Auto merge of #107536 - GuillaumeGomez:rollup-xv7dx2h, r=GuillaumeGomez

Rollup of 12 pull requests

Successful merges:

 - #106898 (Include both md and yaml ICE ticket templates)
 - #107331 (Clean up eslint annotations and remove unused JS function)
 - #107348 (small refactor to new projection code)
 - #107354 (rustdoc: update Source Serif 4 from 4.004 to 4.005)
 - #107412 (avoid needless checks)
 - #107467 (Improve enum checks)
 - #107486 (Track bound types like bound regions)
 - #107491 (rustdoc: remove unused CSS from `.setting-check`)
 - #107508 (`Edition` micro refactor)
 - #107525 (PointeeInfo is advisory only)
 - #107527 (rustdoc: stop making unstable items transparent)
 - #107535 (Replace unwrap with ? in TcpListener doc)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

.github/ISSUE_TEMPLATE/ice.md

@@ -0,0 +1,49 @@
+---
+name: Internal Compiler Error
+about: Create a report for an internal compiler error in rustc.
+labels: C-bug, I-ICE, T-compiler
+---
+<!--
+Thank you for finding an Internal Compiler Error! 🧊  If possible, try to provide
+a minimal verifiable example. You can read "Rust Bug Minimization Patterns" for
+how to create smaller examples.
+http://blog.pnkfx.org/blog/2019/11/18/rust-bug-minimization-patterns/
+-->
+
+### Code
+
+```Rust
+<code>
+```
+
+
+### Meta
+<!--
+If you're using the stable version of the compiler, you should also check if the
+bug also exists in the beta or nightly versions.
+-->
+
+`rustc --version --verbose`:
+```
+<version>
+```
+
+### Error output
+
+```
+<output>
+```
+
+<!--
+Include a backtrace in the code block by setting `RUST_BACKTRACE=1` in your
+environment. E.g. `RUST_BACKTRACE=1 cargo build`.
+-->
+<details><summary><strong>Backtrace</strong></summary>
+<p>
+
+```
+<backtrace>
+```
+
+</p>
+</details>

.github/ISSUE_TEMPLATE/ice.yaml

@@ -1,5 +1,5 @@
-name: Internal Compiler Error
-description: Create a report for an internal compiler error in `rustc`
+name: Internal Compiler Error (Structured form)
+description: For now, you'll want to use the other ICE template, as GitHub forms have strict limits on the size of fields so backtraces cannot be pasted directly.
 labels: ["C-bug", "I-ICE", "T-compiler"]
 title: "[ICE]: "
 body:
@@ -79,4 +79,4 @@ body:
       label: Anything else?
       description: If you have more details you want to give us to reproduce this issue, please add it here
     validations:
-      required: false
+      required: false

compiler/rustc_abi/src/lib.rs

@@ -1456,6 +1456,8 @@ pub enum PointerKind {
     UniqueOwned,
 }
 
+/// Note that this information is advisory only, and backends are free to ignore it.
+/// It can only be used to encode potential optimizations, but no critical information.
 #[derive(Copy, Clone, Debug)]
 pub struct PointeeInfo {
     pub size: Size,

compiler/rustc_ast/src/util/comments.rs

@@ -58,23 +58,24 @@ pub fn beautify_doc_string(data: Symbol, kind: CommentKind) -> Symbol {
         // In case we have doc comments like `/**` or `/*!`, we want to remove stars if they are
         // present. However, we first need to strip the empty lines so they don't get in the middle
         // when we try to compute the "horizontal trim".
-        let lines = if kind == CommentKind::Block {
-            // Whatever happens, we skip the first line.
-            let mut i = lines
-                .get(0)
-                .map(|l| if l.trim_start().starts_with('*') { 0 } else { 1 })
-                .unwrap_or(0);
-            let mut j = lines.len();
+        let lines = match kind {
+            CommentKind::Block => {
+                // Whatever happens, we skip the first line.
+                let mut i = lines
+                    .get(0)
+                    .map(|l| if l.trim_start().starts_with('*') { 0 } else { 1 })
+                    .unwrap_or(0);
+                let mut j = lines.len();
 
-            while i < j && lines[i].trim().is_empty() {
-                i += 1;
+                while i < j && lines[i].trim().is_empty() {
+                    i += 1;
+                }
+                while j > i && lines[j - 1].trim().is_empty() {
+                    j -= 1;
+                }
+                &lines[i..j]
             }
-            while j > i && lines[j - 1].trim().is_empty() {
-                j -= 1;
-            }
-            &lines[i..j]
-        } else {
-            lines
+            CommentKind::Line => lines,
         };
 
         for line in lines {

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -131,7 +131,7 @@ pub fn print_crate<'a>(
 
         // Currently, in Rust 2018 we don't have `extern crate std;` at the crate
         // root, so this is not needed, and actually breaks things.
-        if edition == Edition::Edition2015 {
+        if edition.rust_2015() {
             // `#![no_std]`
             let fake_attr = attr::mk_attr_word(g, ast::AttrStyle::Inner, sym::no_std, DUMMY_SP);
             s.print_attribute(&fake_attr);

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -344,7 +344,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                     } else {
                         err.span_help(source_info.span, "try removing `&mut` here");
                     }
-                } else if decl.mutability == Mutability::Not {
+                } else if decl.mutability.is_not() {
                     if matches!(
                         decl.local_info,
                         Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::ImplicitSelf(

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -2028,7 +2028,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                             }
                         };
 
-                        if ty_to_mut == Mutability::Mut && ty_mut == Mutability::Not {
+                        if ty_to_mut.is_mut() && ty_mut.is_not() {
                             span_mirbug!(
                                 self,
                                 rvalue,

compiler/rustc_codegen_llvm/src/context.rs

@@ -150,17 +150,14 @@ pub unsafe fn create_module<'ll>(
             target_data_layout =
                 "e-m:x-p:32:32-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:32-n8:16:32-a:0:32-S32"
                     .to_string();
-        }
-        if sess.target.arch == "wasm32" {
+        } else if sess.target.arch == "wasm32" {
             target_data_layout = target_data_layout.replace("-p10:8:8-p20:8:8", "");
         }
     }
     if llvm_version < (16, 0, 0) {
         if sess.target.arch == "s390x" {
             target_data_layout = target_data_layout.replace("-v128:64", "");
-        }
-
-        if sess.target.arch == "riscv64" {
+        } else if sess.target.arch == "riscv64" {
             target_data_layout = target_data_layout.replace("-n32:64-", "-n64-");
         }
     }

compiler/rustc_const_eval/src/const_eval/machine.rs

@@ -622,10 +622,9 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
         let alloc = alloc.inner();
         if is_write {
             // Write access. These are never allowed, but we give a targeted error message.
-            if alloc.mutability == Mutability::Not {
-                Err(err_ub!(WriteToReadOnly(alloc_id)).into())
-            } else {
-                Err(ConstEvalErrKind::ModifiedGlobal.into())
+            match alloc.mutability {
+                Mutability::Not => Err(err_ub!(WriteToReadOnly(alloc_id)).into()),
+                Mutability::Mut => Err(ConstEvalErrKind::ModifiedGlobal.into()),
             }
         } else {
             // Read access. These are usually allowed, with some exceptions.

compiler/rustc_const_eval/src/interpret/memory.rs

@@ -304,7 +304,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             .into());
         };
 
-        if alloc.mutability == Mutability::Not {
+        if alloc.mutability.is_not() {
             throw_ub_format!("deallocating immutable allocation {alloc_id:?}");
         }
         if alloc_kind != kind {
@@ -631,7 +631,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         }
 
         let (_kind, alloc) = self.memory.alloc_map.get_mut(id).unwrap();
-        if alloc.mutability == Mutability::Not {
+        if alloc.mutability.is_not() {
             throw_ub!(WriteToReadOnly(id))
         }
         Ok((alloc, &mut self.machine))

compiler/rustc_const_eval/src/transform/validate.rs

@@ -754,7 +754,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                 // FIXME(JakobDegen) The validator should check that `self.mir_phase <
                 // DropsLowered`. However, this causes ICEs with generation of drop shims, which
                 // seem to fail to set their `MirPhase` correctly.
-                if *kind == RetagKind::Raw || *kind == RetagKind::TwoPhase {
+                if matches!(kind, RetagKind::Raw | RetagKind::TwoPhase) {
                     self.fail(location, format!("explicit `{:?}` is forbidden", kind));
                 }
             }

compiler/rustc_errors/src/emitter.rs

@@ -2113,30 +2113,38 @@ impl EmitterWriter {
                         }
                     }
                     for sugg in suggestions {
-                        if sugg.style == SuggestionStyle::CompletelyHidden {
-                            // do not display this suggestion, it is meant only for tools
-                        } else if sugg.style == SuggestionStyle::HideCodeAlways {
-                            if let Err(e) = self.emit_message_default(
-                                &MultiSpan::new(),
-                                &[(sugg.msg.to_owned(), Style::HeaderMsg)],
-                                args,
-                                &None,
-                                &Level::Help,
-                                max_line_num_len,
-                                true,
-                                None,
-                            ) {
-                                panic!("failed to emit error: {}", e);
+                        match sugg.style {
+                            SuggestionStyle::CompletelyHidden => {
+                                // do not display this suggestion, it is meant only for tools
                             }
-                        } else if let Err(e) = self.emit_suggestion_default(
-                            span,
-                            sugg,
-                            args,
-                            &Level::Help,
-                            max_line_num_len,
-                        ) {
-                            panic!("failed to emit error: {}", e);
-                        };
+                            SuggestionStyle::HideCodeAlways => {
+                                if let Err(e) = self.emit_message_default(
+                                    &MultiSpan::new(),
+                                    &[(sugg.msg.to_owned(), Style::HeaderMsg)],
+                                    args,
+                                    &None,
+                                    &Level::Help,
+                                    max_line_num_len,
+                                    true,
+                                    None,
+                                ) {
+                                    panic!("failed to emit error: {}", e);
+                                }
+                            }
+                            SuggestionStyle::HideCodeInline
+                            | SuggestionStyle::ShowCode
+                            | SuggestionStyle::ShowAlways => {
+                                if let Err(e) = self.emit_suggestion_default(
+                                    span,
+                                    sugg,
+                                    args,
+                                    &Level::Help,
+                                    max_line_num_len,
+                                ) {
+                                    panic!("failed to emit error: {}", e);
+                                }
+                            }
+                        }
                     }
                 }
             }

compiler/rustc_errors/src/styled_buffer.rs

@@ -142,7 +142,7 @@ impl StyledBuffer {
     pub fn set_style(&mut self, line: usize, col: usize, style: Style, overwrite: bool) {
         if let Some(ref mut line) = self.lines.get_mut(line) {
             if let Some(StyledChar { style: s, .. }) = line.get_mut(col) {
-                if overwrite || *s == Style::NoStyle || *s == Style::Quotation {
+                if overwrite || matches!(s, Style::NoStyle | Style::Quotation) {
                     *s = style;
                 }
             }

compiler/rustc_expand/src/mbe/macro_parser.rs

@@ -503,7 +503,7 @@ impl TtParser {
                         mp.push_match(metavar_idx, seq_depth, MatchedSeq(vec![]));
                     }
 
