Rollup of 15 pull requests

Cargo.lock

@@ -3655,7 +3655,6 @@ dependencies = [
  "rustc_macros",
  "rustc_serialize",
  "rustc_span",
- "smallvec",
  "tracing",
  "unic-langid",
 ]
@@ -4117,6 +4116,7 @@ dependencies = [
  "rustc_apfloat",
  "rustc_arena",
  "rustc_ast",
+ "rustc_attr_data_structures",
  "rustc_data_structures",
  "rustc_errors",
  "rustc_fluent_macro",
@@ -4446,7 +4446,6 @@ dependencies = [
  "rustc_serialize",
  "rustc_span",
  "rustc_target",
- "smallvec",
  "termize",
  "tracing",
  "windows",

compiler/rustc_ast/src/token.rs

@@ -1085,6 +1085,7 @@ pub enum NtExprKind {
     Expr2021 { inferred: bool },
 }
 
+/// A macro nonterminal, known in documentation as a fragment specifier.
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Encodable, Decodable, Hash, HashStable_Generic)]
 pub enum NonterminalKind {
     Item,

compiler/rustc_attr_data_structures/src/attributes.rs

@@ -212,6 +212,9 @@ pub enum AttributeKind {
         first_span: Span,
     },
 
+    /// Represents `#[const_continue]`.
+    ConstContinue(Span),
+
     /// Represents `#[rustc_const_stable]` and `#[rustc_const_unstable]`.
     ConstStability {
         stability: PartialConstStability,
@@ -231,6 +234,9 @@ pub enum AttributeKind {
     /// Represents `#[inline]` and `#[rustc_force_inline]`.
     Inline(InlineAttr, Span),
 
+    /// Represents `#[loop_match]`.
+    LoopMatch(Span),
+
     /// Represents `#[rustc_macro_transparency]`.
     MacroTransparency(Transparency),
 

compiler/rustc_attr_parsing/src/attributes/loop_match.rs

@@ -0,0 +1,31 @@
+use rustc_attr_data_structures::AttributeKind;
+use rustc_feature::{AttributeTemplate, template};
+use rustc_span::{Symbol, sym};
+
+use crate::attributes::{AttributeOrder, OnDuplicate, SingleAttributeParser};
+use crate::context::{AcceptContext, Stage};
+use crate::parser::ArgParser;
+
+pub(crate) struct LoopMatchParser;
+impl<S: Stage> SingleAttributeParser<S> for LoopMatchParser {
+    const PATH: &[Symbol] = &[sym::loop_match];
+    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepFirst;
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const TEMPLATE: AttributeTemplate = template!(Word);
+
+    fn convert(cx: &mut AcceptContext<'_, '_, S>, _args: &ArgParser<'_>) -> Option<AttributeKind> {
+        Some(AttributeKind::LoopMatch(cx.attr_span))
+    }
+}
+
+pub(crate) struct ConstContinueParser;
+impl<S: Stage> SingleAttributeParser<S> for ConstContinueParser {
+    const PATH: &[Symbol] = &[sym::const_continue];
+    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepFirst;
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const TEMPLATE: AttributeTemplate = template!(Word);
+
+    fn convert(cx: &mut AcceptContext<'_, '_, S>, _args: &ArgParser<'_>) -> Option<AttributeKind> {
+        Some(AttributeKind::ConstContinue(cx.attr_span))
+    }
+}

compiler/rustc_attr_parsing/src/attributes/mod.rs

@@ -32,6 +32,7 @@ pub(crate) mod confusables;
 pub(crate) mod deprecation;
 pub(crate) mod inline;
 pub(crate) mod lint_helpers;
+pub(crate) mod loop_match;
 pub(crate) mod must_use;
 pub(crate) mod repr;
 pub(crate) mod semantics;

compiler/rustc_attr_parsing/src/context.rs

@@ -20,6 +20,7 @@ use crate::attributes::confusables::ConfusablesParser;
 use crate::attributes::deprecation::DeprecationParser;
 use crate::attributes::inline::{InlineParser, RustcForceInlineParser};
 use crate::attributes::lint_helpers::{AsPtrParser, PubTransparentParser};
+use crate::attributes::loop_match::{ConstContinueParser, LoopMatchParser};
 use crate::attributes::must_use::MustUseParser;
 use crate::attributes::repr::{AlignParser, ReprParser};
 use crate::attributes::semantics::MayDangleParser;
@@ -111,9 +112,11 @@ attribute_parsers!(
         // tidy-alphabetical-start
         Single<AsPtrParser>,
         Single<ColdParser>,
+        Single<ConstContinueParser>,
         Single<ConstStabilityIndirectParser>,
         Single<DeprecationParser>,
         Single<InlineParser>,
+        Single<LoopMatchParser>,
         Single<MayDangleParser>,
         Single<MustUseParser>,
         Single<NoMangleParser>,

compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs

@@ -71,7 +71,6 @@ impl<'tcx> BorrowExplanation<'tcx> {
     ) {
         let tcx = cx.infcx.tcx;
         let body = cx.body;
-        let local_names = &cx.local_names;
 
         if let Some(span) = borrow_span {
             let def_id = body.source.def_id();
@@ -220,7 +219,7 @@ impl<'tcx> BorrowExplanation<'tcx> {
                     _ => ("destructor", format!("type `{}`", local_decl.ty)),
                 };
 
-                match local_names[dropped_local] {
+                match cx.local_name(dropped_local) {
                     Some(local_name) if !local_decl.from_compiler_desugaring() => {
                         let message = format!(
                             "{borrow_desc}borrow might be used here, when `{local_name}` is dropped \
@@ -670,10 +669,10 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, 'tcx> {
 
             Some(Cause::DropVar(local, location)) => {
                 let mut should_note_order = false;
-                if self.local_names[local].is_some()
+                if self.local_name(local).is_some()
                     && let Some((WriteKind::StorageDeadOrDrop, place)) = kind_place
                     && let Some(borrowed_local) = place.as_local()
-                    && self.local_names[borrowed_local].is_some()
+                    && self.local_name(borrowed_local).is_some()
                     && local != borrowed_local
                 {
                     should_note_order = true;
@@ -748,7 +747,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, 'tcx> {
                         Operand::Copy(place) | Operand::Move(place) => {
                             if let Some(l) = place.as_local() {
                                 let local_decl = &self.body.local_decls[l];
-                                if self.local_names[l].is_none() {
+                                if self.local_name(l).is_none() {
                                     local_decl.source_info.span
                                 } else {
                                     span
@@ -793,7 +792,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, 'tcx> {
                             Operand::Copy(place) | Operand::Move(place) => {
                                 if let Some(l) = place.as_local() {
                                     let local_decl = &self.body.local_decls[l];
-                                    if self.local_names[l].is_none() {
+                                    if self.local_name(l).is_none() {
                                         local_decl.source_info.span
                                     } else {
                                         span

compiler/rustc_borrowck/src/diagnostics/mod.rs

@@ -7,17 +7,17 @@ use rustc_data_structures::fx::FxIndexMap;
 use rustc_errors::{Applicability, Diag, EmissionGuarantee, MultiSpan, listify};
 use rustc_hir::def::{CtorKind, Namespace};
 use rustc_hir::{self as hir, CoroutineKind, LangItem};
-use rustc_index::IndexSlice;
+use rustc_index::{IndexSlice, IndexVec};
 use rustc_infer::infer::{BoundRegionConversionTime, NllRegionVariableOrigin};
 use rustc_infer::traits::SelectionError;
-use rustc_middle::bug;
 use rustc_middle::mir::{
     AggregateKind, CallSource, ConstOperand, ConstraintCategory, FakeReadCause, Local, LocalInfo,
     LocalKind, Location, Operand, Place, PlaceRef, PlaceTy, ProjectionElem, Rvalue, Statement,
-    StatementKind, Terminator, TerminatorKind, find_self_call,
+    StatementKind, Terminator, TerminatorKind, VarDebugInfoContents, find_self_call,
 };
 use rustc_middle::ty::print::Print;
 use rustc_middle::ty::{self, Ty, TyCtxt};
+use rustc_middle::{bug, span_bug};
 use rustc_mir_dataflow::move_paths::{InitLocation, LookupResult, MoveOutIndex};
 use rustc_span::def_id::LocalDefId;
 use rustc_span::source_map::Spanned;
@@ -190,6 +190,36 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
     ) -> Option<&(PlaceRef<'tcx>, Diag<'infcx>)> {
         self.diags_buffer.buffered_move_errors.get(move_out_indices)
     }
+
+    /// Uses `body.var_debug_info` to find the symbol
+    fn local_name(&self, index: Local) -> Option<Symbol> {
+        *self.local_names().get(index)?
+    }
+
+    fn local_names(&self) -> &IndexSlice<Local, Option<Symbol>> {
+        self.local_names.get_or_init(|| {
+            let mut local_names = IndexVec::from_elem(None, &self.body.local_decls);
+            for var_debug_info in &self.body.var_debug_info {
+                if let VarDebugInfoContents::Place(place) = var_debug_info.value {
+                    if let Some(local) = place.as_local() {
+                        if let Some(prev_name) = local_names[local]
+                            && var_debug_info.name != prev_name
+                        {
+                            span_bug!(
+                                var_debug_info.source_info.span,
+                                "local {:?} has many names (`{}` vs `{}`)",
+                                local,
+                                prev_name,
+                                var_debug_info.name
+                            );
+                        }
+                        local_names[local] = Some(var_debug_info.name);
+                    }
+                }
+            }
+            local_names
+        })
+    }
 }
 
 impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
@@ -430,7 +460,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
     /// a name, or its name was generated by the compiler, then `Err` is returned
     fn append_local_to_string(&self, local: Local, buf: &mut String) -> Result<(), ()> {
         let decl = &self.body.local_decls[local];
-        match self.local_names[local] {
+        match self.local_name(local) {
             Some(name) if !decl.from_compiler_desugaring() => {
                 buf.push_str(name.as_str());
                 Ok(())
@@ -1500,4 +1530,9 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
             }
         }
     }
+
+    /// Skip over locals that begin with an underscore or have no name
+    pub(crate) fn local_excluded_from_unused_mut_lint(&self, index: Local) -> bool {
+        self.local_name(index).is_none_or(|name| name.as_str().starts_with('_'))
+    }
 }

compiler/rustc_borrowck/src/diagnostics/move_errors.rs

@@ -465,11 +465,15 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
 
         if let PlaceRef { local, projection: [] } = deref_base {
             let decl = &self.body.local_decls[local];
+            let local_name = self.local_name(local).map(|sym| format!("`{sym}`"));
             if decl.is_ref_for_guard() {
                 return self
                     .cannot_move_out_of(
                         span,
-                        &format!("`{}` in pattern guard", self.local_names[local].unwrap()),
+                        &format!(
+                            "{} in pattern guard",
+                            local_name.as_deref().unwrap_or("the place")
+                        ),
                     )
                     .with_note(
                         "variables bound in patterns cannot be moved from \
@@ -825,7 +829,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
             }
 
             if binds_to.len() == 1 {
-                let place_desc = &format!("`{}`", self.local_names[*local].unwrap());
+                let place_desc = self.local_name(*local).map(|sym| format!("`{sym}`"));
 
                 if let Some(expr) = self.find_expr(binding_span) {
                     self.suggest_cloning(err, bind_to.ty, expr, None);
@@ -834,7 +838,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                 err.subdiagnostic(crate::session_diagnostics::TypeNoCopy::Label {
                     is_partial_move: false,
                     ty: bind_to.ty,
-                    place: place_desc,
+                    place: place_desc.as_deref().unwrap_or("the place"),
                     span: binding_span,
                 });
             }

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -60,7 +60,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                 if access_place.as_local().is_some() {
                     reason = ", as it is not declared as mutable".to_string();
                 } else {
-                    let name = self.local_names[local].expect("immutable unnamed local");
+                    let name = self.local_name(local).expect("immutable unnamed local");
                     reason = format!(", as `{name}` is not declared as mutable");
                 }
             }
@@ -285,7 +285,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                     .body
                     .local_decls
                     .get(local)
-                    .is_some_and(|l| mut_borrow_of_mutable_ref(l, self.local_names[local])) =>
+                    .is_some_and(|l| mut_borrow_of_mutable_ref(l, self.local_name(local))) =>
             {
                 let decl = &self.body.local_decls[local];
                 err.span_label(span, format!("cannot {act}"));
@@ -481,7 +481,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                 let (pointer_sigil, pointer_desc) =
                     if local_decl.ty.is_ref() { ("&", "reference") } else { ("*const", "pointer") };
 
-                match self.local_names[local] {
+                match self.local_name(local) {
                     Some(name) if !local_decl.from_compiler_desugaring() => {
                         err.span_label(
                             span,

compiler/rustc_borrowck/src/diagnostics/region_errors.rs

@@ -664,14 +664,14 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         let fr_name_and_span = self.regioncx.get_var_name_and_span_for_region(
             self.infcx.tcx,
             self.body,
-            &self.local_names,
+            &self.local_names(),
             &self.upvars,
             errci.fr,
         );
         let outlived_fr_name_and_span = self.regioncx.get_var_name_and_span_for_region(
             self.infcx.tcx,
             self.body,
-            &self.local_names,
+            &self.local_names(),
             &self.upvars,
             errci.outlived_fr,
         );

compiler/rustc_borrowck/src/diagnostics/region_name.rs

@@ -399,7 +399,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, 'tcx> {
             [implicit_inputs + argument_index];
         let (_, span) = self.regioncx.get_argument_name_and_span_for_region(
             self.body,
-            &self.local_names,
+            self.local_names(),
             argument_index,
         );
 
@@ -973,7 +973,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, 'tcx> {
         {
             let (arg_name, arg_span) = self.regioncx.get_argument_name_and_span_for_region(
                 self.body,
-                &self.local_names,
+                self.local_names(),
                 arg_index,
             );
             let region_name = self.synthesize_region_name();