diff --git a/compiler/rustc_ast/src/ast.rs b/compiler/rustc_ast/src/ast.rs
index 5b5ffe11379a..ecb6ef5a2a64 100644
--- a/compiler/rustc_ast/src/ast.rs
+++ b/compiler/rustc_ast/src/ast.rs
@@ -39,7 +39,9 @@
 use crate::ptr::P;
 use crate::token::{self, CommentKind, Delimiter};
 use crate::tokenstream::{DelimSpan, LazyAttrTokenStream, TokenStream};
-pub use crate::util::parser::ExprPrecedence;
+use crate::util::parser::{
+    AssocOp, PREC_CLOSURE, PREC_JUMP, PREC_PREFIX, PREC_RANGE, PREC_UNAMBIGUOUS,
+};
 
 /// A "Label" is an identifier of some point in sources,
 /// e.g. in the following code:
@@ -1314,53 +1316,71 @@ pub fn to_ty(&self) -> Option<P<Ty>> {
         Some(P(Ty { kind, id: self.id, span: self.span, tokens: None }))
     }
 
-    pub fn precedence(&self) -> ExprPrecedence {
+    pub fn precedence(&self) -> i8 {
         match self.kind {
-            ExprKind::Array(_) => ExprPrecedence::Array,
-            ExprKind::ConstBlock(_) => ExprPrecedence::ConstBlock,
-            ExprKind::Call(..) => ExprPrecedence::Call,
-            ExprKind::MethodCall(..) => ExprPrecedence::MethodCall,
-            ExprKind::Tup(_) => ExprPrecedence::Tup,
-            ExprKind::Binary(op, ..) => ExprPrecedence::Binary(op.node),
-            ExprKind::Unary(..) => ExprPrecedence::Unary,
-            ExprKind::Lit(_) | ExprKind::IncludedBytes(..) => ExprPrecedence::Lit,
-            ExprKind::Cast(..) => ExprPrecedence::Cast,
-            ExprKind::Let(..) => ExprPrecedence::Let,
-            ExprKind::If(..) => ExprPrecedence::If,
-            ExprKind::While(..) => ExprPrecedence::While,
-            ExprKind::ForLoop { .. } => ExprPrecedence::ForLoop,
-            ExprKind::Loop(..) => ExprPrecedence::Loop,
-            ExprKind::Match(_, _, MatchKind::Prefix) => ExprPrecedence::Match,
-            ExprKind::Match(_, _, MatchKind::Postfix) => ExprPrecedence::PostfixMatch,
-            ExprKind::Closure(..) => ExprPrecedence::Closure,
-            ExprKind::Block(..) => ExprPrecedence::Block,
-            ExprKind::TryBlock(..) => ExprPrecedence::TryBlock,
-            ExprKind::Gen(..) => ExprPrecedence::Gen,
-            ExprKind::Await(..) => ExprPrecedence::Await,
-            ExprKind::Assign(..) => ExprPrecedence::Assign,
-            ExprKind::AssignOp(..) => ExprPrecedence::AssignOp,
-            ExprKind::Field(..) => ExprPrecedence::Field,
-            ExprKind::Index(..) => ExprPrecedence::Index,
-            ExprKind::Range(..) => ExprPrecedence::Range,
-            ExprKind::Underscore => ExprPrecedence::Path,
-            ExprKind::Path(..) => ExprPrecedence::Path,
-            ExprKind::AddrOf(..) => ExprPrecedence::AddrOf,
-            ExprKind::Break(..) => ExprPrecedence::Break,
-            ExprKind::Continue(..) => ExprPrecedence::Continue,
-            ExprKind::Ret(..) => ExprPrecedence::Ret,
-            ExprKind::Struct(..) => ExprPrecedence::Struct,
-            ExprKind::Repeat(..) => ExprPrecedence::Repeat,
-            ExprKind::Paren(..) => ExprPrecedence::Paren,
-            ExprKind::Try(..) => ExprPrecedence::Try,
-            ExprKind::Yield(..) => ExprPrecedence::Yield,
-            ExprKind::Yeet(..) => ExprPrecedence::Yeet,
-            ExprKind::Become(..) => ExprPrecedence::Become,
-            ExprKind::InlineAsm(..)
-            | ExprKind::Type(..)
-            | ExprKind::OffsetOf(..)
+            ExprKind::Closure(..) => PREC_CLOSURE,
+
+            ExprKind::Break(..)
+            | ExprKind::Continue(..)
+            | ExprKind::Ret(..)
+            | ExprKind::Yield(..)
+            | ExprKind::Yeet(..)
+            | ExprKind::Become(..) => PREC_JUMP,
+
+            // `Range` claims to have higher precedence than `Assign`, but `x .. x = x` fails to
+            // parse, instead of parsing as `(x .. x) = x`. Giving `Range` a lower precedence
+            // ensures that `pprust` will add parentheses in the right places to get the desired
+            // parse.
+            ExprKind::Range(..) => PREC_RANGE,
+
+            // Binop-like expr kinds, handled by `AssocOp`.
+            ExprKind::Binary(op, ..) => AssocOp::from_ast_binop(op.node).precedence() as i8,
+            ExprKind::Cast(..) => AssocOp::As.precedence() as i8,
+
+            ExprKind::Assign(..) |
+            ExprKind::AssignOp(..) => AssocOp::Assign.precedence() as i8,
+
+            // Unary, prefix
+            ExprKind::AddrOf(..)
+            // Here `let pats = expr` has `let pats =` as a "unary" prefix of `expr`.
+            // However, this is not exactly right. When `let _ = a` is the LHS of a binop we
+            // need parens sometimes. E.g. we can print `(let _ = a) && b` as `let _ = a && b`
+            // but we need to print `(let _ = a) < b` as-is with parens.
+            | ExprKind::Let(..)
+            | ExprKind::Unary(..) => PREC_PREFIX,
+
+            // Never need parens
+            ExprKind::Array(_)
+            | ExprKind::Await(..)
+            | ExprKind::Block(..)
+            | ExprKind::Call(..)
+            | ExprKind::ConstBlock(_)
+            | ExprKind::Field(..)
+            | ExprKind::ForLoop { .. }
             | ExprKind::FormatArgs(..)
-            | ExprKind::MacCall(..) => ExprPrecedence::Mac,
-            ExprKind::Err(_) | ExprKind::Dummy => ExprPrecedence::Err,
+            | ExprKind::Gen(..)
+            | ExprKind::If(..)
+            | ExprKind::IncludedBytes(..)
+            | ExprKind::Index(..)
+            | ExprKind::InlineAsm(..)
+            | ExprKind::Lit(_)
+            | ExprKind::Loop(..)
+            | ExprKind::MacCall(..)
+            | ExprKind::Match(..)
+            | ExprKind::MethodCall(..)
+            | ExprKind::OffsetOf(..)
+            | ExprKind::Paren(..)
+            | ExprKind::Path(..)
+            | ExprKind::Repeat(..)
+            | ExprKind::Struct(..)
+            | ExprKind::Try(..)
+            | ExprKind::TryBlock(..)
+            | ExprKind::Tup(_)
+            | ExprKind::Type(..)
+            | ExprKind::Underscore
+            | ExprKind::While(..)
+            | ExprKind::Err(_)
+            | ExprKind::Dummy => PREC_UNAMBIGUOUS,
         }
     }
 
diff --git a/compiler/rustc_ast/src/util/parser.rs b/compiler/rustc_ast/src/util/parser.rs
index d8dad4550c0c..ed9265d51598 100644
--- a/compiler/rustc_ast/src/util/parser.rs
+++ b/compiler/rustc_ast/src/util/parser.rs
@@ -237,121 +237,6 @@ pub fn can_continue_expr_unambiguously(&self) -> bool {
 pub const PREC_UNAMBIGUOUS: i8 = 60;
 pub const PREC_FORCE_PAREN: i8 = 100;
 
-#[derive(Debug, Clone, Copy)]
-pub enum ExprPrecedence {
-    Closure,
-    Break,
-    Continue,
-    Ret,
-    Yield,
-    Yeet,
-    Become,
-
-    Range,
-
-    Binary(BinOpKind),
-
-    Cast,
-
-    Assign,
-    AssignOp,
-
-    AddrOf,
-    Let,
-    Unary,
-
-    Call,
-    MethodCall,
-    Field,
-    Index,
-    Try,
-    Mac,
-
-    Array,
-    Repeat,
-    Tup,
-    Lit,
-    Path,
-    Paren,
-    If,
-    While,
-    ForLoop,
-    Loop,
-    Match,
-    PostfixMatch,
-    ConstBlock,
-    Block,
-    TryBlock,
-    Struct,
-    Gen,
-    Await,
-    Err,
-}
-
-impl ExprPrecedence {
-    pub fn order(self) -> i8 {
-        match self {
-            ExprPrecedence::Closure => PREC_CLOSURE,
-
-            ExprPrecedence::Break
-            | ExprPrecedence::Continue
-            | ExprPrecedence::Ret
-            | ExprPrecedence::Yield
-            | ExprPrecedence::Yeet
-            | ExprPrecedence::Become => PREC_JUMP,
-
-            // `Range` claims to have higher precedence than `Assign`, but `x .. x = x` fails to
-            // parse, instead of parsing as `(x .. x) = x`. Giving `Range` a lower precedence
-            // ensures that `pprust` will add parentheses in the right places to get the desired
-            // parse.
-            ExprPrecedence::Range => PREC_RANGE,
-
-            // Binop-like expr kinds, handled by `AssocOp`.
-            ExprPrecedence::Binary(op) => AssocOp::from_ast_binop(op).precedence() as i8,
-            ExprPrecedence::Cast => AssocOp::As.precedence() as i8,
-
-            ExprPrecedence::Assign |
-            ExprPrecedence::AssignOp => AssocOp::Assign.precedence() as i8,
-
-            // Unary, prefix
-            ExprPrecedence::AddrOf
-            // Here `let pats = expr` has `let pats =` as a "unary" prefix of `expr`.
-            // However, this is not exactly right. When `let _ = a` is the LHS of a binop we
-            // need parens sometimes. E.g. we can print `(let _ = a) && b` as `let _ = a && b`
-            // but we need to print `(let _ = a) < b` as-is with parens.
-            | ExprPrecedence::Let
-            | ExprPrecedence::Unary => PREC_PREFIX,
-
-            // Never need parens
-            ExprPrecedence::Array
-            | ExprPrecedence::Await
-            | ExprPrecedence::Block
-            | ExprPrecedence::Call
-            | ExprPrecedence::ConstBlock
-            | ExprPrecedence::Field
-            | ExprPrecedence::ForLoop
-            | ExprPrecedence::Gen
-            | ExprPrecedence::If
-            | ExprPrecedence::Index
-            | ExprPrecedence::Lit
-            | ExprPrecedence::Loop
-            | ExprPrecedence::Mac
-            | ExprPrecedence::Match
-            | ExprPrecedence::MethodCall
-            | ExprPrecedence::Paren
-            | ExprPrecedence::Path
-            | ExprPrecedence::PostfixMatch
-            | ExprPrecedence::Repeat
-            | ExprPrecedence::Struct
-            | ExprPrecedence::Try
-            | ExprPrecedence::TryBlock
-            | ExprPrecedence::Tup
-            | ExprPrecedence::While
-            | ExprPrecedence::Err => PREC_UNAMBIGUOUS,
-        }
-    }
-}
-
 /// In `let p = e`, operators with precedence `<=` this one requires parentheses in `e`.
 pub fn prec_let_scrutinee_needs_par() -> usize {
     AssocOp::LAnd.precedence()
diff --git a/compiler/rustc_ast_pretty/src/pprust/state/expr.rs b/compiler/rustc_ast_pretty/src/pprust/state/expr.rs
index 893bfaf8f712..04ec135c4289 100644
--- a/compiler/rustc_ast_pretty/src/pprust/state/expr.rs
+++ b/compiler/rustc_ast_pretty/src/pprust/state/expr.rs
@@ -59,7 +59,7 @@ fn print_call_post(&mut self, args: &[P<ast::Expr>]) {
     }
 
     fn print_expr_maybe_paren(&mut self, expr: &ast::Expr, prec: i8, fixup: FixupContext) {
-        self.print_expr_cond_paren(expr, expr.precedence().order() < prec, fixup);
+        self.print_expr_cond_paren(expr, expr.precedence() < prec, fixup);
     }
 
     /// Prints an expr using syntax that's acceptable in a condition position, such as the `cond` in
@@ -615,7 +615,7 @@ pub(super) fn print_expr_outer_attr_style(
                         expr,
                         // Parenthesize if required by precedence, or in the
                         // case of `break 'inner: loop { break 'inner 1 } + 1`
-                        expr.precedence().order() < parser::PREC_JUMP
+                        expr.precedence() < parser::PREC_JUMP
                             || (opt_label.is_none() && classify::leading_labeled_expr(expr)),
                         fixup.subsequent_subexpression(),
                     );
diff --git a/compiler/rustc_ast_pretty/src/pprust/state/fixup.rs b/compiler/rustc_ast_pretty/src/pprust/state/fixup.rs
index 50fd12a4e8b6..6f5382ce61d3 100644
--- a/compiler/rustc_ast_pretty/src/pprust/state/fixup.rs
+++ b/compiler/rustc_ast_pretty/src/pprust/state/fixup.rs
@@ -191,6 +191,6 @@ pub(crate) fn would_cause_statement_boundary(self, expr: &Expr) -> bool {
     ///     "let chain".
     pub(crate) fn needs_par_as_let_scrutinee(self, expr: &Expr) -> bool {
         self.parenthesize_exterior_struct_lit && parser::contains_exterior_struct_lit(expr)
-            || parser::needs_par_as_let_scrutinee(expr.precedence().order())
+            || parser::needs_par_as_let_scrutinee(expr.precedence())
     }
 }
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index fc889c12cb92..12dec75e65cf 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/compiler/rustc_hir/src/hir.rs
@@ -1,7 +1,7 @@
 use std::fmt;
 
 use rustc_abi::ExternAbi;
-use rustc_ast::util::parser::ExprPrecedence;
+use rustc_ast::util::parser::{AssocOp, PREC_CLOSURE, PREC_JUMP, PREC_PREFIX, PREC_UNAMBIGUOUS};
 use rustc_ast::{
     self as ast, Attribute, FloatTy, InlineAsmOptions, InlineAsmTemplatePiece, IntTy, Label,
     LitKind, TraitObjectSyntax, UintTy,
@@ -1708,41 +1708,54 @@ pub struct Expr<'hir> {
 }
 
 impl Expr<'_> {
-    pub fn precedence(&self) -> ExprPrecedence {
+    pub fn precedence(&self) -> i8 {
         match self.kind {
-            ExprKind::ConstBlock(_) => ExprPrecedence::ConstBlock,
-            ExprKind::Array(_) => ExprPrecedence::Array,
-            ExprKind::Call(..) => ExprPrecedence::Call,
-            ExprKind::MethodCall(..) => ExprPrecedence::MethodCall,
-            ExprKind::Tup(_) => ExprPrecedence::Tup,
-            ExprKind::Binary(op, ..) => ExprPrecedence::Binary(op.node),
-            ExprKind::Unary(..) => ExprPrecedence::Unary,
-            ExprKind::Lit(_) => ExprPrecedence::Lit,
-            ExprKind::Cast(..) => ExprPrecedence::Cast,
+            ExprKind::Closure { .. } => PREC_CLOSURE,
+
+            ExprKind::Break(..)
+            | ExprKind::Continue(..)
+            | ExprKind::Ret(..)
+            | ExprKind::Yield(..)
+            | ExprKind::Become(..) => PREC_JUMP,
+
+            // Binop-like expr kinds, handled by `AssocOp`.
+            ExprKind::Binary(op, ..) => AssocOp::from_ast_binop(op.node).precedence() as i8,
+            ExprKind::Cast(..) => AssocOp::As.precedence() as i8,
+
+            ExprKind::Assign(..) |
+            ExprKind::AssignOp(..) => AssocOp::Assign.precedence() as i8,
+
+            // Unary, prefix
+            ExprKind::AddrOf(..)
+            // Here `let pats = expr` has `let pats =` as a "unary" prefix of `expr`.
+            // However, this is not exactly right. When `let _ = a` is the LHS of a binop we
+            // need parens sometimes. E.g. we can print `(let _ = a) && b` as `let _ = a && b`
+            // but we need to print `(let _ = a) < b` as-is with parens.
+            | ExprKind::Let(..)
+            | ExprKind::Unary(..) => PREC_PREFIX,
+
+            // Never need parens
+            ExprKind::Array(_)
+            | ExprKind::Block(..)
+            | ExprKind::Call(..)
+            | ExprKind::ConstBlock(_)
+            | ExprKind::Field(..)
+            | ExprKind::If(..)
+            | ExprKind::Index(..)
+            | ExprKind::InlineAsm(..)
+            | ExprKind::Lit(_)
+            | ExprKind::Loop(..)
+            | ExprKind::Match(..)
+            | ExprKind::MethodCall(..)
+            | ExprKind::OffsetOf(..)
+            | ExprKind::Path(..)
+            | ExprKind::Repeat(..)
+            | ExprKind::Struct(..)
+            | ExprKind::Tup(_)
+            | ExprKind::Type(..)
+            | ExprKind::Err(_) => PREC_UNAMBIGUOUS,
+
             ExprKind::DropTemps(ref expr, ..) => expr.precedence(),
-            ExprKind::If(..) => ExprPrecedence::If,
-            ExprKind::Let(..) => ExprPrecedence::Let,
-            ExprKind::Loop(..) => ExprPrecedence::Loop,
-            ExprKind::Match(..) => ExprPrecedence::Match,
-            ExprKind::Closure { .. } => ExprPrecedence::Closure,
-            ExprKind::Block(..) => ExprPrecedence::Block,
-            ExprKind::Assign(..) => ExprPrecedence::Assign,
-            ExprKind::AssignOp(..) => ExprPrecedence::AssignOp,
-            ExprKind::Field(..) => ExprPrecedence::Field,
-            ExprKind::Index(..) => ExprPrecedence::Index,
-            ExprKind::Path(..) => ExprPrecedence::Path,
-            ExprKind::AddrOf(..) => ExprPrecedence::AddrOf,
-            ExprKind::Break(..) => ExprPrecedence::Break,
-            ExprKind::Continue(..) => ExprPrecedence::Continue,
-            ExprKind::Ret(..) => ExprPrecedence::Ret,
-            ExprKind::Become(..) => ExprPrecedence::Become,
-            ExprKind::Struct(..) => ExprPrecedence::Struct,
-            ExprKind::Repeat(..) => ExprPrecedence::Repeat,
-            ExprKind::Yield(..) => ExprPrecedence::Yield,
-            ExprKind::Type(..) | ExprKind::InlineAsm(..) | ExprKind::OffsetOf(..) => {
-                ExprPrecedence::Mac
-            }
-            ExprKind::Err(_) => ExprPrecedence::Err,
         }
     }
 
diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs
index 5e27ace4cbe4..f6e227377b9b 100644
--- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs
+++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs
@@ -8,7 +8,8 @@
 use rustc_middle::span_bug;
 use rustc_middle::ty::fold::BottomUpFolder;
 use rustc_middle::ty::{
-    self, DynKind, ExistentialPredicateStableCmpExt as _, Ty, TyCtxt, TypeFoldable, Upcast,
+    self, DynKind, ExistentialPredicateStableCmpExt as _, Ty, TyCtxt, TypeFoldable,
+    TypeVisitableExt, Upcast,
 };
 use rustc_span::{ErrorGuaranteed, Span};
 use rustc_trait_selection::error_reporting::traits::report_dyn_incompatibility;
@@ -92,11 +93,20 @@ pub(super) fn lower_trait_object_ty(
 
         let (mut auto_traits, regular_traits): (Vec<_>, Vec<_>) =
             expanded_traits.partition(|i| tcx.trait_is_auto(i.trait_ref().def_id()));
+
+        // We don't support >1 principal
         if regular_traits.len() > 1 {
-            let _ = self.report_trait_object_addition_traits_error(&regular_traits);
-        } else if regular_traits.is_empty() && auto_traits.is_empty() {
-            let reported = self.report_trait_object_with_no_traits_error(span, &trait_bounds);
-            return Ty::new_error(tcx, reported);
+            let guar = self.report_trait_object_addition_traits_error(&regular_traits);
+            return Ty::new_error(tcx, guar);
+        }
+        // We  don't support empty trait objects.
+        if regular_traits.is_empty() && auto_traits.is_empty() {
+            let guar = self.report_trait_object_with_no_traits_error(span, &trait_bounds);
+            return Ty::new_error(tcx, guar);
+        }
+        // Don't create a dyn trait if we have errors in the principal.
+        if let Err(guar) = trait_bounds.error_reported() {
+            return Ty::new_error(tcx, guar);
         }
 
         // Check that there are no gross dyn-compatibility violations;
diff --git a/compiler/rustc_hir_pretty/src/lib.rs b/compiler/rustc_hir_pretty/src/lib.rs
index 1dedf11f7ad1..64c6969d4b9c 100644
--- a/compiler/rustc_hir_pretty/src/lib.rs
+++ b/compiler/rustc_hir_pretty/src/lib.rs
@@ -1011,7 +1011,7 @@ fn print_call_post(&mut self, args: &[hir::Expr<'_>]) {
     }
 
     fn print_expr_maybe_paren(&mut self, expr: &hir::Expr<'_>, prec: i8) {
-        self.print_expr_cond_paren(expr, expr.precedence().order() < prec)
+        self.print_expr_cond_paren(expr, expr.precedence() < prec)
     }
 
     /// Prints an expr using syntax that's acceptable in a condition position, such as the `cond` in
@@ -1045,7 +1045,7 @@ fn print_let(&mut self, pat: &hir::Pat<'_>, ty: Option<&hir::Ty<'_>>, init: &hir
         }
         self.space();
         self.word_space("=");
-        let npals = || parser::needs_par_as_let_scrutinee(init.precedence().order());
+        let npals = || parser::needs_par_as_let_scrutinee(init.precedence());
         self.print_expr_cond_paren(init, Self::cond_needs_par(init) || npals())
     }
 
diff --git a/compiler/rustc_hir_typeck/src/callee.rs b/compiler/rustc_hir_typeck/src/callee.rs
index e6e0f62b54d2..a92482e6a0e3 100644
--- a/compiler/rustc_hir_typeck/src/callee.rs
+++ b/compiler/rustc_hir_typeck/src/callee.rs
@@ -606,7 +606,7 @@ fn suggest_call_as_method(
             };
 
             if let Ok(rest_snippet) = rest_snippet {
-                let sugg = if callee_expr.precedence().order() >= PREC_UNAMBIGUOUS {
+                let sugg = if callee_expr.precedence() >= PREC_UNAMBIGUOUS {
                     vec![
                         (up_to_rcvr_span, "".to_string()),
                         (rest_span, format!(".{}({rest_snippet}", segment.ident)),
diff --git a/compiler/rustc_hir_typeck/src/cast.rs b/compiler/rustc_hir_typeck/src/cast.rs
index 483a8d1d9a9d..0c3f21d540dc 100644
--- a/compiler/rustc_hir_typeck/src/cast.rs
+++ b/compiler/rustc_hir_typeck/src/cast.rs
@@ -1107,7 +1107,7 @@ fn cenum_impl_drop_lint(&self, fcx: &FnCtxt<'a, 'tcx>) {
     }
 
     fn lossy_provenance_ptr2int_lint(&self, fcx: &FnCtxt<'a, 'tcx>, t_c: ty::cast::IntTy) {
-        let expr_prec = self.expr.precedence().order();
+        let expr_prec = self.expr.precedence();
         let needs_parens = expr_prec < rustc_ast::util::parser::PREC_UNAMBIGUOUS;
 
         let needs_cast = !matches!(t_c, ty::cast::IntTy::U(ty::UintTy::Usize));
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs
index 707d98d8311b..b493a61b9f44 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs
@@ -2,7 +2,7 @@
 use core::iter;
 
 use hir::def_id::LocalDefId;
-use rustc_ast::util::parser::{ExprPrecedence, PREC_UNAMBIGUOUS};
+use rustc_ast::util::parser::PREC_UNAMBIGUOUS;
 use rustc_data_structures::packed::Pu128;
 use rustc_errors::{Applicability, Diag, MultiSpan};
 use rustc_hir as hir;
@@ -398,7 +398,7 @@ pub(crate) fn suggest_deref_ref_or_into(
                     // so we remove the user's `clone` call.
                     {
                         vec![(receiver_method.ident.span, conversion_method.name.to_string())]
-                    } else if expr.precedence().order() < ExprPrecedence::MethodCall.order() {
+                    } else if expr.precedence() < PREC_UNAMBIGUOUS {
                         vec![
                             (expr.span.shrink_to_lo(), "(".to_string()),
                             (expr.span.shrink_to_hi(), format!(").{}()", conversion_method.name)),
@@ -1376,7 +1376,7 @@ pub(crate) fn suggest_into(
         {
             let span = expr.span.find_oldest_ancestor_in_same_ctxt();
 