-                    if op == KleeneOp::ZeroOrMore || op == KleeneOp::ZeroOrOne {
+                    if matches!(op, KleeneOp::ZeroOrMore | KleeneOp::ZeroOrOne) {
                         // Try zero matches of this sequence, by skipping over it.
                         self.cur_mps.push(MatcherPos {
                             idx: idx_first_after,

compiler/rustc_hir_analysis/src/astconv/generics.rs

@@ -385,10 +385,9 @@ pub fn check_generic_arg_count_for_call(
 ) -> GenericArgCountResult {
     let empty_args = hir::GenericArgs::none();
     let gen_args = seg.args.unwrap_or(&empty_args);
-    let gen_pos = if is_method_call == IsMethodCall::Yes {
-        GenericArgPosition::MethodCall
-    } else {
-        GenericArgPosition::Value
+    let gen_pos = match is_method_call {
+        IsMethodCall::Yes => GenericArgPosition::MethodCall,
+        IsMethodCall::No => GenericArgPosition::Value,
     };
     let has_self = generics.parent.is_none() && generics.has_self;
 

compiler/rustc_hir_analysis/src/check/check.rs

@@ -606,59 +606,66 @@ fn check_item_type(tcx: TyCtxt<'_>, id: hir::ItemId) {
             };
             check_abi(tcx, it.hir_id(), it.span, abi);
 
-            if abi == Abi::RustIntrinsic {
-                for item in items {
-                    let item = tcx.hir().foreign_item(item.id);
-                    intrinsic::check_intrinsic_type(tcx, item);
-                }
-            } else if abi == Abi::PlatformIntrinsic {
-                for item in items {
-                    let item = tcx.hir().foreign_item(item.id);
-                    intrinsic::check_platform_intrinsic_type(tcx, item);
-                }
-            } else {
-                for item in items {
-                    let def_id = item.id.owner_id.def_id;
-                    let generics = tcx.generics_of(def_id);
-                    let own_counts = generics.own_counts();
-                    if generics.params.len() - own_counts.lifetimes != 0 {
-                        let (kinds, kinds_pl, egs) = match (own_counts.types, own_counts.consts) {
-                            (_, 0) => ("type", "types", Some("u32")),
-                            // We don't specify an example value, because we can't generate
-                            // a valid value for any type.
-                            (0, _) => ("const", "consts", None),
-                            _ => ("type or const", "types or consts", None),
-                        };
-                        struct_span_err!(
-                            tcx.sess,
-                            item.span,
-                            E0044,
-                            "foreign items may not have {kinds} parameters",
-                        )
-                        .span_label(item.span, &format!("can't have {kinds} parameters"))
-                        .help(
-                            // FIXME: once we start storing spans for type arguments, turn this
-                            // into a suggestion.
-                            &format!(
-                                "replace the {} parameters with concrete {}{}",
-                                kinds,
-                                kinds_pl,
-                                egs.map(|egs| format!(" like `{}`", egs)).unwrap_or_default(),
-                            ),
-                        )
-                        .emit();
+            match abi {
+                Abi::RustIntrinsic => {
+                    for item in items {
+                        let item = tcx.hir().foreign_item(item.id);
+                        intrinsic::check_intrinsic_type(tcx, item);
                     }
+                }
 
-                    let item = tcx.hir().foreign_item(item.id);
-                    match &item.kind {
-                        hir::ForeignItemKind::Fn(fn_decl, _, _) => {
-                            require_c_abi_if_c_variadic(tcx, fn_decl, abi, item.span);
+                Abi::PlatformIntrinsic => {
+                    for item in items {
+                        let item = tcx.hir().foreign_item(item.id);
+                        intrinsic::check_platform_intrinsic_type(tcx, item);
+                    }
+                }
+
+                _ => {
+                    for item in items {
+                        let def_id = item.id.owner_id.def_id;
+                        let generics = tcx.generics_of(def_id);
+                        let own_counts = generics.own_counts();
+                        if generics.params.len() - own_counts.lifetimes != 0 {
+                            let (kinds, kinds_pl, egs) = match (own_counts.types, own_counts.consts)
+                            {
+                                (_, 0) => ("type", "types", Some("u32")),
+                                // We don't specify an example value, because we can't generate
+                                // a valid value for any type.
+                                (0, _) => ("const", "consts", None),
+                                _ => ("type or const", "types or consts", None),
+                            };
+                            struct_span_err!(
+                                tcx.sess,
+                                item.span,
+                                E0044,
+                                "foreign items may not have {kinds} parameters",
+                            )
+                            .span_label(item.span, &format!("can't have {kinds} parameters"))
+                            .help(
+                                // FIXME: once we start storing spans for type arguments, turn this
+                                // into a suggestion.
+                                &format!(
+                                    "replace the {} parameters with concrete {}{}",
+                                    kinds,
+                                    kinds_pl,
+                                    egs.map(|egs| format!(" like `{}`", egs)).unwrap_or_default(),
+                                ),
+                            )
+                            .emit();
                         }
-                        hir::ForeignItemKind::Static(..) => {
-                            check_static_inhabited(tcx, def_id);
-                            check_static_linkage(tcx, def_id);
+
+                        let item = tcx.hir().foreign_item(item.id);
+                        match &item.kind {
+                            hir::ForeignItemKind::Fn(fn_decl, _, _) => {
+                                require_c_abi_if_c_variadic(tcx, fn_decl, abi, item.span);
+                            }
+                            hir::ForeignItemKind::Static(..) => {
+                                check_static_inhabited(tcx, def_id);
+                                check_static_linkage(tcx, def_id);
+                            }
+                            _ => {}
                         }
-                        _ => {}
                     }
                 }
             }

compiler/rustc_hir_analysis/src/check/compare_impl_item.rs

@@ -1930,7 +1930,7 @@ pub(super) fn check_type_bounds<'tcx>(
         smallvec::SmallVec::with_capacity(defs.count());
     InternalSubsts::fill_single(&mut substs, defs, &mut |param, _| match param.kind {
         GenericParamDefKind::Type { .. } => {
-            let kind = ty::BoundTyKind::Param(param.name);
+            let kind = ty::BoundTyKind::Param(param.def_id, param.name);
             let bound_var = ty::BoundVariableKind::Ty(kind);
             bound_vars.push(bound_var);
             tcx.mk_ty(ty::Bound(

compiler/rustc_hir_pretty/src/lib.rs

@@ -9,9 +9,7 @@ use rustc_ast_pretty::pp::{self, Breaks};
 use rustc_ast_pretty::pprust::{Comments, PrintState};
 use rustc_hir as hir;
 use rustc_hir::LifetimeParamKind;
-use rustc_hir::{
-    BindingAnnotation, ByRef, GenericArg, GenericParam, GenericParamKind, Mutability, Node, Term,
-};
+use rustc_hir::{BindingAnnotation, ByRef, GenericArg, GenericParam, GenericParamKind, Node, Term};
 use rustc_hir::{GenericBound, PatKind, RangeEnd, TraitBoundModifier};
 use rustc_span::source_map::SourceMap;
 use rustc_span::symbol::{kw, Ident, IdentPrinter, Symbol};
@@ -1746,7 +1744,7 @@ impl<'a> State<'a> {
                 if by_ref == ByRef::Yes {
                     self.word_nbsp("ref");
                 }
-                if mutbl == Mutability::Mut {
+                if mutbl.is_mut() {
                     self.word_nbsp("mut");
                 }
                 self.print_ident(ident);

compiler/rustc_hir_typeck/src/method/probe.rs

@@ -1354,13 +1354,12 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
             return Some(Err(MethodError::Ambiguity(sources)));
         }
 
-        applicable_candidates.pop().map(|(probe, status)| {
-            if status == ProbeResult::Match {
+        applicable_candidates.pop().map(|(probe, status)| match status {
+            ProbeResult::Match => {
                 Ok(probe
                     .to_unadjusted_pick(self_ty, unstable_candidates.cloned().unwrap_or_default()))
-            } else {
-                Err(MethodError::BadReturnType)
             }
+            ProbeResult::NoMatch | ProbeResult::BadReturnType => Err(MethodError::BadReturnType),
         })
     }
 }

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

@@ -90,7 +90,7 @@ impl<'tcx> InferCtxt<'tcx> {
             types: &mut |bound_ty: ty::BoundTy| {
                 self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType {
                     universe: next_universe,
-                    name: bound_ty.var,
+                    name: bound_ty.kind,
                 }))
             },
             consts: &mut |bound_var: ty::BoundVar, ty| {

compiler/rustc_infer/src/infer/mod.rs

@@ -2044,7 +2044,7 @@ fn replace_param_and_infer_substs_with_placeholder<'tcx>(
 ) -> SubstsRef<'tcx> {
     struct ReplaceParamAndInferWithPlaceholder<'tcx> {
         tcx: TyCtxt<'tcx>,
-        idx: usize,
+        idx: u32,
     }
 
     impl<'tcx> TypeFolder<'tcx> for ReplaceParamAndInferWithPlaceholder<'tcx> {
@@ -2056,7 +2056,7 @@ fn replace_param_and_infer_substs_with_placeholder<'tcx>(
             if let ty::Infer(_) = t.kind() {
                 self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType {
                     universe: ty::UniverseIndex::ROOT,
-                    name: ty::BoundVar::from_usize({
+                    name: ty::BoundTyKind::Anon({
                         let idx = self.idx;
                         self.idx += 1;
                         idx
@@ -2077,7 +2077,7 @@ fn replace_param_and_infer_substs_with_placeholder<'tcx>(
                 self.tcx.mk_const(
                     ty::PlaceholderConst {
                         universe: ty::UniverseIndex::ROOT,
-                        name: ty::BoundVar::from_usize({
+                        name: ty::BoundVar::from_u32({
                             let idx = self.idx;
                             self.idx += 1;
                             idx

compiler/rustc_lint/src/builtin.rs

@@ -580,27 +580,28 @@ impl<'tcx> LateLintPass<'tcx> for MissingDoc {
     }
 
     fn check_impl_item(&mut self, cx: &LateContext<'_>, impl_item: &hir::ImplItem<'_>) {
-        // If the method is an impl for a trait, don't doc.
         let context = method_context(cx, impl_item.owner_id.def_id);
-        if context == MethodLateContext::TraitImpl {
-            return;
-        }
 
