Support lints in early attribute parsing

Author: jdonszelmann

Cargo.lock

@@ -3791,7 +3791,6 @@ dependencies = [
  "rustc_error_messages",
  "rustc_fluent_macro",
  "rustc_hashes",
- "rustc_hir_id",
  "rustc_index",
  "rustc_lexer",
  "rustc_lint_defs",

compiler/rustc_attr_parsing/src/interface.rs

@@ -50,6 +50,27 @@ 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 parsed = Self::parse_limited_all(
             sess,
@@ -59,7 +80,7 @@ impl<'sess> AttributeParser<'sess, Early> {
             target_span,
             target_node_id,
             features,
-            ShouldEmit::Nothing,
+            should_emit,
         );
         assert!(parsed.len() <= 1);
         parsed.pop()
@@ -84,9 +105,8 @@ impl<'sess> AttributeParser<'sess, Early> {
             target,
             OmitDoc::Skip,
             std::convert::identity,
-            |_lint| {
-                // FIXME: Can't emit lints here for now
-                // This branch can be hit when an attribute produces a warning during early parsing (such as attributes on macro calls)
+            |lint| {
+                crate::lints::emit_attribute_lint(&lint, sess);
             },
         )
     }
@@ -121,8 +141,8 @@ impl<'sess> AttributeParser<'sess, Early> {
                 cx: &mut parser,
                 target_span,
                 target_id: target_node_id,
-                emit_lint: &mut |_lint| {
-                    panic!("can't emit lints here for now (nothing uses this atm)");
+                emit_lint: &mut |lint| {
+                    crate::lints::emit_attribute_lint(&lint, sess);
                 },
             },
             attr_span: attr.span,

compiler/rustc_attr_parsing/src/lints.rs

@@ -1,13 +1,13 @@
 use std::borrow::Cow;
 
 use rustc_errors::{DiagArgValue, LintEmitter};
+use rustc_hir::Target;
 use rustc_hir::lints::{AttributeLint, AttributeLintKind};
-use rustc_hir::{HirId, Target};
 use rustc_span::sym;
 
 use crate::session_diagnostics;
 
-pub fn emit_attribute_lint<L: LintEmitter>(lint: &AttributeLint<HirId>, lint_emitter: L) {
+pub fn emit_attribute_lint<L: LintEmitter>(lint: &AttributeLint<L::Id>, lint_emitter: L) {
     let AttributeLint { id, span, kind } = lint;
 
     match kind {
@@ -51,7 +51,7 @@ pub fn emit_attribute_lint<L: LintEmitter>(lint: &AttributeLint<HirId>, lint_emi
                 *id,
                 *span,
                 session_diagnostics::InvalidTargetLint {
-                    name,
+                    name: name.clone(),
                     target: target.plural_name(),
                     applied: DiagArgValue::StrListSepByAnd(
                         applied.into_iter().map(|i| Cow::Owned(i.to_string())).collect(),

compiler/rustc_attr_parsing/src/session_diagnostics.rs

@@ -484,9 +484,9 @@ pub(crate) struct EmptyAttributeList {
 #[diag(attr_parsing_invalid_target_lint)]
 #[warning]
 #[help]
-pub(crate) struct InvalidTargetLint<'a> {
-    pub name: &'a AttrPath,
-    pub target: &'a str,
+pub(crate) struct InvalidTargetLint {
+    pub name: AttrPath,
+    pub target: &'static str,
     pub applied: DiagArgValue,
     pub only: &'static str,
     #[suggestion(code = "", applicability = "machine-applicable", style = "tool-only")]

compiler/rustc_errors/Cargo.toml

@@ -14,7 +14,6 @@ rustc_error_codes = { path = "../rustc_error_codes" }
 rustc_error_messages = { path = "../rustc_error_messages" }
 rustc_fluent_macro = { path = "../rustc_fluent_macro" }
 rustc_hashes = { path = "../rustc_hashes" }
-rustc_hir_id = { path = "../rustc_hir_id" }
 rustc_index = { path = "../rustc_index" }
 rustc_lexer = { path = "../rustc_lexer" }
 rustc_lint_defs = { path = "../rustc_lint_defs" }

