_attribute_lint_kind<L: AttributeLintDecorator>(
+    kind: &AttributeLintKind,
+    lint_emitter: L,
+) {
     match kind {
-        &AttributeLintKind::UnusedDuplicate { this, other, warning } => lint_emitter
-            .emit_node_span_lint(
-                rustc_session::lint::builtin::UNUSED_ATTRIBUTES,
-                *id,
-                *span,
-                session_diagnostics::UnusedDuplicate { this, other, warning },
-            ),
+        &AttributeLintKind::UnusedDuplicate { this, other, warning } => {
+            lint_emitter.decorate(session_diagnostics::UnusedDuplicate { this, other, warning })
+        }
         AttributeLintKind::IllFormedAttributeInput { suggestions } => {
-            lint_emitter.emit_node_span_lint(
-                rustc_session::lint::builtin::ILL_FORMED_ATTRIBUTE_INPUT,
-                *id,
-                *span,
-                session_diagnostics::IllFormedAttributeInput {
-                    num_suggestions: suggestions.len(),
-                    suggestions: DiagArgValue::StrListSepByAnd(
-                        suggestions.into_iter().map(|s| format!("`{s}`").into()).collect(),
-                    ),
-                },
-            );
+            lint_emitter.decorate(session_diagnostics::IllFormedAttributeInput {
+                num_suggestions: suggestions.len(),
+                suggestions: DiagArgValue::StrListSepByAnd(
+                    suggestions.into_iter().map(|s| format!("`{s}`").into()).collect(),
+                ),
+            });
         }
-        AttributeLintKind::EmptyAttribute { first_span } => lint_emitter.emit_node_span_lint(
-            rustc_session::lint::builtin::UNUSED_ATTRIBUTES,
-            *id,
-            *first_span,
-            session_diagnostics::EmptyAttributeList { attr_span: *first_span },
-        ),
+
+        AttributeLintKind::EmptyAttribute { first_span } => lint_emitter
+            .decorate(session_diagnostics::EmptyAttributeList { attr_span: *first_span }),
         &AttributeLintKind::InvalidTarget { name, target, ref applied, only } => lint_emitter
-            .emit_node_span_lint(
-                // This check is here because `deprecated` had its own lint group and removing this would be a breaking change
-                if name == sym::deprecated
-                    && ![Target::Closure, Target::Expression, Target::Statement, Target::Arm]
-                        .contains(&target)
-                {
-                    rustc_session::lint::builtin::USELESS_DEPRECATED
-                } else {
-                    rustc_session::lint::builtin::UNUSED_ATTRIBUTES
-                },
-                *id,
-                *span,
-                session_diagnostics::InvalidTargetLint {
-                    name,
-                    target: target.plural_name(),
-                    applied: applied.clone(),
-                    only,
-                },
-            ),
+            .decorate(session_diagnostics::InvalidTargetLint {
+                name,
+                target: target.plural_name(),
+                applied: applied.clone(),
+                only,
+            }),
     }
 }
+
+pub fn emit_attribute_lint<L: DeferedAttributeLintDecorator<ID = HirId>>(
+    lint: &AttributeLint<HirId>,
+    lint_emitter: L,
+) {
+    let AttributeLint { id, span, kind } = lint;
+
+    let lint_name = lint_name(&lint.kind);
+
+    let emit = lint_emitter.prepare(lint_name, *id, *span);
+    decorate_attribute_lint_kind(kind, emit);
+}

compiler/rustc_errors/src/lib.rs

@@ -60,7 +60,6 @@ pub use rustc_error_messages::{
     SubdiagMessage, fallback_fluent_bundle, fluent_bundle,
 };
 use rustc_hashes::Hash128;
-use rustc_hir::HirId;
 pub use rustc_lint_defs::{Applicability, listify, pluralize};
 use rustc_lint_defs::{Lint, LintExpectationId};
 use rustc_macros::{Decodable, Encodable};
@@ -105,17 +104,23 @@ rustc_data_structures::static_assert_size!(PResult<'_, ()>, 24);
 #[cfg(target_pointer_width = "64")]
 rustc_data_structures::static_assert_size!(PResult<'_, bool>, 24);
 
+pub trait AttributeLintDecorator {
+    fn decorate(self, diag: impl for<'a> LintDiagnostic<'a, ()>);
+}
+
 /// Used to avoid depending on `rustc_middle` in `rustc_attr_parsing`.
 /// Always the `TyCtxt`.
-pub trait LintEmitter: Copy {
+pub trait DeferedAttributeLintDecorator: Copy {
+    type ID: Copy;
+    type Decorator: AttributeLintDecorator;
+
     #[track_caller]
-    fn emit_node_span_lint(
+    fn prepare(
         self,
         lint: &'static Lint,
-        hir_id: HirId,
+        id: Self::ID,
         span: impl Into<MultiSpan>,
-        decorator: impl for<'a> LintDiagnostic<'a, ()>,
-    );
+    ) -> Self::Decorator;
 }
 
 #[derive(Debug, PartialEq, Eq, Clone, Copy, Hash, Encodable, Decodable)]

compiler/rustc_hir/src/attrs/data_structures.rs

@@ -324,6 +324,9 @@ pub enum AttributeKind {
     /// Represents `#[coverage(..)]`.
     Coverage(Span, CoverageAttrKind),
 
+    /// Represents `#[crate_name = ...]`
+    CrateName { name: Symbol, name_span: Span, style: AttrStyle },
+
     ///Represents `#[rustc_deny_explicit_impl]`.
     DenyExplicitImpl(Span),
 

compiler/rustc_hir/src/attrs/encode_cross_crate.rs

@@ -7,6 +7,11 @@ pub enum EncodeCrossCrate {
 }
 
 impl AttributeKind {
+    /// Whether this attribute should be encoded in metadata files.
+    ///
+    /// If this is "Yes", then another crate can do `tcx.get_all_attrs(did)` for a did in this crate, and get the attribute.
+    /// When this is No, the attribute is filtered out while encoding and other crate won't be able to observe it.
+    /// This can be unexpectedly good for performance, so unless necessary for cross-crate compilation, prefer No.
     pub fn encode_cross_crate(&self) -> EncodeCrossCrate {
         use AttributeKind::*;
         use EncodeCrossCrate::*;
@@ -31,6 +36,7 @@ impl AttributeKind {
             ConstTrait(..) => No,
             Coroutine(..) => No,
             Coverage(..) => No,
+            CrateName { .. } => No,
             DenyExplicitImpl(..) => No,
             Deprecation { .. } => Yes,
             DoNotImplementViaObject(..) => No,