Auto merge of #136225 - fmease:rollup-fm7m744, r=fmease

Rollup of 7 pull requests

Successful merges:

 - #135625 ([cfg_match] Document the use of expressions.)
 - #135902 (Do not consider child bound assumptions for rigid alias)
 - #135943 (Rename `Piece::String` to `Piece::Lit`)
 - #136104 (Add mermaid graphs of NLL regions and SCCs to polonius MIR dump)
 - #136143 (Update books)
 - #136147 (ABI-required target features: warn when they are missing in base CPU)
 - #136164 (Refactor FnKind variant to hold &Fn)

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

compiler/rustc_ast/src/mut_visit.rs

@@ -954,8 +954,14 @@ fn walk_coroutine_kind<T: MutVisitor>(vis: &mut T, coroutine_kind: &mut Coroutin
 
 fn walk_fn<T: MutVisitor>(vis: &mut T, kind: FnKind<'_>) {
     match kind {
-        FnKind::Fn(_ctxt, _ident, FnSig { header, decl, span }, _visibility, generics, body) => {
+        FnKind::Fn(
+            _ctxt,
+            _ident,
+            _vis,
+            Fn { defaultness, generics, body, sig: FnSig { header, decl, span } },
+        ) => {
             // Identifier and visibility are visited as a part of the item.
+            visit_defaultness(vis, defaultness);
             vis.visit_fn_header(header);
             vis.visit_generics(generics);
             vis.visit_fn_decl(decl);
@@ -1205,13 +1211,8 @@ impl WalkItemKind for ItemKind {
             ItemKind::Const(item) => {
                 visit_const_item(item, vis);
             }
-            ItemKind::Fn(box Fn { defaultness, generics, sig, body }) => {
+            ItemKind::Fn(func) => {
-                visit_defaultness(vis, defaultness);
+                vis.visit_fn(FnKind::Fn(FnCtxt::Free, ident, visibility, &mut *func), span, id);
-                vis.visit_fn(
-                    FnKind::Fn(FnCtxt::Free, ident, sig, visibility, generics, body),
-                    span,
-                    id,
-                );
             }
             ItemKind::Mod(safety, mod_kind) => {
                 visit_safety(vis, safety);
@@ -1329,10 +1330,9 @@ impl WalkItemKind for AssocItemKind {
             AssocItemKind::Const(item) => {
                 visit_const_item(item, visitor);
             }
-            AssocItemKind::Fn(box Fn { defaultness, generics, sig, body }) => {
+            AssocItemKind::Fn(func) => {
-                visit_defaultness(visitor, defaultness);
                 visitor.visit_fn(
-                    FnKind::Fn(FnCtxt::Assoc(ctxt), ident, sig, visibility, generics, body),
+                    FnKind::Fn(FnCtxt::Assoc(ctxt), ident, visibility, &mut *func),
                     span,
                     id,
                 );
@@ -1476,10 +1476,9 @@ impl WalkItemKind for ForeignItemKind {
                 visitor.visit_ty(ty);
                 visit_opt(expr, |expr| visitor.visit_expr(expr));
             }
-            ForeignItemKind::Fn(box Fn { defaultness, generics, sig, body }) => {
+            ForeignItemKind::Fn(func) => {
-                visit_defaultness(visitor, defaultness);
                 visitor.visit_fn(
-                    FnKind::Fn(FnCtxt::Foreign, ident, sig, visibility, generics, body),
+                    FnKind::Fn(FnCtxt::Foreign, ident, visibility, &mut *func),
                     span,
                     id,
                 );
@@ -1965,14 +1964,7 @@ impl<N: DummyAstNode, T: DummyAstNode> DummyAstNode for crate::ast_traits::AstNo
 #[derive(Debug)]
 pub enum FnKind<'a> {
     /// E.g., `fn foo()`, `fn foo(&self)`, or `extern "Abi" fn foo()`.
-    Fn(
+    Fn(FnCtxt, &'a mut Ident, &'a mut Visibility, &'a mut Fn),
-        FnCtxt,
-        &'a mut Ident,
-        &'a mut FnSig,
-        &'a mut Visibility,
-        &'a mut Generics,
-        &'a mut Option<P<Block>>,
-    ),
 
     /// E.g., `|x, y| body`.
     Closure(

compiler/rustc_ast/src/visit.rs

@@ -65,7 +65,7 @@ impl BoundKind {
 #[derive(Copy, Clone, Debug)]
 pub enum FnKind<'a> {
     /// E.g., `fn foo()`, `fn foo(&self)`, or `extern "Abi" fn foo()`.
-    Fn(FnCtxt, &'a Ident, &'a FnSig, &'a Visibility, &'a Generics, &'a Option<P<Block>>),
+    Fn(FnCtxt, &'a Ident, &'a Visibility, &'a Fn),
 
     /// E.g., `|x, y| body`.
     Closure(&'a ClosureBinder, &'a Option<CoroutineKind>, &'a FnDecl, &'a Expr),
@@ -74,7 +74,7 @@ pub enum FnKind<'a> {
 impl<'a> FnKind<'a> {
     pub fn header(&self) -> Option<&'a FnHeader> {
         match *self {
-            FnKind::Fn(_, _, sig, _, _, _) => Some(&sig.header),
+            FnKind::Fn(_, _, _, Fn { sig, .. }) => Some(&sig.header),
             FnKind::Closure(..) => None,
         }
     }
@@ -88,7 +88,7 @@ impl<'a> FnKind<'a> {
 
     pub fn decl(&self) -> &'a FnDecl {
         match self {
-            FnKind::Fn(_, _, sig, _, _, _) => &sig.decl,
+            FnKind::Fn(_, _, _, Fn { sig, .. }) => &sig.decl,
             FnKind::Closure(_, _, decl, _) => decl,
         }
     }
@@ -374,8 +374,8 @@ impl WalkItemKind for ItemKind {
                 try_visit!(visitor.visit_ty(ty));
                 visit_opt!(visitor, visit_expr, expr);
             }
-            ItemKind::Fn(box Fn { defaultness: _, generics, sig, body }) => {
+            ItemKind::Fn(func) => {
-                let kind = FnKind::Fn(FnCtxt::Free, ident, sig, vis, generics, body);
+                let kind = FnKind::Fn(FnCtxt::Free, ident, vis, &*func);
                 try_visit!(visitor.visit_fn(kind, span, id));
             }
             ItemKind::Mod(_unsafety, mod_kind) => match mod_kind {
@@ -715,8 +715,8 @@ impl WalkItemKind for ForeignItemKind {
                 try_visit!(visitor.visit_ty(ty));
                 visit_opt!(visitor, visit_expr, expr);
             }
-            ForeignItemKind::Fn(box Fn { defaultness: _, generics, sig, body }) => {
+            ForeignItemKind::Fn(func) => {
-                let kind = FnKind::Fn(FnCtxt::Foreign, ident, sig, vis, generics, body);
+                let kind = FnKind::Fn(FnCtxt::Foreign, ident, vis, &*func);
                 try_visit!(visitor.visit_fn(kind, span, id));
             }
             ForeignItemKind::TyAlias(box TyAlias {
@@ -858,7 +858,12 @@ pub fn walk_fn_decl<'a, V: Visitor<'a>>(
 
 pub fn walk_fn<'a, V: Visitor<'a>>(visitor: &mut V, kind: FnKind<'a>) -> V::Result {
     match kind {
-        FnKind::Fn(_ctxt, _ident, FnSig { header, decl, span: _ }, _vis, generics, body) => {
+        FnKind::Fn(
+            _ctxt,
+            _ident,
+            _vis,
+            Fn { defaultness: _, sig: FnSig { header, decl, span: _ }, generics, body },
+        ) => {
             // Identifier and visibility are visited as a part of the item.
             try_visit!(visitor.visit_fn_header(header));
             try_visit!(visitor.visit_generics(generics));
@@ -892,8 +897,8 @@ impl WalkItemKind for AssocItemKind {
                 try_visit!(visitor.visit_ty(ty));
                 visit_opt!(visitor, visit_expr, expr);
             }
-            AssocItemKind::Fn(box Fn { defaultness: _, generics, sig, body }) => {
+            AssocItemKind::Fn(func) => {
-                let kind = FnKind::Fn(FnCtxt::Assoc(ctxt), ident, sig, vis, generics, body);
+                let kind = FnKind::Fn(FnCtxt::Assoc(ctxt), ident, vis, &*func);
                 try_visit!(visitor.visit_fn(kind, span, id));
             }
             AssocItemKind::Type(box TyAlias {

compiler/rustc_ast_lowering/src/expr.rs

@@ -2125,7 +2125,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         self.arena.alloc(self.expr_call_mut(span, e, args))
     }
 
-    fn expr_call_lang_item_fn_mut(
+    pub(super) fn expr_call_lang_item_fn_mut(
         &mut self,
         span: Span,
         lang_item: hir::LangItem,
@@ -2135,7 +2135,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         self.expr_call_mut(span, path, args)
     }
 
-    fn expr_call_lang_item_fn(
+    pub(super) fn expr_call_lang_item_fn(
         &mut self,
         span: Span,
         lang_item: hir::LangItem,

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -917,7 +917,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                 walk_list!(self, visit_attribute, &item.attrs);
                 return; // Avoid visiting again.
             }
-            ItemKind::Fn(box Fn { defaultness, sig, generics, body }) => {
+            ItemKind::Fn(func @ box Fn { defaultness, generics: _, sig, body }) => {
                 self.check_defaultness(item.span, *defaultness);
 
                 let is_intrinsic =
@@ -947,7 +947,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
 
                 self.visit_vis(&item.vis);
                 self.visit_ident(&item.ident);
-                let kind = FnKind::Fn(FnCtxt::Free, &item.ident, sig, &item.vis, generics, body);
+                let kind = FnKind::Fn(FnCtxt::Free, &item.ident, &item.vis, &*func);
                 self.visit_fn(kind, item.span, item.id);
                 walk_list!(self, visit_attribute, &item.attrs);
                 return; // Avoid visiting again.
@@ -1348,19 +1348,20 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
         }
 
         if let FnKind::Fn(
-            _,
-            _,
-            FnSig { header: FnHeader { ext: Extern::Implicit(extern_span), .. }, .. },
             _,
             _,
             _,
+            Fn {
+                sig: FnSig { header: FnHeader { ext: Extern::Implicit(extern_span), .. }, .. },
+                ..
+            },
         ) = fk
         {
             self.maybe_lint_missing_abi(*extern_span, id);
         }
 