-            let mut sugg = if expr.precedence().order() >= PREC_UNAMBIGUOUS {
+            let mut sugg = if expr.precedence() >= PREC_UNAMBIGUOUS {
                 vec![(span.shrink_to_hi(), ".into()".to_owned())]
             } else {
                 vec![
@@ -3000,7 +3000,7 @@ pub(crate) fn suggest_cast(
             "change the type of the numeric literal from `{checked_ty}` to `{expected_ty}`",
         );
 
-        let close_paren = if expr.precedence().order() < PREC_UNAMBIGUOUS {
+        let close_paren = if expr.precedence() < PREC_UNAMBIGUOUS {
             sugg.push((expr.span.shrink_to_lo(), "(".to_string()));
             ")"
         } else {
@@ -3025,7 +3025,7 @@ pub(crate) fn suggest_cast(
                 let len = src.trim_end_matches(&checked_ty.to_string()).len();
                 expr.span.with_lo(expr.span.lo() + BytePos(len as u32))
             },
-            if expr.precedence().order() < PREC_UNAMBIGUOUS {
+            if expr.precedence() < PREC_UNAMBIGUOUS {
                 // Readd `)`
                 format!("{expected_ty})")
             } else {
diff --git a/compiler/rustc_lexer/src/lib.rs b/compiler/rustc_lexer/src/lib.rs
index bcb103957bad..b584e7afd98f 100644
--- a/compiler/rustc_lexer/src/lib.rs
+++ b/compiler/rustc_lexer/src/lib.rs
@@ -566,19 +566,19 @@ fn invalid_ident(&mut self) -> TokenKind {
 
     fn c_or_byte_string(
         &mut self,
-        mk_kind: impl FnOnce(bool) -> LiteralKind,
-        mk_kind_raw: impl FnOnce(Option<u8>) -> LiteralKind,
+        mk_kind: fn(bool) -> LiteralKind,
+        mk_kind_raw: fn(Option<u8>) -> LiteralKind,
         single_quoted: Option<fn(bool) -> LiteralKind>,
     ) -> TokenKind {
         match (self.first(), self.second(), single_quoted) {
-            ('\'', _, Some(mk_kind)) => {
+            ('\'', _, Some(single_quoted)) => {
                 self.bump();
                 let terminated = self.single_quoted_string();
                 let suffix_start = self.pos_within_token();
                 if terminated {
                     self.eat_literal_suffix();
                 }
-                let kind = mk_kind(terminated);
+                let kind = single_quoted(terminated);
                 Literal { kind, suffix_start }
             }
             ('"', _, _) => {
diff --git a/compiler/rustc_lexer/src/tests.rs b/compiler/rustc_lexer/src/tests.rs
index 556bbf1f5182..db7225fc2a81 100644
--- a/compiler/rustc_lexer/src/tests.rs
+++ b/compiler/rustc_lexer/src/tests.rs
@@ -77,63 +77,53 @@ fn test_too_many_hashes() {
     check_raw_str(&s2, Err(RawStrError::TooManyDelimiters { found: u32::from(max_count) + 1 }));
 }
 
+// https://github.com/rust-lang/rust/issues/70528
 #[test]
 fn test_valid_shebang() {
-    // https://github.com/rust-lang/rust/issues/70528
-    let input = "#!/usr/bin/rustrun\nlet x = 5;";
-    assert_eq!(strip_shebang(input), Some(18));
-}
+    let input = "#!/bin/bash";
+    assert_eq!(strip_shebang(input), Some(input.len()));
 
-#[test]
-fn test_invalid_shebang_valid_rust_syntax() {
-    // https://github.com/rust-lang/rust/issues/70528
-    let input = "#!    [bad_attribute]";
+    let input = "#![attribute]";
+    assert_eq!(strip_shebang(input), None);
+
+    let input = "#!    /bin/bash";
+    assert_eq!(strip_shebang(input), Some(input.len()));
+
+    let input = "#!    [attribute]";
+    assert_eq!(strip_shebang(input), None);
+
+    let input = "#! /* blah */  /bin/bash";
+    assert_eq!(strip_shebang(input), Some(input.len()));
+
+    let input = "#! /* blah */  [attribute]";
+    assert_eq!(strip_shebang(input), None);
+
+    let input = "#! // blah\n/bin/bash";
+    assert_eq!(strip_shebang(input), Some(10)); // strip up to the newline
+
+    let input = "#! // blah\n[attribute]";
+    assert_eq!(strip_shebang(input), None);
+
+    let input = "#! /* blah\nblah\nblah */  /bin/bash";
+    assert_eq!(strip_shebang(input), Some(10));
+
+    let input = "#! /* blah\nblah\nblah */  [attribute]";
+    assert_eq!(strip_shebang(input), None);
+
+    let input = "#!\n/bin/sh";
+    assert_eq!(strip_shebang(input), Some(2));
+
+    let input = "#!\n[attribute]";
     assert_eq!(strip_shebang(input), None);
-}
 
-#[test]
-fn test_shebang_second_line() {
     // Because shebangs are interpreted by the kernel, they must be on the first line
     let input = "\n#!/bin/bash";
     assert_eq!(strip_shebang(input), None);
-}
 
-#[test]
-fn test_shebang_space() {
-    let input = "#!    /bin/bash";
-    assert_eq!(strip_shebang(input), Some(input.len()));
-}
-
-#[test]
-fn test_shebang_empty_shebang() {
-    let input = "#!    \n[attribute(foo)]";
+    let input = "\n#![attribute]";
     assert_eq!(strip_shebang(input), None);
 }
 
-#[test]
-fn test_invalid_shebang_comment() {
-    let input = "#!//bin/ami/a/comment\n[";
-    assert_eq!(strip_shebang(input), None)
-}
-
-#[test]
-fn test_invalid_shebang_another_comment() {
-    let input = "#!/*bin/ami/a/comment*/\n[attribute";
-    assert_eq!(strip_shebang(input), None)
-}
-
-#[test]
-fn test_shebang_valid_rust_after() {
-    let input = "#!/*bin/ami/a/comment*/\npub fn main() {}";
-    assert_eq!(strip_shebang(input), Some(23))
-}
-
-#[test]
-fn test_shebang_followed_by_attrib() {
-    let input = "#!/bin/rust-scripts\n#![allow_unused(true)]";
-    assert_eq!(strip_shebang(input), Some(19));
-}
-
 fn check_lexing(src: &str, expect: Expect) {
     let actual: String = tokenize(src).map(|token| format!("{:?}\n", token)).collect();
     expect.assert_eq(&actual)
diff --git a/compiler/rustc_middle/src/ty/consts.rs b/compiler/rustc_middle/src/ty/consts.rs
index c4d86c3210e8..d27205e26abb 100644
--- a/compiler/rustc_middle/src/ty/consts.rs
+++ b/compiler/rustc_middle/src/ty/consts.rs
@@ -151,10 +151,6 @@ pub fn new_error_with_message<S: Into<MultiSpan>>(
 }
 
 impl<'tcx> rustc_type_ir::inherent::Const<TyCtxt<'tcx>> for Const<'tcx> {
-    fn try_to_target_usize(self, interner: TyCtxt<'tcx>) -> Option<u64> {
-        self.try_to_target_usize(interner)
-    }
-
     fn new_infer(tcx: TyCtxt<'tcx>, infer: ty::InferConst) -> Self {
         Const::new_infer(tcx, infer)
     }
diff --git a/compiler/rustc_middle/src/ty/error.rs b/compiler/rustc_middle/src/ty/error.rs
index 43d243b0584e..4a82af325595 100644
--- a/compiler/rustc_middle/src/ty/error.rs
+++ b/compiler/rustc_middle/src/ty/error.rs
@@ -58,12 +58,9 @@ fn report_maybe_different(expected: &str, found: &str) -> String {
                 pluralize!(values.found)
             )
             .into(),
-            TypeError::FixedArraySize(values) => format!(
-                "expected an array with a fixed size of {} element{}, found one with {} element{}",
-                values.expected,
-                pluralize!(values.expected),
-                values.found,
-                pluralize!(values.found)
+            TypeError::ArraySize(values) => format!(
+                "expected an array with a size of {}, found one with a size of {}",
+                values.expected, values.found,
             )
             .into(),
             TypeError::ArgCount => "incorrect number of function parameters".into(),
diff --git a/compiler/rustc_middle/src/ty/relate.rs b/compiler/rustc_middle/src/ty/relate.rs
index b06687490d26..afdec7a86d44 100644
--- a/compiler/rustc_middle/src/ty/relate.rs
+++ b/compiler/rustc_middle/src/ty/relate.rs
@@ -3,7 +3,6 @@
 pub use rustc_type_ir::relate::*;
 
 use crate::ty::error::{ExpectedFound, TypeError};
-use crate::ty::predicate::ExistentialPredicateStableCmpExt as _;
 use crate::ty::{self as ty, Ty, TyCtxt};
 
 pub type RelateResult<'tcx, T> = rustc_type_ir::relate::RelateResult<TyCtxt<'tcx>, T>;
@@ -86,10 +85,7 @@ fn relate<R: TypeRelation<TyCtxt<'tcx>>>(
         // in `a`.
         let mut a_v: Vec<_> = a.into_iter().collect();
         let mut b_v: Vec<_> = b.into_iter().collect();
-        // `skip_binder` here is okay because `stable_cmp` doesn't look at binders
-        a_v.sort_by(|a, b| a.skip_binder().stable_cmp(tcx, &b.skip_binder()));
         a_v.dedup();
-        b_v.sort_by(|a, b| a.skip_binder().stable_cmp(tcx, &b.skip_binder()));
         b_v.dedup();
         if a_v.len() != b_v.len() {
             return Err(TypeError::ExistentialMismatch(ExpectedFound::new(a, b)));
diff --git a/compiler/rustc_mir_dataflow/src/framework/cursor.rs b/compiler/rustc_mir_dataflow/src/framework/cursor.rs
index 5ebb343f4e19..11cf8c3e8984 100644
--- a/compiler/rustc_mir_dataflow/src/framework/cursor.rs
+++ b/compiler/rustc_mir_dataflow/src/framework/cursor.rs
@@ -1,6 +1,7 @@
 //! Random access inspection of the results of a dataflow analysis.
 
 use std::cmp::Ordering;
+use std::ops::{Deref, DerefMut};
 
 #[cfg(debug_assertions)]
 use rustc_index::bit_set::BitSet;
@@ -8,18 +9,63 @@
 
 use super::{Analysis, Direction, Effect, EffectIndex, Results};
 
-/// Allows random access inspection of the results of a dataflow analysis.
+/// Some `ResultsCursor`s want to own a `Results`, and some want to borrow a `Results`, either
+/// mutable or immutably. This type allows all of the above. It's similar to `Cow`.
+pub enum ResultsHandle<'a, 'tcx, A>
+where
+    A: Analysis<'tcx>,
+{
+    Borrowed(&'a Results<'tcx, A>),
+    BorrowedMut(&'a mut Results<'tcx, A>),
+    Owned(Results<'tcx, A>),
+}
+
+impl<'tcx, A> Deref for ResultsHandle<'_, 'tcx, A>
+where
+    A: Analysis<'tcx>,
+{
+    type Target = Results<'tcx, A>;
+
+    fn deref(&self) -> &Results<'tcx, A> {
+        match self {
+            ResultsHandle::Borrowed(borrowed) => borrowed,
+            ResultsHandle::BorrowedMut(borrowed) => borrowed,
+            ResultsHandle::Owned(owned) => owned,
+        }
+    }
+}
+
+impl<'tcx, A> DerefMut for ResultsHandle<'_, 'tcx, A>
+where
+    A: Analysis<'tcx>,
+{
+    fn deref_mut(&mut self) -> &mut Results<'tcx, A> {
+        match self {
+            ResultsHandle::Borrowed(_borrowed) => {
+                panic!("tried to deref_mut a `ResultsHandle::Borrowed")
+            }
+            ResultsHandle::BorrowedMut(borrowed) => borrowed,
+            ResultsHandle::Owned(owned) => owned,
+        }
+    }
+}
+
+/// Allows random access inspection of the results of a dataflow analysis. Use this when you want
+/// to inspect domain values only in certain locations; use `ResultsVisitor` if you want to inspect
+/// domain values in many or all locations.
 ///
-/// This cursor only has linear performance within a basic block when its statements are visited in
-/// the same order as the `DIRECTION` of the analysis. In the worst case—when statements are
-/// visited in *reverse* order—performance will be quadratic in the number of statements in the
-/// block. The order in which basic blocks are inspected has no impact on performance.
+/// Because `Results` only has domain values for the entry of each basic block, these inspections
+/// involve some amount of domain value recomputations. This cursor only has linear performance
+/// within a basic block when its statements are visited in the same order as the `DIRECTION` of
+/// the analysis. In the worst case—when statements are visited in *reverse* order—performance will
+/// be quadratic in the number of statements in the block. The order in which basic blocks are
+/// inspected has no impact on performance.
 pub struct ResultsCursor<'mir, 'tcx, A>
 where
     A: Analysis<'tcx>,
 {
     body: &'mir mir::Body<'tcx>,
-    results: Results<'tcx, A>,
+    results: ResultsHandle<'mir, 'tcx, A>,
     state: A::Domain,
 
     pos: CursorPosition,
@@ -47,13 +93,8 @@ pub fn body(&self) -> &'mir mir::Body<'tcx> {
         self.body
     }
 
-    /// Unwraps this cursor, returning the underlying `Results`.
-    pub fn into_results(self) -> Results<'tcx, A> {
-        self.results
-    }
-
     /// Returns a new cursor that can inspect `results`.
-    pub fn new(body: &'mir mir::Body<'tcx>, results: Results<'tcx, A>) -> Self {
+    pub fn new(body: &'mir mir::Body<'tcx>, results: ResultsHandle<'mir, 'tcx, A>) -> Self {
         let bottom_value = results.analysis.bottom_value(body);
         ResultsCursor {
             body,
diff --git a/compiler/rustc_mir_dataflow/src/framework/direction.rs b/compiler/rustc_mir_dataflow/src/framework/direction.rs
index 9a5cf9d4e84f..566a6b09b2b1 100644
--- a/compiler/rustc_mir_dataflow/src/framework/direction.rs
+++ b/compiler/rustc_mir_dataflow/src/framework/direction.rs
@@ -9,10 +9,21 @@
 
 pub trait Direction {
     const IS_FORWARD: bool;
-
     const IS_BACKWARD: bool = !Self::IS_FORWARD;
 
-    /// Applies all effects between the given `EffectIndex`s.
+    /// Called by `iterate_to_fixpoint` during initial analysis computation.
+    fn apply_effects_in_block<'mir, 'tcx, A>(
+        analysis: &mut A,
+        body: &mir::Body<'tcx>,
+        state: &mut A::Domain,
+        block: BasicBlock,
+        block_data: &'mir mir::BasicBlockData<'tcx>,
+        propagate: impl FnMut(BasicBlock, &A::Domain),
+    ) where
+        A: Analysis<'tcx>;
+
+    /// Called by `ResultsCursor` to recompute the domain value for a location
+    /// in a basic block. Applies all effects between the given `EffectIndex`s.
     ///
     /// `effects.start()` must precede or equal `effects.end()` in this direction.
     fn apply_effects_in_range<'tcx, A>(
@@ -24,15 +35,9 @@ fn apply_effects_in_range<'tcx, A>(
     ) where
         A: Analysis<'tcx>;
 
-    fn apply_effects_in_block<'mir, 'tcx, A>(
-        analysis: &mut A,
-        state: &mut A::Domain,
-        block: BasicBlock,
-        block_data: &'mir mir::BasicBlockData<'tcx>,
-    ) -> TerminatorEdges<'mir, 'tcx>
-    where
-        A: Analysis<'tcx>;
-
+    /// Called by `ResultsVisitor` to recompute the analysis domain values for
+    /// all locations in a basic block (starting from the entry value stored
+    /// in `Results`) and to visit them with `vis`.
     fn visit_results_in_block<'mir, 'tcx, A>(
         state: &mut A::Domain,
         block: BasicBlock,
@@ -41,16 +46,6 @@ fn visit_results_in_block<'mir, 'tcx, A>(
         vis: &mut impl ResultsVisitor<'mir, 'tcx, A>,
     ) where
         A: Analysis<'tcx>;
-
-    fn join_state_into_successors_of<'tcx, A>(
-        analysis: &mut A,
-        body: &mir::Body<'tcx>,
-        exit_state: &mut A::Domain,
-        block: BasicBlock,
-        edges: TerminatorEdges<'_, 'tcx>,
-        propagate: impl FnMut(BasicBlock, &A::Domain),
-    ) where
-        A: Analysis<'tcx>;
 }
 
 /// Dataflow that runs from the exit of a block (terminator), to its entry (the first statement).
@@ -61,23 +56,84 @@ impl Direction for Backward {
 
     fn apply_effects_in_block<'mir, 'tcx, A>(
         analysis: &mut A,
+        body: &mir::Body<'tcx>,
         state: &mut A::Domain,
         block: BasicBlock,
         block_data: &'mir mir::BasicBlockData<'tcx>,
-    ) -> TerminatorEdges<'mir, 'tcx>
-    where
+        mut propagate: impl FnMut(BasicBlock, &A::Domain),
+    ) where
         A: Analysis<'tcx>,
     {
         let terminator = block_data.terminator();
         let location = Location { block, statement_index: block_data.statements.len() };
         analysis.apply_before_terminator_effect(state, terminator, location);
-        let edges = analysis.apply_terminator_effect(state, terminator, location);
+        analysis.apply_terminator_effect(state, terminator, location);
         for (statement_index, statement) in block_data.statements.iter().enumerate().rev() {
             let location = Location { block, statement_index };
             analysis.apply_before_statement_effect(state, statement, location);
             analysis.apply_statement_effect(state, statement, location);
         }
-        edges
+
+        let exit_state = state;
+        for pred in body.basic_blocks.predecessors()[block].iter().copied() {
+            match body[pred].terminator().kind {
+                // Apply terminator-specific edge effects.
+                //
+                // FIXME(ecstaticmorse): Avoid cloning the exit state unconditionally.
+                mir::TerminatorKind::Call { destination, target: Some(dest), .. }
+                    if dest == block =>
+                {
+                    let mut tmp = exit_state.clone();
+                    analysis.apply_call_return_effect(
+                        &mut tmp,
+                        pred,
+                        CallReturnPlaces::Call(destination),
+                    );
+                    propagate(pred, &tmp);
+                }
+
+                mir::TerminatorKind::InlineAsm { ref targets, ref operands, .. }
+                    if targets.contains(&block) =>
+                {
+                    let mut tmp = exit_state.clone();
+                    analysis.apply_call_return_effect(
+                        &mut tmp,
+                        pred,
+                        CallReturnPlaces::InlineAsm(operands),
+                    );
+                    propagate(pred, &tmp);
+                }
+
+                mir::TerminatorKind::Yield { resume, resume_arg, .. } if resume == block => {
+                    let mut tmp = exit_state.clone();
+                    analysis.apply_call_return_effect(
+                        &mut tmp,
+                        resume,
+                        CallReturnPlaces::Yield(resume_arg),
+                    );
+                    propagate(pred, &tmp);
+                }
+
+                mir::TerminatorKind::SwitchInt { targets: _, ref discr } => {
+                    let mut applier = BackwardSwitchIntEdgeEffectsApplier {
+                        body,
+                        pred,
+                        exit_state,
+                        block,
+                        propagate: &mut propagate,
+                        effects_applied: false,
+                    };
+
+                    analysis.apply_switch_int_edge_effects(pred, discr, &mut applier);
+
+                    if !applier.effects_applied {
+                        propagate(pred, exit_state)
+                    }
+                }
+
+                _ => propagate(pred, exit_state),
+            }
+        }
     }
 
     fn apply_effects_in_range<'tcx, A>(
@@ -170,7 +226,6 @@ fn visit_results_in_block<'mir, 'tcx, A>(
 
         vis.visit_block_end(state);
 
-        // Terminator
         let loc = Location { block, statement_index: block_data.statements.len() };
         let term = block_data.terminator();
         results.analysis.apply_before_terminator_effect(state, term, loc);
@@ -188,82 +243,13 @@ fn visit_results_in_block<'mir, 'tcx, A>(
 
         vis.visit_block_start(state);
     }
-
-    fn join_state_into_successors_of<'tcx, A>(
-        analysis: &mut A,
-        body: &mir::Body<'tcx>,
-        exit_state: &mut A::Domain,
-        bb: BasicBlock,
-        _edges: TerminatorEdges<'_, 'tcx>,
-        mut propagate: impl FnMut(BasicBlock, &A::Domain),
-    ) where
-        A: Analysis<'tcx>,
-    {
-        for pred in body.basic_blocks.predecessors()[bb].iter().copied() {
-            match body[pred].terminator().kind {
-                // Apply terminator-specific edge effects.
-                //
-                // FIXME(ecstaticmorse): Avoid cloning the exit state unconditionally.
-                mir::TerminatorKind::Call { destination, target: Some(dest), .. } if dest == bb => {
-                    let mut tmp = exit_state.clone();
-                    analysis.apply_call_return_effect(
-                        &mut tmp,
-                        pred,
-                        CallReturnPlaces::Call(destination),
-                    );
-                    propagate(pred, &tmp);
-                }
-
-                mir::TerminatorKind::InlineAsm { ref targets, ref operands, .. }
-                    if targets.contains(&bb) =>
-                {
-                    let mut tmp = exit_state.clone();
-                    analysis.apply_call_return_effect(
-                        &mut tmp,
-                        pred,
-                        CallReturnPlaces::InlineAsm(operands),
-                    );
-                    propagate(pred, &tmp);
-                }
-
-                mir::TerminatorKind::Yield { resume, resume_arg, .. } if resume == bb => {
-                    let mut tmp = exit_state.clone();
-                    analysis.apply_call_return_effect(
-                        &mut tmp,
-                        resume,
-                        CallReturnPlaces::Yield(resume_arg),
-                    );
-                    propagate(pred, &tmp);
-                }
-
-                mir::TerminatorKind::SwitchInt { targets: _, ref discr } => {
-                    let mut applier = BackwardSwitchIntEdgeEffectsApplier {
-                        body,
-                        pred,
-                        exit_state,
-                        bb,
-                        propagate: &mut propagate,
-                        effects_applied: false,
-                    };
-
-                    analysis.apply_switch_int_edge_effects(pred, discr, &mut applier);
-
-                    if !applier.effects_applied {
-                        propagate(pred, exit_state)
-                    }
-                }
-
-                _ => propagate(pred, exit_state),
-            }
-        }
-    }
 }
 
 struct BackwardSwitchIntEdgeEffectsApplier<'mir, 'tcx, D, F> {
     body: &'mir mir::Body<'tcx>,
     pred: BasicBlock,
     exit_state: &'mir mut D,
-    bb: BasicBlock,
+    block: BasicBlock,
     propagate: &'mir mut F,
     effects_applied: bool,
 }
@@ -276,8 +262,8 @@ impl<D, F> super::SwitchIntEdgeEffects<D> for BackwardSwitchIntEdgeEffectsApplie
     fn apply(&mut self, mut apply_edge_effect: impl FnMut(&mut D, SwitchIntTarget)) {
         assert!(!self.effects_applied);
 
-        let values = &self.body.basic_blocks.switch_sources()[&(self.bb, self.pred)];
-        let targets = values.iter().map(|&value| SwitchIntTarget { value, target: self.bb });
+        let values = &self.body.basic_blocks.switch_sources()[&(self.block, self.pred)];
+        let targets = values.iter().map(|&value| SwitchIntTarget { value, target: self.block });
 
         let mut tmp = None;
         for target in targets {
@@ -298,11 +284,12 @@ impl Direction for Forward {
 
     fn apply_effects_in_block<'mir, 'tcx, A>(
         analysis: &mut A,
+        _body: &mir::Body<'tcx>,
         state: &mut A::Domain,
         block: BasicBlock,
         block_data: &'mir mir::BasicBlockData<'tcx>,
-    ) -> TerminatorEdges<'mir, 'tcx>
-    where
+        mut propagate: impl FnMut(BasicBlock, &A::Domain),
+    ) where
         A: Analysis<'tcx>,
     {
         for (statement_index, statement) in block_data.statements.iter().enumerate() {
@@ -313,7 +300,53 @@ fn apply_effects_in_block<'mir, 'tcx, A>(
         let terminator = block_data.terminator();
         let location = Location { block, statement_index: block_data.statements.len() };
         analysis.apply_before_terminator_effect(state, terminator, location);
-        analysis.apply_terminator_effect(state, terminator, location)
+        let edges = analysis.apply_terminator_effect(state, terminator, location);
+
+        let exit_state = state;
+        match edges {
+            TerminatorEdges::None => {}
+            TerminatorEdges::Single(target) => propagate(target, exit_state),
+            TerminatorEdges::Double(target, unwind) => {
+                propagate(target, exit_state);
+                propagate(unwind, exit_state);
+            }
+            TerminatorEdges::AssignOnReturn { return_, cleanup, place } => {
+                // This must be done *first*, otherwise the unwind path will see the assignments.
+                if let Some(cleanup) = cleanup {
+                    propagate(cleanup, exit_state);
+                }
+
+                if !return_.is_empty() {
+                    analysis.apply_call_return_effect(exit_state, block, place);
+                    for &target in return_ {
+                        propagate(target, exit_state);
+                    }
+                }
+            }
+            TerminatorEdges::SwitchInt { targets, discr } => {
+                let mut applier = ForwardSwitchIntEdgeEffectsApplier {
+                    exit_state,
+                    targets,
+                    propagate,
+                    effects_applied: false,
+                };
+
+                analysis.apply_switch_int_edge_effects(block, discr, &mut applier);
+
+                let ForwardSwitchIntEdgeEffectsApplier {
+                    exit_state,
+                    mut propagate,
+                    effects_applied,
+                    ..
+                } = applier;
+
+                if !effects_applied {
+                    for target in targets.all_targets() {
+                        propagate(*target, exit_state);
+                    }
+                }
+            }
+        }
     }
 
     fn apply_effects_in_range<'tcx, A>(
@@ -351,7 +384,8 @@ fn apply_effects_in_range<'tcx, A>(
                 let statement = &block_data.statements[from.statement_index];
                 analysis.apply_statement_effect(state, statement, location);
 
-                // If we only needed to apply the after effect of the statement at `idx`, we are done.
+                // If we only needed to apply the after effect of the statement at `idx`, we are
+                // done.
                 if from == to {
                     return;
                 }
@@ -419,62 +453,6 @@ fn visit_results_in_block<'mir, 'tcx, A>(
 
         vis.visit_block_end(state);
     }
-
-    fn join_state_into_successors_of<'tcx, A>(
-        analysis: &mut A,
-        _body: &mir::Body<'tcx>,
-        exit_state: &mut A::Domain,
-        bb: BasicBlock,
-        edges: TerminatorEdges<'_, 'tcx>,
-        mut propagate: impl FnMut(BasicBlock, &A::Domain),
-    ) where
-        A: Analysis<'tcx>,
-    {
-        match edges {
-            TerminatorEdges::None => {}
-            TerminatorEdges::Single(target) => propagate(target, exit_state),
-            TerminatorEdges::Double(target, unwind) => {
-                propagate(target, exit_state);
-                propagate(unwind, exit_state);
-            }
-            TerminatorEdges::AssignOnReturn { return_, cleanup, place } => {
-                // This must be done *first*, otherwise the unwind path will see the assignments.
-                if let Some(cleanup) = cleanup {
-                    propagate(cleanup, exit_state);
-                }
-
-                if !return_.is_empty() {
-                    analysis.apply_call_return_effect(exit_state, bb, place);
-                    for &target in return_ {
-                        propagate(target, exit_state);
-                    }
-                }
-            }
-            TerminatorEdges::SwitchInt { targets, discr } => {
-                let mut applier = ForwardSwitchIntEdgeEffectsApplier {
-                    exit_state,
-                    targets,
-                    propagate,
-                    effects_applied: false,
-                };
-
-                analysis.apply_switch_int_edge_effects(bb, discr, &mut applier);
-
-                let ForwardSwitchIntEdgeEffectsApplier {
-                    exit_state,
-                    mut propagate,
-                    effects_applied,
-                    ..
-                } = applier;
-
-                if !effects_applied {
-                    for target in targets.all_targets() {
-                        propagate(*target, exit_state);
-                    }
-                }
-            }
-        }
-    }
 }
 
 struct ForwardSwitchIntEdgeEffectsApplier<'mir, D, F> {
diff --git a/compiler/rustc_mir_dataflow/src/framework/fmt.rs b/compiler/rustc_mir_dataflow/src/framework/fmt.rs
index ed540cd148c4..c177d98106f3 100644
--- a/compiler/rustc_mir_dataflow/src/framework/fmt.rs
+++ b/compiler/rustc_mir_dataflow/src/framework/fmt.rs
@@ -230,16 +230,3 @@ fn fmt_with(&self, ctxt: &C, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "{}", ctxt.move_data().move_paths[*self])
     }
 }
-
-impl<T, C> DebugWithContext<C> for crate::lattice::Dual<T>
-where
-    T: DebugWithContext<C>,
-{
-    fn fmt_with(&self, ctxt: &C, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        (self.0).fmt_with(ctxt, f)
-    }
-
-    fn fmt_diff_with(&self, old: &Self, ctxt: &C, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        (self.0).fmt_diff_with(&old.0, ctxt, f)
-    }
-}
diff --git a/compiler/rustc_mir_dataflow/src/framework/graphviz.rs b/compiler/rustc_mir_dataflow/src/framework/graphviz.rs
index 98a4f58cb5dc..6e4994af8b4e 100644
--- a/compiler/rustc_mir_dataflow/src/framework/graphviz.rs
+++ b/compiler/rustc_mir_dataflow/src/framework/graphviz.rs
@@ -47,20 +47,16 @@ impl<'mir, 'tcx, A> Formatter<'mir, 'tcx, A>
 {
     pub(crate) fn new(
         body: &'mir Body<'tcx>,
-        results: Results<'tcx, A>,
+        results: &'mir Results<'tcx, A>,
         style: OutputStyle,
     ) -> Self {
         let reachable = mir::traversal::reachable_as_bitset(body);
-        Formatter { cursor: results.into_results_cursor(body).into(), style, reachable }
+        Formatter { cursor: results.as_results_cursor(body).into(), style, reachable }
     }
 
     fn body(&self) -> &'mir Body<'tcx> {
         self.cursor.borrow().body()
     }
-
-    pub(crate) fn into_results(self) -> Results<'tcx, A> {
-        self.cursor.into_inner().into_results()
-    }
 }
 
 /// A pair of a basic block and an index into that basic blocks `successors`.
diff --git a/compiler/rustc_mir_dataflow/src/framework/lattice.rs b/compiler/rustc_mir_dataflow/src/framework/lattice.rs
index 4d03ee53b7c0..6d2a7a099a09 100644
--- a/compiler/rustc_mir_dataflow/src/framework/lattice.rs
+++ b/compiler/rustc_mir_dataflow/src/framework/lattice.rs
@@ -25,8 +25,8 @@
 //!
 //! ## `PartialOrd`
 //!
-//! Given that they represent partially ordered sets, you may be surprised that [`JoinSemiLattice`]
-//! and [`MeetSemiLattice`] do not have [`PartialOrd`] as a supertrait. This
+//! Given that it represents a partially ordered set, you may be surprised that [`JoinSemiLattice`]
+//! does not have [`PartialOrd`] as a supertrait. This
 //! is because most standard library types use lexicographic ordering instead of set inclusion for
 //! their `PartialOrd` impl. Since we do not actually need to compare lattice elements to run a
 //! dataflow analysis, there's no need for a newtype wrapper with a custom `PartialOrd` impl. The
@@ -58,23 +58,6 @@ pub trait JoinSemiLattice: Eq {
     fn join(&mut self, other: &Self) -> bool;
 }
 
-/// A [partially ordered set][poset] that has a [greatest lower bound][glb] for any pair of
-/// elements in the set.
-///
-/// Dataflow analyses only require that their domains implement [`JoinSemiLattice`], not
-/// `MeetSemiLattice`. However, types that will be used as dataflow domains should implement both
-/// so that they can be used with [`Dual`].
-///
-/// [glb]: https://en.wikipedia.org/wiki/Infimum_and_supremum
-/// [poset]: https://en.wikipedia.org/wiki/Partially_ordered_set
-pub trait MeetSemiLattice: Eq {
-    /// Computes the greatest lower bound of two elements, storing the result in `self` and
-    /// returning `true` if `self` has changed.
-    ///
-    /// The lattice meet operator is abbreviated as `∧`.
-    fn meet(&mut self, other: &Self) -> bool;
-}
-
 /// A set that has a "bottom" element, which is less than or equal to any other element.
 pub trait HasBottom {
     const BOTTOM: Self;
@@ -105,17 +88,6 @@ fn join(&mut self, other: &Self) -> bool {
     }
 }
 
-impl MeetSemiLattice for bool {
-    fn meet(&mut self, other: &Self) -> bool {
-        if let (true, false) = (*self, *other) {
-            *self = false;
-            return true;
-        }
-
-        false
-    }
-}
-
 impl HasBottom for bool {
     const BOTTOM: Self = false;
 
@@ -145,18 +117,6 @@ fn join(&mut self, other: &Self) -> bool {
     }
 }
 
-impl<I: Idx, T: MeetSemiLattice> MeetSemiLattice for IndexVec<I, T> {
-    fn meet(&mut self, other: &Self) -> bool {
-        assert_eq!(self.len(), other.len());
-
-        let mut changed = false;
-        for (a, b) in iter::zip(self, other) {
-            changed |= a.meet(b);
-        }
-        changed
-    }
-}
-
 /// A `BitSet` represents the lattice formed by the powerset of all possible values of
 /// the index type `T` ordered by inclusion. Equivalently, it is a tuple of "two-point" lattices,
 /// one for each possible value of `T`.
@@ -166,60 +126,12 @@ fn join(&mut self, other: &Self) -> bool {
     }
 }
 
-impl<T: Idx> MeetSemiLattice for BitSet<T> {
-    fn meet(&mut self, other: &Self) -> bool {
-        self.intersect(other)
-    }
-}
-
 impl<T: Idx> JoinSemiLattice for ChunkedBitSet<T> {
     fn join(&mut self, other: &Self) -> bool {
         self.union(other)
     }
 }
 
-impl<T: Idx> MeetSemiLattice for ChunkedBitSet<T> {
-    fn meet(&mut self, other: &Self) -> bool {
-        self.intersect(other)
-    }
-}
-
-/// The counterpart of a given semilattice `T` using the [inverse order].
-///
-/// The dual of a join-semilattice is a meet-semilattice and vice versa. For example, the dual of a
-/// powerset has the empty set as its top element and the full set as its bottom element and uses
-/// set *intersection* as its join operator.
-///
-/// [inverse order]: https://en.wikipedia.org/wiki/Duality_(order_theory)
-#[derive(Clone, Copy, Debug, PartialEq, Eq)]
-pub struct Dual<T>(pub T);
-
-impl<T: Idx> BitSetExt<T> for Dual<BitSet<T>> {
-    fn contains(&self, elem: T) -> bool {
-        self.0.contains(elem)
-    }
-
-    fn union(&mut self, other: &HybridBitSet<T>) {
-        self.0.union(other);
-    }
-
-    fn subtract(&mut self, other: &HybridBitSet<T>) {
-        self.0.subtract(other);
-    }
-}
-
-impl<T: MeetSemiLattice> JoinSemiLattice for Dual<T> {
-    fn join(&mut self, other: &Self) -> bool {
-        self.0.meet(&other.0)
-    }
-}
-
-impl<T: JoinSemiLattice> MeetSemiLattice for Dual<T> {
-    fn meet(&mut self, other: &Self) -> bool {
-        self.0.join(&other.0)
-    }
-}
-
 /// Extends a type `T` with top and bottom elements to make it a partially ordered set in which no
 /// value of `T` is comparable with any other.
 ///
@@ -257,22 +169,6 @@ fn join(&mut self, other: &Self) -> bool {
     }
 }
 
-impl<T: Clone + Eq> MeetSemiLattice for FlatSet<T> {
-    fn meet(&mut self, other: &Self) -> bool {
-        let result = match (&*self, other) {
-            (Self::Bottom, _) | (_, Self::Top) => return false,
-            (Self::Elem(ref a), Self::Elem(ref b)) if a == b => return false,
-
-            (Self::Top, Self::Elem(ref x)) => Self::Elem(x.clone()),
-
-            _ => Self::Bottom,
-        };
-
-        *self = result;
-        true
-    }
-}
-
 impl<T> HasBottom for FlatSet<T> {
     const BOTTOM: Self = Self::Bottom;
 
diff --git a/compiler/rustc_mir_dataflow/src/framework/mod.rs b/compiler/rustc_mir_dataflow/src/framework/mod.rs
index 244dfe26ad36..bb652a75caa3 100644
--- a/compiler/rustc_mir_dataflow/src/framework/mod.rs
+++ b/compiler/rustc_mir_dataflow/src/framework/mod.rs
@@ -8,8 +8,9 @@
 //! The `impls` module contains several examples of dataflow analyses.
 //!
 //! Then call `iterate_to_fixpoint` on your type that impls `Analysis` to get a `Results`. From
-//! there, you can use a `ResultsCursor` to inspect the fixpoint solution to your dataflow problem,
-//! or implement the `ResultsVisitor` interface and use `visit_results`. The following example uses
+//! there, you can use a `ResultsCursor` to inspect the fixpoint solution to your dataflow problem
+//! (good for inspecting a small number of locations), or implement the `ResultsVisitor` interface
+//! and use `visit_results` (good for inspecting many or all locations). The following example uses
 //! the `ResultsCursor` approach.
 //!
 //! ```ignore (cross-crate-imports)
@@ -278,22 +279,17 @@ fn iterate_to_fixpoint<'mir>(
         // every iteration.
         let mut state = self.bottom_value(body);
         while let Some(bb) = dirty_queue.pop() {
-            let bb_data = &body[bb];
-
             // Set the state to the entry state of the block.
             // This is equivalent to `state = entry_sets[bb].clone()`,
             // but it saves an allocation, thus improving compile times.
             state.clone_from(&entry_sets[bb]);
 
-            // Apply the block transfer function, using the cached one if it exists.
-            let edges = Self::Direction::apply_effects_in_block(&mut self, &mut state, bb, bb_data);
-
-            Self::Direction::join_state_into_successors_of(
+            Self::Direction::apply_effects_in_block(
                 &mut self,
                 body,
                 &mut state,
                 bb,
-                edges,
+                &body[bb],
                 |target: BasicBlock, state: &Self::Domain| {
                     let set_changed = entry_sets[target].join(state);
                     if set_changed {
@@ -306,14 +302,13 @@ fn iterate_to_fixpoint<'mir>(
         let results = Results { analysis: self, entry_sets };
 
         if tcx.sess.opts.unstable_opts.dump_mir_dataflow {
-            let (res, results) = write_graphviz_results(tcx, body, results, pass_name);
+            let res = write_graphviz_results(tcx, body, &results, pass_name);
             if let Err(e) = res {
                 error!("Failed to write graphviz dataflow results: {}", e);
             }
-            results
-        } else {
-            results
         }
+
+        results
     }
 }
 
@@ -378,16 +373,6 @@ fn kill(&mut self, elem: T) {
     }
 }
 
-impl<T: Idx> GenKill<T> for lattice::Dual<BitSet<T>> {
-    fn gen_(&mut self, elem: T) {
-        self.0.insert(elem);
-    }
-
-    fn kill(&mut self, elem: T) {
-        self.0.remove(elem);
-    }
-}
-
 // NOTE: DO NOT CHANGE VARIANT ORDER. The derived `Ord` impls rely on the current order.
 #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
 enum Effect {
diff --git a/compiler/rustc_mir_dataflow/src/framework/results.rs b/compiler/rustc_mir_dataflow/src/framework/results.rs
index ff6cafbfbaee..8493a7aa44bb 100644
--- a/compiler/rustc_mir_dataflow/src/framework/results.rs
+++ b/compiler/rustc_mir_dataflow/src/framework/results.rs
@@ -17,10 +17,13 @@
 use crate::errors::{
     DuplicateValuesFor, PathMustEndInFilename, RequiresAnArgument, UnknownFormatter,
 };
+use crate::framework::cursor::ResultsHandle;
 
 pub type EntrySets<'tcx, A> = IndexVec<BasicBlock, <A as Analysis<'tcx>>::Domain>;
 
-/// A dataflow analysis that has converged to fixpoint.
+/// A dataflow analysis that has converged to fixpoint. It only holds the domain values at the
+/// entry of each basic block. Domain values in other parts of the block are recomputed on the fly
+/// by visitors (i.e. `ResultsCursor`, or `ResultsVisitor` impls).
 #[derive(Clone)]
 pub struct Results<'tcx, A>
 where
@@ -34,12 +37,30 @@ impl<'tcx, A> Results<'tcx, A>
 where
     A: Analysis<'tcx>,
 {
-    /// Creates a `ResultsCursor` that can inspect these `Results`.
+    /// Creates a `ResultsCursor` that can inspect these `Results`. Immutably borrows the `Results`,
+    /// which is appropriate when the `Results` is used outside the cursor.
+    pub fn as_results_cursor<'mir>(
+        &'mir self,
+        body: &'mir mir::Body<'tcx>,
+    ) -> ResultsCursor<'mir, 'tcx, A> {
+        ResultsCursor::new(body, ResultsHandle::Borrowed(self))
+    }
+
+    /// Creates a `ResultsCursor` that can mutate these `Results`. Mutably borrows the `Results`,
+    /// which is appropriate when the `Results` is used outside the cursor.
+    pub fn as_results_cursor_mut<'mir>(
+        &'mir mut self,
+        body: &'mir mir::Body<'tcx>,
+    ) -> ResultsCursor<'mir, 'tcx, A> {
+        ResultsCursor::new(body, ResultsHandle::BorrowedMut(self))
+    }
+
+    /// Creates a `ResultsCursor` that takes ownership of the `Results`.
     pub fn into_results_cursor<'mir>(
         self,
         body: &'mir mir::Body<'tcx>,
     ) -> ResultsCursor<'mir, 'tcx, A> {
-        ResultsCursor::new(body, self)
+        ResultsCursor::new(body, ResultsHandle::Owned(self))
     }
 
     /// Gets the dataflow state for the given block.
@@ -74,9 +95,9 @@ pub fn visit_reachable_with<'mir>(
 pub(super) fn write_graphviz_results<'tcx, A>(
     tcx: TyCtxt<'tcx>,
     body: &mir::Body<'tcx>,
-    results: Results<'tcx, A>,
+    results: &Results<'tcx, A>,
     pass_name: Option<&'static str>,
-) -> (std::io::Result<()>, Results<'tcx, A>)
+) -> std::io::Result<()>
 where
     A: Analysis<'tcx>,
     A::Domain: DebugWithContext<A>,
@@ -87,7 +108,7 @@ pub(super) fn write_graphviz_results<'tcx, A>(
     let def_id = body.source.def_id();
     let Ok(attrs) = RustcMirAttrs::parse(tcx, def_id) else {
         // Invalid `rustc_mir` attrs are reported in `RustcMirAttrs::parse`
-        return (Ok(()), results);
+        return Ok(());
     };
 
     let file = try {
@@ -104,12 +125,12 @@ pub(super) fn write_graphviz_results<'tcx, A>(
                 create_dump_file(tcx, "dot", false, A::NAME, &pass_name.unwrap_or("-----"), body)?
             }
 
-            _ => return (Ok(()), results),
+            _ => return Ok(()),
         }
     };
     let mut file = match file {
         Ok(f) => f,
-        Err(e) => return (Err(e), results),
+        Err(e) => return Err(e),
     };
 
     let style = match attrs.formatter {
@@ -132,7 +153,7 @@ pub(super) fn write_graphviz_results<'tcx, A>(
         file.write_all(&buf)?;
     };
 
-    (lhs, graphviz.into_results())
+    lhs
 }
 
 #[derive(Default)]
diff --git a/compiler/rustc_mir_dataflow/src/framework/visitor.rs b/compiler/rustc_mir_dataflow/src/framework/visitor.rs
index 5c7539eed4d6..bde41974d472 100644
--- a/compiler/rustc_mir_dataflow/src/framework/visitor.rs
+++ b/compiler/rustc_mir_dataflow/src/framework/visitor.rs
@@ -26,7 +26,9 @@ pub fn visit_results<'mir, 'tcx, A>(
     }
 }
 
-/// A visitor over the results of an `Analysis`.
+/// A visitor over the results of an `Analysis`. Use this when you want to inspect domain values in
+/// many or all locations; use `ResultsCursor` if you want to inspect domain values only in certain
+/// locations.
 pub trait ResultsVisitor<'mir, 'tcx, A>
 where
     A: Analysis<'tcx>,
diff --git a/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs b/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs
index 859019fd1f6e..cec654cac725 100644
--- a/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs
+++ b/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs
@@ -15,7 +15,7 @@
 pub struct MaybeBorrowedLocals;
 
 impl MaybeBorrowedLocals {
-    pub(super) fn transfer_function<'a, T>(&'a self, trans: &'a mut T) -> TransferFunction<'a, T> {
+    pub(super) fn transfer_function<'a, T>(trans: &'a mut T) -> TransferFunction<'a, T> {
         TransferFunction { trans }
     }
 }
@@ -39,7 +39,7 @@ fn apply_statement_effect(
         statement: &Statement<'tcx>,
         location: Location,
     ) {
-        self.transfer_function(trans).visit_statement(statement, location);
+        Self::transfer_function(trans).visit_statement(statement, location);
     }
 
     fn apply_terminator_effect<'mir>(
@@ -48,7 +48,7 @@ fn apply_terminator_effect<'mir>(
         terminator: &'mir Terminator<'tcx>,
         location: Location,
     ) -> TerminatorEdges<'mir, 'tcx> {
-        self.transfer_function(trans).visit_terminator(terminator, location);
+        Self::transfer_function(trans).visit_terminator(terminator, location);
         terminator.edges()
     }
 }
diff --git a/compiler/rustc_mir_dataflow/src/impls/initialized.rs b/compiler/rustc_mir_dataflow/src/impls/initialized.rs
index 9bb50d1e056b..2c10d4b1cd35 100644
--- a/compiler/rustc_mir_dataflow/src/impls/initialized.rs
+++ b/compiler/rustc_mir_dataflow/src/impls/initialized.rs
@@ -12,7 +12,7 @@
 use crate::move_paths::{HasMoveData, InitIndex, InitKind, LookupResult, MoveData, MovePathIndex};
 use crate::{
     Analysis, GenKill, MaybeReachable, drop_flag_effects, drop_flag_effects_for_function_entry,
-    drop_flag_effects_for_location, lattice, on_all_children_bits, on_lookup_result_bits,
+    drop_flag_effects_for_location, on_all_children_bits, on_lookup_result_bits,
 };
 
 /// `MaybeInitializedPlaces` tracks all places that might be
@@ -42,10 +42,10 @@
 /// }
 /// ```
 ///
-/// To determine whether a place *must* be initialized at a
-/// particular control-flow point, one can take the set-difference
-/// between this data and the data from `MaybeUninitializedPlaces` at the
-/// corresponding control-flow point.
+/// To determine whether a place is *definitely* initialized at a
+/// particular control-flow point, one can take the set-complement
+/// of the data from `MaybeUninitializedPlaces` at the corresponding
+/// control-flow point.
 ///
 /// Similarly, at a given `drop` statement, the set-intersection
 /// between this data and `MaybeUninitializedPlaces` yields the set of
@@ -117,10 +117,10 @@ fn move_data(&self) -> &MoveData<'tcx> {
 /// }
 /// ```
 ///
-/// To determine whether a place *must* be uninitialized at a
-/// particular control-flow point, one can take the set-difference
-/// between this data and the data from `MaybeInitializedPlaces` at the
-/// corresponding control-flow point.
+/// To determine whether a place is *definitely* uninitialized at a
+/// particular control-flow point, one can take the set-complement
+/// of the data from `MaybeInitializedPlaces` at the corresponding
+/// control-flow point.
 ///
 /// Similarly, at a given `drop` statement, the set-intersection
 /// between this data and `MaybeInitializedPlaces` yields the set of
@@ -170,57 +170,6 @@ fn move_data(&self) -> &MoveData<'tcx> {
     }
 }
 
-/// `DefinitelyInitializedPlaces` tracks all places that are definitely
-/// initialized upon reaching a particular point in the control flow
-/// for a function.
-///
-/// For example, in code like the following, we have corresponding
-/// dataflow information shown in the right-hand comments.
-///
-/// ```rust
-/// struct S;
-/// fn foo(pred: bool) {                        // definite-init:
-///                                             // {          }
-///     let a = S; let mut b = S; let c; let d; // {a, b      }
-///
-///     if pred {
-///         drop(a);                            // {   b,     }
-///         b = S;                              // {   b,     }
-///
-///     } else {
-///         drop(b);                            // {a,        }
-///         d = S;                              // {a,       d}
-///
-///     }                                       // {          }
-///
-///     c = S;                                  // {       c  }
-/// }
-/// ```
-///
-/// To determine whether a place *may* be uninitialized at a
-/// particular control-flow point, one can take the set-complement
-/// of this data.
-///
-/// Similarly, at a given `drop` statement, the set-difference between
-/// this data and `MaybeInitializedPlaces` yields the set of places
-/// that would require a dynamic drop-flag at that statement.
-pub struct DefinitelyInitializedPlaces<'a, 'tcx> {
-    body: &'a Body<'tcx>,
-    move_data: &'a MoveData<'tcx>,
-}
-
-impl<'a, 'tcx> DefinitelyInitializedPlaces<'a, 'tcx> {
-    pub fn new(body: &'a Body<'tcx>, move_data: &'a MoveData<'tcx>) -> Self {
-        DefinitelyInitializedPlaces { body, move_data }
-    }
-}
-
-impl<'a, 'tcx> HasMoveData<'tcx> for DefinitelyInitializedPlaces<'a, 'tcx> {
-    fn move_data(&self) -> &MoveData<'tcx> {
-        self.move_data
-    }
-}
-
 /// `EverInitializedPlaces` tracks all places that might have ever been
 /// initialized upon reaching a particular point in the control flow
 /// for a function, without an intervening `StorageDead`.
@@ -293,19 +242,6 @@ fn update_bits(
     }
 }
 
-impl<'a, 'tcx> DefinitelyInitializedPlaces<'a, 'tcx> {
-    fn update_bits(
-        trans: &mut <Self as Analysis<'tcx>>::Domain,
-        path: MovePathIndex,
-        state: DropFlagState,
-    ) {
-        match state {
-            DropFlagState::Absent => trans.kill(path),
-            DropFlagState::Present => trans.gen_(path),
-        }
-    }
-}
-
 impl<'tcx> Analysis<'tcx> for MaybeInitializedPlaces<'_, 'tcx> {
     /// There can be many more `MovePathIndex` than there are locals in a MIR body.
     /// We use a chunked bitset to avoid paying too high a memory footprint.
@@ -554,70 +490,6 @@ fn apply_switch_int_edge_effects(
     }
 }
 
-impl<'a, 'tcx> Analysis<'tcx> for DefinitelyInitializedPlaces<'a, 'tcx> {
-    /// Use set intersection as the join operator.
-    type Domain = lattice::Dual<BitSet<MovePathIndex>>;
-
-    const NAME: &'static str = "definite_init";
-
-    fn bottom_value(&self, _: &mir::Body<'tcx>) -> Self::Domain {
-        // bottom = initialized (start_block_effect counters this at outset)
-        lattice::Dual(BitSet::new_filled(self.move_data().move_paths.len()))
-    }
-
-    // sets on_entry bits for Arg places
-    fn initialize_start_block(&self, _: &mir::Body<'tcx>, state: &mut Self::Domain) {
-        state.0.clear();
-
-        drop_flag_effects_for_function_entry(self.body, self.move_data, |path, s| {
-            assert!(s == DropFlagState::Present);
-            state.0.insert(path);
-        });
-    }
-
-    fn apply_statement_effect(
-        &mut self,
-        trans: &mut Self::Domain,
-        _statement: &mir::Statement<'tcx>,
-        location: Location,
-    ) {
-        drop_flag_effects_for_location(self.body, self.move_data, location, |path, s| {
-            Self::update_bits(trans, path, s)
-        })
-    }
-
-    fn apply_terminator_effect<'mir>(
-        &mut self,
-        trans: &mut Self::Domain,
-        terminator: &'mir mir::Terminator<'tcx>,
-        location: Location,
-    ) -> TerminatorEdges<'mir, 'tcx> {
-        drop_flag_effects_for_location(self.body, self.move_data, location, |path, s| {
-            Self::update_bits(trans, path, s)
-        });
-        terminator.edges()
-    }
-
-    fn apply_call_return_effect(
-        &mut self,
-        trans: &mut Self::Domain,
-        _block: mir::BasicBlock,
-        return_places: CallReturnPlaces<'_, 'tcx>,
-    ) {
-        return_places.for_each(|place| {
-            // when a call returns successfully, that means we need to set
-            // the bits for that dest_place to 1 (initialized).
-            on_lookup_result_bits(
-                self.move_data(),
-                self.move_data().rev_lookup.find(place.as_ref()),
-                |mpi| {
-                    trans.gen_(mpi);
-                },
-            );
-        });
-    }
-}
-
 impl<'tcx> Analysis<'tcx> for EverInitializedPlaces<'_, 'tcx> {
     /// There can be many more `InitIndex` than there are locals in a MIR body.
     /// We use a chunked bitset to avoid paying too high a memory footprint.
diff --git a/compiler/rustc_mir_dataflow/src/impls/mod.rs b/compiler/rustc_mir_dataflow/src/impls/mod.rs
index 9b5bfa9bfa00..57ded63c9baa 100644
--- a/compiler/rustc_mir_dataflow/src/impls/mod.rs
+++ b/compiler/rustc_mir_dataflow/src/impls/mod.rs
@@ -9,8 +9,7 @@
 
 pub use self::borrowed_locals::{MaybeBorrowedLocals, borrowed_locals};
 pub use self::initialized::{
-    DefinitelyInitializedPlaces, EverInitializedPlaces, MaybeInitializedPlaces,
-    MaybeUninitializedPlaces,
+    EverInitializedPlaces, MaybeInitializedPlaces, MaybeUninitializedPlaces,
 };
 pub use self::liveness::{
     MaybeLiveLocals, MaybeTransitiveLiveLocals, TransferFunction as LivenessTransferFunction,
diff --git a/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs b/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs
index 576289e228ad..a6a4f849720f 100644
--- a/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs
+++ b/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs
@@ -135,7 +135,7 @@ fn apply_before_statement_effect(
         loc: Location,
     ) {
         // If a place is borrowed in a statement, it needs storage for that statement.
-        self.borrowed_locals.mut_analysis().apply_statement_effect(trans, stmt, loc);
+        MaybeBorrowedLocals::transfer_function(trans).visit_statement(stmt, loc);
 
         match &stmt.kind {
             StatementKind::StorageDead(l) => trans.kill(*l),
@@ -180,10 +180,7 @@ fn apply_before_terminator_effect(
         loc: Location,
     ) {
         // If a place is borrowed in a terminator, it needs storage for that terminator.
-        self.borrowed_locals
-            .mut_analysis()
-            .transfer_function(trans)
-            .visit_terminator(terminator, loc);
+        MaybeBorrowedLocals::transfer_function(trans).visit_terminator(terminator, loc);
 
         match &terminator.kind {
             TerminatorKind::Call { destination, .. } => {
diff --git a/compiler/rustc_mir_dataflow/src/rustc_peek.rs b/compiler/rustc_mir_dataflow/src/rustc_peek.rs
index 99d0ccde1052..34ef8afdde32 100644
--- a/compiler/rustc_mir_dataflow/src/rustc_peek.rs
+++ b/compiler/rustc_mir_dataflow/src/rustc_peek.rs
@@ -12,9 +12,7 @@
     PeekMustBePlaceOrRefPlace, StopAfterDataFlowEndedCompilation,
 };
 use crate::framework::BitSetExt;
-use crate::impls::{
-    DefinitelyInitializedPlaces, MaybeInitializedPlaces, MaybeLiveLocals, MaybeUninitializedPlaces,
-};
+use crate::impls::{MaybeInitializedPlaces, MaybeLiveLocals, MaybeUninitializedPlaces};
 use crate::move_paths::{HasMoveData, LookupResult, MoveData, MovePathIndex};
 use crate::{Analysis, JoinSemiLattice, ResultsCursor};
 
@@ -56,13 +54,6 @@ pub fn sanity_check<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'tcx>) {
         sanity_check_via_rustc_peek(tcx, flow_uninits.into_results_cursor(body));
     }
 
-    if has_rustc_mir_with(tcx, def_id, sym::rustc_peek_definite_init).is_some() {
-        let flow_def_inits =
-            DefinitelyInitializedPlaces::new(body, &move_data).iterate_to_fixpoint(tcx, body, None);
-
-        sanity_check_via_rustc_peek(tcx, flow_def_inits.into_results_cursor(body));
-    }
-
     if has_rustc_mir_with(tcx, def_id, sym::rustc_peek_liveness).is_some() {
         let flow_liveness = MaybeLiveLocals.iterate_to_fixpoint(tcx, body, None);
 
diff --git a/compiler/rustc_mir_transform/src/coroutine.rs b/compiler/rustc_mir_transform/src/coroutine.rs
index 8295a806d712..ae5506b05e74 100644
--- a/compiler/rustc_mir_transform/src/coroutine.rs
+++ b/compiler/rustc_mir_transform/src/coroutine.rs
@@ -676,12 +676,11 @@ fn locals_live_across_suspend_points<'tcx>(
 
     let mut borrowed_locals_cursor = borrowed_locals_results.clone().into_results_cursor(body);
 
-    // Calculate the MIR locals that we actually need to keep storage around
-    // for.
-    let mut requires_storage_cursor =
+    // Calculate the MIR locals that we need to keep storage around for.
+    let mut requires_storage_results =
         MaybeRequiresStorage::new(borrowed_locals_results.into_results_cursor(body))
-            .iterate_to_fixpoint(tcx, body, None)
-            .into_results_cursor(body);
+            .iterate_to_fixpoint(tcx, body, None);
+    let mut requires_storage_cursor = requires_storage_results.as_results_cursor_mut(body);
 
     // Calculate the liveness of MIR locals ignoring borrows.
     let mut liveness =
@@ -754,7 +753,7 @@ fn locals_live_across_suspend_points<'tcx>(
         body,
         &saved_locals,
         always_live_locals.clone(),
-        requires_storage_cursor.into_results(),
+        requires_storage_results,
     );
 
     LivenessInfo {
diff --git a/compiler/rustc_parse/src/lexer/mod.rs b/compiler/rustc_parse/src/lexer/mod.rs
index 5023e83bd67c..8db3b174a89f 100644
--- a/compiler/rustc_parse/src/lexer/mod.rs
+++ b/compiler/rustc_parse/src/lexer/mod.rs
@@ -18,6 +18,7 @@
 use rustc_span::{BytePos, Pos, Span};
 use tracing::debug;
 
+use crate::lexer::diagnostics::TokenTreeDiagInfo;
 use crate::lexer::unicode_chars::UNICODE_ARRAY;
 use crate::{errors, make_unclosed_delims_error};
 
@@ -56,7 +57,7 @@ pub(crate) fn lex_token_trees<'psess, 'src>(
     }
 
     let cursor = Cursor::new(src);
-    let string_reader = StringReader {
+    let mut lexer = Lexer {
         psess,
         start_pos,
         pos: start_pos,
@@ -65,34 +66,31 @@ pub(crate) fn lex_token_trees<'psess, 'src>(
         override_span,
         nbsp_is_whitespace: false,
         last_lifetime: None,
+        token: Token::dummy(),
+        diag_info: TokenTreeDiagInfo::default(),
     };
-    let (stream, res, unmatched_delims) =
-        tokentrees::TokenTreesReader::lex_all_token_trees(string_reader);
-    match res {
-        Ok(()) if unmatched_delims.is_empty() => Ok(stream),
-        _ => {
-            // Return error if there are unmatched delimiters or unclosed delimiters.
-            // We emit delimiter mismatch errors first, then emit the unclosing delimiter mismatch
-            // because the delimiter mismatch is more likely to be the root cause of error
+    let (_open_spacing, stream, res) = lexer.lex_token_trees(/* is_delimited */ false);
+    let unmatched_delims = lexer.diag_info.unmatched_delims;
 
-            let mut buffer = Vec::with_capacity(1);
-            for unmatched in unmatched_delims {
-                if let Some(err) = make_unclosed_delims_error(unmatched, psess) {
-                    buffer.push(err);
-                }
-            }
-            if let Err(errs) = res {
-                // Add unclosing delimiter or diff marker errors
-                for err in errs {
-                    buffer.push(err);
-                }
-            }
-            Err(buffer)
+    if res.is_ok() && unmatched_delims.is_empty() {
+        Ok(stream)
+    } else {
+        // Return error if there are unmatched delimiters or unclosed delimiters.
+        // We emit delimiter mismatch errors first, then emit the unclosing delimiter mismatch
+        // because the delimiter mismatch is more likely to be the root cause of error
+        let mut buffer: Vec<_> = unmatched_delims
+            .into_iter()
+            .filter_map(|unmatched_delim| make_unclosed_delims_error(unmatched_delim, psess))
+            .collect();
+        if let Err(errs) = res {
+            // Add unclosing delimiter or diff marker errors
+            buffer.extend(errs);
         }
+        Err(buffer)
     }
 }
 
-struct StringReader<'psess, 'src> {
+struct Lexer<'psess, 'src> {
     psess: &'psess ParseSess,
     /// Initial position, read-only.
     start_pos: BytePos,
@@ -111,9 +109,14 @@ struct StringReader<'psess, 'src> {
     /// Track the `Span` for the leading `'` of the last lifetime. Used for
     /// diagnostics to detect possible typo where `"` was meant.
     last_lifetime: Option<Span>,
+
+    /// The current token.
+    token: Token,
+
+    diag_info: TokenTreeDiagInfo,
 }
 
-impl<'psess, 'src> StringReader<'psess, 'src> {
+impl<'psess, 'src> Lexer<'psess, 'src> {
     fn dcx(&self) -> DiagCtxtHandle<'psess> {
         self.psess.dcx()
     }
@@ -124,7 +127,7 @@ fn mk_sp(&self, lo: BytePos, hi: BytePos) -> Span {
 
     /// Returns the next token, paired with a bool indicating if the token was
     /// preceded by whitespace.
-    fn next_token(&mut self) -> (Token, bool) {
+    fn next_token_from_cursor(&mut self) -> (Token, bool) {
         let mut preceded_by_whitespace = false;
         let mut swallow_next_invalid = 0;
         // Skip trivial (whitespace & comments) tokens
@@ -231,7 +234,8 @@ fn next_token(&mut self) -> (Token, bool) {
                         .push(span);
                     token::Ident(sym, IdentIsRaw::No)
                 }
-                // split up (raw) c string literals to an ident and a string literal when edition < 2021.
+                // split up (raw) c string literals to an ident and a string literal when edition <
+                // 2021.
                 rustc_lexer::TokenKind::Literal {
                     kind: kind @ (LiteralKind::CStr { .. } | LiteralKind::RawCStr { .. }),
                     suffix_start: _,
@@ -252,7 +256,9 @@ fn next_token(&mut self) -> (Token, bool) {
                     let prefix_span = self.mk_sp(start, lit_start);
                     return (Token::new(self.ident(start), prefix_span), preceded_by_whitespace);
                 }
-                rustc_lexer::TokenKind::GuardedStrPrefix => self.maybe_report_guarded_str(start, str_before),
+                rustc_lexer::TokenKind::GuardedStrPrefix => {
+                    self.maybe_report_guarded_str(start, str_before)
+                }
                 rustc_lexer::TokenKind::Literal { kind, suffix_start } => {
                     let suffix_start = start + BytePos(suffix_start);
                     let (kind, symbol) = self.cook_lexer_literal(start, suffix_start, kind);
@@ -296,13 +302,20 @@ fn next_token(&mut self) -> (Token, bool) {
                     if prefix_span.at_least_rust_2021() {
                         let span = self.mk_sp(start, self.pos);
 
-                        let lifetime_name_without_tick = Symbol::intern(&self.str_from(ident_start));
+                        let lifetime_name_without_tick =
+                            Symbol::intern(&self.str_from(ident_start));
                         if !lifetime_name_without_tick.can_be_raw() {
-                            self.dcx().emit_err(errors::CannotBeRawLifetime { span, ident: lifetime_name_without_tick });
+                            self.dcx().emit_err(
+                                errors::CannotBeRawLifetime {
+                                    span,
+                                    ident: lifetime_name_without_tick
+                                }
+                            );
                         }
 
                         // Put the `'` back onto the lifetime name.
-                        let mut lifetime_name = String::with_capacity(lifetime_name_without_tick.as_str().len() + 1);
+                        let mut lifetime_name =
+                            String::with_capacity(lifetime_name_without_tick.as_str().len() + 1);
                         lifetime_name.push('\'');
                         lifetime_name += lifetime_name_without_tick.as_str();
                         let sym = Symbol::intern(&lifetime_name);
diff --git a/compiler/rustc_parse/src/lexer/tokentrees.rs b/compiler/rustc_parse/src/lexer/tokentrees.rs
index 7b21ffacc841..c6c9eb3b0b26 100644
--- a/compiler/rustc_parse/src/lexer/tokentrees.rs
+++ b/compiler/rustc_parse/src/lexer/tokentrees.rs
@@ -4,41 +4,19 @@
 use rustc_errors::{Applicability, PErr};
 use rustc_span::symbol::kw;
 
-use super::diagnostics::{
-    TokenTreeDiagInfo, report_suspicious_mismatch_block, same_indentation_level,
-};
-use super::{StringReader, UnmatchedDelim};
+use super::diagnostics::{report_suspicious_mismatch_block, same_indentation_level};
+use super::{Lexer, UnmatchedDelim};
 use crate::Parser;
 
-pub(super) struct TokenTreesReader<'psess, 'src> {
-    string_reader: StringReader<'psess, 'src>,
-    /// The "next" token, which has been obtained from the `StringReader` but
-    /// not yet handled by the `TokenTreesReader`.
-    token: Token,
-    diag_info: TokenTreeDiagInfo,
-}
-
-impl<'psess, 'src> TokenTreesReader<'psess, 'src> {
-    pub(super) fn lex_all_token_trees(
-        string_reader: StringReader<'psess, 'src>,
-    ) -> (TokenStream, Result<(), Vec<PErr<'psess>>>, Vec<UnmatchedDelim>) {
-        let mut tt_reader = TokenTreesReader {
-            string_reader,
-            token: Token::dummy(),
-            diag_info: TokenTreeDiagInfo::default(),
-        };
-        let (_open_spacing, stream, res) = tt_reader.lex_token_trees(/* is_delimited */ false);
-        (stream, res, tt_reader.diag_info.unmatched_delims)
-    }
-
+impl<'psess, 'src> Lexer<'psess, 'src> {
     // Lex into a token stream. The `Spacing` in the result is that of the
     // opening delimiter.
-    fn lex_token_trees(
+    pub(super) fn lex_token_trees(
         &mut self,
         is_delimited: bool,
     ) -> (Spacing, TokenStream, Result<(), Vec<PErr<'psess>>>) {
         // Move past the opening delimiter.
-        let (_, open_spacing) = self.bump(false);
+        let open_spacing = self.bump_minimal();
 
         let mut buf = Vec::new();
         loop {
@@ -71,7 +49,7 @@ fn lex_token_trees(
                 }
                 _ => {
                     // Get the next normal token.
-                    let (this_tok, this_spacing) = self.bump(true);
+                    let (this_tok, this_spacing) = self.bump();
                     buf.push(TokenTree::Token(this_tok, this_spacing));
                 }
             }
@@ -80,7 +58,7 @@ fn lex_token_trees(
 
     fn eof_err(&mut self) -> PErr<'psess> {
         let msg = "this file contains an unclosed delimiter";
-        let mut err = self.string_reader.dcx().struct_span_err(self.token.span, msg);
+        let mut err = self.dcx().struct_span_err(self.token.span, msg);
 
         let unclosed_delimiter_show_limit = 5;
         let len = usize::min(unclosed_delimiter_show_limit, self.diag_info.open_braces.len());
@@ -110,7 +88,7 @@ fn eof_err(&mut self) -> PErr<'psess> {
             report_suspicious_mismatch_block(
                 &mut err,
                 &self.diag_info,
-                self.string_reader.psess.source_map(),
+                self.psess.source_map(),
                 *delim,
             )
         }
@@ -136,7 +114,7 @@ fn lex_token_tree_open_delim(
 
         // Expand to cover the entire delimited token tree.
         let delim_span = DelimSpan::from_pair(pre_span, self.token.span);
-        let sm = self.string_reader.psess.source_map();
+        let sm = self.psess.source_map();
 
         let close_spacing = match self.token.kind {
             // Correct delimiter.
@@ -160,7 +138,7 @@ fn lex_token_tree_open_delim(
                 }
 
                 // Move past the closing delimiter.
-                self.bump(false).1
+                self.bump_minimal()
             }
             // Incorrect delimiter.
             token::CloseDelim(close_delim) => {
@@ -203,7 +181,7 @@ fn lex_token_tree_open_delim(
                 //     bar(baz(
                 // }  // Incorrect delimiter but matches the earlier `{`
                 if !self.diag_info.open_braces.iter().any(|&(b, _)| b == close_delim) {
-                    self.bump(false).1
+                    self.bump_minimal()
                 } else {
                     // The choice of value here doesn't matter.
                     Spacing::Alone
@@ -225,14 +203,14 @@ fn lex_token_tree_open_delim(
     }
 
     // Move on to the next token, returning the current token and its spacing.
-    // Will glue adjacent single-char tokens together if `glue` is set.
-    fn bump(&mut self, glue: bool) -> (Token, Spacing) {
+    // Will glue adjacent single-char tokens together.
+    fn bump(&mut self) -> (Token, Spacing) {
         let (this_spacing, next_tok) = loop {
-            let (next_tok, is_next_tok_preceded_by_whitespace) = self.string_reader.next_token();
+            let (next_tok, is_next_tok_preceded_by_whitespace) = self.next_token_from_cursor();
 
             if is_next_tok_preceded_by_whitespace {
                 break (Spacing::Alone, next_tok);
-            } else if glue && let Some(glued) = self.token.glue(&next_tok) {
+            } else if let Some(glued) = self.token.glue(&next_tok) {
                 self.token = glued;
             } else {
                 let this_spacing = if next_tok.is_punct() {
@@ -249,6 +227,26 @@ fn bump(&mut self, glue: bool) -> (Token, Spacing) {
         (this_tok, this_spacing)
     }
 
+    // Cut-down version of `bump` used when the token kind is known in advance.
+    fn bump_minimal(&mut self) -> Spacing {
+        let (next_tok, is_next_tok_preceded_by_whitespace) = self.next_token_from_cursor();
+
+        let this_spacing = if is_next_tok_preceded_by_whitespace {
+            Spacing::Alone
+        } else {
+            if next_tok.is_punct() {
+                Spacing::Joint
+            } else if next_tok == token::Eof {
+                Spacing::Alone
+            } else {
+                Spacing::JointHidden
+            }
+        };
+
+        self.token = next_tok;
+        this_spacing
+    }
+
     fn unclosed_delim_err(
         &mut self,
         tts: TokenStream,
@@ -256,7 +254,7 @@ fn unclosed_delim_err(
     ) -> Vec<PErr<'psess>> {
         // If there are unclosed delims, see if there are diff markers and if so, point them
         // out instead of complaining about the unclosed delims.
-        let mut parser = Parser::new(self.string_reader.psess, tts, None);
+        let mut parser = Parser::new(self.psess, tts, None);
         let mut diff_errs = vec![];
         // Suggest removing a `{` we think appears in an `if`/`while` condition.
         // We want to suggest removing a `{` only if we think we're in an `if`/`while` condition,
@@ -314,14 +312,9 @@ fn close_delim_err(&mut self, delim: Delimiter) -> PErr<'psess> {
         // An unexpected closing delimiter (i.e., there is no matching opening delimiter).
         let token_str = token_to_string(&self.token);
         let msg = format!("unexpected closing delimiter: `{token_str}`");
-        let mut err = self.string_reader.dcx().struct_span_err(self.token.span, msg);
+        let mut err = self.dcx().struct_span_err(self.token.span, msg);
 
-        report_suspicious_mismatch_block(
-            &mut err,
-            &self.diag_info,
-            self.string_reader.psess.source_map(),
-            delim,
-        );
+        report_suspicious_mismatch_block(&mut err, &self.diag_info, self.psess.source_map(), delim);
         err.span_label(self.token.span, "unexpected closing delimiter");
         err
     }
diff --git a/compiler/rustc_parse/src/lexer/unicode_chars.rs b/compiler/rustc_parse/src/lexer/unicode_chars.rs
index d78b3664b1ee..42eef27803eb 100644
--- a/compiler/rustc_parse/src/lexer/unicode_chars.rs
+++ b/compiler/rustc_parse/src/lexer/unicode_chars.rs
@@ -4,7 +4,7 @@
 use rustc_span::symbol::kw;
 use rustc_span::{BytePos, Pos, Span};
 
-use super::StringReader;
+use super::Lexer;
 use crate::errors::TokenSubstitution;
 use crate::token::{self, Delimiter};
 
@@ -338,7 +338,7 @@
 ];
 
 pub(super) fn check_for_substitution(
-    reader: &StringReader<'_, '_>,
+    lexer: &Lexer<'_, '_>,
     pos: BytePos,
     ch: char,
     count: usize,
@@ -351,11 +351,11 @@ pub(super) fn check_for_substitution(
 
     let Some((_, ascii_name, token)) = ASCII_ARRAY.iter().find(|&&(s, _, _)| s == ascii_str) else {
         let msg = format!("substitution character not found for '{ch}'");
-        reader.dcx().span_bug(span, msg);
+        lexer.dcx().span_bug(span, msg);
     };
 
     // special help suggestion for "directed" double quotes
-    let sugg = if let Some(s) = peek_delimited(&reader.src[reader.src_index(pos)..], '“', '”') {
+    let sugg = if let Some(s) = peek_delimited(&lexer.src[lexer.src_index(pos)..], '“', '”') {
         let span = Span::with_root_ctxt(
             pos,
             pos + Pos::from_usize('“'.len_utf8() + s.len() + '”'.len_utf8()),
diff --git a/compiler/rustc_parse/src/parser/pat.rs b/compiler/rustc_parse/src/parser/pat.rs
index c4326427f67b..004b5b348136 100644
--- a/compiler/rustc_parse/src/parser/pat.rs
+++ b/compiler/rustc_parse/src/parser/pat.rs
@@ -1,11 +1,12 @@
 use rustc_ast::mut_visit::{self, MutVisitor};
 use rustc_ast::ptr::P;
 use rustc_ast::token::{self, BinOpToken, Delimiter, IdentIsRaw, Token};
+use rustc_ast::util::parser::AssocOp;
 use rustc_ast::visit::{self, Visitor};
 use rustc_ast::{
-    self as ast, Arm, AttrVec, BinOpKind, BindingMode, ByRef, Expr, ExprKind, ExprPrecedence,
-    LocalKind, MacCall, Mutability, Pat, PatField, PatFieldsRest, PatKind, Path, QSelf, RangeEnd,
-    RangeSyntax, Stmt, StmtKind,
+    self as ast, Arm, AttrVec, BinOpKind, BindingMode, ByRef, Expr, ExprKind, LocalKind, MacCall,
+    Mutability, Pat, PatField, PatFieldsRest, PatKind, Path, QSelf, RangeEnd, RangeSyntax, Stmt,
+    StmtKind,
 };
 use rustc_ast_pretty::pprust;
 use rustc_errors::{Applicability, Diag, DiagArgValue, PResult, StashKey};
@@ -458,7 +459,7 @@ fn maybe_recover_trailing_expr(
                 .create_err(UnexpectedExpressionInPattern {
                     span,
                     is_bound,
-                    expr_precedence: expr.precedence().order(),
+                    expr_precedence: expr.precedence(),
                 })
                 .stash(span, StashKey::ExprInPat)
                 .unwrap(),
@@ -545,7 +546,8 @@ fn maybe_add_suggestions_then_emit(
                             let expr = match &err.args["expr_precedence"] {
                                 DiagArgValue::Number(expr_precedence) => {
                                     if *expr_precedence
-                                        <= ExprPrecedence::Binary(BinOpKind::Eq).order() as i32
+                                        <= AssocOp::from_ast_binop(BinOpKind::Eq).precedence()
+                                            as i32
                                     {
                                         format!("({expr})")
                                     } else {
@@ -568,8 +570,9 @@ fn maybe_add_suggestions_then_emit(
                                 }
                                 Some(guard) => {
                                     // Are parentheses required around the old guard?
-                                    let wrap_guard = guard.precedence().order()
-                                        <= ExprPrecedence::Binary(BinOpKind::And).order();
+                                    let wrap_guard = guard.precedence()
+                                        <= AssocOp::from_ast_binop(BinOpKind::And).precedence()
+                                            as i8;
 
                                     err.subdiagnostic(
                                         UnexpectedExpressionInPatternSugg::UpdateGuard {
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index 46e245fb71f1..5252c446e1d3 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -1728,7 +1728,6 @@
         rustc_partition_reused,
         rustc_pass_by_value,
         rustc_peek,
-        rustc_peek_definite_init,
         rustc_peek_liveness,
         rustc_peek_maybe_init,
         rustc_peek_maybe_uninit,
diff --git a/compiler/rustc_target/src/spec/tests/tests_impl.rs b/compiler/rustc_target/src/spec/tests/tests_impl.rs
index 522b9f837d7c..3225cdc759d9 100644
--- a/compiler/rustc_target/src/spec/tests/tests_impl.rs
+++ b/compiler/rustc_target/src/spec/tests/tests_impl.rs
@@ -1,5 +1,7 @@
 use std::assert_matches::assert_matches;
 
+use rustc_data_structures::fx::FxHashSet;
+
 use super::super::*;
 
 // Test target self-consistency and JSON encoding/decoding roundtrip.
@@ -173,6 +175,27 @@ fn check_consistency(&self) {
             }
             _ => {}
         }
+
+        // Check that the given target-features string makes some basic sense.
+        if !self.features.is_empty() {
+            let mut features_enabled = FxHashSet::default();
+            let mut features_disabled = FxHashSet::default();
+            for feat in self.features.split(',') {
+                if let Some(feat) = feat.strip_prefix("+") {
+                    features_enabled.insert(feat);
+                    if features_disabled.contains(feat) {
+                        panic!("target feature `{feat}` is both enabled and disabled");
+                    }
+                } else if let Some(feat) = feat.strip_prefix("-") {
+                    features_disabled.insert(feat);
+                    if features_enabled.contains(feat) {
+                        panic!("target feature `{feat}` is both enabled and disabled");
+                    }
+                } else {
+                    panic!("target feature `{feat}` is invalid, must start with `+` or `-`");
+                }
+            }
+        }
     }
 
     // Add your target to the whitelist if it has `std` library
diff --git a/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs b/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs
index c7ad14ac0bfc..0f9d4cb1982d 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs
@@ -1792,12 +1792,12 @@ pub fn type_error_additional_suggestions(
 
     fn suggest_specify_actual_length(
         &self,
-        terr: TypeError<'_>,
-        trace: &TypeTrace<'_>,
+        terr: TypeError<'tcx>,
+        trace: &TypeTrace<'tcx>,
         span: Span,
     ) -> Option<TypeErrorAdditionalDiags> {
         let hir = self.tcx.hir();
-        let TypeError::FixedArraySize(sz) = terr else {
+        let TypeError::ArraySize(sz) = terr else {
             return None;
         };
         let tykind = match self.tcx.hir_node_by_def_id(trace.cause.body_id) {
@@ -1838,9 +1838,14 @@ fn visit_stmt(&mut self, s: &'v hir::Stmt<'v>) -> Self::Result {
         if let Some(tykind) = tykind
             && let hir::TyKind::Array(_, length) = tykind
             && let hir::ArrayLen::Body(ct) = length
+            && let Some((scalar, ty)) = sz.found.try_to_scalar()
+            && ty == self.tcx.types.usize
         {
             let span = ct.span();
-            Some(TypeErrorAdditionalDiags::ConsiderSpecifyingLength { span, length: sz.found })
+            Some(TypeErrorAdditionalDiags::ConsiderSpecifyingLength {
+                span,
+                length: scalar.to_target_usize(&self.tcx).unwrap(),
+            })
         } else {
             None
         }
diff --git a/compiler/rustc_type_ir/src/error.rs b/compiler/rustc_type_ir/src/error.rs
index 59dea7695111..55671b84dbc4 100644
--- a/compiler/rustc_type_ir/src/error.rs
+++ b/compiler/rustc_type_ir/src/error.rs
@@ -29,7 +29,7 @@ pub enum TypeError<I: Interner> {
     Mutability,
     ArgumentMutability(usize),
     TupleSize(ExpectedFound<usize>),
-    FixedArraySize(ExpectedFound<u64>),
+    ArraySize(ExpectedFound<I::Const>),
     ArgCount,
 
     RegionsDoesNotOutlive(I::Region, I::Region),
@@ -69,7 +69,7 @@ pub fn must_include_note(self) -> bool {
         use self::TypeError::*;
         match self {
             CyclicTy(_) | CyclicConst(_) | SafetyMismatch(_) | PolarityMismatch(_) | Mismatch
-            | AbiMismatch(_) | FixedArraySize(_) | ArgumentSorts(..) | Sorts(_)
+            | AbiMismatch(_) | ArraySize(_) | ArgumentSorts(..) | Sorts(_)
             | VariadicMismatch(_) | TargetFeatureCast(_) => false,
 
             Mutability
diff --git a/compiler/rustc_type_ir/src/inherent.rs b/compiler/rustc_type_ir/src/inherent.rs
index 3793d2c5241f..a201f2b1c11f 100644
--- a/compiler/rustc_type_ir/src/inherent.rs
+++ b/compiler/rustc_type_ir/src/inherent.rs
@@ -257,8 +257,6 @@ pub trait Const<I: Interner<Const = Self>>:
     + Relate<I>
     + Flags
 {
-    fn try_to_target_usize(self, interner: I) -> Option<u64>;
-
     fn new_infer(interner: I, var: ty::InferConst) -> Self;
 
     fn new_var(interner: I, var: ty::ConstVid) -> Self;
diff --git a/compiler/rustc_type_ir/src/relate.rs b/compiler/rustc_type_ir/src/relate.rs
index 6b301b160605..0b013b2017f1 100644
--- a/compiler/rustc_type_ir/src/relate.rs
+++ b/compiler/rustc_type_ir/src/relate.rs
@@ -501,19 +501,10 @@ pub fn structurally_relate_tys<I: Interner, R: TypeRelation<I>>(
             let t = relation.relate(a_t, b_t)?;
             match relation.relate(sz_a, sz_b) {
                 Ok(sz) => Ok(Ty::new_array_with_const_len(cx, t, sz)),
-                Err(err) => {
-                    // Check whether the lengths are both concrete/known values,
-                    // but are unequal, for better diagnostics.
-                    let sz_a = sz_a.try_to_target_usize(cx);
-                    let sz_b = sz_b.try_to_target_usize(cx);
-
-                    match (sz_a, sz_b) {
-                        (Some(sz_a_val), Some(sz_b_val)) if sz_a_val != sz_b_val => {
-                            Err(TypeError::FixedArraySize(ExpectedFound::new(sz_a_val, sz_b_val)))
-                        }
-                        _ => Err(err),
-                    }
+                Err(TypeError::ConstMismatch(_)) => {
+                    Err(TypeError::ArraySize(ExpectedFound::new(sz_a, sz_b)))
                 }
+                Err(e) => Err(e),
             }
         }
 
diff --git a/library/alloc/src/collections/btree/map/entry.rs b/library/alloc/src/collections/btree/map/entry.rs
index 75bb86916a88..0da6af54bc22 100644
--- a/library/alloc/src/collections/btree/map/entry.rs
+++ b/library/alloc/src/collections/btree/map/entry.rs
@@ -269,6 +269,31 @@ pub fn and_modify<F>(self, f: F) -> Self
             Vacant(entry) => Vacant(entry),
         }
     }
+
+    /// Sets the value of the entry, and returns an `OccupiedEntry`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(btree_entry_insert)]
+    /// use std::collections::BTreeMap;
+    ///
+    /// let mut map: BTreeMap<&str, String> = BTreeMap::new();
+    /// let entry = map.entry("poneyland").insert_entry("hoho".to_string());
+    ///
+    /// assert_eq!(entry.key(), &"poneyland");
+    /// ```
+    #[inline]
+    #[unstable(feature = "btree_entry_insert", issue = "65225")]
+    pub fn insert_entry(self, value: V) -> OccupiedEntry<'a, K, V, A> {
+        match self {
+            Occupied(mut entry) => {
+                entry.insert(value);
+                entry
+            }
+            Vacant(entry) => entry.insert_entry(value),
+        }
+    }
 }
 
 impl<'a, K: Ord, V: Default, A: Allocator + Clone> Entry<'a, K, V, A> {
@@ -348,41 +373,61 @@ pub fn into_key(self) -> K {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_confusables("push", "put")]
-    pub fn insert(mut self, value: V) -> &'a mut V {
-        let out_ptr = match self.handle {
+    pub fn insert(self, value: V) -> &'a mut V {
+        self.insert_entry(value).into_mut()
+    }
+
+    /// Sets the value of the entry with the `VacantEntry`'s key,
+    /// and returns an `OccupiedEntry`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(btree_entry_insert)]
+    /// use std::collections::BTreeMap;
+    /// use std::collections::btree_map::Entry;
+    ///
+    /// let mut map: BTreeMap<&str, u32> = BTreeMap::new();
+    ///
+    /// if let Entry::Vacant(o) = map.entry("poneyland") {
+    ///     let entry = o.insert_entry(37);
+    ///     assert_eq!(entry.get(), &37);
+    /// }
+    /// assert_eq!(map["poneyland"], 37);
+    /// ```
+    #[unstable(feature = "btree_entry_insert", issue = "65225")]
+    pub fn insert_entry(mut self, value: V) -> OccupiedEntry<'a, K, V, A> {
+        let handle = match self.handle {
             None => {
                 // SAFETY: There is no tree yet so no reference to it exists.
-                let map = unsafe { self.dormant_map.awaken() };
-                let mut root = NodeRef::new_leaf(self.alloc.clone());
-                let val_ptr = root.borrow_mut().push(self.key, value);
-                map.root = Some(root.forget_type());
-                map.length = 1;
-                val_ptr
-            }
-            Some(handle) => {
-                let new_handle =
-                    handle.insert_recursing(self.key, value, self.alloc.clone(), |ins| {
-                        drop(ins.left);
-                        // SAFETY: Pushing a new root node doesn't invalidate
-                        // handles to existing nodes.
-                        let map = unsafe { self.dormant_map.reborrow() };
-                        let root = map.root.as_mut().unwrap(); // same as ins.left
-                        root.push_internal_level(self.alloc).push(ins.kv.0, ins.kv.1, ins.right)
-                    });
-
-                // Get the pointer to the value
-                let val_ptr = new_handle.into_val_mut();
-
-                // SAFETY: We have consumed self.handle.
-                let map = unsafe { self.dormant_map.awaken() };
-                map.length += 1;
-                val_ptr
+                let map = unsafe { self.dormant_map.reborrow() };
+                let root = map.root.insert(NodeRef::new_leaf(self.alloc.clone()).forget_type());
+                // SAFETY: We *just* created the root as a leaf, and we're
+                // stacking the new handle on the original borrow lifetime.
+                unsafe {
+                    let mut leaf = root.borrow_mut().cast_to_leaf_unchecked();
+                    leaf.push_with_handle(self.key, value)
+                }
             }
+            Some(handle) => handle.insert_recursing(self.key, value, self.alloc.clone(), |ins| {
+                drop(ins.left);
+                // SAFETY: Pushing a new root node doesn't invalidate
+                // handles to existing nodes.
+                let map = unsafe { self.dormant_map.reborrow() };
+                let root = map.root.as_mut().unwrap(); // same as ins.left
+                root.push_internal_level(self.alloc.clone()).push(ins.kv.0, ins.kv.1, ins.right)
+            }),
         };
 
-        // Now that we have finished growing the tree using borrowed references,
-        // dereference the pointer to a part of it, that we picked up along the way.
-        unsafe { &mut *out_ptr }
+        // SAFETY: modifying the length doesn't invalidate handles to existing nodes.
+        unsafe { self.dormant_map.reborrow().length += 1 };
+
+        OccupiedEntry {
+            handle: handle.forget_node_type(),
+            dormant_map: self.dormant_map,
+            alloc: self.alloc,
+            _marker: PhantomData,
+        }
     }
 }
 
diff --git a/library/alloc/src/collections/btree/node.rs b/library/alloc/src/collections/btree/node.rs
index 64a13bb6a0b3..0c93eff0d20f 100644
--- a/library/alloc/src/collections/btree/node.rs
+++ b/library/alloc/src/collections/btree/node.rs
@@ -739,7 +739,7 @@ pub fn force(
 
 impl<'a, K, V> NodeRef<marker::Mut<'a>, K, V, marker::LeafOrInternal> {
     /// Unsafely asserts to the compiler the static information that this node is a `Leaf`.
-    unsafe fn cast_to_leaf_unchecked(self) -> NodeRef<marker::Mut<'a>, K, V, marker::Leaf> {
+    pub unsafe fn cast_to_leaf_unchecked(self) -> NodeRef<marker::Mut<'a>, K, V, marker::Leaf> {
         debug_assert!(self.height == 0);
         NodeRef { height: self.height, node: self.node, _marker: PhantomData }
     }
diff --git a/library/core/src/mem/maybe_uninit.rs b/library/core/src/mem/maybe_uninit.rs
index 58315cb74f0a..27273e4eedf3 100644
--- a/library/core/src/mem/maybe_uninit.rs
+++ b/library/core/src/mem/maybe_uninit.rs
@@ -255,7 +255,11 @@ fn clone(&self) -> Self {
 #[stable(feature = "maybe_uninit_debug", since = "1.41.0")]
 impl<T> fmt::Debug for MaybeUninit<T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.pad(type_name::<Self>())
+        // NB: there is no `.pad_fmt` so we can't use a simpler `format_args!("MaybeUninit<{..}>").
+        // This needs to be adjusted if `MaybeUninit` moves modules.
+        let full_name = type_name::<Self>();
+        let short_name = full_name.split_once("mem::maybe_uninit::").unwrap().1;
+        f.pad(short_name)
     }
 }
 
diff --git a/library/core/src/slice/mod.rs b/library/core/src/slice/mod.rs
index c855f963771e..b3defba5a982 100644
--- a/library/core/src/slice/mod.rs
+++ b/library/core/src/slice/mod.rs
@@ -10,10 +10,10 @@
 use crate::intrinsics::{exact_div, select_unpredictable, unchecked_sub};
 use crate::mem::{self, SizedTypeProperties};
 use crate::num::NonZero;
-use crate::ops::{Bound, OneSidedRange, Range, RangeBounds};
+use crate::ops::{Bound, OneSidedRange, Range, RangeBounds, RangeInclusive};
 use crate::simd::{self, Simd};
 use crate::ub_checks::assert_unsafe_precondition;
-use crate::{fmt, hint, ptr, slice};
+use crate::{fmt, hint, ptr, range, slice};
 
 #[unstable(
     feature = "slice_internals",
@@ -4469,6 +4469,12 @@ pub fn take_last_mut<'a>(self: &mut &'a mut Self) -> Option<&'a mut T> {
 
     /// Returns mutable references to many indices at once, without doing any checks.
     ///
+    /// An index can be either a `usize`, a [`Range`] or a [`RangeInclusive`]. Note
+    /// that this method takes an array, so all indices must be of the same type.
+    /// If passed an array of `usize`s this method gives back an array of mutable references
+    /// to single elements, while if passed an array of ranges it gives back an array of
+    /// mutable references to slices.
+    ///
     /// For a safe alternative see [`get_many_mut`].
     ///
     /// # Safety
@@ -4489,30 +4495,49 @@ pub fn take_last_mut<'a>(self: &mut &'a mut Self) -> Option<&'a mut T> {
     ///     *b *= 100;
     /// }
     /// assert_eq!(x, &[10, 2, 400]);
+    ///
+    /// unsafe {
+    ///     let [a, b] = x.get_many_unchecked_mut([0..1, 1..3]);
+    ///     a[0] = 8;
+    ///     b[0] = 88;
+    ///     b[1] = 888;
+    /// }
+    /// assert_eq!(x, &[8, 88, 888]);
+    ///
+    /// unsafe {
+    ///     let [a, b] = x.get_many_unchecked_mut([1..=2, 0..=0]);
+    ///     a[0] = 11;
+    ///     a[1] = 111;
+    ///     b[0] = 1;
+    /// }
+    /// assert_eq!(x, &[1, 11, 111]);
     /// ```
     ///
     /// [`get_many_mut`]: slice::get_many_mut
     /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
     #[unstable(feature = "get_many_mut", issue = "104642")]
     #[inline]
-    pub unsafe fn get_many_unchecked_mut<const N: usize>(
+    pub unsafe fn get_many_unchecked_mut<I, const N: usize>(
         &mut self,
-        indices: [usize; N],
-    ) -> [&mut T; N] {
+        indices: [I; N],
+    ) -> [&mut I::Output; N]
+    where
+        I: GetManyMutIndex + SliceIndex<Self>,
+    {
         // NB: This implementation is written as it is because any variation of
         // `indices.map(|i| self.get_unchecked_mut(i))` would make miri unhappy,
         // or generate worse code otherwise. This is also why we need to go
         // through a raw pointer here.
         let slice: *mut [T] = self;
-        let mut arr: mem::MaybeUninit<[&mut T; N]> = mem::MaybeUninit::uninit();
+        let mut arr: mem::MaybeUninit<[&mut I::Output; N]> = mem::MaybeUninit::uninit();
         let arr_ptr = arr.as_mut_ptr();
 
         // SAFETY: We expect `indices` to contain disjunct values that are
         // in bounds of `self`.
         unsafe {
             for i in 0..N {
-                let idx = *indices.get_unchecked(i);
-                *(*arr_ptr).get_unchecked_mut(i) = &mut *slice.get_unchecked_mut(idx);
+                let idx = indices.get_unchecked(i).clone();
+                arr_ptr.cast::<&mut I::Output>().add(i).write(&mut *slice.get_unchecked_mut(idx));
             }
             arr.assume_init()
         }
@@ -4520,8 +4545,18 @@ pub unsafe fn get_many_unchecked_mut<const N: usize>(
 
     /// Returns mutable references to many indices at once.
     ///
-    /// Returns an error if any index is out-of-bounds, or if the same index was
-    /// passed more than once.
+    /// An index can be either a `usize`, a [`Range`] or a [`RangeInclusive`]. Note
+    /// that this method takes an array, so all indices must be of the same type.
+    /// If passed an array of `usize`s this method gives back an array of mutable references
+    /// to single elements, while if passed an array of ranges it gives back an array of
+    /// mutable references to slices.
+    ///
+    /// Returns an error if any index is out-of-bounds, or if there are overlapping indices.
+    /// An empty range is not considered to overlap if it is located at the beginning or at
+    /// the end of another range, but is considered to overlap if it is located in the middle.
+    ///
+    /// This method does a O(n^2) check to check that there are no overlapping indices, so be careful
+    /// when passing many indices.
     ///
     /// # Examples
     ///
@@ -4534,13 +4569,30 @@ pub unsafe fn get_many_unchecked_mut<const N: usize>(
     ///     *b = 612;
     /// }
     /// assert_eq!(v, &[413, 2, 612]);
+    ///
+    /// if let Ok([a, b]) = v.get_many_mut([0..1, 1..3]) {
+    ///     a[0] = 8;
+    ///     b[0] = 88;
+    ///     b[1] = 888;
+    /// }
+    /// assert_eq!(v, &[8, 88, 888]);
+    ///
+    /// if let Ok([a, b]) = v.get_many_mut([1..=2, 0..=0]) {
+    ///     a[0] = 11;
+    ///     a[1] = 111;
+    ///     b[0] = 1;
+    /// }
+    /// assert_eq!(v, &[1, 11, 111]);
     /// ```
     #[unstable(feature = "get_many_mut", issue = "104642")]
     #[inline]
-    pub fn get_many_mut<const N: usize>(
+    pub fn get_many_mut<I, const N: usize>(
         &mut self,
-        indices: [usize; N],
-    ) -> Result<[&mut T; N], GetManyMutError<N>> {
+        indices: [I; N],
+    ) -> Result<[&mut I::Output; N], GetManyMutError<N>>
+    where
+        I: GetManyMutIndex + SliceIndex<Self>,
+    {
         if !get_many_check_valid(&indices, self.len()) {
             return Err(GetManyMutError { _private: () });
         }
@@ -4885,14 +4937,15 @@ fn as_slice(&self) -> &[Self::Item] {
 ///
 /// This will do `binomial(N + 1, 2) = N * (N + 1) / 2 = 0, 1, 3, 6, 10, ..`
 /// comparison operations.
-fn get_many_check_valid<const N: usize>(indices: &[usize; N], len: usize) -> bool {
+#[inline]
+fn get_many_check_valid<I: GetManyMutIndex, const N: usize>(indices: &[I; N], len: usize) -> bool {
     // NB: The optimizer should inline the loops into a sequence
     // of instructions without additional branching.
     let mut valid = true;
-    for (i, &idx) in indices.iter().enumerate() {
-        valid &= idx < len;
-        for &idx2 in &indices[..i] {
-            valid &= idx != idx2;
+    for (i, idx) in indices.iter().enumerate() {
+        valid &= idx.is_in_bounds(len);
+        for idx2 in &indices[..i] {
+            valid &= !idx.is_overlapping(idx2);
         }
     }
     valid
@@ -4916,6 +4969,7 @@ fn as_slice(&self) -> &[Self::Item] {
 #[unstable(feature = "get_many_mut", issue = "104642")]
 // NB: The N here is there to be forward-compatible with adding more details
 // to the error type at a later point
+#[derive(Clone, PartialEq, Eq)]
 pub struct GetManyMutError<const N: usize> {
     _private: (),
 }
@@ -4933,3 +4987,111 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         fmt::Display::fmt("an index is out of bounds or appeared multiple times in the array", f)
     }
 }
+
+mod private_get_many_mut_index {
+    use super::{Range, RangeInclusive, range};
+
+    #[unstable(feature = "get_many_mut_helpers", issue = "none")]
+    pub trait Sealed {}
+
+    #[unstable(feature = "get_many_mut_helpers", issue = "none")]
+    impl Sealed for usize {}
+    #[unstable(feature = "get_many_mut_helpers", issue = "none")]
+    impl Sealed for Range<usize> {}
+    #[unstable(feature = "get_many_mut_helpers", issue = "none")]
+    impl Sealed for RangeInclusive<usize> {}
+    #[unstable(feature = "get_many_mut_helpers", issue = "none")]
+    impl Sealed for range::Range<usize> {}
+    #[unstable(feature = "get_many_mut_helpers", issue = "none")]
+    impl Sealed for range::RangeInclusive<usize> {}
+}
+
+/// A helper trait for `<[T]>::get_many_mut()`.
+///
+/// # Safety
+///
+/// If `is_in_bounds()` returns `true` and `is_overlapping()` returns `false`,
+/// it must be safe to index the slice with the indices.
+#[unstable(feature = "get_many_mut_helpers", issue = "none")]
+pub unsafe trait GetManyMutIndex: Clone + private_get_many_mut_index::Sealed {
+    /// Returns `true` if `self` is in bounds for `len` slice elements.
+    #[unstable(feature = "get_many_mut_helpers", issue = "none")]
+    fn is_in_bounds(&self, len: usize) -> bool;
+
+    /// Returns `true` if `self` overlaps with `other`.
+    ///
+    /// Note that we don't consider zero-length ranges to overlap at the beginning or the end,
+    /// but do consider them to overlap in the middle.
+    #[unstable(feature = "get_many_mut_helpers", issue = "none")]
+    fn is_overlapping(&self, other: &Self) -> bool;
+}
+
+#[unstable(feature = "get_many_mut_helpers", issue = "none")]
+// SAFETY: We implement `is_in_bounds()` and `is_overlapping()` correctly.
+unsafe impl GetManyMutIndex for usize {
+    #[inline]
+    fn is_in_bounds(&self, len: usize) -> bool {
+        *self < len
+    }
+
+    #[inline]
+    fn is_overlapping(&self, other: &Self) -> bool {
+        *self == *other
+    }
+}
+
+#[unstable(feature = "get_many_mut_helpers", issue = "none")]
+// SAFETY: We implement `is_in_bounds()` and `is_overlapping()` correctly.
+unsafe impl GetManyMutIndex for Range<usize> {
+    #[inline]
+    fn is_in_bounds(&self, len: usize) -> bool {
+        (self.start <= self.end) & (self.end <= len)
+    }
+
+    #[inline]
+    fn is_overlapping(&self, other: &Self) -> bool {
+        (self.start < other.end) & (other.start < self.end)
+    }
+}
+
+#[unstable(feature = "get_many_mut_helpers", issue = "none")]
+// SAFETY: We implement `is_in_bounds()` and `is_overlapping()` correctly.
+unsafe impl GetManyMutIndex for RangeInclusive<usize> {
+    #[inline]
+    fn is_in_bounds(&self, len: usize) -> bool {
+        (self.start <= self.end) & (self.end < len)
+    }
+
+    #[inline]
+    fn is_overlapping(&self, other: &Self) -> bool {
+        (self.start <= other.end) & (other.start <= self.end)
+    }
+}
+
+#[unstable(feature = "get_many_mut_helpers", issue = "none")]
+// SAFETY: We implement `is_in_bounds()` and `is_overlapping()` correctly.
+unsafe impl GetManyMutIndex for range::Range<usize> {
+    #[inline]
+    fn is_in_bounds(&self, len: usize) -> bool {
+        Range::from(*self).is_in_bounds(len)
+    }
+
+    #[inline]
+    fn is_overlapping(&self, other: &Self) -> bool {
+        Range::from(*self).is_overlapping(&Range::from(*other))
+    }
+}
+
+#[unstable(feature = "get_many_mut_helpers", issue = "none")]
+// SAFETY: We implement `is_in_bounds()` and `is_overlapping()` correctly.
+unsafe impl GetManyMutIndex for range::RangeInclusive<usize> {
+    #[inline]
+    fn is_in_bounds(&self, len: usize) -> bool {
+        RangeInclusive::from(*self).is_in_bounds(len)
+    }
+
+    #[inline]
+    fn is_overlapping(&self, other: &Self) -> bool {
+        RangeInclusive::from(*self).is_overlapping(&RangeInclusive::from(*other))
+    }
+}
diff --git a/library/core/tests/fmt/mod.rs b/library/core/tests/fmt/mod.rs
index 704d24613994..f7512abae382 100644
--- a/library/core/tests/fmt/mod.rs
+++ b/library/core/tests/fmt/mod.rs
@@ -43,3 +43,10 @@ fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
 
     assert_eq!(format!("{Bar:<03}"), "1  0051  ");
 }
+
+#[test]
+fn test_maybe_uninit_short() {
+    // Ensure that the trimmed `MaybeUninit` Debug implementation doesn't break
+    let x = core::mem::MaybeUninit::new(0u32);
+    assert_eq!(format!("{x:?}"), "MaybeUninit<u32>");
+}
diff --git a/library/core/tests/slice.rs b/library/core/tests/slice.rs
index 9ae2bcc85264..510dd4967c96 100644
--- a/library/core/tests/slice.rs
+++ b/library/core/tests/slice.rs
@@ -2,6 +2,7 @@
 use core::cmp::Ordering;
 use core::mem::MaybeUninit;
 use core::num::NonZero;
+use core::ops::{Range, RangeInclusive};
 use core::slice;
 
 #[test]
@@ -2553,6 +2554,14 @@ fn test_get_many_mut_normal_2() {
     *a += 10;
     *b += 100;
     assert_eq!(v, vec![101, 2, 3, 14, 5]);
+
+    let [a, b] = v.get_many_mut([0..=1, 2..=2]).unwrap();
+    assert_eq!(a, &mut [101, 2][..]);
+    assert_eq!(b, &mut [3][..]);
+    a[0] += 10;
+    a[1] += 20;
+    b[0] += 100;
+    assert_eq!(v, vec![111, 22, 103, 14, 5]);
 }
 
 #[test]
@@ -2563,12 +2572,23 @@ fn test_get_many_mut_normal_3() {
     *b += 100;
     *c += 1000;
     assert_eq!(v, vec![11, 2, 1003, 4, 105]);
+
+    let [a, b, c] = v.get_many_mut([0..1, 4..5, 1..4]).unwrap();
+    assert_eq!(a, &mut [11][..]);
+    assert_eq!(b, &mut [105][..]);
+    assert_eq!(c, &mut [2, 1003, 4][..]);
+    a[0] += 10;
+    b[0] += 100;
+    c[0] += 1000;
+    assert_eq!(v, vec![21, 1002, 1003, 4, 205]);
 }
 
 #[test]
 fn test_get_many_mut_empty() {
     let mut v = vec![1, 2, 3, 4, 5];
-    let [] = v.get_many_mut([]).unwrap();
+    let [] = v.get_many_mut::<usize, 0>([]).unwrap();
+    let [] = v.get_many_mut::<RangeInclusive<usize>, 0>([]).unwrap();
+    let [] = v.get_many_mut::<Range<usize>, 0>([]).unwrap();
     assert_eq!(v, vec![1, 2, 3, 4, 5]);
 }
 
@@ -2606,6 +2626,54 @@ fn test_get_many_mut_duplicate() {
     assert!(v.get_many_mut([1, 3, 3, 4]).is_err());
 }
 
+#[test]
+fn test_get_many_mut_range_oob() {
+    let mut v = vec![1, 2, 3, 4, 5];
+    assert!(v.get_many_mut([0..6]).is_err());
+    assert!(v.get_many_mut([5..6]).is_err());
+    assert!(v.get_many_mut([6..6]).is_err());
+    assert!(v.get_many_mut([0..=5]).is_err());
+    assert!(v.get_many_mut([0..=6]).is_err());
+    assert!(v.get_many_mut([5..=5]).is_err());
+}
+
+#[test]
+fn test_get_many_mut_range_overlapping() {
+    let mut v = vec![1, 2, 3, 4, 5];
+    assert!(v.get_many_mut([0..1, 0..2]).is_err());
+    assert!(v.get_many_mut([0..1, 1..2, 0..1]).is_err());
+    assert!(v.get_many_mut([0..3, 1..1]).is_err());
+    assert!(v.get_many_mut([0..3, 1..2]).is_err());
+    assert!(v.get_many_mut([0..=0, 2..=2, 0..=1]).is_err());
+    assert!(v.get_many_mut([0..=4, 0..=0]).is_err());
+    assert!(v.get_many_mut([4..=4, 0..=0, 3..=4]).is_err());
+}
+
+#[test]
+fn test_get_many_mut_range_empty_at_edge() {
+    let mut v = vec![1, 2, 3, 4, 5];
+    assert_eq!(
+        v.get_many_mut([0..0, 0..5, 5..5]),
+        Ok([&mut [][..], &mut [1, 2, 3, 4, 5], &mut []]),
+    );
+    assert_eq!(
+        v.get_many_mut([0..0, 0..1, 1..1, 1..2, 2..2, 2..3, 3..3, 3..4, 4..4, 4..5, 5..5]),
+        Ok([
+            &mut [][..],
+            &mut [1],
+            &mut [],
+            &mut [2],
+            &mut [],
+            &mut [3],
+            &mut [],
+            &mut [4],
+            &mut [],
+            &mut [5],
+            &mut [],
+        ]),
+    );
+}
+
 #[test]
 fn test_slice_from_raw_parts_in_const() {
     static FANCY: i32 = 4;
diff --git a/library/std/src/sync/rwlock/tests.rs b/library/std/src/sync/rwlock/tests.rs
index 29cad4400f18..48d442921f7f 100644
--- a/library/std/src/sync/rwlock/tests.rs
+++ b/library/std/src/sync/rwlock/tests.rs
@@ -511,12 +511,15 @@ fn test_downgrade_basic() {
 }
 
 #[test]
+// FIXME: On macOS we use a provenance-incorrect implementation and Miri catches that issue.
+// See <https://github.com/rust-lang/rust/issues/121950> for details.
+#[cfg_attr(all(miri, target_os = "macos"), ignore)]
 fn test_downgrade_observe() {
     // Taken from the test `test_rwlock_downgrade` from:
     // https://github.com/Amanieu/parking_lot/blob/master/src/rwlock.rs
 
     const W: usize = 20;
-    const N: usize = 100;
+    const N: usize = if cfg!(miri) { 40 } else { 100 };
 
     // This test spawns `W` writer threads, where each will increment a counter `N` times, ensuring
     // that the value they wrote has not changed after downgrading.
diff --git a/src/tools/clippy/clippy_lints/src/dereference.rs b/src/tools/clippy/clippy_lints/src/dereference.rs
index fce7f9985ea1..1eebfc22af28 100644
--- a/src/tools/clippy/clippy_lints/src/dereference.rs
+++ b/src/tools/clippy/clippy_lints/src/dereference.rs
@@ -963,7 +963,7 @@ fn report<'tcx>(
             // expr_str (the suggestion) is never shown if is_final_ufcs is true, since it's
             // `expr.kind == ExprKind::Call`. Therefore, this is, afaik, always unnecessary.
             /*
-            expr_str = if !expr_is_macro_call && is_final_ufcs && expr.precedence().order() < PREC_PREFIX {
+            expr_str = if !expr_is_macro_call && is_final_ufcs && expr.precedence() < PREC_PREFIX {
                 Cow::Owned(format!("({expr_str})"))
             } else {
                 expr_str
@@ -1003,7 +1003,7 @@ fn report<'tcx>(
                         Node::Expr(e) => match e.kind {
                             ExprKind::Call(callee, _) if callee.hir_id != data.first_expr.hir_id => (0, false),
                             ExprKind::Call(..) => (PREC_UNAMBIGUOUS, matches!(expr.kind, ExprKind::Field(..))),
-                            _ => (e.precedence().order(), false),
+                            _ => (e.precedence(), false),
                         },
                         _ => (0, false),
                     };
@@ -1016,7 +1016,7 @@ fn report<'tcx>(
                     );
 
                     let sugg = if !snip_is_macro
-                        && (calls_field || expr.precedence().order() < precedence)
+                        && (calls_field || expr.precedence() < precedence)
                         && !has_enclosing_paren(&snip)
                         && !is_in_tuple
                     {
@@ -1071,7 +1071,7 @@ fn report<'tcx>(
                     let (snip, snip_is_macro) =
                         snippet_with_context(cx, expr.span, data.first_expr.span.ctxt(), "..", &mut app);
                     let sugg =
-                        if !snip_is_macro && expr.precedence().order() < precedence && !has_enclosing_paren(&snip) {
+                        if !snip_is_macro && expr.precedence() < precedence && !has_enclosing_paren(&snip) {
                             format!("{prefix}({snip})")
                         } else {
                             format!("{prefix}{snip}")
@@ -1158,7 +1158,7 @@ fn check_local_usage(&mut self, cx: &LateContext<'tcx>, e: &Expr<'tcx>, local: H
                         },
                         Some(parent) if !parent.span.from_expansion() => {
                             // Double reference might be needed at this point.
-                            if parent.precedence().order() == PREC_UNAMBIGUOUS {
+                            if parent.precedence() == PREC_UNAMBIGUOUS {
                                 // Parentheses would be needed here, don't lint.
                                 *outer_pat = None;
                             } else {
diff --git a/src/tools/clippy/clippy_lints/src/loops/single_element_loop.rs b/src/tools/clippy/clippy_lints/src/loops/single_element_loop.rs
index 70f76ced09a4..35dc8e9aa4e2 100644
--- a/src/tools/clippy/clippy_lints/src/loops/single_element_loop.rs
+++ b/src/tools/clippy/clippy_lints/src/loops/single_element_loop.rs
@@ -84,7 +84,7 @@ pub(super) fn check<'tcx>(
         if !prefix.is_empty()
             && (
                 // Precedence of internal expression is less than or equal to precedence of `&expr`.
-                arg_expression.precedence().order() <= PREC_PREFIX || is_range_literal(arg_expression)
+                arg_expression.precedence() <= PREC_PREFIX || is_range_literal(arg_expression)
             )
         {
             arg_snip = format!("({arg_snip})").into();
diff --git a/src/tools/clippy/clippy_lints/src/matches/manual_utils.rs b/src/tools/clippy/clippy_lints/src/matches/manual_utils.rs
index d38560998a5a..9c6df4d8ac0d 100644
--- a/src/tools/clippy/clippy_lints/src/matches/manual_utils.rs
+++ b/src/tools/clippy/clippy_lints/src/matches/manual_utils.rs
@@ -117,7 +117,7 @@ pub(super) fn check_with<'tcx, F>(
     // it's being passed by value.
     let scrutinee = peel_hir_expr_refs(scrutinee).0;
     let (scrutinee_str, _) = snippet_with_context(cx, scrutinee.span, expr_ctxt, "..", &mut app);
-    let scrutinee_str = if scrutinee.span.eq_ctxt(expr.span) && scrutinee.precedence().order() < PREC_UNAMBIGUOUS {
+    let scrutinee_str = if scrutinee.span.eq_ctxt(expr.span) && scrutinee.precedence() < PREC_UNAMBIGUOUS {
         format!("({scrutinee_str})")
     } else {
         scrutinee_str.into()
diff --git a/src/tools/clippy/clippy_lints/src/neg_multiply.rs b/src/tools/clippy/clippy_lints/src/neg_multiply.rs
index f84d9fadb85c..a0ba2aaf5523 100644
--- a/src/tools/clippy/clippy_lints/src/neg_multiply.rs
+++ b/src/tools/clippy/clippy_lints/src/neg_multiply.rs
@@ -58,7 +58,7 @@ fn check_mul(cx: &LateContext<'_>, span: Span, lit: &Expr<'_>, exp: &Expr<'_>) {
     {
         let mut applicability = Applicability::MachineApplicable;
         let (snip, from_macro) = snippet_with_context(cx, exp.span, span.ctxt(), "..", &mut applicability);
-        let suggestion = if !from_macro && exp.precedence().order() < PREC_PREFIX && !has_enclosing_paren(&snip) {
+        let suggestion = if !from_macro && exp.precedence() < PREC_PREFIX && !has_enclosing_paren(&snip) {
             format!("-({snip})")
         } else {
             format!("-{snip}")
diff --git a/src/tools/clippy/clippy_lints/src/redundant_slicing.rs b/src/tools/clippy/clippy_lints/src/redundant_slicing.rs
index 0ac818c21d9b..79baa914b031 100644
--- a/src/tools/clippy/clippy_lints/src/redundant_slicing.rs
+++ b/src/tools/clippy/clippy_lints/src/redundant_slicing.rs
@@ -85,7 +85,7 @@ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
             let (expr_ty, expr_ref_count) = peel_middle_ty_refs(cx.typeck_results().expr_ty(expr));
             let (indexed_ty, indexed_ref_count) = peel_middle_ty_refs(cx.typeck_results().expr_ty(indexed));
             let parent_expr = get_parent_expr(cx, expr);
-            let needs_parens_for_prefix = parent_expr.is_some_and(|parent| parent.precedence().order() > PREC_PREFIX);
+            let needs_parens_for_prefix = parent_expr.is_some_and(|parent| parent.precedence() > PREC_PREFIX);
 
             if expr_ty == indexed_ty {
                 if expr_ref_count > indexed_ref_count {
diff --git a/src/tools/clippy/clippy_lints/src/transmute/transmutes_expressible_as_ptr_casts.rs b/src/tools/clippy/clippy_lints/src/transmute/transmutes_expressible_as_ptr_casts.rs
index fca332dba401..cad15b1e9826 100644
--- a/src/tools/clippy/clippy_lints/src/transmute/transmutes_expressible_as_ptr_casts.rs
+++ b/src/tools/clippy/clippy_lints/src/transmute/transmutes_expressible_as_ptr_casts.rs
@@ -1,7 +1,7 @@
 use super::TRANSMUTES_EXPRESSIBLE_AS_PTR_CASTS;
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::sugg::Sugg;
-use rustc_ast::ExprPrecedence;
+use rustc_ast::util::parser::AssocOp;
 use rustc_errors::Applicability;
 use rustc_hir::{Expr, Node};
 use rustc_hir_typeck::cast::check_cast;
@@ -44,7 +44,7 @@ pub(super) fn check<'tcx>(
     };
 
     if let Node::Expr(parent) = cx.tcx.parent_hir_node(e.hir_id)
-        && parent.precedence().order() > ExprPrecedence::Cast.order()
+        && parent.precedence() > AssocOp::As.precedence() as i8
     {
         sugg = format!("({sugg})");
     }
diff --git a/tests/crashes/126359.rs b/tests/crashes/126359.rs
deleted file mode 100644
index 4b28c466b55c..000000000000
--- a/tests/crashes/126359.rs
+++ /dev/null
@@ -1,9 +0,0 @@
-//@ known-bug: rust-lang/rust#126359
-
-struct OppOrder<const N: u8 = 3, T = u32> {
-    arr: [T; N],
-}
-
-fn main() {
-    let _ = OppOrder::<3, u32> { arr: [0, 0, 0] };
-}
diff --git a/tests/crashes/130521.rs b/tests/crashes/130521.rs
index ccc2b444b822..ebcfacf96238 100644
--- a/tests/crashes/130521.rs
+++ b/tests/crashes/130521.rs
@@ -1,7 +1,7 @@
 //@ known-bug: #130521
 
 #![feature(dyn_compatible_for_dispatch)]
-struct Vtable(dyn Cap);
+struct Vtable(dyn Cap<'static>);
 
 trait Cap<'a> {}
 
diff --git a/tests/crashes/131101.rs b/tests/crashes/131101.rs
deleted file mode 100644
index 3ec441101b7d..000000000000
--- a/tests/crashes/131101.rs
+++ /dev/null
@@ -1,12 +0,0 @@
-//@ known-bug: #131101
-trait Foo<const N: u8> {
-    fn do_x(&self) -> [u8; N];
-}
-
-struct Bar;
-
-impl Foo<const 3> for Bar {
-    fn do_x(&self) -> [u8; 3] {
-        [0u8; 3]
-    }
-}
diff --git a/tests/rustdoc-ui/unable-fulfill-trait.rs b/tests/rustdoc-ui/unable-fulfill-trait.rs
index 4edc7ab76c19..49dce32072b6 100644
--- a/tests/rustdoc-ui/unable-fulfill-trait.rs
+++ b/tests/rustdoc-ui/unable-fulfill-trait.rs
@@ -3,7 +3,6 @@
 pub struct Foo<'a, 'b, T> {
     field1: dyn Bar<'a, 'b>,
     //~^ ERROR
-    //~| ERROR
 }
 
 pub trait Bar<'x, 's, U>
diff --git a/tests/rustdoc-ui/unable-fulfill-trait.stderr b/tests/rustdoc-ui/unable-fulfill-trait.stderr
index 12e53546cdac..2786a005cd18 100644
--- a/tests/rustdoc-ui/unable-fulfill-trait.stderr
+++ b/tests/rustdoc-ui/unable-fulfill-trait.stderr
@@ -5,7 +5,7 @@ LL |     field1: dyn Bar<'a, 'b>,
    |                 ^^^ expected 1 generic argument
    |
 note: trait defined here, with 1 generic parameter: `U`
-  --> $DIR/unable-fulfill-trait.rs:9:11
+  --> $DIR/unable-fulfill-trait.rs:8:11
    |
 LL | pub trait Bar<'x, 's, U>
    |           ^^^         -
@@ -14,13 +14,6 @@ help: add missing generic argument
 LL |     field1: dyn Bar<'a, 'b, U>,
    |                           +++
 
-error[E0227]: ambiguous lifetime bound, explicit lifetime bound required
-  --> $DIR/unable-fulfill-trait.rs:4:13
-   |
-LL |     field1: dyn Bar<'a, 'b>,
-   |             ^^^^^^^^^^^^^^^
+error: aborting due to 1 previous error
 
-error: aborting due to 2 previous errors
-
-Some errors have detailed explanations: E0107, E0227.
-For more information about an error, try `rustc --explain E0107`.
+For more information about this error, try `rustc --explain E0107`.
diff --git a/tests/ui/array-slice-vec/match_arr_unknown_len.stderr b/tests/ui/array-slice-vec/match_arr_unknown_len.stderr
index 3ed0d6bdf3ac..f617ff339383 100644
--- a/tests/ui/array-slice-vec/match_arr_unknown_len.stderr
+++ b/tests/ui/array-slice-vec/match_arr_unknown_len.stderr
@@ -2,10 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/match_arr_unknown_len.rs:3:9
    |
 LL |         [1, 2] => true,
-   |         ^^^^^^ expected `2`, found `N`
-   |
-   = note: expected array `[u32; 2]`
-              found array `[u32; N]`
+   |         ^^^^^^ expected an array with a size of 2, found one with a size of N
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/associated-types/issue-22560.rs b/tests/ui/associated-types/issue-22560.rs
index 44be8817b08c..465aea515eef 100644
--- a/tests/ui/associated-types/issue-22560.rs
+++ b/tests/ui/associated-types/issue-22560.rs
@@ -7,9 +7,6 @@ trait Sub<Rhs=Self> {
 }
 
 type Test = dyn Add + Sub;
-//~^ ERROR E0393
-//~| ERROR E0191
-//~| ERROR E0393
-//~| ERROR E0225
+//~^ ERROR E0225
 
 fn main() { }
diff --git a/tests/ui/associated-types/issue-22560.stderr b/tests/ui/associated-types/issue-22560.stderr
index 834040490f94..d0b6adc520c7 100644
--- a/tests/ui/associated-types/issue-22560.stderr
+++ b/tests/ui/associated-types/issue-22560.stderr
@@ -9,56 +9,6 @@ LL | type Test = dyn Add + Sub;
    = help: consider creating a new trait with all of these as supertraits and using that trait here instead: `trait NewTrait: Add + Sub {}`
    = note: auto-traits like `Send` and `Sync` are traits that have special properties; for more information on them, visit <https://doc.rust-lang.org/reference/special-types-and-traits.html#auto-traits>
 
-error[E0191]: the value of the associated types `Output` in `Add`, `Output` in `Sub` must be specified
-  --> $DIR/issue-22560.rs:9:17
-   |
-LL |     type Output;
-   |     ----------- `Output` defined here
-...
-LL |     type Output;
-   |     ----------- `Output` defined here
-...
-LL | type Test = dyn Add + Sub;
-   |                 ^^^   ^^^ associated type `Output` must be specified
-   |                 |
-   |                 associated type `Output` must be specified
-   |
-help: specify the associated types
-   |
-LL | type Test = dyn Add<Output = Type> + Sub<Output = Type>;
-   |                 ~~~~~~~~~~~~~~~~~~   ~~~~~~~~~~~~~~~~~~
+error: aborting due to 1 previous error
 
-error[E0393]: the type parameter `Rhs` must be explicitly specified
-  --> $DIR/issue-22560.rs:9:17
-   |
-LL | trait Add<Rhs=Self> {
-   | ------------------- type parameter `Rhs` must be specified for this
-...
-LL | type Test = dyn Add + Sub;
-   |                 ^^^
-   |
-   = note: because of the default `Self` reference, type parameters must be specified on object types
-help: set the type parameter to the desired type
-   |
-LL | type Test = dyn Add<Rhs> + Sub;
-   |                    +++++
-
-error[E0393]: the type parameter `Rhs` must be explicitly specified
-  --> $DIR/issue-22560.rs:9:23
-   |
-LL | trait Sub<Rhs=Self> {
-   | ------------------- type parameter `Rhs` must be specified for this
-...
-LL | type Test = dyn Add + Sub;
-   |                       ^^^
-   |
-   = note: because of the default `Self` reference, type parameters must be specified on object types
-help: set the type parameter to the desired type
-   |
-LL | type Test = dyn Add + Sub<Rhs>;
-   |                          +++++
-
-error: aborting due to 4 previous errors
-
-Some errors have detailed explanations: E0191, E0225, E0393.
-For more information about an error, try `rustc --explain E0191`.
+For more information about this error, try `rustc --explain E0225`.
diff --git a/tests/ui/associated-types/missing-associated-types.rs b/tests/ui/associated-types/missing-associated-types.rs
index 3c8410e39bd0..4e532715f1e2 100644
--- a/tests/ui/associated-types/missing-associated-types.rs
+++ b/tests/ui/associated-types/missing-associated-types.rs
@@ -11,16 +11,12 @@ trait Fine<Rhs>: Div<Rhs, Output = Rhs> {}
 
 type Foo<Rhs> = dyn Add<Rhs> + Sub<Rhs> + X<Rhs> + Y<Rhs>;
 //~^ ERROR only auto traits can be used as additional traits in a trait object
-//~| ERROR the value of the associated types
 type Bar<Rhs> = dyn Add<Rhs> + Sub<Rhs> + X<Rhs> + Z<Rhs>;
 //~^ ERROR only auto traits can be used as additional traits in a trait object
-//~| ERROR the value of the associated types
 type Baz<Rhs> = dyn Add<Rhs> + Sub<Rhs> + Y<Rhs>;
 //~^ ERROR only auto traits can be used as additional traits in a trait object
-//~| ERROR the value of the associated types
 type Bat<Rhs> = dyn Add<Rhs> + Sub<Rhs> + Fine<Rhs>;
 //~^ ERROR only auto traits can be used as additional traits in a trait object
-//~| ERROR the value of the associated types
 type Bal<Rhs> = dyn X<Rhs>;
 //~^ ERROR the value of the associated types
 
diff --git a/tests/ui/associated-types/missing-associated-types.stderr b/tests/ui/associated-types/missing-associated-types.stderr
index 0636667ea1fd..ce4b57e8af81 100644
--- a/tests/ui/associated-types/missing-associated-types.stderr
+++ b/tests/ui/associated-types/missing-associated-types.stderr
@@ -9,26 +9,8 @@ LL | type Foo<Rhs> = dyn Add<Rhs> + Sub<Rhs> + X<Rhs> + Y<Rhs>;
    = help: consider creating a new trait with all of these as supertraits and using that trait here instead: `trait NewTrait: Add<Rhs> + Sub<Rhs> + X<Rhs> + Y<Rhs> {}`
    = note: auto-traits like `Send` and `Sync` are traits that have special properties; for more information on them, visit <https://doc.rust-lang.org/reference/special-types-and-traits.html#auto-traits>
 
-error[E0191]: the value of the associated types `A` in `Y`, `Output` in `Add`, `Output` in `Mul`, `Output` in `Sub` must be specified
-  --> $DIR/missing-associated-types.rs:12:21
-   |
-LL |     type A;
-   |     ------ `A` defined here
-...
-LL | type Foo<Rhs> = dyn Add<Rhs> + Sub<Rhs> + X<Rhs> + Y<Rhs>;
-   |                     ^^^^^^^^   ^^^^^^^^   ^^^^^^   ^^^^^^ associated type `A` must be specified
-   |                     |          |          |
-   |                     |          |          associated type `Output` must be specified
-   |                     |          associated type `Output` must be specified
-   |                     associated type `Output` must be specified
-   |
-help: specify the associated types
-   |
-LL | type Foo<Rhs> = dyn Add<Rhs, Output = Type> + Sub<Rhs, Output = Type> + X<Rhs, Output = Type> + Y<Rhs, A = Type>;
-   |                     ~~~~~~~~~~~~~~~~~~~~~~~   ~~~~~~~~~~~~~~~~~~~~~~~   ~~~~~~~~~~~~~~~~~~~~~   ~~~~~~~~~~~~~~~~
-
 error[E0225]: only auto traits can be used as additional traits in a trait object
-  --> $DIR/missing-associated-types.rs:15:32
+  --> $DIR/missing-associated-types.rs:14:32
    |
 LL | type Bar<Rhs> = dyn Add<Rhs> + Sub<Rhs> + X<Rhs> + Z<Rhs>;
    |                     --------   ^^^^^^^^ additional non-auto trait
@@ -38,33 +20,8 @@ LL | type Bar<Rhs> = dyn Add<Rhs> + Sub<Rhs> + X<Rhs> + Z<Rhs>;
    = help: consider creating a new trait with all of these as supertraits and using that trait here instead: `trait NewTrait: Add<Rhs> + Sub<Rhs> + X<Rhs> + Z<Rhs> {}`
    = note: auto-traits like `Send` and `Sync` are traits that have special properties; for more information on them, visit <https://doc.rust-lang.org/reference/special-types-and-traits.html#auto-traits>
 
-error[E0191]: the value of the associated types `A` and `B` in `Z`, `Output` and `Output` in `Div`, `Output` in `Add`, `Output` in `Mul`, `Output` in `Sub` must be specified
-  --> $DIR/missing-associated-types.rs:15:21
-   |
-LL |     type A;
-   |     ------ `A` defined here
-LL |     type B;
-   |     ------ `B` defined here
-...
-LL | type Bar<Rhs> = dyn Add<Rhs> + Sub<Rhs> + X<Rhs> + Z<Rhs>;
-   |                     ^^^^^^^^   ^^^^^^^^   ^^^^^^   ^^^^^^ associated types `A`, `B`, `Output` must be specified
-   |                     |          |          |
-   |                     |          |          associated types `Output` (from trait `Div`), `Output` (from trait `Mul`) must be specified
-   |                     |          associated type `Output` must be specified
-   |                     associated type `Output` must be specified
-   |
-help: consider introducing a new type parameter, adding `where` constraints using the fully-qualified path to the associated types
-  --> $DIR/missing-associated-types.rs:15:43
-   |
-LL | type Bar<Rhs> = dyn Add<Rhs> + Sub<Rhs> + X<Rhs> + Z<Rhs>;
-   |                                           ^^^^^^
-help: specify the associated types
-   |
-LL | type Bar<Rhs> = dyn Add<Rhs, Output = Type> + Sub<Rhs, Output = Type> + X<Rhs> + Z<Rhs, A = Type, B = Type, Output = Type>;
-   |                     ~~~~~~~~~~~~~~~~~~~~~~~   ~~~~~~~~~~~~~~~~~~~~~~~            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
 error[E0225]: only auto traits can be used as additional traits in a trait object
-  --> $DIR/missing-associated-types.rs:18:32
+  --> $DIR/missing-associated-types.rs:16:32
    |
 LL | type Baz<Rhs> = dyn Add<Rhs> + Sub<Rhs> + Y<Rhs>;
    |                     --------   ^^^^^^^^ additional non-auto trait
@@ -74,25 +31,8 @@ LL | type Baz<Rhs> = dyn Add<Rhs> + Sub<Rhs> + Y<Rhs>;
    = help: consider creating a new trait with all of these as supertraits and using that trait here instead: `trait NewTrait: Add<Rhs> + Sub<Rhs> + Y<Rhs> {}`
    = note: auto-traits like `Send` and `Sync` are traits that have special properties; for more information on them, visit <https://doc.rust-lang.org/reference/special-types-and-traits.html#auto-traits>
 
-error[E0191]: the value of the associated types `A` in `Y`, `Output` in `Add`, `Output` in `Sub` must be specified
-  --> $DIR/missing-associated-types.rs:18:21
-   |
-LL |     type A;
-   |     ------ `A` defined here
-...
-LL | type Baz<Rhs> = dyn Add<Rhs> + Sub<Rhs> + Y<Rhs>;
-   |                     ^^^^^^^^   ^^^^^^^^   ^^^^^^ associated type `A` must be specified
-   |                     |          |
-   |                     |          associated type `Output` must be specified
-   |                     associated type `Output` must be specified
-   |
-help: specify the associated types
-   |
-LL | type Baz<Rhs> = dyn Add<Rhs, Output = Type> + Sub<Rhs, Output = Type> + Y<Rhs, A = Type>;
-   |                     ~~~~~~~~~~~~~~~~~~~~~~~   ~~~~~~~~~~~~~~~~~~~~~~~   ~~~~~~~~~~~~~~~~
-
 error[E0225]: only auto traits can be used as additional traits in a trait object
-  --> $DIR/missing-associated-types.rs:21:32
+  --> $DIR/missing-associated-types.rs:18:32
    |
 LL | type Bat<Rhs> = dyn Add<Rhs> + Sub<Rhs> + Fine<Rhs>;
    |                     --------   ^^^^^^^^ additional non-auto trait
@@ -102,28 +42,15 @@ LL | type Bat<Rhs> = dyn Add<Rhs> + Sub<Rhs> + Fine<Rhs>;
    = help: consider creating a new trait with all of these as supertraits and using that trait here instead: `trait NewTrait: Add<Rhs> + Sub<Rhs> + Fine<Rhs> {}`
    = note: auto-traits like `Send` and `Sync` are traits that have special properties; for more information on them, visit <https://doc.rust-lang.org/reference/special-types-and-traits.html#auto-traits>
 
-error[E0191]: the value of the associated types `Output` in `Add`, `Output` in `Sub` must be specified
-  --> $DIR/missing-associated-types.rs:21:21
-   |
-LL | type Bat<Rhs> = dyn Add<Rhs> + Sub<Rhs> + Fine<Rhs>;
-   |                     ^^^^^^^^   ^^^^^^^^ associated type `Output` must be specified
-   |                     |
-   |                     associated type `Output` must be specified
-   |
-help: specify the associated types
-   |
-LL | type Bat<Rhs> = dyn Add<Rhs, Output = Type> + Sub<Rhs, Output = Type> + Fine<Rhs>;
-   |                     ~~~~~~~~~~~~~~~~~~~~~~~   ~~~~~~~~~~~~~~~~~~~~~~~
-
 error[E0191]: the value of the associated types `Output` in `Div`, `Output` in `Mul` must be specified
-  --> $DIR/missing-associated-types.rs:24:21
+  --> $DIR/missing-associated-types.rs:20:21
    |
 LL | type Bal<Rhs> = dyn X<Rhs>;
    |                     ^^^^^^ associated types `Output` (from trait `Div`), `Output` (from trait `Mul`) must be specified
    |
    = help: consider introducing a new type parameter, adding `where` constraints using the fully-qualified path to the associated types
 
-error: aborting due to 9 previous errors
+error: aborting due to 5 previous errors
 
 Some errors have detailed explanations: E0191, E0225.
 For more information about an error, try `rustc --explain E0191`.
diff --git a/tests/ui/const-generics/const-argument-cross-crate-mismatch.stderr b/tests/ui/const-generics/const-argument-cross-crate-mismatch.stderr
index d5eefd357536..f58821283e19 100644
--- a/tests/ui/const-generics/const-argument-cross-crate-mismatch.stderr
+++ b/tests/ui/const-generics/const-argument-cross-crate-mismatch.stderr
@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/const-argument-cross-crate-mismatch.rs:6:67
    |
 LL |     let _ = const_generic_lib::function(const_generic_lib::Struct([0u8, 1u8]));
-   |                                         ------------------------- ^^^^^^^^^^ expected an array with a fixed size of 3 elements, found one with 2 elements
+   |                                         ------------------------- ^^^^^^^^^^ expected an array with a size of 3, found one with a size of 2
    |                                         |
    |                                         arguments to this struct are incorrect
    |
@@ -16,7 +16,7 @@ error[E0308]: mismatched types
   --> $DIR/const-argument-cross-crate-mismatch.rs:8:65
    |
 LL |     let _: const_generic_lib::Alias = const_generic_lib::Struct([0u8, 1u8, 2u8]);
-   |                                       ------------------------- ^^^^^^^^^^^^^^^ expected an array with a fixed size of 2 elements, found one with 3 elements
+   |                                       ------------------------- ^^^^^^^^^^^^^^^ expected an array with a size of 2, found one with a size of 3
    |                                       |
    |                                       arguments to this struct are incorrect
    |
diff --git a/tests/ui/const-generics/generic-param-mismatch.stderr b/tests/ui/const-generics/generic-param-mismatch.stderr
index be6b3b90ec72..099ce03317d3 100644
--- a/tests/ui/const-generics/generic-param-mismatch.stderr
+++ b/tests/ui/const-generics/generic-param-mismatch.stderr
@@ -4,10 +4,7 @@ error[E0308]: mismatched types
 LL | fn test<const N: usize, const M: usize>() -> [u8; M] {
    |                                              ------- expected `[u8; M]` because of return type
 LL |     [0; N]
-   |     ^^^^^^ expected `M`, found `N`
-   |
-   = note: expected array `[u8; M]`
-              found array `[u8; N]`
+   |     ^^^^^^ expected an array with a size of M, found one with a size of N
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/const-generics/generic_const_exprs/issue-62504.min.stderr b/tests/ui/const-generics/generic_const_exprs/issue-62504.min.stderr
index 14c67e2528a7..8efd433fd1fe 100644
--- a/tests/ui/const-generics/generic_const_exprs/issue-62504.min.stderr
+++ b/tests/ui/const-generics/generic_const_exprs/issue-62504.min.stderr
@@ -10,12 +10,10 @@ error[E0308]: mismatched types
   --> $DIR/issue-62504.rs:18:21
    |
 LL |         ArrayHolder([0; Self::SIZE])
-   |         ----------- ^^^^^^^^^^^^^^^ expected `X`, found `Self::SIZE`
+   |         ----------- ^^^^^^^^^^^^^^^ expected an array with a size of X, found one with a size of Self::SIZE
    |         |
    |         arguments to this struct are incorrect
    |
-   = note: expected array `[u32; X]`
-              found array `[u32; Self::SIZE]`
 note: tuple struct defined here
   --> $DIR/issue-62504.rs:14:8
    |
diff --git a/tests/ui/const-generics/not_wf_param_in_rpitit.rs b/tests/ui/const-generics/not_wf_param_in_rpitit.rs
index b454562ad497..cb1e90923e75 100644
--- a/tests/ui/const-generics/not_wf_param_in_rpitit.rs
+++ b/tests/ui/const-generics/not_wf_param_in_rpitit.rs
@@ -3,9 +3,6 @@
 trait Trait<const N: dyn Trait = bar> {
     //~^ ERROR: cannot find value `bar` in this scope
     //~| ERROR: cycle detected when computing type of `Trait::N`
-    //~| ERROR: the trait `Trait` cannot be made into an object
-    //~| ERROR: the trait `Trait` cannot be made into an object
-    //~| ERROR: the trait `Trait` cannot be made into an object
     async fn a() {}
 }
 
diff --git a/tests/ui/const-generics/not_wf_param_in_rpitit.stderr b/tests/ui/const-generics/not_wf_param_in_rpitit.stderr
index 2500409e8285..42ae012fa557 100644
--- a/tests/ui/const-generics/not_wf_param_in_rpitit.stderr
+++ b/tests/ui/const-generics/not_wf_param_in_rpitit.stderr
@@ -18,77 +18,7 @@ LL | trait Trait<const N: dyn Trait = bar> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
 
-error[E0038]: the trait `Trait` cannot be made into an object
-  --> $DIR/not_wf_param_in_rpitit.rs:3:22
-   |
-LL | trait Trait<const N: dyn Trait = bar> {
-   |                      ^^^^^^^^^ `Trait` cannot be made into an object
-   |
-note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
-  --> $DIR/not_wf_param_in_rpitit.rs:9:14
-   |
-LL | trait Trait<const N: dyn Trait = bar> {
-   |       ----- this trait cannot be made into an object...
-...
-LL |     async fn a() {}
-   |              ^ ...because associated function `a` has no `self` parameter
-help: consider turning `a` into a method by giving it a `&self` argument
-   |
-LL |     async fn a(&self) {}
-   |                +++++
-help: alternatively, consider constraining `a` so it does not apply to trait objects
-   |
-LL |     async fn a() where Self: Sized {}
-   |                  +++++++++++++++++
+error: aborting due to 2 previous errors
 
-error[E0038]: the trait `Trait` cannot be made into an object
-  --> $DIR/not_wf_param_in_rpitit.rs:3:13
-   |
-LL | trait Trait<const N: dyn Trait = bar> {
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^ `Trait` cannot be made into an object
-   |
-note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
-  --> $DIR/not_wf_param_in_rpitit.rs:9:14
-   |
-LL | trait Trait<const N: dyn Trait = bar> {
-   |       ----- this trait cannot be made into an object...
-...
-LL |     async fn a() {}
-   |              ^ ...because associated function `a` has no `self` parameter
-help: consider turning `a` into a method by giving it a `&self` argument
-   |
-LL |     async fn a(&self) {}
-   |                +++++
-help: alternatively, consider constraining `a` so it does not apply to trait objects
-   |
-LL |     async fn a() where Self: Sized {}
-   |                  +++++++++++++++++
-
-error[E0038]: the trait `Trait` cannot be made into an object
-  --> $DIR/not_wf_param_in_rpitit.rs:3:13
-   |
-LL | trait Trait<const N: dyn Trait = bar> {
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^ `Trait` cannot be made into an object
-   |
-note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
-  --> $DIR/not_wf_param_in_rpitit.rs:9:14
-   |
-LL | trait Trait<const N: dyn Trait = bar> {
-   |       ----- this trait cannot be made into an object...
-...
-LL |     async fn a() {}
-   |              ^ ...because associated function `a` has no `self` parameter
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-help: consider turning `a` into a method by giving it a `&self` argument
-   |
-LL |     async fn a(&self) {}
-   |                +++++
-help: alternatively, consider constraining `a` so it does not apply to trait objects
-   |
-LL |     async fn a() where Self: Sized {}
-   |                  +++++++++++++++++
-
-error: aborting due to 5 previous errors
-
-Some errors have detailed explanations: E0038, E0391, E0425.
-For more information about an error, try `rustc --explain E0038`.
+Some errors have detailed explanations: E0391, E0425.
+For more information about an error, try `rustc --explain E0391`.
diff --git a/tests/ui/consts/array-literal-len-mismatch.stderr b/tests/ui/consts/array-literal-len-mismatch.stderr
index a11506ecb6d6..39b8a647324b 100644
--- a/tests/ui/consts/array-literal-len-mismatch.stderr
+++ b/tests/ui/consts/array-literal-len-mismatch.stderr
@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/array-literal-len-mismatch.rs:1:26
    |
 LL | const NUMBERS: [u8; 3] = [10, 20];
-   |                     -    ^^^^^^^^ expected an array with a fixed size of 3 elements, found one with 2 elements
+   |                     -    ^^^^^^^^ expected an array with a size of 3, found one with a size of 2
    |                     |
    |                     help: consider specifying the actual array length: `2`
 
diff --git a/tests/ui/consts/bad-array-size-in-type-err.rs b/tests/ui/consts/bad-array-size-in-type-err.rs
new file mode 100644
index 000000000000..cb02ad3205db
--- /dev/null
+++ b/tests/ui/consts/bad-array-size-in-type-err.rs
@@ -0,0 +1,10 @@
+struct BadArraySize<const N: u8> {
+    arr: [i32; N],
+    //~^ ERROR the constant `N` is not of type `usize`
+}
+
+fn main() {
+    let _ = BadArraySize::<2> { arr: [0, 0, 0] };
+    //~^ ERROR mismatched types
+    //~| ERROR the constant `2` is not of type `usize`
+}
diff --git a/tests/ui/consts/bad-array-size-in-type-err.stderr b/tests/ui/consts/bad-array-size-in-type-err.stderr
new file mode 100644
index 000000000000..25d14d80c3ec
--- /dev/null
+++ b/tests/ui/consts/bad-array-size-in-type-err.stderr
@@ -0,0 +1,21 @@
+error: the constant `N` is not of type `usize`
+  --> $DIR/bad-array-size-in-type-err.rs:2:10
+   |
+LL |     arr: [i32; N],
+   |          ^^^^^^^^ expected `usize`, found `u8`
+
+error[E0308]: mismatched types
+  --> $DIR/bad-array-size-in-type-err.rs:7:38
+   |
+LL |     let _ = BadArraySize::<2> { arr: [0, 0, 0] };
+   |                                      ^^^^^^^^^ expected an array with a size of 2, found one with a size of 3
+
+error: the constant `2` is not of type `usize`
+  --> $DIR/bad-array-size-in-type-err.rs:7:38
+   |
+LL |     let _ = BadArraySize::<2> { arr: [0, 0, 0] };
+   |                                      ^^^^^^^^^ expected `usize`, found `u8`
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/consts/const-array-oob-arith.rs b/tests/ui/consts/const-array-oob-arith.rs
index 9332cbbd4d7c..0f6e76768cd1 100644
--- a/tests/ui/consts/const-array-oob-arith.rs
+++ b/tests/ui/consts/const-array-oob-arith.rs
@@ -4,10 +4,10 @@
 const BONG: [i32; (ARR[0] - 41) as usize] = [5];
 const BLUB: [i32; (ARR[0] - 40) as usize] = [5];
 //~^ ERROR: mismatched types
-//~| expected an array with a fixed size of 2 elements, found one with 1 element
+//~| expected an array
 const BOO: [i32; (ARR[0] - 41) as usize] = [5, 99];
 //~^ ERROR: mismatched types
-//~| expected an array with a fixed size of 1 element, found one with 2 elements
+//~| expected an array
 
 fn main() {
     let _ = VAL;
diff --git a/tests/ui/consts/const-array-oob-arith.stderr b/tests/ui/consts/const-array-oob-arith.stderr
index 029d94273fae..d3299082aa14 100644
--- a/tests/ui/consts/const-array-oob-arith.stderr
+++ b/tests/ui/consts/const-array-oob-arith.stderr
@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/const-array-oob-arith.rs:5:45
    |
 LL | const BLUB: [i32; (ARR[0] - 40) as usize] = [5];
-   |                   ----------------------    ^^^ expected an array with a fixed size of 2 elements, found one with 1 element
+   |                   ----------------------    ^^^ expected an array with a size of 2, found one with a size of 1
    |                   |
    |                   help: consider specifying the actual array length: `1`
 
@@ -10,7 +10,7 @@ error[E0308]: mismatched types
   --> $DIR/const-array-oob-arith.rs:8:44
    |
 LL | const BOO: [i32; (ARR[0] - 41) as usize] = [5, 99];
-   |                  ----------------------    ^^^^^^^ expected an array with a fixed size of 1 element, found one with 2 elements
+   |                  ----------------------    ^^^^^^^ expected an array with a size of 1, found one with a size of 2
    |                  |
    |                  help: consider specifying the actual array length: `2`
 
diff --git a/tests/ui/inference/array-len-mismatch.stderr b/tests/ui/inference/array-len-mismatch.stderr
index 7358e4783972..7146e3803d53 100644
--- a/tests/ui/inference/array-len-mismatch.stderr
+++ b/tests/ui/inference/array-len-mismatch.stderr
@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/array-len-mismatch.rs:6:26
    |
 LL |     let wrong: [u8; 3] = [10, 20];
-   |                -------   ^^^^^^^^ expected an array with a fixed size of 3 elements, found one with 2 elements
+   |                -------   ^^^^^^^^ expected an array with a size of 3, found one with a size of 2
    |                |    |
    |                |    help: consider specifying the actual array length: `2`
    |                expected due to this
@@ -11,7 +11,7 @@ error[E0308]: mismatched types
   --> $DIR/array-len-mismatch.rs:9:26
    |
 LL |     let wrong: [u8; 3] = returns_arr();
-   |                -------   ^^^^^^^^^^^^^ expected an array with a fixed size of 3 elements, found one with 2 elements
+   |                -------   ^^^^^^^^^^^^^ expected an array with a size of 3, found one with a size of 2
    |                |    |
    |                |    help: consider specifying the actual array length: `2`
    |                expected due to this
diff --git a/tests/ui/issues/issue-23024.rs b/tests/ui/issues/issue-23024.rs
index 25220dc3e611..1b072dd7b69c 100644
--- a/tests/ui/issues/issue-23024.rs
+++ b/tests/ui/issues/issue-23024.rs
@@ -8,5 +8,4 @@ fn h(x:i32) -> i32 {3*x}
     println!("{:?}",(vfnfer[0] as dyn Fn)(3));
     //~^ ERROR the precise format of `Fn`-family traits'
     //~| ERROR missing generics for trait `Fn`
-    //~| ERROR the value of the associated type `Output` in `FnOnce`
 }
diff --git a/tests/ui/issues/issue-23024.stderr b/tests/ui/issues/issue-23024.stderr
index 62278a51be63..51db0414f3a3 100644
--- a/tests/ui/issues/issue-23024.stderr
+++ b/tests/ui/issues/issue-23024.stderr
@@ -19,13 +19,7 @@ help: add missing generic argument
 LL |     println!("{:?}",(vfnfer[0] as dyn Fn<Args>)(3));
    |                                         ++++++
 
-error[E0191]: the value of the associated type `Output` in `FnOnce` must be specified
-  --> $DIR/issue-23024.rs:8:39
-   |
-LL |     println!("{:?}",(vfnfer[0] as dyn Fn)(3));
-   |                                       ^^ help: specify the associated type: `Fn::<Output = Type>`
+error: aborting due to 2 previous errors
 
-error: aborting due to 3 previous errors
-
-Some errors have detailed explanations: E0107, E0191, E0658.
+Some errors have detailed explanations: E0107, E0658.
 For more information about an error, try `rustc --explain E0107`.
diff --git a/tests/ui/issues/issue-34373.rs b/tests/ui/issues/issue-34373.rs
index dc20c5589b33..707aa8cf3383 100644
--- a/tests/ui/issues/issue-34373.rs
+++ b/tests/ui/issues/issue-34373.rs
@@ -6,7 +6,6 @@ fn foo(_: T) {}
 
 pub struct Foo<T = Box<Trait<DefaultFoo>>>;  //~ ERROR cycle detected
 //~^ ERROR `T` is never used
-//~| ERROR `Trait` cannot be made into an object
 type DefaultFoo = Foo;
 
 fn main() {
diff --git a/tests/ui/issues/issue-34373.stderr b/tests/ui/issues/issue-34373.stderr
index 4e8e7c61fee8..063655582173 100644
--- a/tests/ui/issues/issue-34373.stderr
+++ b/tests/ui/issues/issue-34373.stderr
@@ -5,7 +5,7 @@ LL | pub struct Foo<T = Box<Trait<DefaultFoo>>>;
    |                              ^^^^^^^^^^
    |
 note: ...which requires expanding type alias `DefaultFoo`...
-  --> $DIR/issue-34373.rs:10:19
+  --> $DIR/issue-34373.rs:9:19
    |
 LL | type DefaultFoo = Foo;
    |                   ^^^
@@ -17,28 +17,6 @@ LL | pub struct Foo<T = Box<Trait<DefaultFoo>>>;
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
 
-error[E0038]: the trait `Trait` cannot be made into an object
-  --> $DIR/issue-34373.rs:7:24
-   |
-LL | pub struct Foo<T = Box<Trait<DefaultFoo>>>;
-   |                        ^^^^^^^^^^^^^^^^^ `Trait` cannot be made into an object
-   |
-note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
-  --> $DIR/issue-34373.rs:4:8
-   |
-LL | trait Trait<T> {
-   |       ----- this trait cannot be made into an object...
-LL |     fn foo(_: T) {}
-   |        ^^^ ...because associated function `foo` has no `self` parameter
-help: consider turning `foo` into a method by giving it a `&self` argument
-   |
-LL |     fn foo(&self, _: T) {}
-   |            ++++++
-help: alternatively, consider constraining `foo` so it does not apply to trait objects
-   |
-LL |     fn foo(_: T) where Self: Sized {}
-   |                  +++++++++++++++++
-
 error[E0392]: type parameter `T` is never used
   --> $DIR/issue-34373.rs:7:16
    |
@@ -48,7 +26,7 @@ LL | pub struct Foo<T = Box<Trait<DefaultFoo>>>;
    = help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData`
    = help: if you intended `T` to be a const parameter, use `const T: /* Type */` instead
 
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0038, E0391, E0392.
-For more information about an error, try `rustc --explain E0038`.
+Some errors have detailed explanations: E0391, E0392.
+For more information about an error, try `rustc --explain E0391`.
diff --git a/tests/ui/mir-dataflow/def-inits-1.rs b/tests/ui/mir-dataflow/def-inits-1.rs
deleted file mode 100644
index 30460824a167..000000000000
--- a/tests/ui/mir-dataflow/def-inits-1.rs
+++ /dev/null
@@ -1,51 +0,0 @@
-// General test of maybe_uninits state computed by MIR dataflow.
-
-#![feature(core_intrinsics, rustc_attrs)]
-
-use std::intrinsics::rustc_peek;
-use std::mem::{drop, replace};
-
-struct S(i32);
-
-#[rustc_mir(rustc_peek_definite_init,stop_after_dataflow)]
-fn foo(test: bool, x: &mut S, y: S, mut z: S) -> S {
-    let ret;
-    // `ret` starts off uninitialized
-    rustc_peek(&ret);  //~ ERROR rustc_peek: bit not set
-
-    // All function formal parameters start off initialized.
-
-    rustc_peek(&x);
-    rustc_peek(&y);
-    rustc_peek(&z);
-
-    ret = if test {
-        ::std::mem::replace(x, y)
-    } else {
-        z = y;
-        z
-    };
-
-    // `z` may be uninitialized here.
-    rustc_peek(&z); //~ ERROR rustc_peek: bit not set
-
-    // `y` is definitely uninitialized here.
-    rustc_peek(&y); //~ ERROR rustc_peek: bit not set
-
-    // `x` is still (definitely) initialized (replace above is a reborrow).
-    rustc_peek(&x);
-
-    ::std::mem::drop(x);
-
-    // `x` is *definitely* uninitialized here
-    rustc_peek(&x); //~ ERROR rustc_peek: bit not set
-
-    // `ret` is now definitely initialized (via `if` above).
-    rustc_peek(&ret);
-
-    ret
-}
-fn main() {
-    foo(true, &mut S(13), S(14), S(15));
-    foo(false, &mut S(13), S(14), S(15));
-}
diff --git a/tests/ui/mir-dataflow/def-inits-1.stderr b/tests/ui/mir-dataflow/def-inits-1.stderr
deleted file mode 100644
index e2bddb54d9ba..000000000000
--- a/tests/ui/mir-dataflow/def-inits-1.stderr
+++ /dev/null
@@ -1,28 +0,0 @@
-error: rustc_peek: bit not set
-  --> $DIR/def-inits-1.rs:14:5
-   |
-LL |     rustc_peek(&ret);
-   |     ^^^^^^^^^^^^^^^^
-
-error: rustc_peek: bit not set
-  --> $DIR/def-inits-1.rs:30:5
-   |
-LL |     rustc_peek(&z);
-   |     ^^^^^^^^^^^^^^
-
-error: rustc_peek: bit not set
-  --> $DIR/def-inits-1.rs:33:5
-   |
-LL |     rustc_peek(&y);
-   |     ^^^^^^^^^^^^^^
-
-error: rustc_peek: bit not set
-  --> $DIR/def-inits-1.rs:41:5
-   |
-LL |     rustc_peek(&x);
-   |     ^^^^^^^^^^^^^^
-
-error: stop_after_dataflow ended compilation
-
-error: aborting due to 5 previous errors
-
diff --git a/tests/ui/suggestions/use-type-argument-instead-of-assoc-type.rs b/tests/ui/suggestions/use-type-argument-instead-of-assoc-type.rs
index ed262fd39a5a..c2387bf5411d 100644
--- a/tests/ui/suggestions/use-type-argument-instead-of-assoc-type.rs
+++ b/tests/ui/suggestions/use-type-argument-instead-of-assoc-type.rs
@@ -5,8 +5,7 @@ pub trait T<X, Y> {
 }
 pub struct Foo {
     i: Box<dyn T<usize, usize, usize, usize, B=usize>>,
-    //~^ ERROR must be specified
-    //~| ERROR trait takes 2 generic arguments but 4 generic arguments were supplied
+    //~^ ERROR trait takes 2 generic arguments but 4 generic arguments were supplied
 }
 
 
diff --git a/tests/ui/suggestions/use-type-argument-instead-of-assoc-type.stderr b/tests/ui/suggestions/use-type-argument-instead-of-assoc-type.stderr
index 7c84dd4b8ff3..18cf0674f023 100644
--- a/tests/ui/suggestions/use-type-argument-instead-of-assoc-type.stderr
+++ b/tests/ui/suggestions/use-type-argument-instead-of-assoc-type.stderr
@@ -14,19 +14,6 @@ help: replace the generic bounds with the associated types
 LL |     i: Box<dyn T<usize, usize, A = usize, C = usize, B=usize>>,
    |                                +++        +++
 
-error[E0191]: the value of the associated types `C` and `A` in `T` must be specified
-  --> $DIR/use-type-argument-instead-of-assoc-type.rs:7:16
-   |
-LL |     type A;
-   |     ------ `A` defined here
-LL |     type B;
-LL |     type C;
-   |     ------ `C` defined here
-...
-LL |     i: Box<dyn T<usize, usize, usize, usize, B=usize>>,
-   |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ associated types `A`, `C` must be specified
+error: aborting due to 1 previous error
 
-error: aborting due to 2 previous errors
-
-Some errors have detailed explanations: E0107, E0191.
-For more information about an error, try `rustc --explain E0107`.
+For more information about this error, try `rustc --explain E0107`.
diff --git a/tests/ui/traits/bad-sized.rs b/tests/ui/traits/bad-sized.rs
index a15219679788..7e4f37e4ae26 100644
--- a/tests/ui/traits/bad-sized.rs
+++ b/tests/ui/traits/bad-sized.rs
@@ -3,7 +3,4 @@ trait Trait {}
 pub fn main() {
     let x: Vec<dyn Trait + Sized> = Vec::new();
     //~^ ERROR only auto traits can be used as additional traits in a trait object
-    //~| ERROR the size for values of type
-    //~| ERROR the size for values of type
-    //~| ERROR the size for values of type
 }
diff --git a/tests/ui/traits/bad-sized.stderr b/tests/ui/traits/bad-sized.stderr
index 4c1835dfed08..0e82867ef03b 100644
--- a/tests/ui/traits/bad-sized.stderr
+++ b/tests/ui/traits/bad-sized.stderr
@@ -9,37 +9,6 @@ LL |     let x: Vec<dyn Trait + Sized> = Vec::new();
    = help: consider creating a new trait with all of these as supertraits and using that trait here instead: `trait NewTrait: Trait + Sized {}`
    = note: auto-traits like `Send` and `Sync` are traits that have special properties; for more information on them, visit <https://doc.rust-lang.org/reference/special-types-and-traits.html#auto-traits>
 
-error[E0277]: the size for values of type `dyn Trait` cannot be known at compilation time
-  --> $DIR/bad-sized.rs:4:12
-   |
-LL |     let x: Vec<dyn Trait + Sized> = Vec::new();
-   |            ^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
-   |
-   = help: the trait `Sized` is not implemented for `dyn Trait`
-note: required by an implicit `Sized` bound in `Vec`
-  --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
+error: aborting due to 1 previous error
 
-error[E0277]: the size for values of type `dyn Trait` cannot be known at compilation time
-  --> $DIR/bad-sized.rs:4:37
-   |
-LL |     let x: Vec<dyn Trait + Sized> = Vec::new();
-   |                                     ^^^^^^^^^^ doesn't have a size known at compile-time
-   |
-   = help: the trait `Sized` is not implemented for `dyn Trait`
-note: required by a bound in `Vec::<T>::new`
-  --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
-
-error[E0277]: the size for values of type `dyn Trait` cannot be known at compilation time
-  --> $DIR/bad-sized.rs:4:37
-   |
-LL |     let x: Vec<dyn Trait + Sized> = Vec::new();
-   |                                     ^^^ doesn't have a size known at compile-time
-   |
-   = help: the trait `Sized` is not implemented for `dyn Trait`
-note: required by an implicit `Sized` bound in `Vec`
-  --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
-
-error: aborting due to 4 previous errors
-
-Some errors have detailed explanations: E0225, E0277.
-For more information about an error, try `rustc --explain E0225`.
+For more information about this error, try `rustc --explain E0225`.
diff --git a/tests/ui/traits/issue-32963.rs b/tests/ui/traits/issue-32963.rs
index 56a68f3a2312..4c4cd91d72e3 100644
--- a/tests/ui/traits/issue-32963.rs
+++ b/tests/ui/traits/issue-32963.rs
@@ -7,5 +7,4 @@ fn size_of_copy<T: Copy+?Sized>() -> usize { mem::size_of::<T>() }
 fn main() {
     size_of_copy::<dyn Misc + Copy>();
     //~^ ERROR only auto traits can be used as additional traits in a trait object
-    //~| ERROR the trait bound `dyn Misc: Copy` is not satisfied
 }
diff --git a/tests/ui/traits/issue-32963.stderr b/tests/ui/traits/issue-32963.stderr
index bad45e54d642..1c70d0aaa0ac 100644
--- a/tests/ui/traits/issue-32963.stderr
+++ b/tests/ui/traits/issue-32963.stderr
@@ -9,19 +9,6 @@ LL |     size_of_copy::<dyn Misc + Copy>();
    = help: consider creating a new trait with all of these as supertraits and using that trait here instead: `trait NewTrait: Misc + Copy {}`
    = note: auto-traits like `Send` and `Sync` are traits that have special properties; for more information on them, visit <https://doc.rust-lang.org/reference/special-types-and-traits.html#auto-traits>
 
-error[E0277]: the trait bound `dyn Misc: Copy` is not satisfied
-  --> $DIR/issue-32963.rs:8:20
-   |
-LL |     size_of_copy::<dyn Misc + Copy>();
-   |                    ^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `dyn Misc`
-   |
-note: required by a bound in `size_of_copy`
-  --> $DIR/issue-32963.rs:5:20
-   |
-LL | fn size_of_copy<T: Copy+?Sized>() -> usize { mem::size_of::<T>() }
-   |                    ^^^^ required by this bound in `size_of_copy`
+error: aborting due to 1 previous error
 
-error: aborting due to 2 previous errors
-
-Some errors have detailed explanations: E0225, E0277.
-For more information about an error, try `rustc --explain E0225`.
+For more information about this error, try `rustc --explain E0225`.
diff --git a/tests/ui/wf/ice-hir-wf-check-anon-const-issue-122199.rs b/tests/ui/wf/ice-hir-wf-check-anon-const-issue-122199.rs
index 53363319ba0e..a95e10b7265d 100644
--- a/tests/ui/wf/ice-hir-wf-check-anon-const-issue-122199.rs
+++ b/tests/ui/wf/ice-hir-wf-check-anon-const-issue-122199.rs
@@ -1,11 +1,6 @@
 trait Trait<const N: Trait = bar> {
     //~^ ERROR cannot find value `bar` in this scope
     //~| ERROR cycle detected when computing type of `Trait::N`
-    //~| ERROR the trait `Trait` cannot be made into an object
-    //~| ERROR the trait `Trait` cannot be made into an object
-    //~| ERROR the trait `Trait` cannot be made into an object
-    //~| WARN trait objects without an explicit `dyn` are deprecated [bare_trait_objects]
-    //~| WARN this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
     //~| WARN trait objects without an explicit `dyn` are deprecated [bare_trait_objects]
     //~| WARN this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
     fn fnc<const N: Trait = u32>(&self) -> Trait {
@@ -13,9 +8,6 @@ fn fnc<const N: Trait = u32>(&self) -> Trait {
         //~| ERROR expected value, found builtin type `u32`
         //~| ERROR defaults for const parameters are only allowed in `struct`, `enum`, `type`, or `trait` definitions
         //~| ERROR associated item referring to unboxed trait object for its own trait
-        //~| ERROR the trait `Trait` cannot be made into an object
-        //~| WARN trait objects without an explicit `dyn` are deprecated [bare_trait_objects]
-        //~| WARN this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
         //~| WARN trait objects without an explicit `dyn` are deprecated [bare_trait_objects]
         //~| WARN this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
         //~| WARN trait objects without an explicit `dyn` are deprecated [bare_trait_objects]
diff --git a/tests/ui/wf/ice-hir-wf-check-anon-const-issue-122199.stderr b/tests/ui/wf/ice-hir-wf-check-anon-const-issue-122199.stderr
index fefb788fac79..339f7b2cc820 100644
--- a/tests/ui/wf/ice-hir-wf-check-anon-const-issue-122199.stderr
+++ b/tests/ui/wf/ice-hir-wf-check-anon-const-issue-122199.stderr
@@ -1,5 +1,5 @@
 error[E0403]: the name `N` is already used for a generic parameter in this item's generic parameters
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:11:18
+  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:6:18
    |
 LL | trait Trait<const N: Trait = bar> {
    |                   - first use of `N`
@@ -14,13 +14,13 @@ LL | trait Trait<const N: Trait = bar> {
    |                              ^^^ not found in this scope
 
 error[E0423]: expected value, found builtin type `u32`
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:11:29
+  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:6:29
    |
 LL |     fn fnc<const N: Trait = u32>(&self) -> Trait {
    |                             ^^^ not a value
 
 error[E0425]: cannot find value `bar` in this scope
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:23:9
+  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:15:9
    |
 LL |         bar
    |         ^^^ not found in this scope
@@ -53,27 +53,8 @@ LL | trait Trait<const N: Trait = bar> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
 
-error: defaults for const parameters are only allowed in `struct`, `enum`, `type`, or `trait` definitions
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:11:12
-   |
-LL |     fn fnc<const N: Trait = u32>(&self) -> Trait {
-   |            ^^^^^^^^^^^^^^^^^^^^
-
 warning: trait objects without an explicit `dyn` are deprecated
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:11:21
-   |
-LL |     fn fnc<const N: Trait = u32>(&self) -> Trait {
-   |                     ^^^^^
-   |
-   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
-   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
-help: if this is a dyn-compatible trait, use `dyn`
-   |
-LL |     fn fnc<const N: dyn Trait = u32>(&self) -> Trait {
-   |                     +++
-
-warning: trait objects without an explicit `dyn` are deprecated
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:11:44
+  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:6:44
    |
 LL |     fn fnc<const N: Trait = u32>(&self) -> Trait {
    |                                            ^^^^^
@@ -85,54 +66,27 @@ help: if this is a dyn-compatible trait, use `dyn`
 LL |     fn fnc<const N: Trait = u32>(&self) -> dyn Trait {
    |                                            +++
 
-warning: trait objects without an explicit `dyn` are deprecated
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:1:22
+error: defaults for const parameters are only allowed in `struct`, `enum`, `type`, or `trait` definitions
+  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:6:12
    |
-LL | trait Trait<const N: Trait = bar> {
-   |                      ^^^^^
+LL |     fn fnc<const N: Trait = u32>(&self) -> Trait {
+   |            ^^^^^^^^^^^^^^^^^^^^
+
+warning: trait objects without an explicit `dyn` are deprecated
+  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:6:21
+   |
+LL |     fn fnc<const N: Trait = u32>(&self) -> Trait {
+   |                     ^^^^^
    |
    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 help: if this is a dyn-compatible trait, use `dyn`
    |
-LL | trait Trait<const N: dyn Trait = bar> {
-   |                      +++
-
-error[E0038]: the trait `Trait` cannot be made into an object
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:1:22
-   |
-LL | trait Trait<const N: Trait = bar> {
-   |                      ^^^^^ `Trait` cannot be made into an object
-   |
-note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:11:8
-   |
-LL | trait Trait<const N: Trait = bar> {
-   |       ----- this trait cannot be made into an object...
-...
-LL |     fn fnc<const N: Trait = u32>(&self) -> Trait {
-   |        ^^^ ...because method `fnc` has generic type parameters
-   = help: consider moving `fnc` to another trait
-
-error[E0038]: the trait `Trait` cannot be made into an object
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:1:13
-   |
-LL | trait Trait<const N: Trait = bar> {
-   |             ^^^^^^^^^^^^^^^^^^^^ `Trait` cannot be made into an object
-   |
-note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:11:8
-   |
-LL | trait Trait<const N: Trait = bar> {
-   |       ----- this trait cannot be made into an object...
-...
-LL |     fn fnc<const N: Trait = u32>(&self) -> Trait {
-   |        ^^^ ...because method `fnc` has generic type parameters
-   = help: consider moving `fnc` to another trait
+LL |     fn fnc<const N: dyn Trait = u32>(&self) -> Trait {
+   |                     +++
 
 error: associated item referring to unboxed trait object for its own trait
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:11:44
+  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:6:44
    |
 LL | trait Trait<const N: Trait = bar> {
    |       ----- in this trait
@@ -145,54 +99,7 @@ help: you might have meant to use `Self` to refer to the implementing type
 LL |     fn fnc<const N: Trait = u32>(&self) -> Self {
    |                                            ~~~~
 
-warning: trait objects without an explicit `dyn` are deprecated
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:11:21
-   |
-LL |     fn fnc<const N: Trait = u32>(&self) -> Trait {
-   |                     ^^^^^
-   |
-   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
-   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-help: if this is a dyn-compatible trait, use `dyn`
-   |
-LL |     fn fnc<const N: dyn Trait = u32>(&self) -> Trait {
-   |                     +++
+error: aborting due to 7 previous errors; 3 warnings emitted
 
-error[E0038]: the trait `Trait` cannot be made into an object
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:11:21
-   |
-LL |     fn fnc<const N: Trait = u32>(&self) -> Trait {
-   |                     ^^^^^ `Trait` cannot be made into an object
-   |
-note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:11:8
-   |
-LL | trait Trait<const N: Trait = bar> {
-   |       ----- this trait cannot be made into an object...
-...
-LL |     fn fnc<const N: Trait = u32>(&self) -> Trait {
-   |        ^^^ ...because method `fnc` has generic type parameters
-   = help: consider moving `fnc` to another trait
-
-error[E0038]: the trait `Trait` cannot be made into an object
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:1:13
-   |
-LL | trait Trait<const N: Trait = bar> {
-   |             ^^^^^^^^^^^^^^^^^^^^ `Trait` cannot be made into an object
-   |
-note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122199.rs:11:8
-   |
-LL | trait Trait<const N: Trait = bar> {
-   |       ----- this trait cannot be made into an object...
-...
-LL |     fn fnc<const N: Trait = u32>(&self) -> Trait {
-   |        ^^^ ...because method `fnc` has generic type parameters
-   = help: consider moving `fnc` to another trait
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error: aborting due to 11 previous errors; 5 warnings emitted
-
-Some errors have detailed explanations: E0038, E0391, E0403, E0423, E0425.
-For more information about an error, try `rustc --explain E0038`.
+Some errors have detailed explanations: E0391, E0403, E0423, E0425.
+For more information about an error, try `rustc --explain E0391`.