-        // If the method is an impl for an item with docs_hidden, don't doc.
-        if context == MethodLateContext::PlainImpl {
-            let parent = cx.tcx.hir().get_parent_item(impl_item.hir_id());
-            let impl_ty = cx.tcx.type_of(parent);
-            let outerdef = match impl_ty.kind() {
-                ty::Adt(def, _) => Some(def.did()),
-                ty::Foreign(def_id) => Some(*def_id),
-                _ => None,
-            };
-            let is_hidden = match outerdef {
-                Some(id) => cx.tcx.is_doc_hidden(id),
-                None => false,
-            };
-            if is_hidden {
-                return;
+        match context {
+            // If the method is an impl for a trait, don't doc.
+            MethodLateContext::TraitImpl => return,
+            MethodLateContext::TraitAutoImpl => {}
+            // If the method is an impl for an item with docs_hidden, don't doc.
+            MethodLateContext::PlainImpl => {
+                let parent = cx.tcx.hir().get_parent_item(impl_item.hir_id());
+                let impl_ty = cx.tcx.type_of(parent);
+                let outerdef = match impl_ty.kind() {
+                    ty::Adt(def, _) => Some(def.did()),
+                    ty::Foreign(def_id) => Some(*def_id),
+                    _ => None,
+                };
+                let is_hidden = match outerdef {
+                    Some(id) => cx.tcx.is_doc_hidden(id),
+                    None => false,
+                };
+                if is_hidden {
+                    return;
+                }
             }
         }
 

compiler/rustc_metadata/src/dependency_format.rs

@@ -113,37 +113,37 @@ fn calculate_type(tcx: TyCtxt<'_>, ty: CrateType) -> DependencyList {
         CrateType::Staticlib => Linkage::Static,
     };
 
-    if preferred_linkage == Linkage::NotLinked {
+    match preferred_linkage {
         // If the crate is not linked, there are no link-time dependencies.
-        return Vec::new();
-    }
-
-    if preferred_linkage == Linkage::Static {
-        // Attempt static linkage first. For dylibs and executables, we may be
-        // able to retry below with dynamic linkage.
-        if let Some(v) = attempt_static(tcx) {
-            return v;
-        }
-
-        // Staticlibs and static executables must have all static dependencies.
-        // If any are not found, generate some nice pretty errors.
-        if ty == CrateType::Staticlib
-            || (ty == CrateType::Executable
-                && sess.crt_static(Some(ty))
-                && !sess.target.crt_static_allows_dylibs)
-        {
-            for &cnum in tcx.crates(()).iter() {
-                if tcx.dep_kind(cnum).macros_only() {
-                    continue;
-                }
-                let src = tcx.used_crate_source(cnum);
-                if src.rlib.is_some() {
-                    continue;
-                }
-                sess.emit_err(RlibRequired { crate_name: tcx.crate_name(cnum) });
+        Linkage::NotLinked => return Vec::new(),
+        Linkage::Static => {
+            // Attempt static linkage first. For dylibs and executables, we may be
+            // able to retry below with dynamic linkage.
+            if let Some(v) = attempt_static(tcx) {
+                return v;
+            }
+
+            // Staticlibs and static executables must have all static dependencies.
+            // If any are not found, generate some nice pretty errors.
+            if ty == CrateType::Staticlib
+                || (ty == CrateType::Executable
+                    && sess.crt_static(Some(ty))
+                    && !sess.target.crt_static_allows_dylibs)
+            {
+                for &cnum in tcx.crates(()).iter() {
+                    if tcx.dep_kind(cnum).macros_only() {
+                        continue;
+                    }
+                    let src = tcx.used_crate_source(cnum);
+                    if src.rlib.is_some() {
+                        continue;
+                    }
+                    sess.emit_err(RlibRequired { crate_name: tcx.crate_name(cnum) });
+                }
+                return Vec::new();
             }
-            return Vec::new();
         }
+        Linkage::Dynamic | Linkage::IncludedFromDylib => {}
     }
 
     let mut formats = FxHashMap::default();
@@ -283,12 +283,9 @@ fn attempt_static(tcx: TyCtxt<'_>) -> Option<DependencyList> {
     let mut ret = tcx
         .crates(())
         .iter()
-        .map(|&cnum| {
-            if tcx.dep_kind(cnum) == CrateDepKind::Explicit {
-                Linkage::Static
-            } else {
-                Linkage::NotLinked
-            }
+        .map(|&cnum| match tcx.dep_kind(cnum) {
+            CrateDepKind::Explicit => Linkage::Static,
+            CrateDepKind::MacrosOnly | CrateDepKind::Implicit => Linkage::NotLinked,
         })
         .collect::<Vec<_>>();
 

compiler/rustc_metadata/src/native_libs.rs

@@ -107,7 +107,7 @@ impl<'tcx> Collector<'tcx> {
             return;
         };
 
-        if abi == Abi::Rust || abi == Abi::RustIntrinsic || abi == Abi::PlatformIntrinsic {
+        if matches!(abi, Abi::Rust | Abi::RustIntrinsic | Abi::PlatformIntrinsic) {
             return;
         }
 

compiler/rustc_middle/src/mir/coverage.rs

@@ -135,7 +135,10 @@ impl Debug for CoverageKind {
                 "Expression({:?}) = {} {} {}",
                 id.index(),
                 lhs.index(),
-                if *op == Op::Add { "+" } else { "-" },
+                match op {
+                    Op::Add => "+",
+                    Op::Subtract => "-",
+                },
                 rhs.index(),
             ),
             Unreachable => write!(fmt, "Unreachable"),

compiler/rustc_middle/src/mir/graphviz.rs

@@ -110,7 +110,7 @@ fn write_graph_label<'tcx, W: std::fmt::Write>(
         let decl = &body.local_decls[local];
 
         write!(w, "let ")?;
-        if decl.mutability == Mutability::Mut {
+        if decl.mutability.is_mut() {
             write!(w, "mut ")?;
         }
 

compiler/rustc_middle/src/mir/mod.rs

@@ -416,11 +416,7 @@ impl<'tcx> Body<'tcx> {
         (self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
             let local = Local::new(index);
             let decl = &self.local_decls[local];
-            if decl.is_user_variable() && decl.mutability == Mutability::Mut {
-                Some(local)
-            } else {
-                None
-            }
+            (decl.is_user_variable() && decl.mutability.is_mut()).then(|| local)
         })
     }
 

compiler/rustc_middle/src/mir/pretty.rs

@@ -580,7 +580,7 @@ fn write_scope_tree(
             continue;
         }
 
-        let mut_str = if local_decl.mutability == Mutability::Mut { "mut " } else { "" };
+        let mut_str = local_decl.mutability.prefix_str();
 
         let mut indented_decl =
             format!("{0:1$}let {2}{3:?}: {4:?}", INDENT, indent, mut_str, local, local_decl.ty);

compiler/rustc_middle/src/ty/fold.rs

@@ -610,7 +610,9 @@ impl<'tcx> TyCtxt<'tcx> {
                 let index = entry.index();
                 let var = ty::BoundVar::from_usize(index);
                 let kind = entry
-                    .or_insert_with(|| ty::BoundVariableKind::Ty(ty::BoundTyKind::Anon))
+                    .or_insert_with(|| {
+                        ty::BoundVariableKind::Ty(ty::BoundTyKind::Anon(index as u32))
+                    })
                     .expect_ty();
                 self.tcx.mk_ty(ty::Bound(ty::INNERMOST, BoundTy { var, kind }))
             }

compiler/rustc_middle/src/ty/mod.rs

@@ -1369,7 +1369,7 @@ pub struct Placeholder<T> {
 
 pub type PlaceholderRegion = Placeholder<BoundRegionKind>;
 
-pub type PlaceholderType = Placeholder<BoundVar>;
+pub type PlaceholderType = Placeholder<BoundTyKind>;
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
 #[derive(TyEncodable, TyDecodable, PartialOrd, Ord)]

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

@@ -698,8 +698,10 @@ pub trait PrettyPrinter<'tcx>:
             ty::Error(_) => p!("[type error]"),
             ty::Param(ref param_ty) => p!(print(param_ty)),
             ty::Bound(debruijn, bound_ty) => match bound_ty.kind {
-                ty::BoundTyKind::Anon => self.pretty_print_bound_var(debruijn, bound_ty.var)?,
-                ty::BoundTyKind::Param(p) => p!(write("{}", p)),
+                ty::BoundTyKind::Anon(bv) => {
+                    self.pretty_print_bound_var(debruijn, ty::BoundVar::from_u32(bv))?
+                }
+                ty::BoundTyKind::Param(_, s) => p!(write("{}", s)),
             },
             ty::Adt(def, substs) => {
                 p!(print_def_path(def.did(), substs));

compiler/rustc_middle/src/ty/structural_impls.rs

@@ -240,6 +240,7 @@ TrivialTypeTraversalAndLiftImpls! {
     crate::ty::AssocKind,
     crate::ty::AliasKind,
     crate::ty::Placeholder<crate::ty::BoundRegionKind>,
+    crate::ty::Placeholder<crate::ty::BoundTyKind>,
     crate::ty::ClosureKind,
     crate::ty::FreeRegion,
     crate::ty::InferTy,

compiler/rustc_middle/src/ty/sty.rs

@@ -1504,13 +1504,22 @@ pub struct BoundTy {
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
 #[derive(HashStable)]
 pub enum BoundTyKind {
-    Anon,
-    Param(Symbol),
+    Anon(u32),
+    Param(DefId, Symbol),
+}
+
+impl BoundTyKind {
+    pub fn expect_anon(self) -> u32 {
+        match self {
+            BoundTyKind::Anon(i) => i,
+            _ => bug!(),
+        }
+    }
 }
 
 impl From<BoundVar> for BoundTy {
     fn from(var: BoundVar) -> Self {
-        BoundTy { var, kind: BoundTyKind::Anon }
+        BoundTy { var, kind: BoundTyKind::Anon(var.as_u32()) }
     }
 }
 

compiler/rustc_mir_build/src/build/expr/as_temp.rs

@@ -44,7 +44,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         let expr_ty = expr.ty;
         let temp = {
             let mut local_decl = LocalDecl::new(expr_ty, expr_span);
-            if mutability == Mutability::Not {
+            if mutability.is_not() {
                 local_decl = local_decl.immutable();
             }
 

compiler/rustc_mir_transform/src/const_prop.rs

@@ -5,7 +5,6 @@ use std::cell::Cell;
 
 use either::Right;
 
