Auto merge of #105746 - matthiaskrgr:rollup-sz3grbv, r=matthiaskrgr

Rollup of 11 pull requests

Successful merges:

 - #104592 (Ensure async trait impls are async (or otherwise return an opaque type))
 - #105623 (Fix `-Z print-type-sizes` for generators with discriminant field ordered first)
 - #105627 (Auto traits in `dyn Trait + Auto` are suggestable)
 - #105633 (Make `report_projection_error` more `Term` agnostic)
 - #105683 (Various cleanups to dest prop)
 - #105692 (Add regression test for #104678)
 - #105707 (rustdoc: remove unnecessary CSS `kbd { cursor: default }`)
 - #105715 (Do not mention long types in E0599 label)
 - #105722 (more clippy::complexity fixes)
 - #105724 (rustdoc: remove no-op CSS `.scrape-example .src-line-numbers { margin: 0 }`)
 - #105730 (rustdoc: remove no-op CSS `.item-info:before { color }`)

Failed merges:

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

61 files changed, 509 insertions, 325 deletions

diff --git a/compiler/rustc_ast/src/ast.rs b/compiler/rustc_ast/src/ast.rs
index 2e86970bcfd..f933b9b161c 100644
--- a/compiler/rustc_ast/src/ast.rs
+++ b/compiler/rustc_ast/src/ast.rs
@@ -2466,7 +2466,7 @@ pub enum ModKind {
     Unloaded,
 }
 
-#[derive(Copy, Clone, Encodable, Decodable, Debug)]
+#[derive(Copy, Clone, Encodable, Decodable, Debug, Default)]
 pub struct ModSpans {
     /// `inner_span` covers the body of the module; for a file module, its the whole file.
     /// For an inline module, its the span inside the `{ ... }`, not including the curly braces.
@@ -2474,12 +2474,6 @@ pub struct ModSpans {
     pub inject_use_span: Span,
 }
 
-impl Default for ModSpans {
-    fn default() -> ModSpans {
-        ModSpans { inner_span: Default::default(), inject_use_span: Default::default() }
-    }
-}
-
 /// Foreign module declaration.
 ///
 /// E.g., `extern { .. }` or `extern "C" { .. }`.
diff --git a/compiler/rustc_data_structures/src/sorted_map.rs b/compiler/rustc_data_structures/src/sorted_map.rs
index 03ff5e5b375..05f059c89d5 100644
--- a/compiler/rustc_data_structures/src/sorted_map.rs
+++ b/compiler/rustc_data_structures/src/sorted_map.rs
@@ -126,13 +126,13 @@ impl<K: Ord, V> SortedMap<K, V> {
     /// Iterate over the keys, sorted
     #[inline]
     pub fn keys(&self) -> impl Iterator<Item = &K> + ExactSizeIterator + DoubleEndedIterator {
-        self.data.iter().map(|&(ref k, _)| k)
+        self.data.iter().map(|(k, _)| k)
     }
 
     /// Iterate over values, sorted by key
     #[inline]
     pub fn values(&self) -> impl Iterator<Item = &V> + ExactSizeIterator + DoubleEndedIterator {
-        self.data.iter().map(|&(_, ref v)| v)
+        self.data.iter().map(|(_, v)| v)
     }
 
     #[inline]
@@ -222,7 +222,7 @@ impl<K: Ord, V> SortedMap<K, V> {
         K: Borrow<Q>,
         Q: Ord + ?Sized,
     {
-        self.data.binary_search_by(|&(ref x, _)| x.borrow().cmp(key))
+        self.data.binary_search_by(|(x, _)| x.borrow().cmp(key))
     }
 
     #[inline]
@@ -300,7 +300,7 @@ impl<K: Ord, V> FromIterator<(K, V)> for SortedMap<K, V> {
     fn from_iter<T: IntoIterator<Item = (K, V)>>(iter: T) -> Self {
         let mut data: Vec<(K, V)> = iter.into_iter().collect();
 
-        data.sort_unstable_by(|&(ref k1, _), &(ref k2, _)| k1.cmp(k2));
+        data.sort_unstable_by(|(k1, _), (k2, _)| k1.cmp(k2));
         data.dedup_by(|&mut (ref k1, _), &mut (ref k2, _)| k1.cmp(k2) == Ordering::Equal);
 
         SortedMap { data }
diff --git a/compiler/rustc_error_messages/locales/en-US/hir_analysis.ftl b/compiler/rustc_error_messages/locales/en-US/hir_analysis.ftl
index e33323a7795..26cdf8a58f3 100644
--- a/compiler/rustc_error_messages/locales/en-US/hir_analysis.ftl
+++ b/compiler/rustc_error_messages/locales/en-US/hir_analysis.ftl
@@ -20,6 +20,10 @@ hir_analysis_lifetimes_or_bounds_mismatch_on_trait =
     .where_label = this `where` clause might not match the one in the trait
     .bounds_label = this bound might be missing in the impl
 
+hir_analysis_async_trait_impl_should_be_async =
+    method `{$method_name}` should be async because the method from the trait is async
+    .trait_item_label = required because the trait method is async
+
 hir_analysis_drop_impl_on_wrong_item =
     the `Drop` trait may only be implemented for local structs, enums, and unions
     .label = must be a struct, enum, or union in the current crate
diff --git a/compiler/rustc_errors/src/emitter.rs b/compiler/rustc_errors/src/emitter.rs
index c62e358e804..e2a0e436fd5 100644
--- a/compiler/rustc_errors/src/emitter.rs
+++ b/compiler/rustc_errors/src/emitter.rs
@@ -2313,7 +2313,7 @@ impl FileWithAnnotatedLines {
         }
 
         // Find overlapping multiline annotations, put them at different depths
-        multiline_annotations.sort_by_key(|&(_, ref ml)| (ml.line_start, usize::MAX - ml.line_end));
+        multiline_annotations.sort_by_key(|(_, ml)| (ml.line_start, usize::MAX - ml.line_end));
         for (_, ann) in multiline_annotations.clone() {
             for (_, a) in multiline_annotations.iter_mut() {
                 // Move all other multiline annotations overlapping with this one
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index eb0506c459a..518b5ec10f8 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -324,7 +324,7 @@ impl CodeSuggestion {
                         // Account for the difference between the width of the current code and the
                         // snippet being suggested, so that the *later* suggestions are correctly
                         // aligned on the screen.
-                        acc += len as isize - (cur_hi.col.0 - cur_lo.col.0) as isize;
+                        acc += len - (cur_hi.col.0 - cur_lo.col.0) as isize;
                     }
                     prev_hi = cur_hi;
                     prev_line = sf.get_line(prev_hi.line - 1);
diff --git a/compiler/rustc_hir_analysis/src/check/compare_method.rs b/compiler/rustc_hir_analysis/src/check/compare_method.rs
index 4f4e9a89fc7..6b9ce9a4599 100644
--- a/compiler/rustc_hir_analysis/src/check/compare_method.rs
+++ b/compiler/rustc_hir_analysis/src/check/compare_method.rs
@@ -67,6 +67,10 @@ pub(crate) fn compare_impl_method<'tcx>(
         return;
     }
 
+    if let Err(_) = compare_asyncness(tcx, impl_m, impl_m_span, trait_m, trait_item_span) {
+        return;
+    }
+
     if let Err(_) = compare_predicate_entailment(tcx, impl_m, impl_m_span, trait_m, impl_trait_ref)
     {
         return;
@@ -323,6 +327,34 @@ fn compare_predicate_entailment<'tcx>(
     Ok(())
 }
 
+fn compare_asyncness<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    impl_m: &ty::AssocItem,
+    impl_m_span: Span,
+    trait_m: &ty::AssocItem,
+    trait_item_span: Option<Span>,
+) -> Result<(), ErrorGuaranteed> {
+    if tcx.asyncness(trait_m.def_id) == hir::IsAsync::Async {
+        match tcx.fn_sig(impl_m.def_id).skip_binder().output().kind() {
+            ty::Alias(ty::Opaque, ..) => {
+                // allow both `async fn foo()` and `fn foo() -> impl Future`
+            }
+            ty::Error(rustc_errors::ErrorGuaranteed { .. }) => {
+                // We don't know if it's ok, but at least it's already an error.
+            }
+            _ => {
+                return Err(tcx.sess.emit_err(crate::errors::AsyncTraitImplShouldBeAsync {
+                    span: impl_m_span,
+                    method_name: trait_m.name,
+                    trait_item_span,
+                }));
+            }
+        };
+    }
+
+    Ok(())
+}
+
 #[instrument(skip(tcx), level = "debug", ret)]
 pub fn collect_trait_impl_trait_tys<'tcx>(
     tcx: TyCtxt<'tcx>,
diff --git a/compiler/rustc_hir_analysis/src/errors.rs b/compiler/rustc_hir_analysis/src/errors.rs
index d9697c63c56..d383fcacb3a 100644
--- a/compiler/rustc_hir_analysis/src/errors.rs
+++ b/compiler/rustc_hir_analysis/src/errors.rs
@@ -52,6 +52,17 @@ pub struct LifetimesOrBoundsMismatchOnTrait {
 }
 
 #[derive(Diagnostic)]
+#[diag(hir_analysis_async_trait_impl_should_be_async)]
+pub struct AsyncTraitImplShouldBeAsync {
+    #[primary_span]
+    // #[label]
+    pub span: Span,
+    #[label(trait_item_label)]
+    pub trait_item_span: Option<Span>,
+    pub method_name: Symbol,
+}
+
+#[derive(Diagnostic)]
 #[diag(hir_analysis_drop_impl_on_wrong_item, code = "E0120")]
 pub struct DropImplOnWrongItem {
     #[primary_span]
diff --git a/compiler/rustc_hir_pretty/src/lib.rs b/compiler/rustc_hir_pretty/src/lib.rs
index ef98c4ba54c..29a6902ccb0 100644
--- a/compiler/rustc_hir_pretty/src/lib.rs
+++ b/compiler/rustc_hir_pretty/src/lib.rs
@@ -1757,7 +1757,6 @@ impl<'a> State<'a> {
                 self.print_qpath(qpath, true);
                 self.popen();
                 if let Some(ddpos) = ddpos.as_opt_usize() {
-                    let ddpos = ddpos as usize;
                     self.commasep(Inconsistent, &elts[..ddpos], |s, p| s.print_pat(p));
                     if ddpos != 0 {
                         self.word_space(",");
diff --git a/compiler/rustc_hir_typeck/src/method/suggest.rs b/compiler/rustc_hir_typeck/src/method/suggest.rs
index 0103f58d061..5c0d5f32f0f 100644
--- a/compiler/rustc_hir_typeck/src/method/suggest.rs
+++ b/compiler/rustc_hir_typeck/src/method/suggest.rs
@@ -893,7 +893,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             }
                         }
                     } else {
-                        err.span_label(span, format!("{item_kind} cannot be called on `{ty_str}` due to unsatisfied trait bounds"));
+                        let ty_str = if ty_str.len() > 50 {
+                            String::new()
+                        } else {
+                            format!("on `{ty_str}` ")
+                        };
+                        err.span_label(span, format!(
+                            "{item_kind} cannot be called {ty_str}due to unsatisfied trait bounds"
+                        ));
                     }
                 };
 
diff --git a/compiler/rustc_macros/src/diagnostics/diagnostic.rs b/compiler/rustc_macros/src/diagnostics/diagnostic.rs
index 684835d8c5c..13f06fe7473 100644
--- a/compiler/rustc_macros/src/diagnostics/diagnostic.rs
+++ b/compiler/rustc_macros/src/diagnostics/diagnostic.rs
@@ -192,7 +192,7 @@ impl Mismatch {
         let crate_name = std::env::var("CARGO_CRATE_NAME").ok()?;
 
         // If we're not in a "rustc_" crate, bail.
-        let Some(("rustc", slug_prefix)) = crate_name.split_once("_") else { return None };
+        let Some(("rustc", slug_prefix)) = crate_name.split_once('_') else { return None };
 
         let slug_name = slug.segments.first()?.ident.to_string();
         if !slug_name.starts_with(slug_prefix) {
diff --git a/compiler/rustc_middle/src/ty/diagnostics.rs b/compiler/rustc_middle/src/ty/diagnostics.rs
index d8d476d3fef..8c22df7395f 100644
--- a/compiler/rustc_middle/src/ty/diagnostics.rs
+++ b/compiler/rustc_middle/src/ty/diagnostics.rs
@@ -3,8 +3,8 @@
 use std::ops::ControlFlow;
 
 use crate::ty::{
-    visit::TypeVisitable, AliasTy, Const, ConstKind, DefIdTree, ExistentialPredicate, InferConst,
-    InferTy, Opaque, PolyTraitPredicate, Ty, TyCtxt, TypeSuperVisitable, TypeVisitor,
+    visit::TypeVisitable, AliasTy, Const, ConstKind, DefIdTree, InferConst, InferTy, Opaque,
+    PolyTraitPredicate, Ty, TyCtxt, TypeSuperVisitable, TypeVisitor,
 };
 
 use rustc_data_structures::fx::FxHashMap;
@@ -469,17 +469,6 @@ impl<'tcx> TypeVisitor<'tcx> for IsSuggestableVisitor<'tcx> {
                 }
             }
 
-            Dynamic(dty, _, _) => {
-                for pred in *dty {
-                    match pred.skip_binder() {
-                        ExistentialPredicate::Trait(_) | ExistentialPredicate::Projection(_) => {
-                            // Okay
-                        }
-                        _ => return ControlFlow::Break(()),
-                    }
-                }
-            }
-
             Param(param) => {
                 // FIXME: It would be nice to make this not use string manipulation,
                 // but it's pretty hard to do this, since `ty::ParamTy` is missing
diff --git a/compiler/rustc_mir_transform/src/dest_prop.rs b/compiler/rustc_mir_transform/src/dest_prop.rs
index 97485c4f57b..3e45319431c 100644
--- a/compiler/rustc_mir_transform/src/dest_prop.rs
+++ b/compiler/rustc_mir_transform/src/dest_prop.rs
@@ -132,15 +132,12 @@ use std::collections::hash_map::{Entry, OccupiedEntry};
 use crate::MirPass;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_index::bit_set::BitSet;
+use rustc_middle::mir::visit::{MutVisitor, PlaceContext, Visitor};
 use rustc_middle::mir::{dump_mir, PassWhere};
 use rustc_middle::mir::{
     traversal, BasicBlock, Body, InlineAsmOperand, Local, LocalKind, Location, Operand, Place,
     Rvalue, Statement, StatementKind, TerminatorKind,
 };
-use rustc_middle::mir::{
-    visit::{MutVisitor, PlaceContext, Visitor},
-    ProjectionElem,
-};
 use rustc_middle::ty::TyCtxt;
 use rustc_mir_dataflow::impls::MaybeLiveLocals;
 use rustc_mir_dataflow::{Analysis, ResultsCursor};
@@ -359,40 +356,45 @@ struct FilterInformation<'a, 'body, 'alloc, 'tcx> {
 // through these methods, and not directly.
 impl<'alloc> Candidates<'alloc> {
     /// Just `Vec::retain`, but the condition is inverted and we add debugging output
-    fn vec_remove_debug(
+    fn vec_filter_candidates(
         src: Local,
         v: &mut Vec<Local>,
-        mut f: impl FnMut(Local) -> bool,
+        mut f: impl FnMut(Local) -> CandidateFilter,
         at: Location,
     ) {
         v.retain(|dest| {
             let remove = f(*dest);
-            if remove {
+            if remove == CandidateFilter::Remove {
                 trace!("eliminating {:?} => {:?} due to conflict at {:?}", src, dest, at);
             }
-            !remove
+            remove == CandidateFilter::Keep
         });
     }
 
-    /// `vec_remove_debug` but for an `Entry`
-    fn entry_remove(
+    /// `vec_filter_candidates` but for an `Entry`
+    fn entry_filter_candidates(
         mut entry: OccupiedEntry<'_, Local, Vec<Local>>,
         p: Local,
-        f: impl FnMut(Local) -> bool,
+        f: impl FnMut(Local) -> CandidateFilter,
         at: Location,
     ) {
         let candidates = entry.get_mut();
-        Self::vec_remove_debug(p, candidates, f, at);
+        Self::vec_filter_candidates(p, candidates, f, at);
         if candidates.len() == 0 {
             entry.remove();
         }
     }
 
-    /// Removes all candidates `(p, q)` or `(q, p)` where `p` is the indicated local and `f(q)` is true.
-    fn remove_candidates_if(&mut self, p: Local, mut f: impl FnMut(Local) -> bool, at: Location) {
+    /// For all candidates `(p, q)` or `(q, p)` removes the candidate if `f(q)` says to do so
+    fn filter_candidates_by(
+        &mut self,
+        p: Local,
+        mut f: impl FnMut(Local) -> CandidateFilter,
+        at: Location,
+    ) {
         // Cover the cases where `p` appears as a `src`
         if let Entry::Occupied(entry) = self.c.entry(p) {
-            Self::entry_remove(entry, p, &mut f, at);
+            Self::entry_filter_candidates(entry, p, &mut f, at);
         }
         // And the cases where `p` appears as a `dest`
         let Some(srcs) = self.reverse.get_mut(&p) else {
@@ -401,18 +403,31 @@ impl<'alloc> Candidates<'alloc> {
         // We use `retain` here to remove the elements from the reverse set if we've removed the
         // matching candidate in the forward set.
         srcs.retain(|src| {
-            if !f(*src) {
+            if f(*src) == CandidateFilter::Keep {
                 return true;
             }
             let Entry::Occupied(entry) = self.c.entry(*src) else {
                 return false;
             };
-            Self::entry_remove(entry, *src, |dest| dest == p, at);
+            Self::entry_filter_candidates(
+                entry,
+                *src,
+                |dest| {
+                    if dest == p { CandidateFilter::Remove } else { CandidateFilter::Keep }
+                },
+                at,
+            );
             false
         });
     }
 }
 
+#[derive(Copy, Clone, PartialEq, Eq)]
+enum CandidateFilter {
+    Keep,
+    Remove,
+}
+
 impl<'a, 'body, 'alloc, 'tcx> FilterInformation<'a, 'body, 'alloc, 'tcx> {
     /// Filters the set of candidates to remove those that conflict.
     ///
@@ -460,7 +475,7 @@ impl<'a, 'body, 'alloc, 'tcx> FilterInformation<'a, 'body, 'alloc, 'tcx> {
             for (i, statement) in data.statements.iter().enumerate().rev() {
                 self.at = Location { block, statement_index: i };
                 self.live.seek_after_primary_effect(self.at);
-                self.get_statement_write_info(&statement.kind);
+                self.write_info.for_statement(&statement.kind, self.body);
                 self.apply_conflicts();
             }
         }
@@ -469,80 +484,59 @@ impl<'a, 'body, 'alloc, 'tcx> FilterInformation<'a, 'body, 'alloc, 'tcx> {
     fn apply_conflicts(&mut self) {
         let writes = &self.write_info.writes;
         for p in writes {
-            self.candidates.remove_candidates_if(
+            let other_skip = self.write_info.skip_pair.and_then(|(a, b)| {
+                if a == *p {
+                    Some(b)
+                } else if b == *p {
+                    Some(a)
+                } else {
+                    None
+                }
+            });
+            self.candidates.filter_candidates_by(
                 *p,
-                // It is possible that a local may be live for less than the
-                // duration of a statement This happens in the case of function
-                // calls or inline asm. Because of this, we also mark locals as
-                // conflicting when both of them are written to in the same
-                // statement.
-                |q| self.live.contains(q) || writes.contains(&q),
+                |q| {
+                    if Some(q) == other_skip {
+                        return CandidateFilter::Keep;
+                    }
+                    // It is possible that a local may be live for less than the
+                    // duration of a statement This happens in the case of function
+                    // calls or inline asm. Because of this, we also mark locals as
+                    // conflicting when both of them are written to in the same
+                    // statement.
+                    if self.live.contains(q) || writes.contains(&q) {
+                        CandidateFilter::Remove
+                    } else {
+                        CandidateFilter::Keep
+                    }
+                },
                 self.at,
             );
         }
     }
-
-    /// Gets the write info for the `statement`.
-    fn get_statement_write_info(&mut self, statement: &StatementKind<'tcx>) {
-        self.write_info.writes.clear();
-        match statement {
-            StatementKind::Assign(box (lhs, rhs)) => match rhs {
-                Rvalue::Use(op) => {
-                    if !lhs.is_indirect() {
-                        self.get_assign_use_write_info(*lhs, op);
-                        return;
-                    }
-                }
-                _ => (),
-            },
-            _ => (),
-        }
-
-        self.write_info.for_statement(statement);
-    }
-
-    fn get_assign_use_write_info(&mut self, lhs: Place<'tcx>, rhs: &Operand<'tcx>) {
-        // We register the writes for the operand unconditionally
-        self.write_info.add_operand(rhs);
-        // However, we cannot do the same thing for the `lhs` as that would always block the
-        // optimization. Instead, we consider removing candidates manually.
-        let Some(rhs) = rhs.place() else {
-            self.write_info.add_place(lhs);
-            return;
-        };
-        // Find out which candidate pair we should skip, if any
-        let Some((src, dest)) = places_to_candidate_pair(lhs, rhs, self.body) else {
-            self.write_info.add_place(lhs);
-            return;
-        };
-        self.candidates.remove_candidates_if(
-            lhs.local,
-            |other| {
-                // Check if this is the candidate pair that should not be removed
-                if (lhs.local == src && other == dest) || (lhs.local == dest && other == src) {
-                    return false;
-                }
-                // Otherwise, do the "standard" thing
-                self.live.contains(other)
-            },
-            self.at,
-        )
-    }
 }
 
 /// Describes where a statement/terminator writes to
 #[derive(Default, Debug)]
 struct WriteInfo {
     writes: Vec<Local>,
+    /// If this pair of locals is a candidate pair, completely skip processing it during this
+    /// statement. All other candidates are unaffected.
+    skip_pair: Option<(Local, Local)>,
 }
 
 impl WriteInfo {
-    fn for_statement<'tcx>(&mut self, statement: &StatementKind<'tcx>) {
+    fn for_statement<'tcx>(&mut self, statement: &StatementKind<'tcx>, body: &Body<'tcx>) {
+        self.reset();
         match statement {
             StatementKind::Assign(box (lhs, rhs)) => {
                 self.add_place(*lhs);
                 match rhs {
-                    Rvalue::Use(op) | Rvalue::Repeat(op, _) => {
+                    Rvalue::Use(op) => {
+                        self.add_operand(op);
+                        self.consider_skipping_for_assign_use(*lhs, op, body);
+                    }
+                    Rvalue::Repeat(op, _) => {
                         self.add_operand(op);
                     }
                     Rvalue::Cast(_, op, _)
@@ -586,8 +580,22 @@ impl WriteInfo {
         }
     }
 
+    fn consider_skipping_for_assign_use<'tcx>(
+        &mut self,
+        lhs: Place<'tcx>,
+        rhs: &Operand<'tcx>,
+        body: &Body<'tcx>,
+    ) {
+        let Some(rhs) = rhs.place() else {
+            return
+        };
+        if let Some(pair) = places_to_candidate_pair(lhs, rhs, body) {
+            self.skip_pair = Some(pair);
+        }
+    }
+
     fn for_terminator<'tcx>(&mut self, terminator: &TerminatorKind<'tcx>) {
-        self.writes.clear();
+        self.reset();
         match terminator {
             TerminatorKind::SwitchInt { discr: op, .. }
             | TerminatorKind::Assert { cond: op, .. } => {
@@ -657,15 +665,16 @@ impl WriteInfo {
             Operand::Copy(_) | Operand::Constant(_) => (),
         }
     }
+
+    fn reset(&mut self) {
+        self.writes.clear();
+        self.skip_pair = None;
+    }
 }
 
 /////////////////////////////////////////////////////
 // Candidate accumulation
 
-fn is_constant<'tcx>(place: Place<'tcx>) -> bool {
-    place.projection.iter().all(|p| !matches!(p, ProjectionElem::Deref | ProjectionElem::Index(_)))
-}
-
 /// If the pair of places is being considered for merging, returns the candidate which would be
 /// merged in order to accomplish this.
 ///
@@ -741,10 +750,6 @@ impl<'tcx> Visitor<'tcx> for FindAssignments<'_, '_, 'tcx> {
             Rvalue::Use(Operand::Copy(rhs) | Operand::Move(rhs)),
         )) = &statement.kind
         {
-            if !is_constant(*lhs) || !is_constant(*rhs) {
-                return;
-            }
-
             let Some((src, dest)) = places_to_candidate_pair(*lhs, *rhs, self.body) else {
                 return;
             };
diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index 6de564a3a06..3bafd3730bd 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -875,18 +875,12 @@ pub struct PacRet {
     pub key: PAuthKey,
 }
 
-#[derive(Clone, Copy, Hash, Debug, PartialEq)]
+#[derive(Clone, Copy, Hash, Debug, PartialEq, Default)]
 pub struct BranchProtection {
     pub bti: bool,
     pub pac_ret: Option<PacRet>,
 }
 
-impl Default for BranchProtection {
-    fn default() -> Self {
-        BranchProtection { bti: false, pac_ret: None }
-    }
-}
-
 pub const fn default_lib_output() -> CrateType {
     CrateType::Rlib
 }
@@ -1875,7 +1869,7 @@ fn parse_opt_level(
         .into_iter()
         .flat_map(|(i, s)| {
             // NB: This can match a string without `=`.
-            if let Some("opt-level") = s.splitn(2, '=').next() { Some(i) } else { None }
+            if let Some("opt-level") = s.split('=').next() { Some(i) } else { None }
         })
         .max();
     if max_o > max_c {
@@ -1912,7 +1906,7 @@ fn select_debuginfo(
         .into_iter()
         .flat_map(|(i, s)| {
             // NB: This can match a string without `=`.
-            if let Some("debuginfo") = s.splitn(2, '=').next() { Some(i) } else { None }
+            if let Some("debuginfo") = s.split('=').next() { Some(i) } else { None }
         })
         .max();
     if max_g > max_c {
diff --git a/compiler/rustc_span/src/analyze_source_file.rs b/compiler/rustc_span/src/analyze_source_file.rs
index d3c2c5113bc..26cd54210d0 100644
--- a/compiler/rustc_span/src/analyze_source_file.rs
+++ b/compiler/rustc_span/src/analyze_source_file.rs
@@ -175,7 +175,7 @@ cfg_if::cfg_if! {
             // There might still be a tail left to analyze
             let tail_start = chunk_count * CHUNK_SIZE + intra_chunk_offset;
             if tail_start < src.len() {
-                analyze_source_file_generic(&src[tail_start as usize ..],
+                analyze_source_file_generic(&src[tail_start ..],
                                         src.len() - tail_start,
                                         output_offset + BytePos::from_usize(tail_start),
                                         lines,
@@ -219,7 +219,7 @@ fn analyze_source_file_generic(
     while i < scan_len {
         let byte = unsafe {
             // We verified that i < scan_len <= src.len()
-            *src_bytes.get_unchecked(i as usize)
+            *src_bytes.get_unchecked(i)
         };
 
         // How much to advance in order to get to the next UTF-8 char in the
diff --git a/compiler/rustc_span/src/lib.rs b/compiler/rustc_span/src/lib.rs
index 335bfc3302f..5525eb5331c 100644
--- a/compiler/rustc_span/src/lib.rs
+++ b/compiler/rustc_span/src/lib.rs
@@ -1381,7 +1381,7 @@ impl<S: Encoder> Encodable<S> for SourceFile {
                     4 => {
                         raw_diffs = Vec::with_capacity(bytes_per_diff * num_diffs);
                         for diff in diff_iter {
-                            raw_diffs.extend_from_slice(&(diff.0 as u32).to_le_bytes());
+                            raw_diffs.extend_from_slice(&(diff.0).to_le_bytes());
                         }
                     }
                     _ => unreachable!(),
diff --git a/compiler/rustc_span/src/source_map.rs b/compiler/rustc_span/src/source_map.rs
index a4e0f54d276..fb3e4a6c083 100644
--- a/compiler/rustc_span/src/source_map.rs
+++ b/compiler/rustc_span/src/source_map.rs
@@ -941,7 +941,7 @@ impl SourceMap {
     /// Otherwise, the span reached to limit is returned.
     pub fn span_look_ahead(&self, span: Span, expect: Option<&str>, limit: Option<usize>) -> Span {
         let mut sp = span;
-        for _ in 0..limit.unwrap_or(100 as usize) {
+        for _ in 0..limit.unwrap_or(100_usize) {
             sp = self.next_point(sp);
             if let Ok(ref snippet) = self.span_to_snippet(sp) {
                 if expect.map_or(false, |es| snippet == es) {
diff --git a/compiler/rustc_target/src/spec/apple_base.rs b/compiler/rustc_target/src/spec/apple_base.rs
index fc6a2edabb7..44644c4733e 100644
--- a/compiler/rustc_target/src/spec/apple_base.rs
+++ b/compiler/rustc_target/src/spec/apple_base.rs
@@ -81,7 +81,7 @@ fn pre_link_args(os: &'static str, arch: Arch, abi: &'static str) -> LinkArgs {
         _ => os.into(),
     };
 
-    let platform_version: StaticCow<str> = match os.as_ref() {
+    let platform_version: StaticCow<str> = match os {
         "ios" => ios_lld_platform_version(),
         "tvos" => tvos_lld_platform_version(),
         "watchos" => watchos_lld_platform_version(),
diff --git a/compiler/rustc_target/src/spec/powerpc64_ibm_aix.rs b/compiler/rustc_target/src/spec/powerpc64_ibm_aix.rs
index e3eb9bccd5e..34934379c7e 100644
--- a/compiler/rustc_target/src/spec/powerpc64_ibm_aix.rs
+++ b/compiler/rustc_target/src/spec/powerpc64_ibm_aix.rs
@@ -5,12 +5,7 @@ pub fn target() -> Target {
     base.max_atomic_width = Some(64);
     base.add_pre_link_args(
         LinkerFlavor::Unix(Cc::No),
-        &[
-            "-b64".into(),
-            "-bpT:0x100000000".into(),
-            "-bpD:0x110000000".into(),
-            "-bcdtors:all:0:s".into(),
-        ],
+        &["-b64", "-bpT:0x100000000", "-bpD:0x110000000", "-bcdtors:all:0:s"],
     );
 
     Target {
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
index 654346bfa71..3c5e36123ec 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
@@ -1636,17 +1636,30 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                     infer::LateBoundRegionConversionTime::HigherRankedType,
                     bound_predicate.rebind(data),
                 );
-                let normalized_ty = ocx.normalize(
-                    &obligation.cause,
-                    obligation.param_env,
-                    self.tcx.mk_projection(data.projection_ty.def_id, data.projection_ty.substs),
-                );
+                let unnormalized_term = match data.term.unpack() {
+                    ty::TermKind::Ty(_) => self
+                        .tcx
+                        .mk_projection(data.projection_ty.def_id, data.projection_ty.substs)
+                        .into(),
+                    ty::TermKind::Const(ct) => self
+                        .tcx
+                        .mk_const(
+                            ty::UnevaluatedConst {
+                                def: ty::WithOptConstParam::unknown(data.projection_ty.def_id),
+                                substs: data.projection_ty.substs,
+                            },
+                            ct.ty(),
+                        )
+                        .into(),
+                };
+                let normalized_term =
+                    ocx.normalize(&obligation.cause, obligation.param_env, unnormalized_term);
 
                 debug!(?obligation.cause, ?obligation.param_env);
 
-                debug!(?normalized_ty, data.ty = ?data.term);
+                debug!(?normalized_term, data.ty = ?data.term);
 
-                let is_normalized_ty_expected = !matches!(
+                let is_normalized_term_expected = !matches!(
                     obligation.cause.code().peel_derives(),
                     ObligationCauseCode::ItemObligation(_)
                         | ObligationCauseCode::BindingObligation(_, _)
@@ -1655,7 +1668,6 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                         | ObligationCauseCode::ObjectCastObligation(..)
                         | ObligationCauseCode::OpaqueType
                 );
-                let expected_ty = data.term.ty().unwrap_or_else(|| self.tcx.ty_error());
 
                 // constrain inference variables a bit more to nested obligations from normalize so
                 // we can have more helpful errors.
@@ -1664,11 +1676,11 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 if let Err(new_err) = ocx.eq_exp(
                     &obligation.cause,
                     obligation.param_env,
-                    is_normalized_ty_expected,
-                    normalized_ty,
-                    expected_ty,
+                    is_normalized_term_expected,
+                    normalized_term,
+                    data.term,
                 ) {
-                    (Some((data, is_normalized_ty_expected, normalized_ty, expected_ty)), new_err)
+                    (Some((data, is_normalized_term_expected, normalized_term, data.term)), new_err)
                 } else {
                     (None, error.err)
                 }
@@ -1677,12 +1689,8 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
             };
 
             let msg = values
-                .and_then(|(predicate, _, normalized_ty, expected_ty)| {
-                    self.maybe_detailed_projection_msg(
-                        predicate,
-                        normalized_ty.into(),
-                        expected_ty.into(),
-                    )
+                .and_then(|(predicate, _, normalized_term, expected_term)| {
+                    self.maybe_detailed_projection_msg(predicate, normalized_term, expected_term)
                 })
                 .unwrap_or_else(|| format!("type mismatch resolving `{}`", predicate));
             let mut diag = struct_span_err!(self.tcx.sess, obligation.cause.span, E0271, "{msg}");
diff --git a/compiler/rustc_ty_utils/src/layout.rs b/compiler/rustc_ty_utils/src/layout.rs
index 9589342b3c7..c761a4dbe45 100644
--- a/compiler/rustc_ty_utils/src/layout.rs
+++ b/compiler/rustc_ty_utils/src/layout.rs
@@ -919,7 +919,7 @@ fn variant_info_for_generator<'tcx>(
     def_id: DefId,
     substs: ty::SubstsRef<'tcx>,
 ) -> (Vec<VariantInfo>, Option<Size>) {
-    let Variants::Multiple { tag, ref tag_encoding, .. } = layout.variants else {
+    let Variants::Multiple { tag, ref tag_encoding, tag_field, .. } = layout.variants else {
         return (vec![], None);
     };
 
@@ -975,12 +975,28 @@ fn variant_info_for_generator<'tcx>(
             if variant_size == Size::ZERO {
                 variant_size = upvars_size;
             }
-            // We need to add the discriminant size back into min_size, since it is subtracted
-            // later during printing.
-            variant_size += match tag_encoding {
-                TagEncoding::Direct => tag.size(cx),
-                _ => Size::ZERO,
-            };
+
+            // This `if` deserves some explanation.
+            //
+            // The layout code has a choice of where to place the discriminant of this generator.
+            // If the discriminant of the generator is placed early in the layout (before the
+            // variant's own fields), then it'll implicitly be counted towards the size of the
+            // variant, since we use the maximum offset to calculate size.
+            //    (side-note: I know this is a bit problematic given upvars placement, etc).
+            //
+            // This is important, since the layout printing code always subtracts this discriminant
+            // size from the variant size if the struct is "enum"-like, so failing to account for it
+            // will either lead to numerical underflow, or an underreported variant size...
+            //
+            // However, if the discriminant is placed past the end of the variant, then we need
+            // to factor in the size of the discriminant manually. This really should be refactored
+            // better, but this "works" for now.
+            if layout.fields.offset(tag_field) >= variant_size {
+                variant_size += match tag_encoding {
+                    TagEncoding::Direct => tag.size(cx),
+                    _ => Size::ZERO,
+                };
+            }
 
             VariantInfo {
                 name: Some(Symbol::intern(&ty::GeneratorSubsts::variant_name(variant_idx))),
diff --git a/compiler/rustc_type_ir/src/sty.rs b/compiler/rustc_type_ir/src/sty.rs
index e9ffbca9628..f30ae82d7cd 100644
--- a/compiler/rustc_type_ir/src/sty.rs
+++ b/compiler/rustc_type_ir/src/sty.rs
@@ -250,9 +250,9 @@ impl<I: Interner> Clone for TyKind<I> {
         match self {
             Bool => Bool,
             Char => Char,
-            Int(i) => Int(i.clone()),
-            Uint(u) => Uint(u.clone()),
-            Float(f) => Float(f.clone()),
+            Int(i) => Int(*i),
+            Uint(u) => Uint(*u),
+            Float(f) => Float(*f),
             Adt(d, s) => Adt(d.clone(), s.clone()),
             Foreign(d) => Foreign(d.clone()),
             Str => Str,
@@ -262,7 +262,7 @@ impl<I: Interner> Clone for TyKind<I> {
             Ref(r, t, m) => Ref(r.clone(), t.clone(), m.clone()),
             FnDef(d, s) => FnDef(d.clone(), s.clone()),
             FnPtr(s) => FnPtr(s.clone()),
-            Dynamic(p, r, repr) => Dynamic(p.clone(), r.clone(), repr.clone()),
+            Dynamic(p, r, repr) => Dynamic(p.clone(), r.clone(), *repr),
             Closure(d, s) => Closure(d.clone(), s.clone()),
             Generator(d, s, m) => Generator(d.clone(), s.clone(), m.clone()),
             GeneratorWitness(g) => GeneratorWitness(g.clone()),
@@ -270,7 +270,7 @@ impl<I: Interner> Clone for TyKind<I> {
             Tuple(t) => Tuple(t.clone()),
             Alias(k, p) => Alias(*k, p.clone()),
             Param(p) => Param(p.clone()),
-            Bound(d, b) => Bound(d.clone(), b.clone()),
+            Bound(d, b) => Bound(*d, b.clone()),
             Placeholder(p) => Placeholder(p.clone()),
             Infer(t) => Infer(t.clone()),
             Error(e) => Error(e.clone()),
@@ -936,7 +936,7 @@ impl<I: Interner> Clone for RegionKind<I> {
     fn clone(&self) -> Self {
         match self {
             ReEarlyBound(r) => ReEarlyBound(r.clone()),
-            ReLateBound(d, r) => ReLateBound(d.clone(), r.clone()),
+            ReLateBound(d, r) => ReLateBound(*d, r.clone()),
             ReFree(r) => ReFree(r.clone()),
             ReStatic => ReStatic,
             ReVar(r) => ReVar(r.clone()),
diff --git a/src/librustdoc/html/static/css/rustdoc.css b/src/librustdoc/html/static/css/rustdoc.css
index c485ac9ddb8..bc1e15b3593 100644
--- a/src/librustdoc/html/static/css/rustdoc.css
+++ b/src/librustdoc/html/static/css/rustdoc.css
@@ -1396,7 +1396,6 @@ kbd {
 	vertical-align: middle;
 	border: solid 1px var(--border-color);
 	border-radius: 3px;
-	cursor: default;
 	color: var(--kbd--color);
 	background-color: var(--kbd-background);
 	box-shadow: inset 0 -1px 0 var(--kbd-box-shadow-color);
@@ -1970,7 +1969,6 @@ in storage.js
 }
 
 .scraped-example .code-wrapper .src-line-numbers {
-	margin: 0;
 	padding: 14px 0;
 }
 
diff --git a/src/librustdoc/html/static/css/themes/ayu.css b/src/librustdoc/html/static/css/themes/ayu.css
index eba845bf5a9..a4097c45613 100644
--- a/src/librustdoc/html/static/css/themes/ayu.css
+++ b/src/librustdoc/html/static/css/themes/ayu.css
@@ -150,8 +150,6 @@ pre, .rustdoc.source .example-wrap {
 	color: #c5c5c5;
 }
 
-.content .item-info::before { color: #ccc; }
-
 .sidebar h2 a,
 .sidebar h3 a {
 	color: white;
diff --git a/src/librustdoc/html/static/css/themes/dark.css b/src/librustdoc/html/static/css/themes/dark.css
index d945e956c53..a11aba12e0a 100644
--- a/src/librustdoc/html/static/css/themes/dark.css
+++ b/src/librustdoc/html/static/css/themes/dark.css
@@ -85,8 +85,6 @@
 	--table-alt-row-background-color: #2A2A2A;
 }
 
-.content .item-info::before { color: #ccc; }
-
 body.source .example-wrap pre.rust a {
 	background: #333;
 }
diff --git a/src/librustdoc/html/static/css/themes/light.css b/src/librustdoc/html/static/css/themes/light.css
index 58955a79316..f697724468f 100644
--- a/src/librustdoc/html/static/css/themes/light.css
+++ b/src/librustdoc/html/static/css/themes/light.css
@@ -82,8 +82,6 @@
 	--table-alt-row-background-color: #F5F5F5;
 }
 
-.content .item-info::before { color: #ccc; }
-
 body.source .example-wrap pre.rust a {
 	background: #eee;
 }
diff --git a/src/test/rustdoc-gui/help-page.goml b/src/test/rustdoc-gui/help-page.goml
index 799ba851c92..80203901ed3 100644
--- a/src/test/rustdoc-gui/help-page.goml
+++ b/src/test/rustdoc-gui/help-page.goml
@@ -27,7 +27,6 @@ define-function: (
             "color": |color|,
             "background-color": |background|,
             "box-shadow": |box_shadow| + " 0px -1px 0px 0px inset",
-            "cursor": "default",
         }, ALL)),
     ],
 )
diff --git a/src/test/ui/argument-suggestions/display-is-suggestable.rs b/src/test/ui/argument-suggestions/display-is-suggestable.rs
new file mode 100644
index 00000000000..d765bc4f74d
--- /dev/null
+++ b/src/test/ui/argument-suggestions/display-is-suggestable.rs
@@ -0,0 +1,8 @@
+use std::fmt::Display;
+
+fn foo(x: &(dyn Display + Send)) {}
+
+fn main() {
+    foo();
+    //~^ ERROR this function takes 1 argument but 0 arguments were supplied
+}
diff --git a/src/test/ui/argument-suggestions/display-is-suggestable.stderr b/src/test/ui/argument-suggestions/display-is-suggestable.stderr
new file mode 100644
index 00000000000..edd72b53eb3
--- /dev/null
+++ b/src/test/ui/argument-suggestions/display-is-suggestable.stderr
@@ -0,0 +1,19 @@
+error[E0061]: this function takes 1 argument but 0 arguments were supplied
+  --> $DIR/display-is-suggestable.rs:6:5
+   |
+LL |     foo();
+   |     ^^^-- an argument of type `&dyn std::fmt::Display + Send` is missing
+   |
+note: function defined here
+  --> $DIR/display-is-suggestable.rs:3:4
+   |
+LL | fn foo(x: &(dyn Display + Send)) {}
+   |    ^^^ ------------------------
+help: provide the argument
+   |
+LL |     foo(/* &dyn std::fmt::Display + Send */);
+   |        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0061`.
diff --git a/src/test/ui/associated-type-bounds/const-projection-err.gce.stderr b/src/test/ui/associated-type-bounds/const-projection-err.gce.stderr
new file mode 100644
index 00000000000..0f1ec9ad052
--- /dev/null
+++ b/src/test/ui/associated-type-bounds/const-projection-err.gce.stderr
@@ -0,0 +1,24 @@
+warning: the feature `generic_const_exprs` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/const-projection-err.rs:4:26
+   |
+LL | #![cfg_attr(gce, feature(generic_const_exprs))]
+   |                          ^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #76560 <https://github.com/rust-lang/rust/issues/76560> for more information
+   = note: `#[warn(incomplete_features)]` on by default
+
+error[E0271]: type mismatch resolving `<T as TraitWAssocConst>::A == 1`
+  --> $DIR/const-projection-err.rs:14:11
+   |
+LL |     foo::<T>();
+   |           ^ expected `0`, found `1`
+   |
+note: required by a bound in `foo`
+  --> $DIR/const-projection-err.rs:11:28
+   |
+LL | fn foo<T: TraitWAssocConst<A = 1>>() {}
+   |                            ^^^^^ required by this bound in `foo`
+
+error: aborting due to previous error; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0271`.
diff --git a/src/test/ui/associated-type-bounds/const-projection-err.rs b/src/test/ui/associated-type-bounds/const-projection-err.rs
new file mode 100644
index 00000000000..bead8563001
--- /dev/null
+++ b/src/test/ui/associated-type-bounds/const-projection-err.rs
@@ -0,0 +1,18 @@
+// revisions: stock gce
+
+#![feature(associated_const_equality)]
+#![cfg_attr(gce, feature(generic_const_exprs))]
+//[gce]~^ WARN the feature `generic_const_exprs` is incomplete
+
+trait TraitWAssocConst {
+    const A: usize;
+}
+
+fn foo<T: TraitWAssocConst<A = 1>>() {}
+
+fn bar<T: TraitWAssocConst<A = 0>>() {
+    foo::<T>();
+    //~^ ERROR type mismatch resolving `<T as TraitWAssocConst>::A == 1`
+}
+
+fn main() {}
diff --git a/src/test/ui/associated-type-bounds/const-projection-err.stock.stderr b/src/test/ui/associated-type-bounds/const-projection-err.stock.stderr
new file mode 100644
index 00000000000..bf0824259a5
--- /dev/null
+++ b/src/test/ui/associated-type-bounds/const-projection-err.stock.stderr
@@ -0,0 +1,17 @@
+error[E0271]: type mismatch resolving `<T as TraitWAssocConst>::A == 1`
+  --> $DIR/const-projection-err.rs:14:11
+   |
+LL |     foo::<T>();
+   |           ^ expected `1`, found `<T as TraitWAssocConst>::A`
+   |
+   = note: expected constant `1`
+              found constant `<T as TraitWAssocConst>::A`
+note: required by a bound in `foo`
+  --> $DIR/const-projection-err.rs:11:28
+   |
+LL | fn foo<T: TraitWAssocConst<A = 1>>() {}
+   |                            ^^^^^ required by this bound in `foo`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0271`.
diff --git a/src/test/ui/async-await/in-trait/async-example-desugared-boxed.rs b/src/test/ui/async-await/in-trait/async-example-desugared-boxed.rs
index 61d7e2520ea..1b1b3cffd58 100644
--- a/src/test/ui/async-await/in-trait/async-example-desugared-boxed.rs
+++ b/src/test/ui/async-await/in-trait/async-example-desugared-boxed.rs
@@ -1,4 +1,3 @@
-// check-pass
 // edition: 2021
 
 #![feature(async_fn_in_trait)]
@@ -13,11 +12,9 @@ trait MyTrait {
 }
 
 impl MyTrait for i32 {
-    // This will break once a PR that implements #102745 is merged
     fn foo(&self) -> Pin<Box<dyn Future<Output = i32> + '_>> {
-        Box::pin(async {
-            *self
-        })
+        //~^ ERROR method `foo` should be async
+        Box::pin(async { *self })
     }
 }
 
diff --git a/src/test/ui/async-await/in-trait/async-example-desugared-boxed.stderr b/src/test/ui/async-await/in-trait/async-example-desugared-boxed.stderr
new file mode 100644
index 00000000000..60fa534a64f
--- /dev/null
+++ b/src/test/ui/async-await/in-trait/async-example-desugared-boxed.stderr
@@ -0,0 +1,11 @@
+error: method `foo` should be async because the method from the trait is async
+  --> $DIR/async-example-desugared-boxed.rs:15:5
+   |
+LL |     async fn foo(&self) -> i32;
+   |     --------------------------- required because the trait method is async
+...
+LL |     fn foo(&self) -> Pin<Box<dyn Future<Output = i32> + '_>> {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/async-await/in-trait/async-example-desugared-extra.rs b/src/test/ui/async-await/in-trait/async-example-desugared-extra.rs
new file mode 100644
index 00000000000..81e1e59a362
--- /dev/null
+++ b/src/test/ui/async-await/in-trait/async-example-desugared-extra.rs
@@ -0,0 +1,37 @@
+// check-pass
+// edition: 2021
+
+#![feature(async_fn_in_trait)]
+#![feature(return_position_impl_trait_in_trait)]
+#![allow(incomplete_features)]
+
+use std::future::Future;
+use std::pin::Pin;
+use std::task::Poll;
+
+trait MyTrait {
+    async fn foo(&self) -> i32;
+}
+
+#[derive(Clone)]
+struct MyFuture(i32);
+
+impl Future for MyFuture {
+    type Output = i32;
+    fn poll(
+        self: Pin<&mut Self>,
+        _: &mut std::task::Context<'_>,
+    ) -> Poll<<Self as Future>::Output> {
+        Poll::Ready(self.0)
+    }
+}
+
+impl MyTrait for i32 {
+    // FIXME: this should eventually require `#[refine]` to compile, because it also provides
+    // `Clone`.
+    fn foo(&self) -> impl Future<Output = i32> + Clone {
+        MyFuture(*self)
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/async-await/in-trait/async-example-desugared-manual.rs b/src/test/ui/async-await/in-trait/async-example-desugared-manual.rs
new file mode 100644
index 00000000000..71473e7455f
--- /dev/null
+++ b/src/test/ui/async-await/in-trait/async-example-desugared-manual.rs
@@ -0,0 +1,29 @@
+// edition: 2021
+
+#![feature(async_fn_in_trait)]
+#![feature(return_position_impl_trait_in_trait)]
+#![allow(incomplete_features)]
+
+use std::future::Future;
+use std::task::Poll;
+
+trait MyTrait {
+    async fn foo(&self) -> i32;
+}
+
+struct MyFuture;
+impl Future for MyFuture {
+    type Output = i32;
+    fn poll(self: std::pin::Pin<&mut Self>, _: &mut std::task::Context<'_>) -> Poll<Self::Output> {
+        Poll::Ready(0)
+    }
+}
+
+impl MyTrait for u32 {
+    fn foo(&self) -> MyFuture {
+        //~^ ERROR method `foo` should be async
+        MyFuture
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/async-await/in-trait/async-example-desugared-manual.stderr b/src/test/ui/async-await/in-trait/async-example-desugared-manual.stderr
new file mode 100644
index 00000000000..567a36a86d1
--- /dev/null
+++ b/src/test/ui/async-await/in-trait/async-example-desugared-manual.stderr
@@ -0,0 +1,11 @@
+error: method `foo` should be async because the method from the trait is async
+  --> $DIR/async-example-desugared-manual.rs:23:5
+   |
+LL |     async fn foo(&self) -> i32;
+   |     --------------------------- required because the trait method is async
+...
+LL |     fn foo(&self) -> MyFuture {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/async-await/in-trait/async-example-desugared.rs b/src/test/ui/async-await/in-trait/async-example-desugared.rs
index 1313c9edd86..fb92ec78674 100644
--- a/src/test/ui/async-await/in-trait/async-example-desugared.rs
+++ b/src/test/ui/async-await/in-trait/async-example-desugared.rs
@@ -12,11 +12,8 @@ trait MyTrait {
 }
 
 impl MyTrait for i32 {
-    // This will break once a PR that implements #102745 is merged
     fn foo(&self) -> impl Future<Output = i32> + '_ {
-        async {
-            *self
-        }
+        async { *self }
     }
 }
 
diff --git a/src/test/ui/async-await/in-trait/fn-not-async-err.rs b/src/test/ui/async-await/in-trait/fn-not-async-err.rs
index f94d32145a2..9598d53bce8 100644
--- a/src/test/ui/async-await/in-trait/fn-not-async-err.rs
+++ b/src/test/ui/async-await/in-trait/fn-not-async-err.rs
@@ -9,7 +9,7 @@ trait MyTrait {
 
 impl MyTrait for i32 {
     fn foo(&self) -> i32 {
-        //~^ ERROR: `i32` is not a future [E0277]
+        //~^ ERROR: method `foo` should be async
         *self
     }
 }
diff --git a/src/test/ui/async-await/in-trait/fn-not-async-err.stderr b/src/test/ui/async-await/in-trait/fn-not-async-err.stderr
index 03321dc5b5a..579801d0f39 100644
--- a/src/test/ui/async-await/in-trait/fn-not-async-err.stderr
+++ b/src/test/ui/async-await/in-trait/fn-not-async-err.stderr
@@ -1,17 +1,11 @@
-error[E0277]: `i32` is not a future
-  --> $DIR/fn-not-async-err.rs:11:22
-   |
-LL |     fn foo(&self) -> i32 {
-   |                      ^^^ `i32` is not a future
-   |
-   = help: the trait `Future` is not implemented for `i32`
-   = note: i32 must be a future or must implement `IntoFuture` to be awaited
-note: required by a bound in `MyTrait::foo::{opaque#0}`
-  --> $DIR/fn-not-async-err.rs:7:28
+error: method `foo` should be async because the method from the trait is async
+  --> $DIR/fn-not-async-err.rs:11:5
    |
 LL |     async fn foo(&self) -> i32;
-   |                            ^^^ required by this bound in `MyTrait::foo::{opaque#0}`
+   |     --------------------------- required because the trait method is async
+...
+LL |     fn foo(&self) -> i32 {
+   |     ^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/async-await/in-trait/fn-not-async-err2.rs b/src/test/ui/async-await/in-trait/fn-not-async-err2.rs
index 594baa91ad8..2c4ed553580 100644
--- a/src/test/ui/async-await/in-trait/fn-not-async-err2.rs
+++ b/src/test/ui/async-await/in-trait/fn-not-async-err2.rs
@@ -12,9 +12,7 @@ trait MyTrait {
 impl MyTrait for i32 {
     fn foo(&self) -> impl Future<Output = i32> {
         //~^ ERROR `impl Trait` only allowed in function and inherent method return types, not in `impl` method return [E0562]
-        async {
-            *self
-        }
+        async { *self }
     }
 }
 
diff --git a/src/test/ui/async-await/in-trait/issue-104678.rs b/src/test/ui/async-await/in-trait/issue-104678.rs
new file mode 100644
index 00000000000..e396df4e5d1
--- /dev/null
+++ b/src/test/ui/async-await/in-trait/issue-104678.rs
@@ -0,0 +1,31 @@
+// edition:2021
+// check-pass
+
+#![feature(async_fn_in_trait)]
+#![allow(incomplete_features)]
+
+use std::future::Future;
+pub trait Pool {
+    type Conn;
+
+    async fn async_callback<'a, F: FnOnce(&'a Self::Conn) -> Fut, Fut: Future<Output = ()>>(
+        &'a self,
+        callback: F,
+    ) -> ();
+}
+
+pub struct PoolImpl;
+pub struct ConnImpl;
+
+impl Pool for PoolImpl {
+    type Conn = ConnImpl;
+
+    async fn async_callback<'a, F: FnOnce(&'a Self::Conn) -> Fut, Fut: Future<Output = ()>>(
+        &'a self,
+        _callback: F,
+    ) -> () {
+        todo!()
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/higher-rank-trait-bounds/issue-30786.stderr b/src/test/ui/higher-rank-trait-bounds/issue-30786.stderr
index c1e235441d6..d1d76916b26 100644
--- a/src/test/ui/higher-rank-trait-bounds/issue-30786.stderr
+++ b/src/test/ui/higher-rank-trait-bounds/issue-30786.stderr
@@ -8,7 +8,7 @@ LL | pub struct Map<S, F> {
    | doesn't satisfy `_: StreamExt`
 ...
 LL |     let filter = map.filterx(|x: &_| true);
-   |                      ^^^^^^^ method cannot be called on `Map<Repeat, [closure@$DIR/issue-30786.rs:117:27: 117:34]>` due to unsatisfied trait bounds
+   |                      ^^^^^^^ method cannot be called due to unsatisfied trait bounds
    |
 note: the following trait bounds were not satisfied:
       `&'a mut &Map<Repeat, [closure@$DIR/issue-30786.rs:117:27: 117:34]>: Stream`
@@ -29,7 +29,7 @@ LL | pub struct Filter<S, F> {
    | doesn't satisfy `_: StreamExt`
 ...
 LL |     let count = filter.countx();
-   |                        ^^^^^^ method cannot be called on `Filter<Map<Repeat, for<'a> fn(&'a u64) -> &'a u64 {identity::<u64>}>, [closure@$DIR/issue-30786.rs:129:30: 129:37]>` due to unsatisfied trait bounds
+   |                        ^^^^^^ method cannot be called due to unsatisfied trait bounds
    |
 note: the following trait bounds were not satisfied:
       `&'a mut &Filter<Map<Repeat, for<'a> fn(&'a u64) -> &'a u64 {identity::<u64>}>, [closure@$DIR/issue-30786.rs:129:30: 129:37]>: Stream`
diff --git a/src/test/ui/issues/issue-105330.stderr b/src/test/ui/issues/issue-105330.stderr
index 92f2ccb6544..30c380152a5 100644
--- a/src/test/ui/issues/issue-105330.stderr
+++ b/src/test/ui/issues/issue-105330.stderr
@@ -55,8 +55,10 @@ error[E0271]: type mismatch resolving `<Demo as TraitWAssocConst>::A == 32`
   --> $DIR/issue-105330.rs:12:11
    |
 LL |     foo::<Demo>()();
-   |           ^^^^ types differ
+   |           ^^^^ expected `32`, found `<Demo as TraitWAssocConst>::A`
    |
+   = note: expected constant `32`
+              found constant `<Demo as TraitWAssocConst>::A`
 note: required by a bound in `foo`
   --> $DIR/issue-105330.rs:11:28
    |
@@ -89,8 +91,10 @@ error[E0271]: type mismatch resolving `<Demo as TraitWAssocConst>::A == 32`
   --> $DIR/issue-105330.rs:19:11
    |
 LL |     foo::<Demo>();
-   |           ^^^^ types differ
+   |           ^^^^ expected `32`, found `<Demo as TraitWAssocConst>::A`
    |
+   = note: expected constant `32`
+              found constant `<Demo as TraitWAssocConst>::A`
 note: required by a bound in `foo`
   --> $DIR/issue-105330.rs:11:28
    |
diff --git a/src/test/ui/issues/issue-31173.stderr b/src/test/ui/issues/issue-31173.stderr
index b667ae0a789..a32359c2b9f 100644
--- a/src/test/ui/issues/issue-31173.stderr
+++ b/src/test/ui/issues/issue-31173.stderr
@@ -13,7 +13,7 @@ error[E0599]: the method `collect` exists for struct `Cloned<TakeWhile<&mut std:
   --> $DIR/issue-31173.rs:12:10
    |
 LL |         .collect();
-   |          ^^^^^^^ method cannot be called on `Cloned<TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:7:21: 7:25]>>` due to unsatisfied trait bounds
+   |          ^^^^^^^ method cannot be called due to unsatisfied trait bounds
   --> $SRC_DIR/core/src/iter/adapters/take_while.rs:LL:COL
    |
    = note: doesn't satisfy `<_ as Iterator>::Item = &_`
diff --git a/src/test/ui/mismatched_types/issue-36053-2.stderr b/src/test/ui/mismatched_types/issue-36053-2.stderr
index b91f75b97f8..3151bc76891 100644
--- a/src/test/ui/mismatched_types/issue-36053-2.stderr
+++ b/src/test/ui/mismatched_types/issue-36053-2.stderr
@@ -17,7 +17,7 @@ error[E0599]: the method `count` exists for struct `Filter<Fuse<std::iter::Once<
   --> $DIR/issue-36053-2.rs:7:55
    |
 LL |     once::<&str>("str").fuse().filter(|a: &str| true).count();
-   |                                       ---------       ^^^^^ method cannot be called on `Filter<Fuse<std::iter::Once<&str>>, [closure@$DIR/issue-36053-2.rs:7:39: 7:48]>` due to unsatisfied trait bounds
+   |                                       ---------       ^^^^^ method cannot be called due to unsatisfied trait bounds
    |                                       |
    |                                       doesn't satisfy `<_ as FnOnce<(&&str,)>>::Output = bool`
    |                                       doesn't satisfy `_: FnMut<(&&str,)>`
diff --git a/src/test/ui/print_type_sizes/async.rs b/src/test/ui/print_type_sizes/async.rs
index 3491ad5afbc..1598b069691 100644
--- a/src/test/ui/print_type_sizes/async.rs
+++ b/src/test/ui/print_type_sizes/async.rs
@@ -1,19 +1,11 @@
-// compile-flags: -Z print-type-sizes
+// compile-flags: -Z print-type-sizes --crate-type lib
 // edition:2021
 // build-pass
 // ignore-pass
 
-#![feature(start)]
-
 async fn wait() {}
 
-async fn test(arg: [u8; 8192]) {
+pub async fn test(arg: [u8; 8192]) {
     wait().await;
     drop(arg);
 }
-
-#[start]
-fn start(_: isize, _: *const *const u8) -> isize {
-    let _ = test([0; 8192]);
-    0
-}
diff --git a/src/test/ui/print_type_sizes/async.stdout b/src/test/ui/print_type_sizes/async.stdout
index 94ad09ef296..6e47bb4930d 100644
--- a/src/test/ui/print_type_sizes/async.stdout
+++ b/src/test/ui/print_type_sizes/async.stdout
@@ -1,4 +1,4 @@
-print-type-size type: `[async fn body@$DIR/async.rs:10:32: 13:2]`: 16386 bytes, alignment: 1 bytes
+print-type-size type: `[async fn body@$DIR/async.rs:8:36: 11:2]`: 16386 bytes, alignment: 1 bytes
 print-type-size     discriminant: 1 bytes
 print-type-size     variant `Suspend0`: 16385 bytes
 print-type-size         field `.arg`: 8192 bytes, offset: 0 bytes, alignment: 1 bytes
@@ -16,14 +16,14 @@ print-type-size type: `std::mem::MaybeUninit<[u8; 8192]>`: 8192 bytes, alignment
 print-type-size     variant `MaybeUninit`: 8192 bytes
 print-type-size         field `.uninit`: 0 bytes
 print-type-size         field `.value`: 8192 bytes
-print-type-size type: `[async fn body@$DIR/async.rs:8:17: 8:19]`: 1 bytes, alignment: 1 bytes
+print-type-size type: `[async fn body@$DIR/async.rs:6:17: 6:19]`: 1 bytes, alignment: 1 bytes
 print-type-size     discriminant: 1 bytes
 print-type-size     variant `Unresumed`: 0 bytes
 print-type-size     variant `Returned`: 0 bytes
 print-type-size     variant `Panicked`: 0 bytes
-print-type-size type: `std::mem::ManuallyDrop<[async fn body@$DIR/async.rs:8:17: 8:19]>`: 1 bytes, alignment: 1 bytes
+print-type-size type: `std::mem::ManuallyDrop<[async fn body@$DIR/async.rs:6:17: 6:19]>`: 1 bytes, alignment: 1 bytes
 print-type-size     field `.value`: 1 bytes
-print-type-size type: `std::mem::MaybeUninit<[async fn body@$DIR/async.rs:8:17: 8:19]>`: 1 bytes, alignment: 1 bytes
+print-type-size type: `std::mem::MaybeUninit<[async fn body@$DIR/async.rs:6:17: 6:19]>`: 1 bytes, alignment: 1 bytes
 print-type-size     variant `MaybeUninit`: 1 bytes
 print-type-size         field `.uninit`: 0 bytes
 print-type-size         field `.value`: 1 bytes
diff --git a/src/test/ui/print_type_sizes/generator.rs b/src/test/ui/print_type_sizes/generator.rs
index a46db612104..d1cd36274ef 100644
--- a/src/test/ui/print_type_sizes/generator.rs
+++ b/src/test/ui/print_type_sizes/generator.rs
@@ -1,8 +1,8 @@
-// compile-flags: -Z print-type-sizes
+// compile-flags: -Z print-type-sizes --crate-type=lib
 // build-pass
 // ignore-pass
 
-#![feature(start, generators, generator_trait)]
+#![feature(generators, generator_trait)]
 
 use std::ops::Generator;
 
@@ -13,8 +13,6 @@ fn generator<const C: usize>(array: [u8; C]) -> impl Generator<Yield = (), Retur
     }
 }
 
-#[start]
-fn start(_: isize, _: *const *const u8) -> isize {
+pub fn foo() {
     let _ = generator([0; 8192]);
-    0
 }
diff --git a/src/test/ui/print_type_sizes/generator_discr_placement.rs b/src/test/ui/print_type_sizes/generator_discr_placement.rs
new file mode 100644
index 00000000000..1a85fe95bb6
--- /dev/null
+++ b/src/test/ui/print_type_sizes/generator_discr_placement.rs
@@ -0,0 +1,23 @@
+// compile-flags: -Z print-type-sizes --crate-type lib
+// build-pass
+// ignore-pass
+
+// Tests a generator that has its discriminant as the *final* field.
+
+// Avoid emitting panic handlers, like the rest of these tests...
+#![feature(generators)]
+
+pub fn foo() {
+    let a = || {
+        {
+            let w: i32 = 4;
+            yield;
+            drop(w);
+        }
+        {
+            let z: i32 = 7;
+            yield;
+            drop(z);
+        }
+    };
+}
diff --git a/src/test/ui/print_type_sizes/generator_discr_placement.stdout b/src/test/ui/print_type_sizes/generator_discr_placement.stdout
new file mode 100644
index 00000000000..7f8f4ccae7c
--- /dev/null
+++ b/src/test/ui/print_type_sizes/generator_discr_placement.stdout
@@ -0,0 +1,11 @@
+print-type-size type: `[generator@$DIR/generator_discr_placement.rs:11:13: 11:15]`: 8 bytes, alignment: 4 bytes
+print-type-size     discriminant: 1 bytes
+print-type-size     variant `Suspend0`: 7 bytes
+print-type-size         padding: 3 bytes
+print-type-size         field `.w`: 4 bytes, alignment: 4 bytes
+print-type-size     variant `Suspend1`: 7 bytes
+print-type-size         padding: 3 bytes
+print-type-size         field `.z`: 4 bytes, alignment: 4 bytes
+print-type-size     variant `Unresumed`: 0 bytes
+print-type-size     variant `Returned`: 0 bytes
+print-type-size     variant `Panicked`: 0 bytes
diff --git a/src/test/ui/print_type_sizes/generics.rs b/src/test/ui/print_type_sizes/generics.rs
index 3ef7b60db2c..05097087d5a 100644
--- a/src/test/ui/print_type_sizes/generics.rs
+++ b/src/test/ui/print_type_sizes/generics.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Z print-type-sizes
+// compile-flags: -Z print-type-sizes --crate-type=lib
 // build-pass
 // ignore-pass
 // ^-- needed because `--pass check` does not emit the output needed.
@@ -8,24 +8,6 @@
 // monomorphized, in the MIR of the original function in which they
 // occur, to have their size reported.
 
-#![feature(start)]
-
-// In an ad-hoc attempt to avoid the injection of unwinding code
-// (which clutters the output of `-Z print-type-sizes` with types from
-// `unwind::libunwind`):
-//
-//   * I am not using Default to build values because that seems to
-//     cause the injection of unwinding code. (Instead I just make `fn new`
-//     methods.)
-//
-//   * Pair derive Copy to ensure that we don't inject
-//     unwinding code into generic uses of Pair when T itself is also
-//     Copy.
-//
-//     (I suspect this reflect some naivety within the rust compiler
-//      itself; it should be checking for drop glue, i.e., a destructor
-//      somewhere in the monomorphized types. It should not matter whether
-//      the type is Copy.)
 #[derive(Copy, Clone)]
 pub struct Pair<T> {
     _car: T,
@@ -61,11 +43,9 @@ pub fn f1<T:Copy>(x: T) {
         Pair::new(FiftyBytes::new(), FiftyBytes::new());
 }
 
-#[start]
-fn start(_: isize, _: *const *const u8) -> isize {
+pub fn start() {
     let _b: Pair<u8> = Pair::new(0, 0);
     let _s: Pair<SevenBytes> = Pair::new(SevenBytes::new(), SevenBytes::new());
     let ref _z: ZeroSized = ZeroSized;
     f1::<SevenBytes>(SevenBytes::new());
-    0
 }
diff --git a/src/test/ui/print_type_sizes/multiple_types.rs b/src/test/ui/print_type_sizes/multiple_types.rs
index f1ad27ec131..91590389247 100644
--- a/src/test/ui/print_type_sizes/multiple_types.rs
+++ b/src/test/ui/print_type_sizes/multiple_types.rs
@@ -1,11 +1,9 @@
-// compile-flags: -Z print-type-sizes
+// compile-flags: -Z print-type-sizes --crate-type=lib
 // build-pass
 
 // This file illustrates that when multiple structural types occur in
 // a function, every one of them is included in the output.
 
-#![feature(start)]
-
 pub struct SevenBytes([u8;  7]);
 pub struct FiftyBytes([u8; 50]);
 
@@ -13,11 +11,3 @@ pub enum Enum {
     Small(SevenBytes),
     Large(FiftyBytes),
 }
-
-#[start]
-fn start(_: isize, _: *const *const u8) -> isize {
-    let _e: Enum;
-    let _f: FiftyBytes;
-    let _s: SevenBytes;
-    0
-}
diff --git a/src/test/ui/print_type_sizes/niche-filling.rs b/src/test/ui/print_type_sizes/niche-filling.rs
index 0716cee21c6..5e620f248b6 100644
--- a/src/test/ui/print_type_sizes/niche-filling.rs
+++ b/src/test/ui/print_type_sizes/niche-filling.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Z print-type-sizes
+// compile-flags: -Z print-type-sizes --crate-type=lib
 // build-pass
 // ignore-pass
 // ^-- needed because `--pass check` does not emit the output needed.
@@ -14,7 +14,6 @@
 // aligned (while on most it is 8-byte aligned) and so the resulting
 // padding and overall computed sizes can be quite different.
 
-#![feature(start)]
 #![feature(rustc_attrs)]
 #![allow(dead_code)]
 
@@ -56,7 +55,7 @@ pub struct NestedNonZero {
 
 impl Default for NestedNonZero {
     fn default() -> Self {
-        NestedNonZero { pre: 0, val: NonZeroU32::new(1).unwrap(), post: 0 }
+        NestedNonZero { pre: 0, val: unsafe { NonZeroU32::new_unchecked(1) }, post: 0 }
     }
 }
 
@@ -76,8 +75,7 @@ pub union Union2<A: Copy, B: Copy> {
     b: B,
 }
 
-#[start]
-fn start(_: isize, _: *const *const u8) -> isize {
+pub fn test() {
     let _x: MyOption<NonZeroU32> = Default::default();
     let _y: EmbeddedDiscr = Default::default();
     let _z: MyOption<IndirectNonZero> = Default::default();
@@ -96,6 +94,4 @@ fn start(_: isize, _: *const *const u8) -> isize {
     // ...even when theoretically possible.
     let _j: MyOption<Union1<NonZeroU32>> = Default::default();
     let _k: MyOption<Union2<NonZeroU32, NonZeroU32>> = