Rollup of 10 pull requests

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -1,6 +1,4 @@
-use rustc_errors::{
-    Applicability, Diagnostic, DiagnosticBuilder, EmissionGuarantee, ErrorGuaranteed,
-};
+use rustc_errors::{Applicability, Diagnostic};
 use rustc_hir as hir;
 use rustc_hir::intravisit::Visitor;
 use rustc_hir::Node;
@@ -629,25 +627,20 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
         self.buffer_error(err);
     }
 
-    fn suggest_map_index_mut_alternatives(
-        &self,
-        ty: Ty<'_>,
-        err: &mut DiagnosticBuilder<'_, ErrorGuaranteed>,
-        span: Span,
-    ) {
+    fn suggest_map_index_mut_alternatives(&self, ty: Ty<'tcx>, err: &mut Diagnostic, span: Span) {
         let Some(adt) = ty.ty_adt_def() else { return };
         let did = adt.did();
         if self.infcx.tcx.is_diagnostic_item(sym::HashMap, did)
             || self.infcx.tcx.is_diagnostic_item(sym::BTreeMap, did)
         {
-            struct V<'a, 'b, 'tcx, G: EmissionGuarantee> {
+            struct V<'a, 'tcx> {
                 assign_span: Span,
-                err: &'a mut DiagnosticBuilder<'b, G>,
+                err: &'a mut Diagnostic,
                 ty: Ty<'tcx>,
                 suggested: bool,
             }
-            impl<'a, 'b: 'a, 'hir, 'tcx, G: EmissionGuarantee> Visitor<'hir> for V<'a, 'b, 'tcx, G> {
-                fn visit_stmt(&mut self, stmt: &'hir hir::Stmt<'hir>) {
+            impl<'a, 'tcx> Visitor<'tcx> for V<'a, 'tcx> {
+                fn visit_stmt(&mut self, stmt: &'tcx hir::Stmt<'tcx>) {
                     hir::intravisit::walk_stmt(self, stmt);
                     let expr = match stmt.kind {
                         hir::StmtKind::Semi(expr) | hir::StmtKind::Expr(expr) => expr,
@@ -705,7 +698,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                                     ),
                                     (rv.span.shrink_to_hi(), ")".to_string()),
                                 ],
-                            ].into_iter(),
+                            ],
                             Applicability::MachineApplicable,
                         );
                         self.suggested = true;

compiler/rustc_errors/src/diagnostic.rs

@@ -688,10 +688,10 @@ impl Diagnostic {
         &mut self,
         sp: Span,
         msg: impl Into<SubdiagnosticMessage>,
-        suggestions: impl Iterator<Item = String>,
+        suggestions: impl IntoIterator<Item = String>,
         applicability: Applicability,
     ) -> &mut Self {
-        let mut suggestions: Vec<_> = suggestions.collect();
+        let mut suggestions: Vec<_> = suggestions.into_iter().collect();
         suggestions.sort();
 
         debug_assert!(
@@ -717,7 +717,7 @@ impl Diagnostic {
     pub fn multipart_suggestions(
         &mut self,
         msg: impl Into<SubdiagnosticMessage>,
-        suggestions: impl Iterator<Item = Vec<(Span, String)>>,
+        suggestions: impl IntoIterator<Item = Vec<(Span, String)>>,
         applicability: Applicability,
     ) -> &mut Self {
         let suggestions: Vec<_> = suggestions.collect();

compiler/rustc_errors/src/diagnostic_builder.rs

@@ -594,13 +594,13 @@ impl<'a, G: EmissionGuarantee> DiagnosticBuilder<'a, G> {
         &mut self,
         sp: Span,
         msg: impl Into<SubdiagnosticMessage>,
-        suggestions: impl Iterator<Item = String>,
+        suggestions: impl IntoIterator<Item = String>,
         applicability: Applicability,
     ) -> &mut Self);
     forward!(pub fn multipart_suggestions(
         &mut self,
         msg: impl Into<SubdiagnosticMessage>,
-        suggestions: impl Iterator<Item = Vec<(Span, String)>>,
+        suggestions: impl IntoIterator<Item = Vec<(Span, String)>>,
         applicability: Applicability,
     ) -> &mut Self);
     forward!(pub fn span_suggestion_short(

compiler/rustc_hir_analysis/src/check/compare_method.rs

@@ -664,10 +664,7 @@ impl<'tcx> TypeFolder<'tcx> for ImplTraitInTraitCollector<'_, 'tcx> {
             });
             self.types.insert(proj.item_def_id, (infer_ty, proj.substs));
             // Recurse into bounds
-            for pred in self.tcx().bound_explicit_item_bounds(proj.item_def_id).transpose_iter() {
-                let pred_span = pred.0.1;
-
-                let pred = pred.map_bound(|(pred, _)| *pred).subst(self.tcx(), proj.substs);
+            for (pred, pred_span) in self.tcx().bound_explicit_item_bounds(proj.item_def_id).subst_iter_copied(self.tcx(), proj.substs) {
                 let pred = pred.fold_with(self);
                 let pred = self.ocx.normalize(
                     ObligationCause::misc(self.span, self.body_id),
@@ -1752,15 +1749,10 @@ pub fn check_type_bounds<'tcx>(
 
     let obligations = tcx
         .bound_explicit_item_bounds(trait_ty.def_id)
-        .transpose_iter()
-        .map(|e| e.map_bound(|e| *e).transpose_tuple2())
-        .map(|(bound, span)| {
-            debug!(?bound);
-            // this is where opaque type is found
-            let concrete_ty_bound = bound.subst(tcx, rebased_substs);
+        .subst_iter_copied(tcx, rebased_substs)
+        .map(|(concrete_ty_bound, span)| {
             debug!("check_type_bounds: concrete_ty_bound = {:?}", concrete_ty_bound);
-
-            traits::Obligation::new(mk_cause(span.0), param_env, concrete_ty_bound)
+            traits::Obligation::new(mk_cause(span), param_env, concrete_ty_bound)
         })
         .collect();
     debug!("check_type_bounds: item_bounds={:?}", obligations);

compiler/rustc_hir_typeck/src/_match.rs

@@ -514,8 +514,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 }
 
                 for ty in [first_ty, second_ty] {
-                    for pred in self.tcx.bound_explicit_item_bounds(rpit_def_id).transpose_iter() {
-                        let pred = pred.map_bound(|(pred, _)| *pred).subst(self.tcx, substs);
+                    for (pred, _) in self
+                        .tcx
+                        .bound_explicit_item_bounds(rpit_def_id)
+                        .subst_iter_copied(self.tcx, substs)
+                    {
                         let pred = match pred.kind().skip_binder() {
                             ty::PredicateKind::Trait(mut trait_pred) => {
                                 assert_eq!(trait_pred.trait_ref.self_ty(), opaque_ty);

compiler/rustc_hir_typeck/src/closure.rs

@@ -176,24 +176,23 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         match *expected_ty.kind() {
             ty::Opaque(def_id, substs) => {
                 let bounds = self.tcx.bound_explicit_item_bounds(def_id);
-                let sig = bounds
-                    .transpose_iter()
-                    .map(|e| e.map_bound(|e| *e).transpose_tuple2())
-                    .find_map(|(pred, span)| match pred.0.kind().skip_binder() {
+                let sig =
+                    bounds.subst_iter_copied(self.tcx, substs).find_map(|(pred, span)| match pred
+                        .kind()
+                        .skip_binder()
+                    {
                         ty::PredicateKind::Projection(proj_predicate) => self
                             .deduce_sig_from_projection(
-                                Some(span.0),
-                                pred.0
-                                    .kind()
-                                    .rebind(pred.rebind(proj_predicate).subst(self.tcx, substs)),
+                                Some(span),
+                                pred.kind().rebind(proj_predicate),
                             ),
                         _ => None,
                     });
 
                 let kind = bounds
-                    .transpose_iter()
-                    .map(|e| e.map_bound(|e| *e).transpose_tuple2())
-                    .filter_map(|(pred, _)| match pred.0.kind().skip_binder() {
+                    .0
+                    .iter()
+                    .filter_map(|(pred, _)| match pred.kind().skip_binder() {
                         ty::PredicateKind::Trait(tp) => {
                             self.tcx.fn_trait_kind_from_lang_item(tp.def_id())
                         }
@@ -697,18 +696,16 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             ty::Opaque(def_id, substs) => self
                 .tcx
                 .bound_explicit_item_bounds(def_id)
-                .transpose_iter()
-                .map(|e| e.map_bound(|e| *e).transpose_tuple2())
-                .find_map(|(p, s)| get_future_output(p.subst(self.tcx, substs), s.0))?,
+                .subst_iter_copied(self.tcx, substs)
+                .find_map(|(p, s)| get_future_output(p, s))?,
             ty::Error(_) => return None,
             ty::Projection(proj)
                 if self.tcx.def_kind(proj.item_def_id) == DefKind::ImplTraitPlaceholder =>
             {
                 self.tcx
                     .bound_explicit_item_bounds(proj.item_def_id)
-                    .transpose_iter()
-                    .map(|e| e.map_bound(|e| *e).transpose_tuple2())
-                    .find_map(|(p, s)| get_future_output(p.subst(self.tcx, proj.substs), s.0))?
+                    .subst_iter_copied(self.tcx, proj.substs)
+                    .find_map(|(p, s)| get_future_output(p, s))?
             }
             _ => span_bug!(
                 self.tcx.def_span(expr_def_id),

compiler/rustc_infer/src/infer/error_reporting/mod.rs

@@ -338,8 +338,7 @@ impl<'tcx> InferCtxt<'tcx> {
 
             let bounds = self.tcx.bound_explicit_item_bounds(*def_id);
 
-            for predicate in bounds.transpose_iter().map(|e| e.map_bound(|(p, _)| *p)) {
-                let predicate = predicate.subst(self.tcx, substs);
+            for (predicate, _) in bounds.subst_iter_copied(self.tcx, substs) {
                 let output = predicate
                     .kind()
                     .map_bound(|kind| match kind {
@@ -2272,6 +2271,25 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                 struct_span_err!(self.tcx.sess, span, E0580, "{}", failure_str)
             }
             FailureCode::Error0308(failure_str) => {
+                fn escape_literal(s: &str) -> String {
+                    let mut escaped = String::with_capacity(s.len());
+                    let mut chrs = s.chars().peekable();
+                    while let Some(first) = chrs.next() {
+                        match (first, chrs.peek()) {
+                            ('\\', Some(&delim @ '"') | Some(&delim @ '\'')) => {
+                                escaped.push('\\');
+                                escaped.push(delim);
+                                chrs.next();
+                            }
+                            ('"' | '\'', _) => {
+                                escaped.push('\\');
+                                escaped.push(first)
+                            }
+                            (c, _) => escaped.push(c),
+                        };
+                    }
+                    escaped
+                }
                 let mut err = struct_span_err!(self.tcx.sess, span, E0308, "{}", failure_str);
                 if let Some((expected, found)) = trace.values.ty() {
                     match (expected.kind(), found.kind()) {
@@ -2293,7 +2311,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                                 err.span_suggestion(
                                     span,
                                     "if you meant to write a `char` literal, use single quotes",
-                                    format!("'{}'", code),
+                                    format!("'{}'", escape_literal(code)),
                                     Applicability::MachineApplicable,
                                 );
                             }
@@ -2308,7 +2326,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                                     err.span_suggestion(
                                         span,
                                         "if you meant to write a `str` literal, use double quotes",
-                                        format!("\"{}\"", code),
+                                        format!("\"{}\"", escape_literal(code)),
                                         Applicability::MachineApplicable,
                                     );
                                 }

compiler/rustc_infer/src/infer/opaque_types.rs

@@ -1,6 +1,7 @@
 use crate::errors::OpaqueHiddenTypeDiag;
 use crate::infer::{DefiningAnchor, InferCtxt, InferOk};
 use crate::traits;
+use hir::def::DefKind;
 use hir::def_id::{DefId, LocalDefId};
 use hir::{HirId, OpaqueTyOrigin};
 use rustc_data_structures::sync::Lrc;
@@ -543,16 +544,18 @@ impl<'tcx> InferCtxt<'tcx> {
 
         let item_bounds = tcx.bound_explicit_item_bounds(def_id.to_def_id());
 
-        for predicate in item_bounds.transpose_iter().map(|e| e.map_bound(|(p, _)| *p)) {
-            debug!(?predicate);
-            let predicate = predicate.subst(tcx, substs);
-
+        for (predicate, _) in item_bounds.subst_iter_copied(tcx, substs) {
             let predicate = predicate.fold_with(&mut BottomUpFolder {
                 tcx,
                 ty_op: |ty| match *ty.kind() {
                     // We can't normalize associated types from `rustc_infer`,
                     // but we can eagerly register inference variables for them.
-                    ty::Projection(projection_ty) if !projection_ty.has_escaping_bound_vars() => {
+                    // FIXME(RPITIT): Don't replace RPITITs with inference vars.
+                    ty::Projection(projection_ty)
+                        if !projection_ty.has_escaping_bound_vars()
+                            && tcx.def_kind(projection_ty.item_def_id)
+                                != DefKind::ImplTraitPlaceholder =>
+                    {
                         self.infer_projection(
                             param_env,
                             projection_ty,
@@ -568,6 +571,12 @@ impl<'tcx> InferCtxt<'tcx> {
                     {
                         hidden_ty
                     }
+                    // FIXME(RPITIT): This can go away when we move to associated types
+                    ty::Projection(proj)
+                        if def_id.to_def_id() == proj.item_def_id && substs == proj.substs =>
+                    {
+                        hidden_ty
+                    }
                     _ => ty,
                 },
                 lt_op: |lt| lt,

compiler/rustc_lint/src/levels.rs

@@ -960,7 +960,7 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
                                         sp,
                                         "did you mean",
                                         suggestion,
-                                        Applicability::MachineApplicable,
+                                        Applicability::MaybeIncorrect,
                                     );
                                 }
                                 lint

compiler/rustc_lint/src/opaque_hidden_inferred_bound.rs

@@ -91,14 +91,12 @@ impl<'tcx> LateLintPass<'tcx> for OpaqueHiddenInferredBound {
             // For example, in `impl Trait<Assoc = impl Send>`, for all of the bounds on `Assoc`,
             // e.g. `type Assoc: OtherTrait`, replace `<impl Trait as Trait>::Assoc: OtherTrait`
             // with `impl Send: OtherTrait`.
-            for assoc_pred_and_span in
-                cx.tcx.bound_explicit_item_bounds(proj.projection_ty.item_def_id).transpose_iter()
+            for (assoc_pred, assoc_pred_span) in cx
+                .tcx
+                .bound_explicit_item_bounds(proj.projection_ty.item_def_id)
+                .subst_iter_copied(cx.tcx, &proj.projection_ty.substs)
             {
-                let assoc_pred_span = assoc_pred_and_span.0.1;
-                let assoc_pred = assoc_pred_and_span
-                    .map_bound(|(pred, _)| *pred)
-                    .subst(cx.tcx, &proj.projection_ty.substs)
-                    .fold_with(proj_replacer);
+                let assoc_pred = assoc_pred.fold_with(proj_replacer);
                 let Ok(assoc_pred) = traits::fully_normalize(infcx, traits::ObligationCause::dummy(), cx.param_env, assoc_pred) else {
                     continue;
                 };

compiler/rustc_middle/src/ty/print/pretty.rs

@@ -795,8 +795,7 @@ pub trait PrettyPrinter<'tcx>:
         let mut fn_traits = FxIndexMap::default();
         let mut is_sized = false;
 
-        for predicate in bounds.transpose_iter().map(|e| e.map_bound(|(p, _)| *p)) {
-            let predicate = predicate.subst(tcx, substs);
+        for (predicate, _) in bounds.subst_iter_copied(tcx, substs) {
             let bound_predicate = predicate.kind();
 
             match bound_predicate.skip_binder() {

compiler/rustc_middle/src/ty/subst.rs

@@ -6,6 +6,7 @@ use crate::ty::sty::{ClosureSubsts, GeneratorSubsts, InlineConstSubsts};
 use crate::ty::visit::{TypeVisitable, TypeVisitor};
 use crate::ty::{self, Lift, List, ParamConst, Ty, TyCtxt};
 
+use rustc_data_structures::captures::Captures;
 use rustc_data_structures::intern::{Interned, WithStableHash};
 use rustc_hir::def_id::DefId;
 use rustc_macros::HashStable;
@@ -558,6 +559,28 @@ impl<T, U> EarlyBinder<(T, U)> {
     }
 }
 
+impl<'tcx, 's, T: IntoIterator<Item = I>, I: TypeFoldable<'tcx>> EarlyBinder<T> {
+    pub fn subst_iter(
+        self,
+        tcx: TyCtxt<'tcx>,
+        substs: &'s [GenericArg<'tcx>],
+    ) -> impl Iterator<Item = I> + Captures<'s> + Captures<'tcx> {
+        self.0.into_iter().map(move |t| EarlyBinder(t).subst(tcx, substs))
+    }
+}
+
+impl<'tcx, 's, 'a, T: IntoIterator<Item = &'a I>, I: Copy + TypeFoldable<'tcx> + 'a>
+    EarlyBinder<T>
+{
+    pub fn subst_iter_copied(
+        self,
+        tcx: TyCtxt<'tcx>,
+        substs: &'s [GenericArg<'tcx>],
+    ) -> impl Iterator<Item = I> + Captures<'s> + Captures<'tcx> + Captures<'a> {
+        self.0.into_iter().map(move |t| EarlyBinder(*t).subst(tcx, substs))
+    }
+}
+
 pub struct EarlyBinderIter<T> {
     t: T,
 }

compiler/rustc_parse/src/lexer/unescape_error_reporting.rs

@@ -113,11 +113,26 @@ pub(crate) fn emit_unescape_error(
                 } else {
                     ("", "if you meant to write a `str` literal, use double quotes")
                 };
-
+                let mut escaped = String::with_capacity(lit.len());
+                let mut chrs = lit.chars().peekable();
+                while let Some(first) = chrs.next() {
+                    match (first, chrs.peek()) {
+                        ('\\', Some('"')) => {
+                            escaped.push('\\');
+                            escaped.push('"');
+                            chrs.next();
+                        }
+                        ('"', _) => {
+                            escaped.push('\\');
+                            escaped.push('"')
+                        }
+                        (c, _) => escaped.push(c),
+                    };
+                }
                 handler.span_suggestion(
                     span_with_quotes,
                     msg,
-                    format!("{}\"{}\"", prefix, lit),
+                    format!("{prefix}\"{escaped}\""),
                     Applicability::MachineApplicable,
                 );
             }