         // Functions without bodies cannot have patterns.
-        if let FnKind::Fn(ctxt, _, sig, _, _, None) = fk {
+        if let FnKind::Fn(ctxt, _, _, Fn { body: None, sig, .. }) = fk {
             Self::check_decl_no_pat(&sig.decl, |span, ident, mut_ident| {
                 if mut_ident && matches!(ctxt, FnCtxt::Assoc(_)) {
                     if let Some(ident) = ident {
@@ -1394,7 +1395,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                         .is_some();
 
         let disallowed = (!tilde_const_allowed).then(|| match fk {
-            FnKind::Fn(_, ident, _, _, _, _) => TildeConstReason::Function { ident: ident.span },
+            FnKind::Fn(_, ident, _, _) => TildeConstReason::Function { ident: ident.span },
             FnKind::Closure(..) => TildeConstReason::Closure,
         });
         self.with_tilde_const(disallowed, |this| visit::walk_fn(this, fk));
@@ -1470,15 +1471,14 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
             self.outer_trait_or_trait_impl.as_ref().and_then(TraitOrTraitImpl::constness).is_some();
 
         match &item.kind {
-            AssocItemKind::Fn(box Fn { sig, generics, body, .. })
+            AssocItemKind::Fn(func)
                 if parent_is_const
                     || ctxt == AssocCtxt::Trait
-                    || matches!(sig.header.constness, Const::Yes(_)) =>
+                    || matches!(func.sig.header.constness, Const::Yes(_)) =>
             {
                 self.visit_vis(&item.vis);
                 self.visit_ident(&item.ident);
-                let kind =
+                let kind = FnKind::Fn(FnCtxt::Assoc(ctxt), &item.ident, &item.vis, &*func);
-                    FnKind::Fn(FnCtxt::Assoc(ctxt), &item.ident, sig, &item.vis, generics, body);
                 walk_list!(self, visit_attribute, &item.attrs);
                 self.visit_fn(kind, item.span, item.id);
             }

compiler/rustc_ast_pretty/src/pprust/state/item.rs

@@ -34,8 +34,8 @@ impl<'a> State<'a> {
         self.maybe_print_comment(span.lo());
         self.print_outer_attributes(attrs);
         match kind {
-            ast::ForeignItemKind::Fn(box ast::Fn { defaultness, sig, generics, body }) => {
+            ast::ForeignItemKind::Fn(func) => {
-                self.print_fn_full(sig, ident, generics, vis, *defaultness, body.as_deref(), attrs);
+                self.print_fn_full(ident, vis, attrs, &*func);
             }
             ast::ForeignItemKind::Static(box ast::StaticItem { ty, mutability, expr, safety }) => {
                 self.print_item_const(
@@ -199,16 +199,8 @@ impl<'a> State<'a> {
                     *defaultness,
                 );
             }
-            ast::ItemKind::Fn(box ast::Fn { defaultness, sig, generics, body }) => {
+            ast::ItemKind::Fn(func) => {
-                self.print_fn_full(
+                self.print_fn_full(item.ident, &item.vis, &item.attrs, &*func);
-                    sig,
-                    item.ident,
-                    generics,
-                    &item.vis,
-                    *defaultness,
-                    body.as_deref(),
-                    &item.attrs,
-                );
             }
             ast::ItemKind::Mod(safety, mod_kind) => {
                 self.head(Self::to_string(|s| {
@@ -542,8 +534,8 @@ impl<'a> State<'a> {
         self.maybe_print_comment(span.lo());
         self.print_outer_attributes(attrs);
         match kind {
-            ast::AssocItemKind::Fn(box ast::Fn { defaultness, sig, generics, body }) => {
+            ast::AssocItemKind::Fn(func) => {
-                self.print_fn_full(sig, ident, generics, vis, *defaultness, body.as_deref(), attrs);
+                self.print_fn_full(ident, vis, attrs, &*func);
             }
             ast::AssocItemKind::Const(box ast::ConstItem { defaultness, generics, ty, expr }) => {
                 self.print_item_const(
@@ -653,19 +645,17 @@ impl<'a> State<'a> {
 
     fn print_fn_full(
         &mut self,
-        sig: &ast::FnSig,
         name: Ident,
-        generics: &ast::Generics,
         vis: &ast::Visibility,
-        defaultness: ast::Defaultness,
-        body: Option<&ast::Block>,
         attrs: &[ast::Attribute],
+        func: &ast::Fn,
     ) {
+        let ast::Fn { defaultness, generics, sig, body } = func;
         if body.is_some() {
             self.head("");
         }
         self.print_visibility(vis);
-        self.print_defaultness(defaultness);
+        self.print_defaultness(*defaultness);
         self.print_fn(&sig.decl, sig.header, Some(name), generics);
         if let Some(body) = body {
             self.nbsp();

compiler/rustc_borrowck/src/polonius/dump.rs

@@ -1,14 +1,18 @@
 use std::io;
 
+use rustc_data_structures::fx::FxHashSet;
+use rustc_index::IndexVec;
 use rustc_middle::mir::pretty::{
     PassWhere, PrettyPrintMirOptions, create_dump_file, dump_enabled, dump_mir_to_writer,
 };
 use rustc_middle::mir::{Body, ClosureRegionRequirements};
-use rustc_middle::ty::TyCtxt;
+use rustc_middle::ty::{RegionVid, TyCtxt};
 use rustc_session::config::MirIncludeSpans;
 
 use crate::borrow_set::BorrowSet;
+use crate::constraints::OutlivesConstraint;
 use crate::polonius::{LocalizedOutlivesConstraint, LocalizedOutlivesConstraintSet};
+use crate::type_check::Locations;
 use crate::{BorrowckInferCtxt, RegionInferenceContext};
 
 /// `-Zdump-mir=polonius` dumps MIR annotated with NLL and polonius specific information.
@@ -50,6 +54,8 @@ pub(crate) fn dump_polonius_mir<'tcx>(
 /// - the NLL MIR
 /// - the list of polonius localized constraints
 /// - a mermaid graph of the CFG
+/// - a mermaid graph of the NLL regions and the constraints between them
+/// - a mermaid graph of the NLL SCCs and the constraints between them
 fn emit_polonius_dump<'tcx>(
     tcx: TyCtxt<'tcx>,
     body: &Body<'tcx>,
@@ -68,7 +74,7 @@ fn emit_polonius_dump<'tcx>(
     // Section 1: the NLL + Polonius MIR.
     writeln!(out, "<div>")?;
     writeln!(out, "Raw MIR dump")?;
-    writeln!(out, "<code><pre>")?;
+    writeln!(out, "<pre><code>")?;
     emit_html_mir(
         tcx,
         body,
@@ -78,15 +84,31 @@ fn emit_polonius_dump<'tcx>(
         closure_region_requirements,
         out,
     )?;
-    writeln!(out, "</pre></code>")?;
+    writeln!(out, "</code></pre>")?;
     writeln!(out, "</div>")?;
 
     // Section 2: mermaid visualization of the CFG.
     writeln!(out, "<div>")?;
     writeln!(out, "Control-flow graph")?;
-    writeln!(out, "<code><pre class='mermaid'>")?;
+    writeln!(out, "<pre class='mermaid'>")?;
     emit_mermaid_cfg(body, out)?;
-    writeln!(out, "</pre></code>")?;
+    writeln!(out, "</pre>")?;
+    writeln!(out, "</div>")?;
+
+    // Section 3: mermaid visualization of the NLL region graph.
+    writeln!(out, "<div>")?;
+    writeln!(out, "NLL regions")?;
+    writeln!(out, "<pre class='mermaid'>")?;
+    emit_mermaid_nll_regions(regioncx, out)?;
+    writeln!(out, "</pre>")?;
+    writeln!(out, "</div>")?;
+
+    // Section 4: mermaid visualization of the NLL SCC graph.
+    writeln!(out, "<div>")?;
+    writeln!(out, "NLL SCCs")?;
+    writeln!(out, "<pre class='mermaid'>")?;
+    emit_mermaid_nll_sccs(regioncx, out)?;
+    writeln!(out, "</pre>")?;
     writeln!(out, "</div>")?;
 
     // Finalize the dump with the HTML epilogue.
@@ -261,3 +283,112 @@ fn emit_mermaid_cfg(body: &Body<'_>, out: &mut dyn io::Write) -> io::Result<()>
 
     Ok(())
 }
+
+/// Emits a region's label: index, universe, external name.
+fn render_region(
+    region: RegionVid,
+    regioncx: &RegionInferenceContext<'_>,
+    out: &mut dyn io::Write,
+) -> io::Result<()> {
+    let def = regioncx.region_definition(region);
+    let universe = def.universe;
+
+    write!(out, "'{}", region.as_usize())?;
+    if !universe.is_root() {
+        write!(out, "/{universe:?}")?;
+    }
+    if let Some(name) = def.external_name.and_then(|e| e.get_name()) {
+        write!(out, " ({name})")?;
+    }
+    Ok(())
+}
+
+/// Emits a mermaid flowchart of the NLL regions and the outlives constraints between them, similar
+/// to the graphviz version.
+fn emit_mermaid_nll_regions<'tcx>(
+    regioncx: &RegionInferenceContext<'tcx>,
+    out: &mut dyn io::Write,
+) -> io::Result<()> {
+    // The mermaid chart type: a top-down flowchart.
+    writeln!(out, "flowchart TD")?;
+
+    // Emit the region nodes.
+    for region in regioncx.var_infos.indices() {
+        write!(out, "{}[\"", region.as_usize())?;
+        render_region(region, regioncx, out)?;
+        writeln!(out, "\"]")?;
+    }
+
+    // Get a set of edges to check for the reverse edge being present.
+    let edges: FxHashSet<_> = regioncx.outlives_constraints().map(|c| (c.sup, c.sub)).collect();
+
+    // Order (and deduplicate) edges for traversal, to display them in a generally increasing order.
+    let constraint_key = |c: &OutlivesConstraint<'_>| {
+        let min = c.sup.min(c.sub);
+        let max = c.sup.max(c.sub);
+        (min, max)
+    };
+    let mut ordered_edges: Vec<_> = regioncx.outlives_constraints().collect();
+    ordered_edges.sort_by_key(|c| constraint_key(c));
+    ordered_edges.dedup_by_key(|c| constraint_key(c));
+
+    for outlives in ordered_edges {
+        // Source node.
+        write!(out, "{} ", outlives.sup.as_usize())?;
+
+        // The kind of arrow: bidirectional if the opposite edge exists in the set.
+        if edges.contains(&(outlives.sub, outlives.sup)) {
+            write!(out, "&lt;")?;
+        }
+        write!(out, "-- ")?;
+
+        // Edge label from its `Locations`.
+        match outlives.locations {
+            Locations::All(_) => write!(out, "All")?,
+            Locations::Single(location) => write!(out, "{:?}", location)?,
+        }
+
+        // Target node.
+        writeln!(out, " --> {}", outlives.sub.as_usize())?;
+    }
+    Ok(())
+}
+
+/// Emits a mermaid flowchart of the NLL SCCs and the outlives constraints between them, similar
+/// to the graphviz version.
+fn emit_mermaid_nll_sccs<'tcx>(
+    regioncx: &RegionInferenceContext<'tcx>,
+    out: &mut dyn io::Write,
+) -> io::Result<()> {
+    // The mermaid chart type: a top-down flowchart.
+    writeln!(out, "flowchart TD")?;
+
+    // Gather and emit the SCC nodes.
+    let mut nodes_per_scc: IndexVec<_, _> =
+        regioncx.constraint_sccs().all_sccs().map(|_| Vec::new()).collect();
+    for region in regioncx.var_infos.indices() {
+        let scc = regioncx.constraint_sccs().scc(region);
+        nodes_per_scc[scc].push(region);
+    }
+    for (scc, regions) in nodes_per_scc.iter_enumerated() {
+        // The node label: the regions contained in the SCC.
+        write!(out, "{scc}[\"SCC({scc}) = {{", scc = scc.as_usize())?;
+        for (idx, &region) in regions.iter().enumerate() {
+            render_region(region, regioncx, out)?;
+            if idx < regions.len() - 1 {
+                write!(out, ",")?;
+            }
+        }
+        writeln!(out, "}}\"]")?;
+    }
+
+    // Emit the edges between SCCs.
+    let edges = regioncx.constraint_sccs().all_sccs().flat_map(|source| {
+        regioncx.constraint_sccs().successors(source).iter().map(move |&target| (source, target))
+    });
+    for (source, target) in edges {
+        writeln!(out, "{} --> {}", source.as_usize(), target.as_usize())?;
+    }
+
+    Ok(())
+}

compiler/rustc_builtin_macros/src/asm.rs

@@ -651,7 +651,7 @@ fn expand_preparsed_asm(
             .map(|span| template_span.from_inner(InnerSpan::new(span.start, span.end)));
         for piece in unverified_pieces {
             match piece {
-                parse::Piece::String(s) => {
+                parse::Piece::Lit(s) => {
                     template.push(ast::InlineAsmTemplatePiece::String(s.to_string().into()))
                 }
                 parse::Piece::NextArgument(arg) => {

compiler/rustc_builtin_macros/src/format.rs

@@ -406,7 +406,7 @@ fn make_format_args(
 
     for piece in &pieces {
         match *piece {
-            parse::Piece::String(s) => {
+            parse::Piece::Lit(s) => {
                 unfinished_literal.push_str(s);
             }
             parse::Piece::NextArgument(box parse::Argument { position, position_span, format }) => {

compiler/rustc_codegen_gcc/src/gcc_util.rs

@@ -1,10 +1,8 @@
-use std::iter::FromIterator;
-
 #[cfg(feature = "master")]
 use gccjit::Context;
 use rustc_codegen_ssa::codegen_attrs::check_tied_features;
 use rustc_codegen_ssa::errors::TargetFeatureDisableOrEnable;
-use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::unord::UnordSet;
 use rustc_session::Session;
 use rustc_target::target_features::RUSTC_SPECIFIC_FEATURES;
@@ -45,12 +43,6 @@ pub(crate) fn global_gcc_features(sess: &Session, diagnostics: bool) -> Vec<Stri
     let known_features = sess.target.rust_target_features();
     let mut featsmap = FxHashMap::default();
 
-    // Ensure that all ABI-required features are enabled, and the ABI-forbidden ones
-    // are disabled.
-    let abi_feature_constraints = sess.target.abi_required_features();
-    let abi_incompatible_set =
-        FxHashSet::from_iter(abi_feature_constraints.incompatible.iter().copied());
-
     // Compute implied features
     let mut all_rust_features = vec![];
     for feature in sess.opts.cg.target_feature.split(',') {
@@ -117,51 +109,11 @@ pub(crate) fn global_gcc_features(sess: &Session, diagnostics: bool) -> Vec<Stri
                 }
             }
 
-            // Ensure that the features we enable/disable are compatible with the ABI.
-            if enable {
-                if abi_incompatible_set.contains(feature) {
-                    sess.dcx().emit_warn(ForbiddenCTargetFeature {
-                        feature,
-                        enabled: "enabled",
-                        reason: "this feature is incompatible with the target ABI",
-                    });
-                }
-            } else {
-                // FIXME: we have to request implied features here since
-                // negative features do not handle implied features above.
-                for &required in abi_feature_constraints.required.iter() {
-                    let implied = sess.target.implied_target_features(std::iter::once(required));
-                    if implied.contains(feature) {
-                        sess.dcx().emit_warn(ForbiddenCTargetFeature {
-                            feature,
-                            enabled: "disabled",
-                            reason: "this feature is required by the target ABI",
-                        });
-                    }
-                }
-            }
-
             // FIXME(nagisa): figure out how to not allocate a full hashset here.
             featsmap.insert(feature, enable);
         }
     }
 
-    // To be sure the ABI-relevant features are all in the right state, we explicitly
-    // (un)set them here. This means if the target spec sets those features wrong,
-    // we will silently correct them rather than silently producing wrong code.
-    // (The target sanity check tries to catch this, but we can't know which features are
-    // enabled in GCC by default so we can't be fully sure about that check.)
-    // We add these at the beginning of the list so that `-Ctarget-features` can
-    // still override it... that's unsound, but more compatible with past behavior.
-    all_rust_features.splice(
-        0..0,
-        abi_feature_constraints
-            .required
-            .iter()
-            .map(|&f| (true, f))
-            .chain(abi_feature_constraints.incompatible.iter().map(|&f| (false, f))),
-    );
-
     // Translate this into GCC features.
     let feats =
         all_rust_features.iter().flat_map(|&(enable, feature)| {

compiler/rustc_codegen_gcc/src/lib.rs

@@ -493,9 +493,10 @@ fn target_features_cfg(
     sess.target
         .rust_target_features()
         .iter()
-        .filter(|&&(_, gate, _)| gate.in_cfg())
         .filter_map(|&(feature, gate, _)| {
-            if sess.is_nightly_build() || allow_unstable || gate.requires_nightly().is_none() {
+            if allow_unstable
+                || (gate.in_cfg() && (sess.is_nightly_build() || gate.requires_nightly().is_none()))
+            {
                 Some(feature)
             } else {
                 None

compiler/rustc_codegen_llvm/src/llvm_util.rs

@@ -319,7 +319,6 @@ pub fn target_features_cfg(sess: &Session, allow_unstable: bool) -> Vec<Symbol>
         sess.target
             .rust_target_features()
             .iter()
-            .filter(|(_, gate, _)| gate.in_cfg())
             .filter(|(feature, _, _)| {
                 // skip checking special features, as LLVM may not understand them
                 if RUSTC_SPECIAL_FEATURES.contains(feature) {
@@ -388,9 +387,13 @@ pub fn target_features_cfg(sess: &Session, allow_unstable: bool) -> Vec<Symbol>
     sess.target
         .rust_target_features()
         .iter()
-        .filter(|(_, gate, _)| gate.in_cfg())
         .filter_map(|(feature, gate, _)| {
-            if sess.is_nightly_build() || allow_unstable || gate.requires_nightly().is_none() {
+            // The `allow_unstable` set is used by rustc internally to determined which target
+            // features are truly available, so we want to return even perma-unstable "forbidden"
+            // features.
+            if allow_unstable
+                || (gate.in_cfg() && (sess.is_nightly_build() || gate.requires_nightly().is_none()))
+            {
                 Some(*feature)
             } else {
                 None
@@ -670,12 +673,6 @@ pub(crate) fn global_llvm_features(
         // Will only be filled when `diagnostics` is set!
         let mut featsmap = FxHashMap::default();
 
-        // Ensure that all ABI-required features are enabled, and the ABI-forbidden ones
-        // are disabled.
-        let abi_feature_constraints = sess.target.abi_required_features();
-        let abi_incompatible_set =
-            FxHashSet::from_iter(abi_feature_constraints.incompatible.iter().copied());
-
         // Compute implied features
         let mut all_rust_features = vec![];
         for feature in sess.opts.cg.target_feature.split(',') {
@@ -746,52 +743,11 @@ pub(crate) fn global_llvm_features(
                     }
                 }
 
-                // Ensure that the features we enable/disable are compatible with the ABI.
-                if enable {
-                    if abi_incompatible_set.contains(feature) {
-                        sess.dcx().emit_warn(ForbiddenCTargetFeature {
-                            feature,
-                            enabled: "enabled",
-                            reason: "this feature is incompatible with the target ABI",
-                        });
-                    }
-                } else {
-                    // FIXME: we have to request implied features here since
-                    // negative features do not handle implied features above.
-                    for &required in abi_feature_constraints.required.iter() {
-                        let implied =
-                            sess.target.implied_target_features(std::iter::once(required));
-                        if implied.contains(feature) {
-                            sess.dcx().emit_warn(ForbiddenCTargetFeature {
-                                feature,
-                                enabled: "disabled",
-                                reason: "this feature is required by the target ABI",
-                            });
-                        }
-                    }
-                }
-
                 // FIXME(nagisa): figure out how to not allocate a full hashset here.
                 featsmap.insert(feature, enable);
             }
         }
 
-        // To be sure the ABI-relevant features are all in the right state, we explicitly
-        // (un)set them here. This means if the target spec sets those features wrong,
-        // we will silently correct them rather than silently producing wrong code.
-        // (The target sanity check tries to catch this, but we can't know which features are
-        // enabled in LLVM by default so we can't be fully sure about that check.)
-        // We add these at the beginning of the list so that `-Ctarget-features` can
-        // still override it... that's unsound, but more compatible with past behavior.
-        all_rust_features.splice(
-            0..0,
-            abi_feature_constraints
-                .required
-                .iter()
-                .map(|&f| (true, f))
-                .chain(abi_feature_constraints.incompatible.iter().map(|&f| (false, f))),
-        );
-
         // Translate this into LLVM features.
         let feats = all_rust_features
             .iter()

compiler/rustc_hir_analysis/src/check/mod.rs

@@ -457,7 +457,7 @@ fn fn_sig_suggestion<'tcx>(
 
     let asyncness = if tcx.asyncness(assoc.def_id).is_async() {
         output = if let ty::Alias(_, alias_ty) = *output.kind() {
-            tcx.explicit_item_super_predicates(alias_ty.def_id)
+            tcx.explicit_item_self_bounds(alias_ty.def_id)
                 .iter_instantiated_copied(tcx, alias_ty.args)
                 .find_map(|(bound, _)| {
                     bound.as_projection_clause()?.no_bound_vars()?.term.as_type()

compiler/rustc_hir_analysis/src/collect.rs

@@ -65,9 +65,9 @@ pub fn provide(providers: &mut Providers) {
         type_alias_is_lazy: type_of::type_alias_is_lazy,
         item_bounds: item_bounds::item_bounds,
         explicit_item_bounds: item_bounds::explicit_item_bounds,
-        item_super_predicates: item_bounds::item_super_predicates,
+        item_self_bounds: item_bounds::item_self_bounds,
-        explicit_item_super_predicates: item_bounds::explicit_item_super_predicates,
+        explicit_item_self_bounds: item_bounds::explicit_item_self_bounds,
-        item_non_self_assumptions: item_bounds::item_non_self_assumptions,
+        item_non_self_bounds: item_bounds::item_non_self_bounds,
         impl_super_outlives: item_bounds::impl_super_outlives,
         generics_of: generics_of::generics_of,
         predicates_of: predicates_of::predicates_of,
@@ -328,9 +328,9 @@ impl<'tcx> Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
         self.tcx.ensure().generics_of(def_id);
         self.tcx.ensure().predicates_of(def_id);
         self.tcx.ensure().explicit_item_bounds(def_id);
-        self.tcx.ensure().explicit_item_super_predicates(def_id);
+        self.tcx.ensure().explicit_item_self_bounds(def_id);
         self.tcx.ensure().item_bounds(def_id);
-        self.tcx.ensure().item_super_predicates(def_id);
+        self.tcx.ensure().item_self_bounds(def_id);
         if self.tcx.is_conditionally_const(def_id) {
             self.tcx.ensure().explicit_implied_const_bounds(def_id);
             self.tcx.ensure().const_conditions(def_id);
@@ -822,7 +822,7 @@ fn lower_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
 
         hir::TraitItemKind::Type(_, Some(_)) => {
             tcx.ensure().item_bounds(def_id);
-            tcx.ensure().item_super_predicates(def_id);
+            tcx.ensure().item_self_bounds(def_id);
             tcx.ensure().type_of(def_id);
             // Account for `type T = _;`.
             let mut visitor = HirPlaceholderCollector::default();
@@ -839,7 +839,7 @@ fn lower_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
 
         hir::TraitItemKind::Type(_, None) => {
             tcx.ensure().item_bounds(def_id);
-            tcx.ensure().item_super_predicates(def_id);
+            tcx.ensure().item_self_bounds(def_id);
             // #74612: Visit and try to find bad placeholders
             // even if there is no concrete type.
             let mut visitor = HirPlaceholderCollector::default();

compiler/rustc_hir_analysis/src/collect/item_bounds.rs

@@ -350,7 +350,7 @@ pub(super) fn explicit_item_bounds(
     explicit_item_bounds_with_filter(tcx, def_id, PredicateFilter::All)
 }
 
-pub(super) fn explicit_item_super_predicates(
+pub(super) fn explicit_item_self_bounds(
     tcx: TyCtxt<'_>,
     def_id: LocalDefId,
 ) -> ty::EarlyBinder<'_, &'_ [(ty::Clause<'_>, Span)]> {
@@ -434,11 +434,11 @@ pub(super) fn item_bounds(tcx: TyCtxt<'_>, def_id: DefId) -> ty::EarlyBinder<'_,
     })
 }
 
-pub(super) fn item_super_predicates(
+pub(super) fn item_self_bounds(
     tcx: TyCtxt<'_>,
     def_id: DefId,
 ) -> ty::EarlyBinder<'_, ty::Clauses<'_>> {
-    tcx.explicit_item_super_predicates(def_id).map_bound(|bounds| {
+    tcx.explicit_item_self_bounds(def_id).map_bound(|bounds| {
         tcx.mk_clauses_from_iter(
             util::elaborate(tcx, bounds.iter().map(|&(bound, _span)| bound)).filter_only_self(),
         )
@@ -447,13 +447,12 @@ pub(super) fn item_super_predicates(
 
 /// This exists as an optimization to compute only the item bounds of the item
 /// that are not `Self` bounds.
-pub(super) fn item_non_self_assumptions(
+pub(super) fn item_non_self_bounds(
     tcx: TyCtxt<'_>,
     def_id: DefId,
 ) -> ty::EarlyBinder<'_, ty::Clauses<'_>> {
     let all_bounds: FxIndexSet<_> = tcx.item_bounds(def_id).skip_binder().iter().collect();
-    let own_bounds: FxIndexSet<_> =
+    let own_bounds: FxIndexSet<_> = tcx.item_self_bounds(def_id).skip_binder().iter().collect();
-        tcx.item_super_predicates(def_id).skip_binder().iter().collect();
     if all_bounds.len() == own_bounds.len() {
         ty::EarlyBinder::bind(ty::ListWithCachedTypeInfo::empty())
     } else {

compiler/rustc_hir_typeck/src/closure.rs

@@ -308,7 +308,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     expected_ty,
                     closure_kind,
                     self.tcx
-                        .explicit_item_super_predicates(def_id)
+                        .explicit_item_self_bounds(def_id)
                         .iter_instantiated_copied(self.tcx, args)
                         .map(|(c, s)| (c.as_predicate(), s)),
                 ),
@@ -1019,7 +1019,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             }
             ty::Alias(ty::Opaque, ty::AliasTy { def_id, args, .. }) => self
                 .tcx
-                .explicit_item_super_predicates(def_id)
+                .explicit_item_self_bounds(def_id)
                 .iter_instantiated_copied(self.tcx, args)
                 .find_map(|(p, s)| get_future_output(p.as_predicate(), s))?,
             ty::Error(_) => return Some(ret_ty),

compiler/rustc_hir_typeck/src/coercion.rs

@@ -1847,30 +1847,26 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> {
             fcx.probe(|_| {
                 let ocx = ObligationCtxt::new(fcx);
                 ocx.register_obligations(
-                    fcx.tcx.item_super_predicates(rpit_def_id).iter_identity().filter_map(
+                    fcx.tcx.item_self_bounds(rpit_def_id).iter_identity().filter_map(|clause| {
-                        |clause| {
+                        let predicate = clause
-                            let predicate = clause
+                            .kind()
-                                .kind()
+                            .map_bound(|clause| match clause {
-                                .map_bound(|clause| match clause {
+                                ty::ClauseKind::Trait(trait_pred) => Some(ty::ClauseKind::Trait(
-                                    ty::ClauseKind::Trait(trait_pred) => Some(
+                                    trait_pred.with_self_ty(fcx.tcx, ty),
-                                        ty::ClauseKind::Trait(trait_pred.with_self_ty(fcx.tcx, ty)),
+                                )),
-                                    ),
+                                ty::ClauseKind::Projection(proj_pred) => Some(
-                                    ty::ClauseKind::Projection(proj_pred) => {
+                                    ty::ClauseKind::Projection(proj_pred.with_self_ty(fcx.tcx, ty)),
-                                        Some(ty::ClauseKind::Projection(
+                                ),
-                                            proj_pred.with_self_ty(fcx.tcx, ty),
+                                _ => None,
-                                        ))
+                            })
-                                    }
+                            .transpose()?;
-                                    _ => None,
+                        Some(Obligation::new(
-                                })
+                            fcx.tcx,
-                                .transpose()?;
+                            ObligationCause::dummy(),
-                            Some(Obligation::new(
+                            fcx.param_env,
-                                fcx.tcx,
+                            predicate,
-                                ObligationCause::dummy(),
+                        ))
-                                fcx.param_env,
+                    }),
-                                predicate,
-                            ))
-                        },
-                    ),
                 );
                 ocx.select_where_possible().is_empty()
             })

compiler/rustc_infer/src/infer/outlives/verify.rs

@@ -281,7 +281,7 @@ impl<'cx, 'tcx> VerifyBoundCx<'cx, 'tcx> {
         alias_ty: ty::AliasTy<'tcx>,
     ) -> impl Iterator<Item = ty::Region<'tcx>> {
         let tcx = self.tcx;
-        let bounds = tcx.item_super_predicates(alias_ty.def_id);
+        let bounds = tcx.item_self_bounds(alias_ty.def_id);
         trace!("{:#?}", bounds.skip_binder());
         bounds
             .iter_instantiated(tcx, alias_ty.args)

compiler/rustc_interface/messages.ftl

@@ -1,3 +1,8 @@
+interface_abi_required_feature =
+    target feature `{$feature}` must be {$enabled} to ensure that the ABI of the current target can be implemented correctly
+    .note = this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+interface_abi_required_feature_issue = for more information, see issue #116344 <https://github.com/rust-lang/rust/issues/116344>
+
 interface_cant_emit_mir =
     could not emit MIR: {$error}
 

compiler/rustc_interface/src/errors.rs

@@ -103,3 +103,12 @@ pub struct IgnoringOutDir;
 #[derive(Diagnostic)]
 #[diag(interface_multiple_output_types_to_stdout)]
 pub struct MultipleOutputTypesToStdout;
+
+#[derive(Diagnostic)]
+#[diag(interface_abi_required_feature)]
+#[note]
+#[note(interface_abi_required_feature_issue)]
+pub(crate) struct AbiRequiredTargetFeature<'a> {
+    pub feature: &'a str,
+    pub enabled: &'a str,
+}

compiler/rustc_interface/src/interface.rs

@@ -492,6 +492,8 @@ pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Se
             }
             sess.lint_store = Some(Lrc::new(lint_store));
 
+            util::check_abi_required_features(&sess);
+
             let compiler = Compiler {
                 sess,
                 codegen_backend,

compiler/rustc_interface/src/util.rs

@@ -18,21 +18,25 @@ use rustc_session::{EarlyDiagCtxt, Session, filesearch};
 use rustc_span::edit_distance::find_best_match_for_name;
 use rustc_span::edition::Edition;
 use rustc_span::source_map::SourceMapInputs;
-use rustc_span::sym;
+use rustc_span::{Symbol, sym};
 use rustc_target::spec::Target;
 use tracing::info;
 
 use crate::errors;
 
 /// Function pointer type that constructs a new CodegenBackend.
-pub type MakeBackendFn = fn() -> Box<dyn CodegenBackend>;
+type MakeBackendFn = fn() -> Box<dyn CodegenBackend>;
 
 /// Adds `target_feature = "..."` cfgs for a variety of platform
 /// specific features (SSE, NEON etc.).
 ///
 /// This is performed by checking whether a set of permitted features
 /// is available on the target machine, by querying the codegen backend.
-pub fn add_configuration(cfg: &mut Cfg, sess: &mut Session, codegen_backend: &dyn CodegenBackend) {
+pub(crate) fn add_configuration(
+    cfg: &mut Cfg,
+    sess: &mut Session,
+    codegen_backend: &dyn CodegenBackend,
+) {
     let tf = sym::target_feature;
 
     let unstable_target_features = codegen_backend.target_features_cfg(sess, true);
@@ -48,6 +52,34 @@ pub fn add_configuration(cfg: &mut Cfg, sess: &mut Session, codegen_backend: &dy
     }
 }
 
+/// Ensures that all target features required by the ABI are present.
+/// Must be called after `unstable_target_features` has been populated!
+pub(crate) fn check_abi_required_features(sess: &Session) {
+    let abi_feature_constraints = sess.target.abi_required_features();
+    // We check this against `unstable_target_features` as that is conveniently already
+    // back-translated to rustc feature names, taking into account `-Ctarget-cpu` and `-Ctarget-feature`.
+    // Just double-check that the features we care about are actually on our list.
+    for feature in
+        abi_feature_constraints.required.iter().chain(abi_feature_constraints.incompatible.iter())
+    {
+        assert!(
+            sess.target.rust_target_features().iter().any(|(name, ..)| feature == name),
+            "target feature {feature} is required/incompatible for the current ABI but not a recognized feature for this target"
+        );
+    }
+
+    for feature in abi_feature_constraints.required {
+        if !sess.unstable_target_features.contains(&Symbol::intern(feature)) {
+            sess.dcx().emit_warn(errors::AbiRequiredTargetFeature { feature, enabled: "enabled" });
+        }
+    }
+    for feature in abi_feature_constraints.incompatible {
+        if sess.unstable_target_features.contains(&Symbol::intern(feature)) {
+            sess.dcx().emit_warn(errors::AbiRequiredTargetFeature { feature, enabled: "disabled" });
+        }
+    }
+}
+
 pub static STACK_SIZE: OnceLock<usize> = OnceLock::new();
 pub const DEFAULT_STACK_SIZE: usize = 8 * 1024 * 1024;
 

compiler/rustc_lint/src/builtin.rs

@@ -330,10 +330,12 @@ impl EarlyLintPass for UnsafeCode {
         if let FnKind::Fn(
             ctxt,
             _,
-            ast::FnSig { header: ast::FnHeader { safety: ast::Safety::Unsafe(_), .. }, .. },
             _,
-            _,
+            ast::Fn {
-            body,
+                sig: ast::FnSig { header: ast::FnHeader { safety: ast::Safety::Unsafe(_), .. }, .. },
+                body,
+                ..
+            },
         ) = fk
         {
             let decorator = match ctxt {

compiler/rustc_lint/src/unused.rs

@@ -289,25 +289,22 @@ impl<'tcx> LateLintPass<'tcx> for UnusedResults {
                 }
                 ty::Adt(def, _) => is_def_must_use(cx, def.did(), span),
                 ty::Alias(ty::Opaque | ty::Projection, ty::AliasTy { def_id: def, .. }) => {
-                    elaborate(
+                    elaborate(cx.tcx, cx.tcx.explicit_item_self_bounds(def).iter_identity_copied())
-                        cx.tcx,
+                        // We only care about self bounds for the impl-trait
-                        cx.tcx.explicit_item_super_predicates(def).iter_identity_copied(),
+                        .filter_only_self()
-                    )
+                        .find_map(|(pred, _span)| {
-                    // We only care about self bounds for the impl-trait
+                            // We only look at the `DefId`, so it is safe to skip the binder here.
-                    .filter_only_self()
+                            if let ty::ClauseKind::Trait(ref poly_trait_predicate) =
-                    .find_map(|(pred, _span)| {
+                                pred.kind().skip_binder()
-                        // We only look at the `DefId`, so it is safe to skip the binder here.
+                            {
-                        if let ty::ClauseKind::Trait(ref poly_trait_predicate) =
+                                let def_id = poly_trait_predicate.trait_ref.def_id;
-                            pred.kind().skip_binder()
-                        {
-                            let def_id = poly_trait_predicate.trait_ref.def_id;
 
-                            is_def_must_use(cx, def_id, span)
+                                is_def_must_use(cx, def_id, span)
-                        } else {
+                            } else {
-                            None
+                                None
-                        }
+                            }
-                    })
+                        })
-                    .map(|inner| MustUsePath::Opaque(Box::new(inner)))
+                        .map(|inner| MustUsePath::Opaque(Box::new(inner)))
                 }
                 ty::Dynamic(binders, _, _) => binders.iter().find_map(|predicate| {
                     if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate.skip_binder()

compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs

@@ -241,7 +241,7 @@ impl IntoArgs for (CrateNum, SimplifiedType) {
 
 provide! { tcx, def_id, other, cdata,
     explicit_item_bounds => { table_defaulted_array }
-    explicit_item_super_predicates => { table_defaulted_array }
+    explicit_item_self_bounds => { table_defaulted_array }
     explicit_predicates_of => { table }
     generics_of => { table }
     inferred_outlives_of => { table_defaulted_array }

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -1554,7 +1554,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
             }
             if let DefKind::OpaqueTy = def_kind {
                 self.encode_explicit_item_bounds(def_id);
-                self.encode_explicit_item_super_predicates(def_id);
+                self.encode_explicit_item_self_bounds(def_id);
                 record!(self.tables.opaque_ty_origin[def_id] <- self.tcx.opaque_ty_origin(def_id));
                 self.encode_precise_capturing_args(def_id);
                 if tcx.is_conditionally_const(def_id) {
@@ -1667,10 +1667,10 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         record_defaulted_array!(self.tables.explicit_item_bounds[def_id] <- bounds);
     }
 
-    fn encode_explicit_item_super_predicates(&mut self, def_id: DefId) {
+    fn encode_explicit_item_self_bounds(&mut self, def_id: DefId) {
-        debug!("EncodeContext::encode_explicit_item_super_predicates({:?})", def_id);
+        debug!("EncodeContext::encode_explicit_item_self_bounds({:?})", def_id);
-        let bounds = self.tcx.explicit_item_super_predicates(def_id).skip_binder();
+        let bounds = self.tcx.explicit_item_self_bounds(def_id).skip_binder();
-        record_defaulted_array!(self.tables.explicit_item_super_predicates[def_id] <- bounds);
+        record_defaulted_array!(self.tables.explicit_item_self_bounds[def_id] <- bounds);
     }
 
     #[instrument(level = "debug", skip(self))]
@@ -1685,7 +1685,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
             AssocItemContainer::Trait => {
                 if let ty::AssocKind::Type = item.kind {
                     self.encode_explicit_item_bounds(def_id);
-                    self.encode_explicit_item_super_predicates(def_id);
+                    self.encode_explicit_item_self_bounds(def_id);
                     if tcx.is_conditionally_const(def_id) {
                         record_defaulted_array!(self.tables.explicit_implied_const_bounds[def_id]
                             <- self.tcx.explicit_implied_const_bounds(def_id).skip_binder());

compiler/rustc_metadata/src/rmeta/mod.rs

@@ -386,7 +386,7 @@ define_tables! {
     // corresponding DefPathHash.
     def_path_hashes: Table<DefIndex, u64>,
     explicit_item_bounds: Table<DefIndex, LazyArray<(ty::Clause<'static>, Span)>>,
-    explicit_item_super_predicates: Table<DefIndex, LazyArray<(ty::Clause<'static>, Span)>>,
+    explicit_item_self_bounds: Table<DefIndex, LazyArray<(ty::Clause<'static>, Span)>>,
     inferred_outlives_of: Table<DefIndex, LazyArray<(ty::Clause<'static>, Span)>>,
     explicit_super_predicates_of: Table<DefIndex, LazyArray<(ty::Clause<'static>, Span)>>,
     explicit_implied_predicates_of: Table<DefIndex, LazyArray<(ty::Clause<'static>, Span)>>,

compiler/rustc_middle/src/query/mod.rs

@@ -393,7 +393,7 @@ rustc_queries! {
     /// like closure signature deduction.
     ///
     /// [explicit item bounds]: Self::explicit_item_bounds
-    query explicit_item_super_predicates(key: DefId) -> ty::EarlyBinder<'tcx, &'tcx [(ty::Clause<'tcx>, Span)]> {
+    query explicit_item_self_bounds(key: DefId) -> ty::EarlyBinder<'tcx, &'tcx [(ty::Clause<'tcx>, Span)]> {
         desc { |tcx| "finding item bounds for `{}`", tcx.def_path_str(key) }
         cache_on_disk_if { key.is_local() }
         separate_provide_extern
@@ -427,11 +427,11 @@ rustc_queries! {
         desc { |tcx| "elaborating item bounds for `{}`", tcx.def_path_str(key) }
     }
 
-    query item_super_predicates(key: DefId) -> ty::EarlyBinder<'tcx, ty::Clauses<'tcx>> {
+    query item_self_bounds(key: DefId) -> ty::EarlyBinder<'tcx, ty::Clauses<'tcx>> {
         desc { |tcx| "elaborating item assumptions for `{}`", tcx.def_path_str(key) }
     }
 
-    query item_non_self_assumptions(key: DefId) -> ty::EarlyBinder<'tcx, ty::Clauses<'tcx>> {
+    query item_non_self_bounds(key: DefId) -> ty::EarlyBinder<'tcx, ty::Clauses<'tcx>> {
         desc { |tcx| "elaborating item assumptions for `{}`", tcx.def_path_str(key) }
     }
 

compiler/rustc_middle/src/ty/context.rs

@@ -345,6 +345,20 @@ impl<'tcx> Interner for TyCtxt<'tcx> {
         self.item_bounds(def_id).map_bound(IntoIterator::into_iter)
     }
 
+    fn item_self_bounds(
+        self,
+        def_id: DefId,
+    ) -> ty::EarlyBinder<'tcx, impl IntoIterator<Item = ty::Clause<'tcx>>> {
+        self.item_self_bounds(def_id).map_bound(IntoIterator::into_iter)
+    }
+
+    fn item_non_self_bounds(
+        self,
+        def_id: DefId,
+    ) -> ty::EarlyBinder<'tcx, impl IntoIterator<Item = ty::Clause<'tcx>>> {
+        self.item_non_self_bounds(def_id).map_bound(IntoIterator::into_iter)
+    }
+
     fn predicates_of(
         self,
         def_id: DefId,
@@ -2577,7 +2591,7 @@ impl<'tcx> TyCtxt<'tcx> {
         let ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. }) = ty.kind() else { return false };
         let future_trait = self.require_lang_item(LangItem::Future, None);
 
-        self.explicit_item_super_predicates(def_id).skip_binder().iter().any(|&(predicate, _)| {
+        self.explicit_item_self_bounds(def_id).skip_binder().iter().any(|&(predicate, _)| {
             let ty::ClauseKind::Trait(trait_predicate) = predicate.kind().skip_binder() else {
                 return false;
             };

compiler/rustc_middle/src/ty/return_position_impl_trait_in_trait.rs

@@ -64,7 +64,7 @@ impl<'tcx> TyCtxt<'tcx> {
         args: ty::GenericArgsRef<'tcx>,
     ) -> &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>> {
         let mut bounds: Vec<_> = self
-            .item_super_predicates(def_id)
+            .item_self_bounds(def_id)
             .iter_instantiated(self, args)
             .filter_map(|clause| {
                 clause

compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs

@@ -19,6 +19,11 @@ use crate::solve::{
     MaybeCause, NoSolution, QueryResult,
 };
 
+enum AliasBoundKind {
+    SelfBounds,
+    NonSelfBounds,
+}
+
 /// A candidate is a possible way to prove a goal.
 ///
 /// It consists of both the `source`, which describes how that goal would be proven,
@@ -510,7 +515,12 @@ where
         candidates: &mut Vec<Candidate<I>>,
     ) {
         let () = self.probe(|_| ProbeKind::NormalizedSelfTyAssembly).enter(|ecx| {
-            ecx.assemble_alias_bound_candidates_recur(goal.predicate.self_ty(), goal, candidates);
+            ecx.assemble_alias_bound_candidates_recur(
+                goal.predicate.self_ty(),
+                goal,
+                candidates,
+                AliasBoundKind::SelfBounds,
+            );
         });
     }
 
@@ -528,6 +538,7 @@ where
         self_ty: I::Ty,
         goal: Goal<I, G>,
         candidates: &mut Vec<Candidate<I>>,
+        consider_self_bounds: AliasBoundKind,
     ) {
         let (kind, alias_ty) = match self_ty.kind() {
             ty::Bool
@@ -580,16 +591,37 @@ where
             }
         };
 
-        for assumption in
+        match consider_self_bounds {
-            self.cx().item_bounds(alias_ty.def_id).iter_instantiated(self.cx(), alias_ty.args)
+            AliasBoundKind::SelfBounds => {
-        {
+                for assumption in self
-            candidates.extend(G::probe_and_consider_implied_clause(
+                    .cx()
-                self,
+                    .item_self_bounds(alias_ty.def_id)
-                CandidateSource::AliasBound,
+                    .iter_instantiated(self.cx(), alias_ty.args)
-                goal,
+                {
-                assumption,
+                    candidates.extend(G::probe_and_consider_implied_clause(
-                [],
+                        self,
-            ));
+                        CandidateSource::AliasBound,
+                        goal,
+                        assumption,
+                        [],
+                    ));
+                }
+            }
+            AliasBoundKind::NonSelfBounds => {
+                for assumption in self
+                    .cx()
+                    .item_non_self_bounds(alias_ty.def_id)
+                    .iter_instantiated(self.cx(), alias_ty.args)
+                {
+                    candidates.extend(G::probe_and_consider_implied_clause(
+                        self,
+                        CandidateSource::AliasBound,
+                        goal,
+                        assumption,
+                        [],
+                    ));
+                }
+            }
         }
 
         candidates.extend(G::consider_additional_alias_assumptions(self, goal, alias_ty));
@@ -600,9 +632,12 @@ where
 
         // Recurse on the self type of the projection.
         match self.structurally_normalize_ty(goal.param_env, alias_ty.self_ty()) {
-            Ok(next_self_ty) => {
+            Ok(next_self_ty) => self.assemble_alias_bound_candidates_recur(
-                self.assemble_alias_bound_candidates_recur(next_self_ty, goal, candidates)
+                next_self_ty,
-            }
+                goal,
+                candidates,
+                AliasBoundKind::NonSelfBounds,
+            ),
             Err(NoSolution) => {}
         }
     }

compiler/rustc_parse_format/src/lib.rs

@@ -16,11 +16,8 @@
 #![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
-use std::{iter, str, string};
-
 pub use Alignment::*;
 pub use Count::*;
-pub use Piece::*;
 pub use Position::*;
 use rustc_lexer::unescape;
 
@@ -86,7 +83,7 @@ impl InnerOffset {
 #[derive(Clone, Debug, PartialEq)]
 pub enum Piece<'a> {
     /// A literal string which should directly be emitted
-    String(&'a str),
+    Lit(&'a str),
     /// This describes that formatting should process the next argument (as
     /// specified inside) for emission.
     NextArgument(Box<Argument<'a>>),
@@ -205,11 +202,11 @@ pub enum Count<'a> {
 }
 
 pub struct ParseError {
-    pub description: string::String,
+    pub description: String,
-    pub note: Option<string::String>,
+    pub note: Option<String>,
-    pub label: string::String,
+    pub label: String,
     pub span: InnerSpan,
-    pub secondary_label: Option<(string::String, InnerSpan)>,
+    pub secondary_label: Option<(String, InnerSpan)>,
     pub suggestion: Suggestion,
 }
 
@@ -225,7 +222,7 @@ pub enum Suggestion {
     /// `format!("{foo:?#}")` -> `format!("{foo:#?}")`
     /// `format!("{foo:?x}")` -> `format!("{foo:x?}")`
     /// `format!("{foo:?X}")` -> `format!("{foo:X?}")`
-    ReorderFormatParameter(InnerSpan, string::String),
+    ReorderFormatParameter(InnerSpan, String),
 }
 
 /// The parser structure for interpreting the input format string. This is
@@ -237,7 +234,7 @@ pub enum Suggestion {
 pub struct Parser<'a> {
     mode: ParseMode,
     input: &'a str,
-    cur: iter::Peekable<str::CharIndices<'a>>,
+    cur: std::iter::Peekable<std::str::CharIndices<'a>>,
     /// Error messages accumulated during parsing
     pub errors: Vec<ParseError>,
     /// Current position of implicit positional argument pointer
@@ -278,7 +275,7 @@ impl<'a> Iterator for Parser<'a> {
                     if self.consume('{') {
                         self.last_opening_brace = curr_last_brace;
 
-                        Some(String(self.string(pos + 1)))
+                        Some(Piece::Lit(self.string(pos + 1)))
                     } else {
                         let arg = self.argument(lbrace_end);
                         if let Some(rbrace_pos) = self.consume_closing_brace(&arg) {
@@ -299,13 +296,13 @@ impl<'a> Iterator for Parser<'a> {
                                 _ => self.suggest_positional_arg_instead_of_captured_arg(arg),
                             }
                         }
-                        Some(NextArgument(Box::new(arg)))
+                        Some(Piece::NextArgument(Box::new(arg)))
                     }
                 }
                 '}' => {
                     self.cur.next();
                     if self.consume('}') {
-                        Some(String(self.string(pos + 1)))
+                        Some(Piece::Lit(self.string(pos + 1)))
                     } else {
                         let err_pos = self.to_span_index(pos);
                         self.err_with_note(
@@ -317,7 +314,7 @@ impl<'a> Iterator for Parser<'a> {
                         None
                     }
                 }
-                _ => Some(String(self.string(pos))),
+                _ => Some(Piece::Lit(self.string(pos))),
             }
         } else {
             if self.is_source_literal {
@@ -336,7 +333,7 @@ impl<'a> Parser<'a> {
     pub fn new(
         s: &'a str,
         style: Option<usize>,
-        snippet: Option<string::String>,
+        snippet: Option<String>,
         append_newline: bool,
         mode: ParseMode,
     ) -> Parser<'a> {
@@ -366,7 +363,7 @@ impl<'a> Parser<'a> {
     /// Notifies of an error. The message doesn't actually need to be of type
     /// String, but I think it does when this eventually uses conditions so it
     /// might as well start using it now.
-    fn err<S1: Into<string::String>, S2: Into<string::String>>(
+    fn err<S1: Into<String>, S2: Into<String>>(
         &mut self,
         description: S1,
         label: S2,
@@ -385,11 +382,7 @@ impl<'a> Parser<'a> {
     /// Notifies of an error. The message doesn't actually need to be of type
     /// String, but I think it does when this eventually uses conditions so it
     /// might as well start using it now.
-    fn err_with_note<
+    fn err_with_note<S1: Into<String>, S2: Into<String>, S3: Into<String>>(
-        S1: Into<string::String>,
-        S2: Into<string::String>,
-        S3: Into<string::String>,
-    >(
         &mut self,
         description: S1,
         label: S2,
@@ -968,7 +961,7 @@ impl<'a> Parser<'a> {
 /// in order to properly synthesise the intra-string `Span`s for error diagnostics.
 fn find_width_map_from_snippet(
     input: &str,
-    snippet: Option<string::String>,
+    snippet: Option<String>,
     str_style: Option<usize>,
 ) -> InputStringKind {
     let snippet = match snippet {
@@ -1083,8 +1076,8 @@ fn find_width_map_from_snippet(
     InputStringKind::Literal { width_mappings }
 }
 
-fn unescape_string(string: &str) -> Option<string::String> {
+fn unescape_string(string: &str) -> Option<String> {
-    let mut buf = string::String::new();
+    let mut buf = String::new();
     let mut ok = true;
     unescape::unescape_unicode(string, unescape::Mode::Str, &mut |_, unescaped_char| {
         match unescaped_char {

compiler/rustc_parse_format/src/tests.rs

@@ -1,3 +1,5 @@
+use Piece::*;
+
 use super::*;
 
 #[track_caller]
@@ -32,12 +34,12 @@ fn musterr(s: &str) {
 
 #[test]
 fn simple() {
-    same("asdf", &[String("asdf")]);
+    same("asdf", &[Lit("asdf")]);
-    same("a{{b", &[String("a"), String("{b")]);
+    same("a{{b", &[Lit("a"), Lit("{b")]);
-    same("a}}b", &[String("a"), String("}b")]);
+    same("a}}b", &[Lit("a"), Lit("}b")]);
-    same("a}}", &[String("a"), String("}")]);
+    same("a}}", &[Lit("a"), Lit("}")]);
-    same("}}", &[String("}")]);
+    same("}}", &[Lit("}")]);
-    same("\\}}", &[String("\\"), String("}")]);
+    same("\\}}", &[Lit("\\"), Lit("}")]);
 }
 
 #[test]
@@ -370,7 +372,7 @@ fn format_flags() {
 #[test]
 fn format_mixture() {
     same("abcd {3:x} efg", &[
-        String("abcd "),
+        Lit("abcd "),
         NextArgument(Box::new(Argument {
             position: ArgumentIs(3),
             position_span: InnerSpan { start: 7, end: 8 },
@@ -390,7 +392,7 @@ fn format_mixture() {
                 ty_span: None,
             },
         })),
-        String(" efg"),
+        Lit(" efg"),
     ]);
 }
 #[test]

compiler/rustc_resolve/src/def_collector.rs

@@ -170,9 +170,12 @@ impl<'a, 'ra, 'tcx> visit::Visitor<'a> for DefCollector<'a, 'ra, 'tcx> {
 
     fn visit_fn(&mut self, fn_kind: FnKind<'a>, span: Span, _: NodeId) {
         match fn_kind {
-            FnKind::Fn(_ctxt, _ident, FnSig { header, decl, span: _ }, _vis, generics, body)
+            FnKind::Fn(
-                if let Some(coroutine_kind) = header.coroutine_kind =>
+                _ctxt,
-            {
+                _ident,
+                _vis,
+                Fn { sig: FnSig { header, decl, span: _ }, generics, body, .. },
+            ) if let Some(coroutine_kind) = header.coroutine_kind => {
                 self.visit_fn_header(header);
                 self.visit_generics(generics);
 

compiler/rustc_resolve/src/late.rs

@@ -986,8 +986,8 @@ impl<'ra: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'_, 'ast, 'r
         match fn_kind {
             // Bail if the function is foreign, and thus cannot validly have
             // a body, or if there's no body for some other reason.
-            FnKind::Fn(FnCtxt::Foreign, _, sig, _, generics, _)
+            FnKind::Fn(FnCtxt::Foreign, _, _, Fn { sig, generics, .. })
-            | FnKind::Fn(_, _, sig, _, generics, None) => {
+            | FnKind::Fn(_, _, _, Fn { sig, generics, body: None, .. }) => {
                 self.visit_fn_header(&sig.header);
                 self.visit_generics(generics);
                 self.with_lifetime_rib(
@@ -1019,7 +1019,7 @@ impl<'ra: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'_, 'ast, 'r
             // Create a label rib for the function.
             this.with_label_rib(RibKind::FnOrCoroutine, |this| {
                 match fn_kind {
-                    FnKind::Fn(_, _, sig, _, generics, body) => {
+                    FnKind::Fn(_, _, _, Fn { sig, generics, body, .. }) => {
                         this.visit_generics(generics);
 
                         let declaration = &sig.decl;

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -224,7 +224,7 @@ impl<'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                 let suggestion = if self.current_trait_ref.is_none()
                     && let Some((fn_kind, _)) = self.diag_metadata.current_function
                     && let Some(FnCtxt::Assoc(_)) = fn_kind.ctxt()
-                    && let FnKind::Fn(_, _, sig, ..) = fn_kind
+                    && let FnKind::Fn(_, _, _, ast::Fn { sig, .. }) = fn_kind
                     && let Some(items) = self.diag_metadata.current_impl_items
                     && let Some(item) = items.iter().find(|i| {
                         i.ident.name == item_str.name
@@ -560,7 +560,7 @@ impl<'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                 Applicability::MaybeIncorrect,
             );
             if !self.self_value_is_available(path[0].ident.span) {
-                if let Some((FnKind::Fn(_, _, sig, ..), fn_span)) =
+                if let Some((FnKind::Fn(_, _, _, ast::Fn { sig, .. }), fn_span)) =
                     &self.diag_metadata.current_function
                 {
                     let (span, sugg) = if let Some(param) = sig.decl.inputs.get(0) {
@@ -3249,7 +3249,7 @@ impl<'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                     {
                         let pre = if lt.kind == MissingLifetimeKind::Ampersand
                             && let Some((kind, _span)) = self.diag_metadata.current_function
-                            && let FnKind::Fn(_, _, sig, _, _, _) = kind
+                            && let FnKind::Fn(_, _, _, ast::Fn { sig, .. }) = kind
                             && !sig.decl.inputs.is_empty()
                             && let sugg = sig
                                 .decl
@@ -3290,7 +3290,7 @@ impl<'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                         } else if (lt.kind == MissingLifetimeKind::Ampersand
                             || lt.kind == MissingLifetimeKind::Underscore)
                             && let Some((kind, _span)) = self.diag_metadata.current_function
-                            && let FnKind::Fn(_, _, sig, _, _, _) = kind
+                            && let FnKind::Fn(_, _, _, ast::Fn { sig, .. }) = kind
                             && let ast::FnRetTy::Ty(ret_ty) = &sig.decl.output
                             && !sig.decl.inputs.is_empty()
                             && let arg_refs = sig
@@ -3350,7 +3350,7 @@ impl<'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                         let mut owned_sugg = lt.kind == MissingLifetimeKind::Ampersand;
                         let mut sugg = vec![(lt.span, String::new())];
                         if let Some((kind, _span)) = self.diag_metadata.current_function
-                            && let FnKind::Fn(_, _, sig, _, _, _) = kind
+                            && let FnKind::Fn(_, _, _, ast::Fn { sig, .. }) = kind
                             && let ast::FnRetTy::Ty(ty) = &sig.decl.output
                         {
                             let mut lt_finder =

compiler/rustc_target/src/target_features.rs

@@ -108,21 +108,19 @@ impl Stability {
 // per-function level, since we would then allow safe calls from functions with `+soft-float` to
 // functions without that feature!
 //
-// It is important for soundness that features allowed here do *not* change the function call ABI.
+// It is important for soundness to consider the interaction of targets features and the function
-// For example, disabling the `x87` feature on x86 changes how scalar floats are passed as
+// call ABI. For example, disabling the `x87` feature on x86 changes how scalar floats are passed as
-// arguments, so enabling toggling that feature would be unsound. In fact, since `-Ctarget-feature`
+// arguments, so letting people toggle that feature would be unsound. To this end, the
-// will just allow unknown features (with a warning), we have to explicitly list features that change
+// `abi_required_features` function computes which target features must and must not be enabled for
-// the ABI as `Forbidden` to ensure using them causes an error. Note that this is only effective if
+// any given target, and individual features can also be marked as `Forbidden`.
-// such features can never be toggled via `-Ctarget-cpu`! If that is ever a possibility, we will need
+// See https://github.com/rust-lang/rust/issues/116344 for some more context.
-// extra checks ensuring that the LLVM-computed target features for a CPU did not (un)set a
-// `Forbidden` feature. See https://github.com/rust-lang/rust/issues/116344 for some more context.
-// FIXME: add such "forbidden" features for non-x86 targets.
 //
 // The one exception to features that change the ABI is features that enable larger vector
-// registers. Those are permitted to be listed here. This is currently unsound (see
+// registers. Those are permitted to be listed here. The `*_FOR_CORRECT_VECTOR_ABI` arrays store
-// https://github.com/rust-lang/rust/issues/116558); in the future we will have to ensure that
+// information about which target feature is ABI-required for which vector size; this is used to
-// functions can only use such vectors as arguments/return types if the corresponding target feature
+// ensure that vectors can only be passed via `extern "C"` when the right feature is enabled. (For
-// is enabled.
+// the "Rust" ABI we generally pass vectors by-ref exactly to avoid these issues.)
+// Also see https://github.com/rust-lang/rust/issues/116558.
 //
 // Stabilizing a target feature requires t-lang approval.
 

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

@@ -196,7 +196,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         let item_def_id = self.tcx.associated_item_def_ids(future_trait)[0];
 
         self.tcx
-            .explicit_item_super_predicates(def_id)
+            .explicit_item_self_bounds(def_id)
             .iter_instantiated_copied(self.tcx, args)
             .find_map(|(predicate, _)| {
                 predicate

compiler/rustc_trait_selection/src/error_reporting/infer/note_and_explain.rs

@@ -293,7 +293,7 @@ impl<T> Trait<T> for X {
                     (ty::Dynamic(t, _, ty::DynKind::Dyn), ty::Alias(ty::Opaque, alias))
                         if let Some(def_id) = t.principal_def_id()
                             && tcx
-                                .explicit_item_super_predicates(alias.def_id)
+                                .explicit_item_self_bounds(alias.def_id)
                                 .skip_binder()
                                 .iter()
                                 .any(|(pred, _span)| match pred.kind().skip_binder() {
@@ -422,7 +422,7 @@ impl<T> Trait<T> for X {
                             ty::Alias(..) => values.expected,
                             _ => values.found,
                         };
-                        let preds = tcx.explicit_item_super_predicates(opaque_ty.def_id);
+                        let preds = tcx.explicit_item_self_bounds(opaque_ty.def_id);
                         for (pred, _span) in preds.skip_binder() {
                             let ty::ClauseKind::Trait(trait_predicate) = pred.kind().skip_binder()
                             else {

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

@@ -799,7 +799,7 @@ impl<'tcx> OnUnimplementedFormatString {
         let mut result = Ok(());
         for token in &mut parser {
             match token {
-                Piece::String(_) => (), // Normal string, no need to check it
+                Piece::Lit(_) => (), // Normal string, no need to check it
                 Piece::NextArgument(a) => {
                     let format_spec = a.format;
                     if self.is_diagnostic_namespace_variant
@@ -950,7 +950,7 @@ impl<'tcx> OnUnimplementedFormatString {
         let item_context = (options.get(&sym::ItemContext)).unwrap_or(&empty_string);
         let constructed_message = (&mut parser)
             .map(|p| match p {
-                Piece::String(s) => s.to_owned(),
+                Piece::Lit(s) => s.to_owned(),
                 Piece::NextArgument(a) => match a.position {
                     Position::ArgumentNamed(arg) => {
                         let s = Symbol::intern(arg);

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

@@ -1087,28 +1087,27 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                         sig_parts.map_bound(|sig| sig.tupled_inputs_ty.tuple_fields().as_slice()),
                     ))
                 }
-                ty::Alias(ty::Opaque, ty::AliasTy { def_id, args, .. }) => self
+                ty::Alias(ty::Opaque, ty::AliasTy { def_id, args, .. }) => {
-                    .tcx
+                    self.tcx.item_self_bounds(def_id).instantiate(self.tcx, args).iter().find_map(
-                    .item_super_predicates(def_id)
+                        |pred| {
-                    .instantiate(self.tcx, args)
+                            if let ty::ClauseKind::Projection(proj) = pred.kind().skip_binder()
-                    .iter()
-                    .find_map(|pred| {
-                        if let ty::ClauseKind::Projection(proj) = pred.kind().skip_binder()
                             && self
                                 .tcx
                                 .is_lang_item(proj.projection_term.def_id, LangItem::FnOnceOutput)
                             // args tuple will always be args[1]
                             && let ty::Tuple(args) = proj.projection_term.args.type_at(1).kind()
-                        {
+                            {
-                            Some((
+                                Some((
-                                DefIdOrName::DefId(def_id),
+                                    DefIdOrName::DefId(def_id),
-                                pred.kind().rebind(proj.term.expect_type()),
+                                    pred.kind().rebind(proj.term.expect_type()),
-                                pred.kind().rebind(args.as_slice()),
+                                    pred.kind().rebind(args.as_slice()),
-                            ))
+                                ))
-                        } else {
+                            } else {
-                            None
+                                None
-                        }
+                            }
-                    }),
+                        },
+                    )
+                }
                 ty::Dynamic(data, _, ty::Dyn) => data.iter().find_map(|pred| {
                     if let ty::ExistentialPredicate::Projection(proj) = pred.skip_binder()
                         && self.tcx.is_lang_item(proj.def_id, LangItem::FnOnceOutput)

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

@@ -1620,9 +1620,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             // projections, we will never be able to equate, e.g. `<T as Tr>::A`
             // with `<<T as Tr>::A as Tr>::A`.
             let relevant_bounds = if in_parent_alias_type {
-                self.tcx().item_non_self_assumptions(alias_ty.def_id)
+                self.tcx().item_non_self_bounds(alias_ty.def_id)
             } else {
-                self.tcx().item_super_predicates(alias_ty.def_id)
+                self.tcx().item_self_bounds(alias_ty.def_id)
             };
 
             for bound in relevant_bounds.instantiate(self.tcx(), alias_ty.args) {

compiler/rustc_type_ir/src/interner.rs

@@ -203,6 +203,16 @@ pub trait Interner:
         def_id: Self::DefId,
     ) -> ty::EarlyBinder<Self, impl IntoIterator<Item = Self::Clause>>;
 
+    fn item_self_bounds(
+        self,
+        def_id: Self::DefId,
+    ) -> ty::EarlyBinder<Self, impl IntoIterator<Item = Self::Clause>>;
+
+    fn item_non_self_bounds(
+        self,
+        def_id: Self::DefId,
+    ) -> ty::EarlyBinder<Self, impl IntoIterator<Item = Self::Clause>>;
+
     fn predicates_of(
         self,
         def_id: Self::DefId,

library/core/src/macros/mod.rs

@@ -313,6 +313,17 @@ pub macro cfg_match {
 ///     }
 /// }
 /// ```
+///
+/// If desired, it is possible to return expressions through the use of surrounding braces:
+///
+/// ```
+/// #![feature(cfg_match)]
+///
+/// let _some_string = cfg_match! {{
+///     unix => { "With great power comes great electricity bills" }
+///     _ => { "Behind every successful diet is an unwatched pizza" }
+/// }};
+/// ```
 #[cfg(not(bootstrap))]
 #[unstable(feature = "cfg_match", issue = "115585")]
 #[rustc_diagnostic_item = "cfg_match"]

src/doc/book

@@ -1 +1 @@
-Subproject commit 82a4a49789bc96db1a1b2a210b4c5ed7c9ef0c0d
+Subproject commit fa312a343fbff01bc6cef393e326817f70719813

src/doc/edition-guide

@@ -1 +1 @@
-Subproject commit d56e0f3a0656b7702ca466d4b191e16c28262b82
+Subproject commit 4ed5a1a4a2a7ecc2e529a5baaef04f7bc7917eda

src/doc/nomicon

@@ -1 +1 @@
-Subproject commit 625b200e5b33a5af35589db0bc454203a3d46d20
+Subproject commit bc2298865544695c63454fc1f9f98a3dc22e9948

src/doc/reference

@@ -1 +1 @@
-Subproject commit 293af991003772bdccf2d6b980182d84dd055942
+Subproject commit 93b921c7d3213d38d920f7f905a3bec093d2217d

src/tools/clippy/clippy_lints/src/future_not_send.rs

@@ -79,7 +79,7 @@ impl<'tcx> LateLintPass<'tcx> for FutureNotSend {
             && let Some(future_trait) = cx.tcx.lang_items().future_trait()
             && let Some(send_trait) = cx.tcx.get_diagnostic_item(sym::Send)
         {
-            let preds = cx.tcx.explicit_item_super_predicates(def_id);
+            let preds = cx.tcx.explicit_item_self_bounds(def_id);
             let is_future = preds.iter_instantiated_copied(cx.tcx, args).any(|(p, _)| {
                 p.as_trait_clause()
                     .is_some_and(|trait_pred| trait_pred.skip_binder().trait_ref.def_id == future_trait)

src/tools/clippy/clippy_lints/src/multiple_bound_locations.rs

@@ -1,5 +1,5 @@
 use rustc_ast::visit::FnKind;
-use rustc_ast::{NodeId, WherePredicateKind};
+use rustc_ast::{Fn, NodeId, WherePredicateKind};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_lint::{EarlyContext, EarlyLintPass};
 use rustc_session::declare_lint_pass;
@@ -39,7 +39,7 @@ declare_lint_pass!(MultipleBoundLocations => [MULTIPLE_BOUND_LOCATIONS]);
 
 impl EarlyLintPass for MultipleBoundLocations {
     fn check_fn(&mut self, cx: &EarlyContext<'_>, kind: FnKind<'_>, _: Span, _: NodeId) {
-        if let FnKind::Fn(_, _, _, _, generics, _) = kind
+        if let FnKind::Fn(_, _, _, Fn { generics, .. }) = kind
             && !generics.params.is_empty()
             && !generics.where_clause.predicates.is_empty()
         {

src/tools/clippy/clippy_utils/src/ty/mod.rs

@@ -96,7 +96,7 @@ pub fn contains_ty_adt_constructor_opaque<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'
                         return false;
                     }
 
-                    for (predicate, _span) in cx.tcx.explicit_item_super_predicates(def_id).iter_identity_copied() {
+                    for (predicate, _span) in cx.tcx.explicit_item_self_bounds(def_id).iter_identity_copied() {
                         match predicate.kind().skip_binder() {
                             // For `impl Trait<U>`, it will register a predicate of `T: Trait<U>`, so we go through
                             // and check substitutions to find `U`.
@@ -322,7 +322,7 @@ pub fn is_must_use_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
         },
         ty::Tuple(args) => args.iter().any(|ty| is_must_use_ty(cx, ty)),
         ty::Alias(ty::Opaque, AliasTy { def_id, .. }) => {
-            for (predicate, _) in cx.tcx.explicit_item_super_predicates(def_id).skip_binder() {
+            for (predicate, _) in cx.tcx.explicit_item_self_bounds(def_id).skip_binder() {
                 if let ty::ClauseKind::Trait(trait_predicate) = predicate.kind().skip_binder() {
                     if cx.tcx.has_attr(trait_predicate.trait_ref.def_id, sym::must_use) {
                         return true;
@@ -712,7 +712,7 @@ pub fn ty_sig<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option<ExprFnSig<'t
         ty::Alias(ty::Opaque, AliasTy { def_id, args, .. }) => sig_from_bounds(
             cx,
             ty,
-            cx.tcx.item_super_predicates(def_id).iter_instantiated(cx.tcx, args),
+            cx.tcx.item_self_bounds(def_id).iter_instantiated(cx.tcx, args),
             cx.tcx.opt_parent(def_id),
         ),
         ty::FnPtr(sig_tys, hdr) => Some(ExprFnSig::Sig(sig_tys.with(hdr), None)),

src/tools/miri/tests/pass/shims/x86/intrinsics-x86-pause-without-sse2.rs

@@ -1,5 +1,5 @@
-// We're testing x86 target specific features
+// We're testing x86-32 target specific features. SSE always exists on x86-64.
-//@only-target: x86_64 i686
+//@only-target: i686
 //@compile-flags: -C target-feature=-sse2
 
 #[cfg(target_arch = "x86")]

src/tools/rust-analyzer/crates/hir-def/src/body/lower/asm.rs

@@ -229,7 +229,7 @@ impl ExprCollector<'_> {
                     };
                     for piece in unverified_pieces {
                         match piece {
-                            rustc_parse_format::Piece::String(_) => {}
+                            rustc_parse_format::Piece::Lit(_) => {}
                             rustc_parse_format::Piece::NextArgument(arg) => {
                                 // let span = arg_spans.next();
 

src/tools/rust-analyzer/crates/hir-def/src/hir/format_args.rs

@@ -287,7 +287,7 @@ pub(crate) fn parse(
 
     for piece in pieces {
         match piece {
-            parse::Piece::String(s) => {
+            parse::Piece::Lit(s) => {
                 unfinished_literal.push_str(s);
             }
             parse::Piece::NextArgument(arg) => {

src/tools/rustfmt/src/items.rs

@@ -333,19 +333,19 @@ impl<'a> FnSig<'a> {
         defaultness: ast::Defaultness,
     ) -> FnSig<'a> {
         match *fn_kind {
-            visit::FnKind::Fn(visit::FnCtxt::Assoc(..), _, fn_sig, vis, generics, _) => {
+            visit::FnKind::Fn(visit::FnCtxt::Assoc(..), _, vis, ast::Fn { sig, generics, .. }) => {
-                let mut fn_sig = FnSig::from_method_sig(fn_sig, generics, vis);
+                let mut fn_sig = FnSig::from_method_sig(sig, generics, vis);
                 fn_sig.defaultness = defaultness;
                 fn_sig
             }
-            visit::FnKind::Fn(_, _, fn_sig, vis, generics, _) => FnSig {
+            visit::FnKind::Fn(_, _, vis, ast::Fn { sig, generics, .. }) => FnSig {
                 decl,
                 generics,
-                ext: fn_sig.header.ext,
+                ext: sig.header.ext,
-                constness: fn_sig.header.constness,
+                constness: sig.header.constness,
-                coroutine_kind: Cow::Borrowed(&fn_sig.header.coroutine_kind),
+                coroutine_kind: Cow::Borrowed(&sig.header.coroutine_kind),
                 defaultness,
-                safety: fn_sig.header.safety,
+                safety: sig.header.safety,
                 visibility: vis,
             },
             _ => unreachable!(),
@@ -3453,6 +3453,7 @@ impl Rewrite for ast::ForeignItem {
                     ref sig,
                     ref generics,
                     ref body,
+                    ..
                 } = **fn_kind;
                 if body.is_some() {
                     let mut visitor = FmtVisitor::from_context(context);
@@ -3461,7 +3462,7 @@ impl Rewrite for ast::ForeignItem {
                     let inner_attrs = inner_attributes(&self.attrs);
                     let fn_ctxt = visit::FnCtxt::Foreign;
                     visitor.visit_fn(
-                        visit::FnKind::Fn(fn_ctxt, &self.ident, sig, &self.vis, generics, body),
+                        visit::FnKind::Fn(fn_ctxt, &self.ident, &self.vis, fn_kind),
                         &sig.decl,
                         self.span,
                         defaultness,

src/tools/rustfmt/src/visitor.rs

@@ -386,7 +386,14 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
         let indent = self.block_indent;
         let block;
         let rewrite = match fk {
-            visit::FnKind::Fn(_, ident, _, _, _, Some(ref b)) => {
+            visit::FnKind::Fn(
+                _,
+                ident,
+                _,
+                ast::Fn {
+                    body: Some(ref b), ..
+                },
+            ) => {
                 block = b;
                 self.rewrite_fn_before_block(
                     indent,
@@ -539,6 +546,7 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
                         ref sig,
                         ref generics,
                         ref body,
+                        ..
                     } = **fn_kind;
                     if body.is_some() {
                         let inner_attrs = inner_attributes(&item.attrs);
@@ -547,7 +555,7 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
                             _ => visit::FnCtxt::Foreign,
                         };
                         self.visit_fn(
-                            visit::FnKind::Fn(fn_ctxt, &item.ident, sig, &item.vis, generics, body),
+                            visit::FnKind::Fn(fn_ctxt, &item.ident, &item.vis, fn_kind),
                             &sig.decl,
                             item.span,
                             defaultness,
@@ -640,12 +648,13 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
                     ref sig,
                     ref generics,
                     ref body,
+                    ..
                 } = **fn_kind;
                 if body.is_some() {
                     let inner_attrs = inner_attributes(&ai.attrs);
                     let fn_ctxt = visit::FnCtxt::Assoc(assoc_ctxt);
                     self.visit_fn(
-                        visit::FnKind::Fn(fn_ctxt, &ai.ident, sig, &ai.vis, generics, body),
+                        visit::FnKind::Fn(fn_ctxt, &ai.ident, &ai.vis, fn_kind),
                         &sig.decl,
                         ai.span,
                         defaultness,

tests/codegen/target-feature-overrides.rs

@@ -39,8 +39,8 @@ pub unsafe fn banana() -> u32 {
 }
 
 // CHECK: attributes [[APPLEATTRS]]
-// COMPAT-SAME: "target-features"="+x87,+sse2,+avx,+avx2,{{.*}}"
+// COMPAT-SAME: "target-features"="+avx,+avx2,{{.*}}"
-// INCOMPAT-SAME: "target-features"="+x87,+sse2,-avx2,-avx,+avx,{{.*}}"
+// INCOMPAT-SAME: "target-features"="-avx2,-avx,+avx,{{.*}}"
 // CHECK: attributes [[BANANAATTRS]]
-// COMPAT-SAME: "target-features"="+x87,+sse2,+avx,+avx2,{{.*}}"
+// COMPAT-SAME: "target-features"="+avx,+avx2,{{.*}}"
-// INCOMPAT-SAME: "target-features"="+x87,+sse2,-avx2,-avx"
+// INCOMPAT-SAME: "target-features"="-avx2,-avx"

tests/codegen/tied-features-strength.rs

@@ -11,11 +11,10 @@
 // ENABLE_SVE: attributes #0 = { {{.*}} "target-features"="{{((\+outline-atomics,?)|(\+v8a,?)|(\+fpmr,?)?|(\+sve,?)|(\+neon,?)|(\+fp-armv8,?))*}}" }
 
 //@ [DISABLE_SVE] compile-flags: -C target-feature=-sve -Copt-level=0
-// DISABLE_SVE: attributes #0 = { {{.*}} "target-features"="{{((\+outline-atomics,?)|(\+v8a,?)|(\+fpmr,?)?|(-sve,?)|(\+neon,?)|(\+fp-armv8,?))*}}" }
+// DISABLE_SVE: attributes #0 = { {{.*}} "target-features"="{{((\+outline-atomics,?)|(\+v8a,?)|(\+fpmr,?)?|(-sve,?)|(\+neon,?))*}}" }
 
 //@ [DISABLE_NEON] compile-flags: -C target-feature=-neon -Copt-level=0
-// `neon` and `fp-armv8` get enabled as target base features, but then disabled again at the end of the list.
+// DISABLE_NEON: attributes #0 = { {{.*}} "target-features"="{{((\+outline-atomics,?)|(\+v8a,?)|(\+fpmr,?)?|(-fp-armv8,?)|(-neon,?))*}}" }
-// DISABLE_NEON: attributes #0 = { {{.*}} "target-features"="{{((\+outline-atomics,?)|(\+v8a,?)|(\+fp-armv8,?)|(\+neon,?))*}},-neon,-fp-armv8{{(,\+fpmr)?}}" }
 
 //@ [ENABLE_NEON] compile-flags: -C target-feature=+neon -Copt-level=0
 // ENABLE_NEON: attributes #0 = { {{.*}} "target-features"="{{((\+outline-atomics,?)|(\+v8a,?)|(\+fpmr,?)?|(\+fp-armv8,?)|(\+neon,?))*}}" }

tests/ui-fulldeps/codegen-backend/hotplug.rs

@@ -6,6 +6,10 @@
 //@ normalize-stdout: "libthe_backend.dylib" -> "libthe_backend.so"
 //@ normalize-stdout: "the_backend.dll" -> "libthe_backend.so"
 
+// Pick a target that requires no target features, so that no warning is shown
+// about missing target features.
+//@ compile-flags: --target arm-unknown-linux-gnueabi
+//@ needs-llvm-components: arm
 //@ revisions: normal dep bindep
 //@ compile-flags: --crate-type=lib
 //@ [normal] compile-flags: --emit=link=-

tests/ui/associated-type-bounds/cant-see-copy-bound-from-child-rigid.current.stderr

@@ -1,5 +1,5 @@
 error[E0382]: use of moved value: `x`
-  --> $DIR/cant-see-copy-bound-from-child-rigid.rs:14:9
+  --> $DIR/cant-see-copy-bound-from-child-rigid.rs:18:9
    |
 LL | fn foo<T: Trait>(x: T::Assoc) -> (T::Assoc, T::Assoc)
    |                  - move occurs because `x` has type `<T as Trait>::Assoc`, which does not implement the `Copy` trait

tests/ui/associated-type-bounds/cant-see-copy-bound-from-child-rigid.next.stderr

@@ -0,0 +1,14 @@
+error[E0382]: use of moved value: `x`
+  --> $DIR/cant-see-copy-bound-from-child-rigid.rs:18:9
+   |
+LL | fn foo<T: Trait>(x: T::Assoc) -> (T::Assoc, T::Assoc)
+   |                  - move occurs because `x` has type `<T as Trait>::Assoc`, which does not implement the `Copy` trait
+...
+LL |     (x, x)
+   |      -  ^ value used here after move
+   |      |
+   |      value moved here
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0382`.

tests/ui/associated-type-bounds/cant-see-copy-bound-from-child-rigid.rs

@@ -1,3 +1,7 @@
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
+
 trait Id {
     type This: ?Sized;
 }

tests/ui/target-feature/feature-hierarchy.aarch64-sve2.stderr

@@ -1,7 +0,0 @@
-warning: target feature `neon` cannot be disabled with `-Ctarget-feature`: this feature is required by the target ABI
-   |
-   = note: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-   = note: for more information, see issue #116344 <https://github.com/rust-lang/rust/issues/116344>
-
-warning: 1 warning emitted
-

tests/ui/target-feature/forbidden-hardfloat-target-feature-flag-disable-implied.stderr

@@ -1,4 +1,4 @@
-warning: target feature `sse` cannot be disabled with `-Ctarget-feature`: this feature is required by the target ABI
+warning: target feature `sse2` must be enabled to ensure that the ABI of the current target can be implemented correctly
    |
    = note: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #116344 <https://github.com/rust-lang/rust/issues/116344>

tests/ui/target-feature/forbidden-hardfloat-target-feature-flag-disable-neon.stderr

@@ -1,4 +1,4 @@
-warning: target feature `neon` cannot be disabled with `-Ctarget-feature`: this feature is required by the target ABI
+warning: target feature `neon` must be enabled to ensure that the ABI of the current target can be implemented correctly
    |
    = note: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #116344 <https://github.com/rust-lang/rust/issues/116344>

tests/ui/target-feature/forbidden-hardfloat-target-feature-flag-disable.stderr

@@ -1,11 +1,11 @@
-warning: unstable feature specified for `-Ctarget-feature`: `x87`
+warning: target feature `x87` must be enabled to ensure that the ABI of the current target can be implemented correctly
-   |
-   = note: this feature is not stably supported; its behavior can change in the future
-
-warning: target feature `x87` cannot be disabled with `-Ctarget-feature`: this feature is required by the target ABI
    |
    = note: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #116344 <https://github.com/rust-lang/rust/issues/116344>
 
+warning: unstable feature specified for `-Ctarget-feature`: `x87`
+   |
+   = note: this feature is not stably supported; its behavior can change in the future
+
 warning: 2 warnings emitted
 

tests/ui/traits/const-traits/const-impl-trait.stderr

@@ -99,26 +99,6 @@ note: `PartialEq` can't be used with `~const` because it isn't annotated with `#
   --> $SRC_DIR/core/src/cmp.rs:LL:COL
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
-error: `~const` can only be applied to `#[const_trait]` traits
-  --> $DIR/const-impl-trait.rs:23:22
-   |
-LL |     fn huh() -> impl ~const PartialEq + ~const Destruct + Copy;
-   |                      ^^^^^^ can't be applied to `PartialEq`
-   |
-note: `PartialEq` can't be used with `~const` because it isn't annotated with `#[const_trait]`
-  --> $SRC_DIR/core/src/cmp.rs:LL:COL
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error: `~const` can only be applied to `#[const_trait]` traits
-  --> $DIR/const-impl-trait.rs:23:22
-   |
-LL |     fn huh() -> impl ~const PartialEq + ~const Destruct + Copy;
-   |                      ^^^^^^ can't be applied to `PartialEq`
-   |
-note: `PartialEq` can't be used with `~const` because it isn't annotated with `#[const_trait]`
-  --> $SRC_DIR/core/src/cmp.rs:LL:COL
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
 error: `~const` can only be applied to `#[const_trait]` traits
   --> $DIR/const-impl-trait.rs:27:22
    |
@@ -149,6 +129,36 @@ note: `PartialEq` can't be used with `~const` because it isn't annotated with `#
   --> $SRC_DIR/core/src/cmp.rs:LL:COL
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
+error: `~const` can only be applied to `#[const_trait]` traits
+  --> $DIR/const-impl-trait.rs:23:22
+   |
+LL |     fn huh() -> impl ~const PartialEq + ~const Destruct + Copy;
+   |                      ^^^^^^ can't be applied to `PartialEq`
+   |
+note: `PartialEq` can't be used with `~const` because it isn't annotated with `#[const_trait]`
+  --> $SRC_DIR/core/src/cmp.rs:LL:COL
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error: `~const` can only be applied to `#[const_trait]` traits
+  --> $DIR/const-impl-trait.rs:23:22
+   |
+LL |     fn huh() -> impl ~const PartialEq + ~const Destruct + Copy;
+   |                      ^^^^^^ can't be applied to `PartialEq`
+   |
+note: `PartialEq` can't be used with `~const` because it isn't annotated with `#[const_trait]`
+  --> $SRC_DIR/core/src/cmp.rs:LL:COL
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error: `~const` can only be applied to `#[const_trait]` traits
+  --> $DIR/const-impl-trait.rs:23:22
+   |
+LL |     fn huh() -> impl ~const PartialEq + ~const Destruct + Copy;
+   |                      ^^^^^^ can't be applied to `PartialEq`
+   |
+note: `PartialEq` can't be used with `~const` because it isn't annotated with `#[const_trait]`
+  --> $SRC_DIR/core/src/cmp.rs:LL:COL
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
 error[E0015]: cannot call non-const operator in constants
   --> $DIR/const-impl-trait.rs:35:13
    |
@@ -181,7 +191,7 @@ LL |     a == a
    |
    = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants
 
-error: aborting due to 20 previous errors
+error: aborting due to 21 previous errors
 
 Some errors have detailed explanations: E0015, E0635.
 For more information about an error, try `rustc --explain E0015`.