compiler/rustc_errors/src/lib.rs

@@ -61,7 +61,6 @@ pub use rustc_error_messages::{
     fallback_fluent_bundle, fluent_bundle, into_diag_arg_using_display,
 };
 use rustc_hashes::Hash128;
-use rustc_hir_id::HirId;
 pub use rustc_lint_defs::{Applicability, listify, pluralize};
 use rustc_lint_defs::{Lint, LintExpectationId};
 use rustc_macros::{Decodable, Encodable};
@@ -110,13 +109,14 @@ rustc_data_structures::static_assert_size!(PResult<'_, bool>, 24);
 /// Used to avoid depending on `rustc_middle` in `rustc_attr_parsing`.
 /// Always the `TyCtxt`.
 pub trait LintEmitter: Copy {
+    type Id: Copy;
     #[track_caller]
     fn emit_node_span_lint(
         self,
         lint: &'static Lint,
-        hir_id: HirId,
+        hir_id: Self::Id,
         span: impl Into<MultiSpan>,
-        decorator: impl for<'a> LintDiagnostic<'a, ()>,
+        decorator: impl for<'a> LintDiagnostic<'a, ()> + DynSend + 'static,
     );
 }
 

compiler/rustc_middle/src/ty/context.rs

@@ -1421,6 +1421,8 @@ pub struct TyCtxt<'tcx> {
 }
 
 impl<'tcx> LintEmitter for TyCtxt<'tcx> {
+    type Id = HirId;
+
     fn emit_node_span_lint(
         self,
         lint: &'static Lint,

compiler/rustc_session/src/session.rs

@@ -7,6 +7,7 @@ use std::sync::atomic::AtomicBool;
 use std::{env, fmt, io};
 
 use rand::{RngCore, rng};
+use rustc_ast::NodeId;
 use rustc_data_structures::base_n::{CASE_INSENSITIVE, ToBaseN};
 use rustc_data_structures::flock;
 use rustc_data_structures::fx::{FxHashMap, FxIndexSet};
@@ -22,7 +23,7 @@ use rustc_errors::timings::TimingSectionHandler;
 use rustc_errors::translation::Translator;
 use rustc_errors::{
     Diag, DiagCtxt, DiagCtxtHandle, DiagMessage, Diagnostic, ErrorGuaranteed, FatalAbort,
-    TerminalUrl, fallback_fluent_bundle,
+    LintEmitter, TerminalUrl, fallback_fluent_bundle,
 };
 use rustc_macros::HashStable_Generic;
 pub use rustc_span::def_id::StableCrateId;
@@ -223,6 +224,20 @@ pub struct Session {
     pub invocation_temp: Option<String>,
 }
 
+impl LintEmitter for &'_ Session {
+    type Id = NodeId;
+
+    fn emit_node_span_lint(
+        self,
+        lint: &'static rustc_lint_defs::Lint,
+        node_id: Self::Id,
+        span: impl Into<rustc_errors::MultiSpan>,
+        decorator: impl for<'a> rustc_errors::LintDiagnostic<'a, ()> + DynSend + 'static,
+    ) {
+        self.psess.buffer_lint(lint, span, node_id, decorator);
+    }
+}
+
 #[derive(Clone, Copy)]
 pub enum CodegenUnits {
     /// Specified by the user. In this case we try fairly hard to produce the

tests/ui/lint/unused/unused_attributes-must_use.fixed

@@ -66,6 +66,8 @@ extern "Rust" {
 }
 
  //~ ERROR unused attribute
+//~^ ERROR `#[must_use]` attribute cannot be used on macro calls
+//~| WARN this was previously accepted by the compiler but is being phased out
 global_asm!("");
 
  //~ ERROR attribute cannot be used on

tests/ui/lint/unused/unused_attributes-must_use.rs

@@ -66,6 +66,8 @@ extern "Rust" {
 }
 
 #[must_use] //~ ERROR unused attribute
+//~^ ERROR `#[must_use]` attribute cannot be used on macro calls
+//~| WARN this was previously accepted by the compiler but is being phased out
 global_asm!("");
 
 #[must_use] //~ ERROR attribute cannot be used on