-use rustc_ast::Mutability;
 use rustc_const_eval::const_eval::CheckAlignment;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir::def::DefKind;
@@ -289,7 +288,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for ConstPropMachine<'mir, 'tcx>
         }
         // If the static allocation is mutable, then we can't const prop it as its content
         // might be different at runtime.
-        if alloc.inner().mutability == Mutability::Mut {
+        if alloc.inner().mutability.is_mut() {
             throw_machine_stop_str!("can't access mutable globals in ConstProp");
         }
 
@@ -528,7 +527,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
         let r = self.use_ecx(|this| this.ecx.read_immediate(&this.ecx.eval_operand(right, None)?));
         let l = self.use_ecx(|this| this.ecx.read_immediate(&this.ecx.eval_operand(left, None)?));
         // Check for exceeding shifts *even if* we cannot evaluate the LHS.
-        if op == BinOp::Shr || op == BinOp::Shl {
+        if matches!(op, BinOp::Shr | BinOp::Shl) {
             let r = r.clone()?;
             // We need the type of the LHS. We cannot use `place_layout` as that is the type
             // of the result, which for checked binops is not the same!

compiler/rustc_mir_transform/src/const_prop_lint.rs

@@ -368,7 +368,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
             this.ecx.read_immediate(&this.ecx.eval_operand(left, None)?)
         });
         // Check for exceeding shifts *even if* we cannot evaluate the LHS.
-        if op == BinOp::Shr || op == BinOp::Shl {
+        if matches!(op, BinOp::Shr | BinOp::Shl) {
             let r = r.clone()?;
             // We need the type of the LHS. We cannot use `place_layout` as that is the type
             // of the result, which for checked binops is not the same!

compiler/rustc_mir_transform/src/coverage/debug.rs

@@ -323,7 +323,10 @@ impl DebugCounters {
                         String::new()
                     },
                     self.format_operand(lhs),
-                    if op == Op::Add { "+" } else { "-" },
+                    match op {
+                        Op::Add => "+",
+                        Op::Subtract => "-",
+                    },
                     self.format_operand(rhs),
                 );
             }

compiler/rustc_mir_transform/src/shim.rs

@@ -427,7 +427,7 @@ impl<'tcx> CloneShimBuilder<'tcx> {
     fn make_place(&mut self, mutability: Mutability, ty: Ty<'tcx>) -> Place<'tcx> {
         let span = self.span;
         let mut local = LocalDecl::new(ty, span);
-        if mutability == Mutability::Not {
+        if mutability.is_not() {
             local = local.immutable();
         }
         Place::from(self.local_decls.push(local))

compiler/rustc_parse/src/parser/stmt.rs

@@ -93,11 +93,12 @@ impl<'a> Parser<'a> {
             // or `auto trait` items. We aim to parse an arbitrary path `a::b` but not something
             // that starts like a path (1 token), but it fact not a path.
             // Also, we avoid stealing syntax from `parse_item_`.
-            if force_collect == ForceCollect::Yes {
-                self.collect_tokens_no_attrs(|this| this.parse_stmt_path_start(lo, attrs))
-            } else {
-                self.parse_stmt_path_start(lo, attrs)
-            }?
+            match force_collect {
+                ForceCollect::Yes => {
+                    self.collect_tokens_no_attrs(|this| this.parse_stmt_path_start(lo, attrs))?
+                }
+                ForceCollect::No => self.parse_stmt_path_start(lo, attrs)?,
+            }
         } else if let Some(item) = self.parse_item_common(
             attrs.clone(),
             false,
@@ -113,13 +114,12 @@ impl<'a> Parser<'a> {
             self.mk_stmt(lo, StmtKind::Empty)
         } else if self.token != token::CloseDelim(Delimiter::Brace) {
             // Remainder are line-expr stmts.
-            let e = if force_collect == ForceCollect::Yes {
-                self.collect_tokens_no_attrs(|this| {
+            let e = match force_collect {
+                ForceCollect::Yes => self.collect_tokens_no_attrs(|this| {
                     this.parse_expr_res(Restrictions::STMT_EXPR, Some(attrs))
-                })
-            } else {
-                self.parse_expr_res(Restrictions::STMT_EXPR, Some(attrs))
-            }?;
+                })?,
+                ForceCollect::No => self.parse_expr_res(Restrictions::STMT_EXPR, Some(attrs))?,
+            };
             if matches!(e.kind, ExprKind::Assign(..)) && self.eat_keyword(kw::Else) {
                 let bl = self.parse_block()?;
                 // Destructuring assignment ... else.

compiler/rustc_parse/src/parser/ty.rs

@@ -323,13 +323,14 @@ impl<'a> Parser<'a> {
         } else if self.can_begin_bound() {
             self.parse_bare_trait_object(lo, allow_plus)?
         } else if self.eat(&token::DotDotDot) {
-            if allow_c_variadic == AllowCVariadic::Yes {
-                TyKind::CVarArgs
-            } else {
-                // FIXME(Centril): Should we just allow `...` syntactically
-                // anywhere in a type and use semantic restrictions instead?
-                self.error_illegal_c_varadic_ty(lo);
-                TyKind::Err
+            match allow_c_variadic {
+                AllowCVariadic::Yes => TyKind::CVarArgs,
+                AllowCVariadic::No => {
+                    // FIXME(Centril): Should we just allow `...` syntactically
+                    // anywhere in a type and use semantic restrictions instead?
+                    self.error_illegal_c_varadic_ty(lo);
+                    TyKind::Err
+                }
             }
         } else {
             let msg = format!("expected type, found {}", super::token_descr(&self.token));
@@ -343,10 +344,9 @@ impl<'a> Parser<'a> {
         let mut ty = self.mk_ty(span, kind);
 
         // Try to recover from use of `+` with incorrect priority.
-        if allow_plus == AllowPlus::Yes {
-            self.maybe_recover_from_bad_type_plus(&ty)?;
-        } else {
-            self.maybe_report_ambiguous_plus(impl_dyn_multi, &ty);
+        match allow_plus {
+            AllowPlus::Yes => self.maybe_recover_from_bad_type_plus(&ty)?,
+            AllowPlus::No => self.maybe_report_ambiguous_plus(impl_dyn_multi, &ty),
         }
         if RecoverQuestionMark::Yes == recover_question_mark {
             ty = self.maybe_recover_from_question_mark(ty);

compiler/rustc_passes/src/check_attr.rs

@@ -864,33 +864,39 @@ impl CheckAttrVisitor<'_> {
         target: Target,
         specified_inline: &mut Option<(bool, Span)>,
     ) -> bool {
-        if target == Target::Use || target == Target::ExternCrate {
-            let do_inline = meta.name_or_empty() == sym::inline;
-            if let Some((prev_inline, prev_span)) = *specified_inline {
-                if do_inline != prev_inline {
-                    let mut spans = MultiSpan::from_spans(vec![prev_span, meta.span()]);
-                    spans.push_span_label(prev_span, fluent::passes_doc_inline_conflict_first);
-                    spans.push_span_label(meta.span(), fluent::passes_doc_inline_conflict_second);
-                    self.tcx.sess.emit_err(errors::DocKeywordConflict { spans });
-                    return false;
+        match target {
+            Target::Use | Target::ExternCrate => {
+                let do_inline = meta.name_or_empty() == sym::inline;
+                if let Some((prev_inline, prev_span)) = *specified_inline {
+                    if do_inline != prev_inline {
+                        let mut spans = MultiSpan::from_spans(vec![prev_span, meta.span()]);
+                        spans.push_span_label(prev_span, fluent::passes_doc_inline_conflict_first);
+                        spans.push_span_label(
+                            meta.span(),
+                            fluent::passes_doc_inline_conflict_second,
+                        );
+                        self.tcx.sess.emit_err(errors::DocKeywordConflict { spans });
+                        return false;
+                    }
+                    true
+                } else {
+                    *specified_inline = Some((do_inline, meta.span()));
+                    true
                 }
-                true
-            } else {
-                *specified_inline = Some((do_inline, meta.span()));
-                true
             }
-        } else {
-            self.tcx.emit_spanned_lint(
-                INVALID_DOC_ATTRIBUTES,
-                hir_id,
-                meta.span(),
-                errors::DocInlineOnlyUse {
-                    attr_span: meta.span(),
-                    item_span: (attr.style == AttrStyle::Outer)
-                        .then(|| self.tcx.hir().span(hir_id)),
-                },
-            );
-            false
+            _ => {
+                self.tcx.emit_spanned_lint(
+                    INVALID_DOC_ATTRIBUTES,
+                    hir_id,
+                    meta.span(),
+                    errors::DocInlineOnlyUse {
+                        attr_span: meta.span(),
+                        item_span: (attr.style == AttrStyle::Outer)
+                            .then(|| self.tcx.hir().span(hir_id)),
+                    },
+                );
+                false
+            }
         }
     }
 
@@ -1137,7 +1143,7 @@ impl CheckAttrVisitor<'_> {
                                     errors::DocTestUnknownInclude {
                                         path,
                                         value: value.to_string(),
-                                        inner: if attr.style == AttrStyle::Inner { "!" } else { "" },
+                                        inner: match attr.style { AttrStyle::Inner=>  "!" , AttrStyle::Outer => "" },
                                         sugg: (attr.meta().unwrap().span, applicability),
                                     }
                                 );

compiler/rustc_passes/src/stability.rs

@@ -125,7 +125,7 @@ impl<'a, 'tcx> Annotator<'a, 'tcx> {
         if let Some((depr, span)) = &depr {
             is_deprecated = true;
 
-            if kind == AnnotationKind::Prohibited || kind == AnnotationKind::DeprecationProhibited {
+            if matches!(kind, AnnotationKind::Prohibited | AnnotationKind::DeprecationProhibited) {
                 let hir_id = self.tcx.hir().local_def_id_to_hir_id(def_id);
                 self.tcx.emit_spanned_lint(
                     USELESS_DEPRECATED,

compiler/rustc_resolve/src/build_reduced_graph.rs

@@ -298,14 +298,15 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
                             self.r.record_partial_res(id, PartialRes::new(res));
                         }
                         if module.is_normal() {
-                            if res == Res::Err {
-                                Ok(ty::Visibility::Public)
-                            } else {
-                                let vis = ty::Visibility::Restricted(res.def_id());
-                                if self.r.is_accessible_from(vis, parent_scope.module) {
-                                    Ok(vis.expect_local())
-                                } else {
-                                    Err(VisResolutionError::AncestorOnly(path.span))
+                            match res {
+                                Res::Err => Ok(ty::Visibility::Public),
+                                _ => {
+                                    let vis = ty::Visibility::Restricted(res.def_id());
+                                    if self.r.is_accessible_from(vis, parent_scope.module) {
+                                        Ok(vis.expect_local())
+                                    } else {
+                                        Err(VisResolutionError::AncestorOnly(path.span))
+                                    }
                                 }
                             }
                         } else {

compiler/rustc_resolve/src/diagnostics.rs

@@ -1552,12 +1552,12 @@ impl<'a> Resolver<'a> {
             if b.is_extern_crate() && ident.span.rust_2018() {
                 help_msgs.push(format!("use `::{ident}` to refer to this {thing} unambiguously"))
             }
-            if misc == AmbiguityErrorMisc::SuggestCrate {
-                help_msgs
-                    .push(format!("use `crate::{ident}` to refer to this {thing} unambiguously"))
-            } else if misc == AmbiguityErrorMisc::SuggestSelf {
-                help_msgs
-                    .push(format!("use `self::{ident}` to refer to this {thing} unambiguously"))
+            match misc {
+                AmbiguityErrorMisc::SuggestCrate => help_msgs
+                    .push(format!("use `crate::{ident}` to refer to this {thing} unambiguously")),
+                AmbiguityErrorMisc::SuggestSelf => help_msgs
+                    .push(format!("use `self::{ident}` to refer to this {thing} unambiguously")),
+                AmbiguityErrorMisc::FromPrelude | AmbiguityErrorMisc::None => {}
             }
 
             err.span_note(b.span, &note_msg);
@@ -1717,7 +1717,7 @@ impl<'a> Resolver<'a> {
                         Applicability::MaybeIncorrect,
                     )),
                 )
-            } else if self.session.edition() == Edition::Edition2015 {
+            } else if self.session.rust_2015() {
                 (
                     format!("maybe a missing crate `{ident}`?"),
                     Some((

compiler/rustc_resolve/src/ident.rs

@@ -7,7 +7,6 @@ use rustc_middle::ty;
 use rustc_session::lint::builtin::PROC_MACRO_DERIVE_RESOLUTION_FALLBACK;
 use rustc_session::lint::BuiltinLintDiagnostics;
 use rustc_span::def_id::LocalDefId;
-use rustc_span::edition::Edition;
 use rustc_span::hygiene::{ExpnId, ExpnKind, LocalExpnId, MacroKind, SyntaxContext};
 use rustc_span::symbol::{kw, Ident};
 use rustc_span::{Span, DUMMY_SP};
@@ -86,7 +85,7 @@ impl<'a> Resolver<'a> {
         // 4c. Standard library prelude (de-facto closed, controlled).
         // 6. Language prelude: builtin attributes (closed, controlled).
 
-        let rust_2015 = ctxt.edition() == Edition::Edition2015;
+        let rust_2015 = ctxt.edition().rust_2015();
         let (ns, macro_kind, is_absolute_path) = match scope_set {
             ScopeSet::All(ns, _) => (ns, None, false),
             ScopeSet::AbsolutePath(ns) => (ns, None, true),

compiler/rustc_save_analysis/src/sig.rs

@@ -29,7 +29,6 @@ use crate::{id_from_def_id, SaveContext};
 
 use rls_data::{SigElement, Signature};
 
-use rustc_ast::Mutability;
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir_pretty::id_to_string;
@@ -769,9 +768,8 @@ impl<'hir> Sig for hir::ForeignItem<'hir> {
             }
             hir::ForeignItemKind::Static(ref ty, m) => {
                 let mut text = "static ".to_owned();
-                if m == Mutability::Mut {
-                    text.push_str("mut ");
-                }
+                text.push_str(m.prefix_str());
+
                 let name = self.ident.to_string();
                 let defs = vec![SigElement {
                     id: id_from_def_id(self.owner_id.to_def_id()),

compiler/rustc_session/src/session.rs

@@ -918,23 +918,24 @@ impl Session {
         ret
     }
 
+    /// Is this edition 2015?
     pub fn rust_2015(&self) -> bool {
-        self.edition() == Edition::Edition2015
+        self.edition().rust_2015()
     }
 
     /// Are we allowed to use features from the Rust 2018 edition?
     pub fn rust_2018(&self) -> bool {
-        self.edition() >= Edition::Edition2018
+        self.edition().rust_2018()
     }
 
     /// Are we allowed to use features from the Rust 2021 edition?
     pub fn rust_2021(&self) -> bool {
-        self.edition() >= Edition::Edition2021
+        self.edition().rust_2021()
     }
 
     /// Are we allowed to use features from the Rust 2024 edition?
     pub fn rust_2024(&self) -> bool {
-        self.edition() >= Edition::Edition2024
+        self.edition().rust_2024()
     }
 
     /// Returns `true` if we cannot skip the PLT for shared library calls.

compiler/rustc_span/src/edition.rs

@@ -49,8 +49,8 @@ impl fmt::Display for Edition {
 }
 
 impl Edition {
-    pub fn lint_name(&self) -> &'static str {
-        match *self {
+    pub fn lint_name(self) -> &'static str {
+        match self {
             Edition::Edition2015 => "rust_2015_compatibility",
             Edition::Edition2018 => "rust_2018_compatibility",
             Edition::Edition2021 => "rust_2021_compatibility",
@@ -58,8 +58,8 @@ impl Edition {
         }
     }
 
-    pub fn feature_name(&self) -> Symbol {
-        match *self {
+    pub fn feature_name(self) -> Symbol {
+        match self {
             Edition::Edition2015 => sym::rust_2015_preview,
             Edition::Edition2018 => sym::rust_2018_preview,
             Edition::Edition2021 => sym::rust_2021_preview,
@@ -67,8 +67,8 @@ impl Edition {
         }
     }
 
-    pub fn is_stable(&self) -> bool {
-        match *self {
+    pub fn is_stable(self) -> bool {
+        match self {
             Edition::Edition2015 => true,
             Edition::Edition2018 => true,
             Edition::Edition2021 => true,
@@ -76,23 +76,24 @@ impl Edition {
         }
     }
 
-    pub fn rust_2015(&self) -> bool {
-        *self == Edition::Edition2015
+    /// Is this edition 2015?
+    pub fn rust_2015(self) -> bool {
+        self == Edition::Edition2015
     }
 
     /// Are we allowed to use features from the Rust 2018 edition?
-    pub fn rust_2018(&self) -> bool {
-        *self >= Edition::Edition2018
+    pub fn rust_2018(self) -> bool {
+        self >= Edition::Edition2018
     }
 
     /// Are we allowed to use features from the Rust 2021 edition?
-    pub fn rust_2021(&self) -> bool {
-        *self >= Edition::Edition2021
+    pub fn rust_2021(self) -> bool {
+        self >= Edition::Edition2021
     }
 
     /// Are we allowed to use features from the Rust 2024 edition?
-    pub fn rust_2024(&self) -> bool {
-        *self >= Edition::Edition2024
+    pub fn rust_2024(self) -> bool {
+        self >= Edition::Edition2024
     }
 }
 

compiler/rustc_span/src/lib.rs

@@ -706,22 +706,22 @@ impl Span {
 
     #[inline]
     pub fn rust_2015(self) -> bool {
-        self.edition() == edition::Edition::Edition2015
+        self.edition().rust_2015()
     }
 
     #[inline]
     pub fn rust_2018(self) -> bool {
-        self.edition() >= edition::Edition::Edition2018
+        self.edition().rust_2018()
     }
 
     #[inline]
     pub fn rust_2021(self) -> bool {
-        self.edition() >= edition::Edition::Edition2021
+        self.edition().rust_2021()
     }
 
     #[inline]
     pub fn rust_2024(self) -> bool {
-        self.edition() >= edition::Edition::Edition2024
+        self.edition().rust_2024()
     }
 
     /// Returns the source callee.

compiler/rustc_trait_selection/src/solve/mod.rs

@@ -161,6 +161,7 @@ impl<'tcx> InferCtxtEvalExt<'tcx> for InferCtxt<'tcx> {
             search_graph: &mut search_graph,
             infcx: self,
             var_values: CanonicalVarValues::dummy(),
+            in_projection_eq_hack: false,
         }
         .evaluate_goal(goal);
 
@@ -174,6 +175,10 @@ struct EvalCtxt<'a, 'tcx> {
     var_values: CanonicalVarValues<'tcx>,
 
     search_graph: &'a mut search_graph::SearchGraph<'tcx>,
+
+    /// This field is used by a debug assertion in [`EvalCtxt::evaluate_goal`],
+    /// see the comment in that method for more details.
+    in_projection_eq_hack: bool,
 }
 
 impl<'a, 'tcx> EvalCtxt<'a, 'tcx> {
@@ -209,7 +214,8 @@ impl<'a, 'tcx> EvalCtxt<'a, 'tcx> {
         loop {
             let (ref infcx, goal, var_values) =
                 tcx.infer_ctxt().build_with_canonical(DUMMY_SP, &canonical_goal);
-            let mut ecx = EvalCtxt { infcx, var_values, search_graph };
+            let mut ecx =
+                EvalCtxt { infcx, var_values, search_graph, in_projection_eq_hack: false };
             let result = ecx.compute_goal(goal);
 
             // FIXME: `Response` should be `Copy`
@@ -239,10 +245,28 @@ impl<'a, 'tcx> EvalCtxt<'a, 'tcx> {
         let canonical_goal = self.infcx.canonicalize_query(goal, &mut orig_values);
         let canonical_response =
             EvalCtxt::evaluate_canonical_goal(self.tcx(), self.search_graph, canonical_goal)?;
-        Ok((
-            !canonical_response.value.var_values.is_identity(),
-            instantiate_canonical_query_response(self.infcx, &orig_values, canonical_response),
-        ))
+
+        let has_changed = !canonical_response.value.var_values.is_identity();
+        let certainty =
+            instantiate_canonical_query_response(self.infcx, &orig_values, canonical_response);
+
+        // Check that rerunning this query with its inference constraints applied
+        // doesn't result in new inference constraints and has the same result.
+        //
+        // If we have projection goals like `<T as Trait>::Assoc == u32` we recursively
+        // call `exists<U> <T as Trait>::Assoc == U` to enable better caching. This goal
+        // could constrain `U` to `u32` which would cause this check to result in a
+        // solver cycle.
+        if cfg!(debug_assertions) && has_changed && !self.in_projection_eq_hack {
+            let mut orig_values = OriginalQueryValues::default();
+            let canonical_goal = self.infcx.canonicalize_query(goal, &mut orig_values);
+            let canonical_response =
+                EvalCtxt::evaluate_canonical_goal(self.tcx(), self.search_graph, canonical_goal)?;
+            assert!(canonical_response.value.var_values.is_identity());
+            assert_eq!(certainty, canonical_response.value.certainty);
+        }
+
+        Ok((has_changed, certainty))
     }
 
     fn compute_goal(&mut self, goal: Goal<'tcx, ty::Predicate<'tcx>>) -> QueryResult<'tcx> {

compiler/rustc_trait_selection/src/solve/project_goals.rs

@@ -45,8 +45,9 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
                 projection_ty: goal.predicate.projection_ty,
                 term: unconstrained_rhs,
             });
-            let (_has_changed, normalize_certainty) =
-                self.evaluate_goal(goal.with(self.tcx(), unconstrained_predicate))?;
+            let (_has_changed, normalize_certainty) = self.in_projection_eq_hack(|this| {
+                this.evaluate_goal(goal.with(this.tcx(), unconstrained_predicate))
+            })?;
 
             let nested_eq_goals =
                 self.infcx.eq(goal.param_env, unconstrained_rhs, predicate.term)?;
@@ -55,6 +56,15 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
         }
     }
 
+    /// This sets a flag used by a debug assert in [`EvalCtxt::evaluate_goal`],
+    /// see the comment in that method for more details.
+    fn in_projection_eq_hack<T>(&mut self, f: impl FnOnce(&mut Self) -> T) -> T {
+        self.in_projection_eq_hack = true;
+        let result = f(self);
+        self.in_projection_eq_hack = false;
+        result
+    }
+
     /// Is the projection predicate is of the form `exists<T> <Ty as Trait>::Assoc = T`.
     ///
     /// This is the case if the `term` is an inference variable in the innermost universe
@@ -122,6 +132,28 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
             && goal.param_env.visit_with(&mut visitor).is_continue()
     }
 
+    /// After normalizing the projection to `normalized_alias` with the given
+    /// `normalization_certainty`, constrain the inference variable `term` to it
+    /// and return a query response.
+    fn eq_term_and_make_canonical_response(
+        &mut self,
+        goal: Goal<'tcx, ProjectionPredicate<'tcx>>,
+        normalization_certainty: Certainty,
+        normalized_alias: impl Into<ty::Term<'tcx>>,
+    ) -> QueryResult<'tcx> {
+        // The term of our goal should be fully unconstrained, so this should never fail.
+        //
+        // It can however be ambiguous when the `normalized_alias` contains a projection.
+        let nested_goals = self
+            .infcx
+            .eq(goal.param_env, goal.predicate.term, normalized_alias.into())
+            .expect("failed to unify with unconstrained term");
+        let rhs_certainty =
+            self.evaluate_all(nested_goals).expect("failed to unify with unconstrained term");
+
+        self.make_canonical_response(normalization_certainty.unify_and(rhs_certainty))
+    }
+
     fn merge_project_candidates(
         &mut self,
         mut candidates: Vec<Candidate<'tcx>>,
@@ -218,7 +250,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
                 .map(|pred| goal.with(tcx, pred));
 
             nested_goals.extend(where_clause_bounds);
-            let trait_ref_certainty = ecx.evaluate_all(nested_goals)?;
+            let match_impl_certainty = ecx.evaluate_all(nested_goals)?;
 
             // In case the associated item is hidden due to specialization, we have to
             // return ambiguity this would otherwise be incomplete, resulting in
@@ -230,7 +262,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
                 goal.predicate.def_id(),
                 impl_def_id
             )? else {
-                return ecx.make_canonical_response(trait_ref_certainty.unify_and(Certainty::AMBIGUOUS));
+                return ecx.make_canonical_response(match_impl_certainty.unify_and(Certainty::AMBIGUOUS));
             };
 
             if !assoc_def.item.defaultness(tcx).has_value() {
@@ -277,17 +309,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
                 ty.map_bound(|ty| ty.into())
             };
 
-            // The term of our goal should be fully unconstrained, so this should never fail.
-            //
-            // It can however be ambiguous when the resolved type is a projection.
-            let nested_goals = ecx
-                .infcx
-                .eq(goal.param_env, goal.predicate.term, term.subst(tcx, substs))
-                .expect("failed to unify with unconstrained term");
-            let rhs_certainty =
-                ecx.evaluate_all(nested_goals).expect("failed to unify with unconstrained term");
-
-            ecx.make_canonical_response(trait_ref_certainty.unify_and(rhs_certainty))
+            ecx.eq_term_and_make_canonical_response(goal, match_impl_certainty, term.subst(tcx, substs))
         })
     }
 
@@ -309,18 +331,11 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
                 )?;
                 let subst_certainty = ecx.evaluate_all(nested_goals)?;
 
-                // The term of our goal should be fully unconstrained, so this should never fail.
-                //
-                // It can however be ambiguous when the resolved type is a projection.
-                let nested_goals = ecx
-                    .infcx
-                    .eq(goal.param_env, goal.predicate.term, assumption_projection_pred.term)
-                    .expect("failed to unify with unconstrained term");
-                let rhs_certainty = ecx
-                    .evaluate_all(nested_goals)
-                    .expect("failed to unify with unconstrained term");
-
-                ecx.make_canonical_response(subst_certainty.unify_and(rhs_certainty))
+                ecx.eq_term_and_make_canonical_response(
+                    goal,
+                    subst_certainty,
+                    assumption_projection_pred.term,
+                )
             })
         } else {
             Err(NoSolution)
@@ -437,14 +452,12 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
                         [ty::GenericArg::from(goal.predicate.self_ty())],
                     ));
 
-                    let mut nested_goals = ecx.infcx.eq(
-                        goal.param_env,
-                        goal.predicate.term.ty().unwrap(),
+                    let is_sized_certainty = ecx.evaluate_goal(goal.with(tcx, sized_predicate))?.1;
+                    return ecx.eq_term_and_make_canonical_response(
+                        goal,
+                        is_sized_certainty,
                         tcx.types.unit,
-                    )?;
-                    nested_goals.push(goal.with(tcx, sized_predicate));
-
-                    return ecx.evaluate_all_and_make_canonical_response(nested_goals);
+                    );
                 }
 
                 ty::Adt(def, substs) if def.is_struct() => {
@@ -456,7 +469,8 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
                                 tcx,
                                 ty::Binder::dummy(goal.predicate.with_self_ty(tcx, self_ty)),
                             );
-                            return ecx.evaluate_all_and_make_canonical_response(vec![new_goal]);
+                            let (_, certainty) = ecx.evaluate_goal(new_goal)?;
+                            return ecx.make_canonical_response(certainty);
                         }
                     }
                 }
@@ -469,7 +483,8 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
                             tcx,
                             ty::Binder::dummy(goal.predicate.with_self_ty(tcx, self_ty)),
                         );
-                        return ecx.evaluate_all_and_make_canonical_response(vec![new_goal]);
+                        let (_, certainty) = ecx.evaluate_goal(new_goal)?;
+                        return ecx.make_canonical_response(certainty);
                     }
                 },
 
@@ -482,9 +497,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
                 ),
             };
 
-            let nested_goals =
-                ecx.infcx.eq(goal.param_env, goal.predicate.term.ty().unwrap(), metadata_ty)?;
-            ecx.evaluate_all_and_make_canonical_response(nested_goals)
+            ecx.eq_term_and_make_canonical_response(goal, Certainty::Yes, metadata_ty)
         })
     }
 

compiler/rustc_trait_selection/src/solve/search_graph/mod.rs

@@ -45,6 +45,7 @@ impl<'tcx> SearchGraph<'tcx> {
     /// Tries putting the new goal on the stack, returning an error if it is already cached.
     ///
     /// This correctly updates the provisional cache if there is a cycle.
+    #[instrument(level = "debug", skip(self, tcx), ret)]
     pub(super) fn try_push_stack(
         &mut self,
         tcx: TyCtxt<'tcx>,
@@ -79,8 +80,10 @@ impl<'tcx> SearchGraph<'tcx> {
             Entry::Occupied(entry_index) => {
                 let entry_index = *entry_index.get();
 
-                cache.add_dependency_of_leaf_on(entry_index);
                 let stack_depth = cache.depth(entry_index);
+                debug!("encountered cycle with depth {stack_depth:?}");
+
+                cache.add_dependency_of_leaf_on(entry_index);
 
                 self.stack[stack_depth].has_been_used = true;
                 // NOTE: The goals on the stack aren't the only goals involved in this cycle.
@@ -117,6 +120,7 @@ impl<'tcx> SearchGraph<'tcx> {
     /// updated the provisional cache and we have to recompute the current goal.
     ///
     /// FIXME: Refer to the rustc-dev-guide entry once it exists.
+    #[instrument(level = "debug", skip(self, tcx, actual_goal), ret)]
     pub(super) fn try_finalize_goal(
         &mut self,
         tcx: TyCtxt<'tcx>,

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -1230,20 +1230,23 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                     }
 
                     ty::PredicateKind::WellFormed(ty) => {
-                        if self.tcx.sess.opts.unstable_opts.trait_solver == TraitSolver::Classic {
-                            // WF predicates cannot themselves make
-                            // errors. They can only block due to
-                            // ambiguity; otherwise, they always
-                            // degenerate into other obligations
-                            // (which may fail).
-                            span_bug!(span, "WF predicate not satisfied for {:?}", ty);
-                        } else {
-                            // FIXME: we'll need a better message which takes into account
-                            // which bounds actually failed to hold.
-                            self.tcx.sess.struct_span_err(
-                                span,
-                                &format!("the type `{}` is not well-formed", ty),
-                            )
+                        match self.tcx.sess.opts.unstable_opts.trait_solver {
+                            TraitSolver::Classic => {
+                                // WF predicates cannot themselves make
+                                // errors. They can only block due to
+                                // ambiguity; otherwise, they always
+                                // degenerate into other obligations
+                                // (which may fail).
+                                span_bug!(span, "WF predicate not satisfied for {:?}", ty);
+                            }
+                            TraitSolver::Chalk | TraitSolver::Next => {
+                                // FIXME: we'll need a better message which takes into account
+                                // which bounds actually failed to hold.
+                                self.tcx.sess.struct_span_err(
+                                    span,
+                                    &format!("the type `{}` is not well-formed", ty),
+                                )
+                            }
                         }
                     }
 

compiler/rustc_trait_selection/src/traits/project.rs

@@ -783,7 +783,7 @@ impl<'tcx> TypeFolder<'tcx> for BoundVarReplacer<'_, 'tcx> {
             }
             ty::Bound(debruijn, bound_ty) if debruijn >= self.current_index => {
                 let universe = self.universe_for(debruijn);
-                let p = ty::PlaceholderType { universe, name: bound_ty.var };
+                let p = ty::PlaceholderType { universe, name: bound_ty.kind };
                 self.mapped_types.insert(p, bound_ty);
                 self.infcx.tcx.mk_ty(ty::Placeholder(p))
             }

compiler/rustc_trait_selection/src/traits/select/confirmation.rs

@@ -524,7 +524,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                             .kind
                         {
                             GenericParamDefKind::Type { .. } => {
-                                let kind = ty::BoundTyKind::Param(param.name);
+                                let kind = ty::BoundTyKind::Param(param.def_id, param.name);
                                 let bound_var = ty::BoundVariableKind::Ty(kind);
                                 bound_vars.push(bound_var);
                                 tcx.mk_ty(ty::Bound(

compiler/rustc_traits/src/chalk/db.rs

@@ -725,7 +725,7 @@ fn bound_vars_for_item(tcx: TyCtxt<'_>, def_id: DefId) -> SubstsRef<'_> {
                 ty::INNERMOST,
                 ty::BoundTy {
                     var: ty::BoundVar::from(param.index),
-                    kind: ty::BoundTyKind::Param(param.name),
+                    kind: ty::BoundTyKind::Param(param.def_id, param.name),
                 },
             ))
             .into(),

compiler/rustc_traits/src/chalk/lowering.rs

@@ -370,7 +370,7 @@ impl<'tcx> LowerInto<'tcx, chalk_ir::Ty<RustInterner<'tcx>>> for Ty<'tcx> {
             ty::Placeholder(_placeholder) => {
                 chalk_ir::TyKind::Placeholder(chalk_ir::PlaceholderIndex {
                     ui: chalk_ir::UniverseIndex { counter: _placeholder.universe.as_usize() },
-                    idx: _placeholder.name.as_usize(),
+                    idx: _placeholder.name.expect_anon() as usize,
                 })
             }
             ty::Infer(_infer) => unimplemented!(),
@@ -452,10 +452,6 @@ impl<'tcx> LowerInto<'tcx, Ty<'tcx>> for &chalk_ir::Ty<RustInterner<'tcx>> {
             ),
             TyKind::Foreign(def_id) => ty::Foreign(def_id.0),
             TyKind::Error => return interner.tcx.ty_error(),
-            TyKind::Placeholder(placeholder) => ty::Placeholder(ty::Placeholder {
-                universe: ty::UniverseIndex::from_usize(placeholder.ui.counter),
-                name: ty::BoundVar::from_usize(placeholder.idx),
-            }),
             TyKind::Alias(alias_ty) => match alias_ty {
                 chalk_ir::AliasTy::Projection(projection) => ty::Alias(
                     ty::Projection,
@@ -473,13 +469,17 @@ impl<'tcx> LowerInto<'tcx, Ty<'tcx>> for &chalk_ir::Ty<RustInterner<'tcx>> {
                 ),
             },
             TyKind::Function(_quantified_ty) => unimplemented!(),
-            TyKind::BoundVar(_bound) => ty::Bound(
-                ty::DebruijnIndex::from_usize(_bound.debruijn.depth() as usize),
+            TyKind::BoundVar(bound) => ty::Bound(
+                ty::DebruijnIndex::from_usize(bound.debruijn.depth() as usize),
                 ty::BoundTy {
-                    var: ty::BoundVar::from_usize(_bound.index),
-                    kind: ty::BoundTyKind::Anon,
+                    var: ty::BoundVar::from_usize(bound.index),
+                    kind: ty::BoundTyKind::Anon(bound.index as u32),
                 },
             ),
+            TyKind::Placeholder(placeholder) => ty::Placeholder(ty::Placeholder {
+                universe: ty::UniverseIndex::from_usize(placeholder.ui.counter),
+                name: ty::BoundTyKind::Anon(placeholder.idx as u32),
+            }),
             TyKind::InferenceVar(_, _) => unimplemented!(),
             TyKind::Dyn(_) => unimplemented!(),
         };
@@ -504,7 +504,7 @@ impl<'tcx> LowerInto<'tcx, chalk_ir::Lifetime<RustInterner<'tcx>>> for Region<'t
             ty::RePlaceholder(placeholder_region) => {
                 chalk_ir::LifetimeData::Placeholder(chalk_ir::PlaceholderIndex {
                     ui: chalk_ir::UniverseIndex { counter: placeholder_region.universe.index() },
-                    idx: 0,
+                    idx: 0, // FIXME: This `idx: 0` is sus.
                 })
                 .intern(interner)
             }
@@ -674,7 +674,7 @@ impl<'tcx> LowerInto<'tcx, chalk_ir::Binders<chalk_ir::QuantifiedWhereClauses<Ru
         let self_ty = interner.tcx.mk_ty(ty::Bound(
             // This is going to be wrapped in a binder
             ty::DebruijnIndex::from_usize(1),
-            ty::BoundTy { var: ty::BoundVar::from_usize(0), kind: ty::BoundTyKind::Anon },
+            ty::BoundTy { var: ty::BoundVar::from_usize(0), kind: ty::BoundTyKind::Anon(0) },
         ));
         let where_clauses = predicates.into_iter().map(|predicate| {
             let (predicate, binders, _named_regions) =
@@ -1038,7 +1038,7 @@ pub(crate) struct ParamsSubstitutor<'tcx> {
     binder_index: ty::DebruijnIndex,
     list: Vec<rustc_middle::ty::ParamTy>,
     next_ty_placeholder: usize,
-    pub(crate) params: rustc_data_structures::fx::FxHashMap<usize, rustc_middle::ty::ParamTy>,
+    pub(crate) params: rustc_data_structures::fx::FxHashMap<u32, rustc_middle::ty::ParamTy>,
     pub(crate) named_regions: BTreeMap<DefId, u32>,
 }
 
@@ -1072,15 +1072,15 @@ impl<'tcx> TypeFolder<'tcx> for ParamsSubstitutor<'tcx> {
             ty::Param(param) => match self.list.iter().position(|r| r == &param) {
                 Some(idx) => self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType {
                     universe: ty::UniverseIndex::from_usize(0),
-                    name: ty::BoundVar::from_usize(idx),
+                    name: ty::BoundTyKind::Anon(idx as u32),
                 })),
                 None => {
                     self.list.push(param);
                     let idx = self.list.len() - 1 + self.next_ty_placeholder;
-                    self.params.insert(idx, param);
+                    self.params.insert(idx as u32, param);
                     self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType {
                         universe: ty::UniverseIndex::from_usize(0),
-                        name: ty::BoundVar::from_usize(idx),
+                        name: ty::BoundTyKind::Anon(idx as u32),
                     }))
                 }
             },
@@ -1119,13 +1119,13 @@ impl<'tcx> TypeFolder<'tcx> for ParamsSubstitutor<'tcx> {
 
 pub(crate) struct ReverseParamsSubstitutor<'tcx> {
     tcx: TyCtxt<'tcx>,
-    params: rustc_data_structures::fx::FxHashMap<usize, rustc_middle::ty::ParamTy>,
+    params: rustc_data_structures::fx::FxHashMap<u32, rustc_middle::ty::ParamTy>,
 }
 
 impl<'tcx> ReverseParamsSubstitutor<'tcx> {
     pub(crate) fn new(
         tcx: TyCtxt<'tcx>,
-        params: rustc_data_structures::fx::FxHashMap<usize, rustc_middle::ty::ParamTy>,
+        params: rustc_data_structures::fx::FxHashMap<u32, rustc_middle::ty::ParamTy>,
     ) -> Self {
         Self { tcx, params }
     }
@@ -1139,7 +1139,7 @@ impl<'tcx> TypeFolder<'tcx> for ReverseParamsSubstitutor<'tcx> {
     fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
         match *t.kind() {
             ty::Placeholder(ty::PlaceholderType { universe: ty::UniverseIndex::ROOT, name }) => {
-                match self.params.get(&name.as_usize()) {
+                match self.params.get(&name.expect_anon()) {
                     Some(param) => self.tcx.mk_ty(ty::Param(*param)),
                     None => t,
                 }
@@ -1171,7 +1171,8 @@ impl<'tcx> TypeVisitor<'tcx> for PlaceholdersCollector {
     fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
         match t.kind() {
             ty::Placeholder(p) if p.universe == self.universe_index => {
-                self.next_ty_placeholder = self.next_ty_placeholder.max(p.name.as_usize() + 1);
+                self.next_ty_placeholder =
+                    self.next_ty_placeholder.max(p.name.expect_anon() as usize + 1);
             }
 
             _ => (),
@@ -1186,6 +1187,7 @@ impl<'tcx> TypeVisitor<'tcx> for PlaceholdersCollector {
                 if let ty::BoundRegionKind::BrAnon(anon, _) = p.name {
                     self.next_anon_region_placeholder = self.next_anon_region_placeholder.max(anon);
                 }
+                // FIXME: This doesn't seem to handle BrNamed at all?
             }
 
             _ => (),

compiler/rustc_traits/src/chalk/mod.rs

@@ -6,12 +6,10 @@
 pub(crate) mod db;
 pub(crate) mod lowering;
 
-use rustc_data_structures::fx::FxHashMap;
-
 use rustc_middle::infer::canonical::{CanonicalTyVarKind, CanonicalVarKind};
 use rustc_middle::traits::ChalkRustInterner;
 use rustc_middle::ty::query::Providers;
-use rustc_middle::ty::{self, ParamTy, TyCtxt, TypeFoldable, TypeVisitable};
+use rustc_middle::ty::{self, TyCtxt, TypeFoldable, TypeVisitable};
 
 use rustc_infer::infer::canonical::{
     Canonical, CanonicalVarValues, Certainty, QueryRegionConstraints, QueryResponse,
@@ -41,7 +39,7 @@ pub(crate) fn evaluate_goal<'tcx>(
     let mut params_substitutor =
         ParamsSubstitutor::new(tcx, placeholders_collector.next_ty_placeholder);
     let obligation = obligation.fold_with(&mut params_substitutor);
-    let params: FxHashMap<usize, ParamTy> = params_substitutor.params;
+    let params = params_substitutor.params;
 
     let max_universe = obligation.max_universe.index();
 

library/std/src/net/tcp.rs

@@ -829,7 +829,7 @@ impl TcpListener {
     /// }
     ///
     /// fn main() -> std::io::Result<()> {
-    ///     let listener = TcpListener::bind("127.0.0.1:80").unwrap();
+    ///     let listener = TcpListener::bind("127.0.0.1:80")?;
     ///
     ///     for stream in listener.incoming() {
     ///         match stream {

src/librustdoc/html/render/print_item.rs

@@ -355,7 +355,7 @@ fn item_module(w: &mut Buffer, cx: &mut Context<'_>, item: &clean::Item, items:
             }
 
             clean::ImportItem(ref import) => {
-                let (stab, stab_tags) = if let Some(import_def_id) = import.source.did {
+                let stab_tags = if let Some(import_def_id) = import.source.did {
                     let ast_attrs = cx.tcx().get_attrs_unchecked(import_def_id);
                     let import_attrs = Box::new(clean::Attributes::from_ast(ast_attrs));
 
@@ -367,15 +367,12 @@ fn item_module(w: &mut Buffer, cx: &mut Context<'_>, item: &clean::Item, items:
                         ..myitem.clone()
                     };
 
-                    let stab = import_item.stability_class(cx.tcx());
                     let stab_tags = Some(extra_info_tags(&import_item, item, cx.tcx()));
-                    (stab, stab_tags)
+                    stab_tags
                 } else {
-                    (None, None)
+                    None
                 };
 
-                let add = if stab.is_some() { " " } else { "" };
-
                 w.write_str(ITEM_TABLE_ROW_OPEN);
                 let id = match import.kind {
                     clean::ImportKind::Simple(s) => {
@@ -391,11 +388,10 @@ fn item_module(w: &mut Buffer, cx: &mut Context<'_>, item: &clean::Item, items:
                 };
                 write!(
                     w,
-                    "<div class=\"item-left{add}{stab}\"{id}>\
+                    "<div class=\"item-left\"{id}>\
                          <code>{vis}{imp}</code>\
                      </div>\
                      {stab_tags_before}{stab_tags}{stab_tags_after}",
-                    stab = stab.unwrap_or_default(),
                     vis = visibility_print_with_space(myitem.visibility(tcx), myitem.item_id, cx),
                     imp = import.print(cx),
                 );
@@ -417,9 +413,6 @@ fn item_module(w: &mut Buffer, cx: &mut Context<'_>, item: &clean::Item, items:
                     _ => "",
                 };
 
-                let stab = myitem.stability_class(cx.tcx());
-                let add = if stab.is_some() { " " } else { "" };
-
                 let visibility_emoji = match myitem.visibility(tcx) {
                     Some(ty::Visibility::Restricted(_)) => {
                         "<span title=\"Restricted Visibility\">&nbsp;🔒</span> "
@@ -437,7 +430,7 @@ fn item_module(w: &mut Buffer, cx: &mut Context<'_>, item: &clean::Item, items:
                 };
                 write!(
                     w,
-                    "<div class=\"item-left{add}{stab}\">\
+                    "<div class=\"item-left\">\
                         <a class=\"{class}\" href=\"{href}\" title=\"{title}\">{name}</a>\
                         {visibility_emoji}\
                         {unsafety_flag}\
@@ -448,8 +441,6 @@ fn item_module(w: &mut Buffer, cx: &mut Context<'_>, item: &clean::Item, items:
                     visibility_emoji = visibility_emoji,
                     stab_tags = extra_info_tags(myitem, item, cx.tcx()),
                     class = myitem.type_(),
-                    add = add,
-                    stab = stab.unwrap_or_default(),
                     unsafety_flag = unsafety_flag,
                     href = item_path(myitem.type_(), myitem.name.unwrap().as_str()),
                     title = [myitem.type_().to_string(), full_path(cx, myitem)]

src/librustdoc/html/static/css/rustdoc.css

@@ -1,3 +1,11 @@
+/* When static files are updated, their suffixes need to be updated.
+	1. In the top directory run:
+		./x.py doc --stage 1 library/core
+	2. Find the directory containing files named with updated suffixes:
+		find build -path '*'/stage1-std/'*'/static.files
+	3. Copy the filenames with updated suffixes from the directory.
+*/
+
 /* See FiraSans-LICENSE.txt for the Fira Sans license. */
 @font-face {
 	font-family: 'Fira Sans';
@@ -22,7 +30,7 @@
 	font-style: normal;
 	font-weight: 400;
 	src: local('Source Serif 4'),
-		url("SourceSerif4-Regular-1f7d512b176f0f72.ttf.woff2") format("woff2");
+		url("SourceSerif4-Regular-46f98efaafac5295.ttf.woff2") format("woff2");
 	font-display: swap;
 }
 @font-face {
@@ -30,7 +38,7 @@
 	font-style: italic;
 	font-weight: 400;
 	src: local('Source Serif 4 Italic'),
-		url("SourceSerif4-It-d034fe4ef9d0fa00.ttf.woff2") format("woff2");
+		url("SourceSerif4-It-acdfaf1a8af734b1.ttf.woff2") format("woff2");
 	font-display: swap;
 }
 @font-face {
@@ -38,7 +46,7 @@
 	font-style: normal;
 	font-weight: 700;
 	src: local('Source Serif 4 Bold'),
-		url("SourceSerif4-Bold-124a1ca42af929b6.ttf.woff2") format("woff2");
+		url("SourceSerif4-Bold-a2c9cd1067f8b328.ttf.woff2") format("woff2");
 	font-display: swap;
 }
 
@@ -977,10 +985,6 @@ so that we can apply CSS-filters to change the arrow color in themes */
 		0 -1px 0 black;
 }
 
-.item-left.unstable {
-	opacity: 0.65;
-}
-
 .since {
 	font-weight: normal;
 	font-size: initial;

src/librustdoc/html/static/css/settings.css

@@ -40,8 +40,6 @@
 }
 
 .setting-check {
-	position: relative;
-	width: 100%;
 	margin-right: 20px;
 	display: flex;
 	align-items: center;

src/librustdoc/html/static/fonts/SourceSerif4-LICENSE.md

@@ -1,4 +1,4 @@
-Copyright 2014-2021 Adobe (http://www.adobe.com/), with Reserved Font Name 'Source'. All Rights Reserved. Source is a trademark of Adobe in the United States and/or other countries.
+Copyright 2014 - 2023 Adobe (http://www.adobe.com/), with Reserved Font Name ‘Source’. All Rights Reserved. Source is a trademark of Adobe in the United States and/or other countries.
 
 This Font Software is licensed under the SIL Open Font License, Version 1.1.
 

src/librustdoc/html/static/js/main.js

@@ -180,7 +180,6 @@ function browserSupportsHistoryApi() {
     return window.history && typeof window.history.pushState === "function";
 }
 
-// eslint-disable-next-line no-unused-vars
 function loadCss(cssUrl) {
     const link = document.createElement("link");
     link.href = cssUrl;

src/librustdoc/html/static/js/storage.js

@@ -51,7 +51,6 @@ function hasClass(elem, className) {
     return elem && elem.classList && elem.classList.contains(className);
 }
 
-// eslint-disable-next-line no-unused-vars
 function addClass(elem, className) {
     if (!elem || !elem.classList) {
         return;

tests/rustdoc/inline_cross/macros.rs

@@ -6,9 +6,9 @@
 
 extern crate macros;
 
-// @has foo/index.html '//*[@class="item-left unstable deprecated"]/span[@class="stab deprecated"]' \
+// @has foo/index.html '//*[@class="item-left"]/span[@class="stab deprecated"]' \
 //         Deprecated
-// @has - '//*[@class="item-left unstable deprecated"]/span[@class="stab unstable"]' \
+// @has - '//*[@class="item-left"]/span[@class="stab unstable"]' \
 //         Experimental
 
 // @has foo/macro.my_macro.html

tests/rustdoc/issue-32374.rs

@@ -2,9 +2,9 @@
 #![doc(issue_tracker_base_url = "https://issue_url/")]
 #![unstable(feature = "test", issue = "32374")]
 
-// @matches issue_32374/index.html '//*[@class="item-left unstable deprecated"]/span[@class="stab deprecated"]' \
+// @matches issue_32374/index.html '//*[@class="item-left"]/span[@class="stab deprecated"]' \
 //      'Deprecated'
-// @matches issue_32374/index.html '//*[@class="item-left unstable deprecated"]/span[@class="stab unstable"]' \
+// @matches issue_32374/index.html '//*[@class="item-left"]/span[@class="stab unstable"]' \
 //      'Experimental'
 // @matches issue_32374/index.html '//*[@class="item-right docblock-short"]/text()' 'Docs'
 

tests/rustdoc/reexport-check.rs

@@ -4,7 +4,6 @@
 extern crate reexport_check;
 
 // @!has 'foo/index.html' '//code' 'pub use self::i32;'
-// @has 'foo/index.html' '//div[@class="item-left deprecated"]' 'i32'
 // @has 'foo/i32/index.html'
 #[allow(deprecated, deprecated_in_future)]
 pub use std::i32;
@@ -12,6 +11,9 @@ pub use std::i32;
 // @has 'foo/index.html' '//div[@class="item-left"]' 'String'
 pub use std::string::String;
 
+// i32 is deprecated, String is not
+// @count 'foo/index.html' '//span[@class="stab deprecated"]' 1
+
 // @has 'foo/index.html' '//div[@class="item-right docblock-short"]' 'Docs in original'
 // this is a no-op, but shows what happens if there's an attribute that isn't a doc-comment
 #[doc(inline)]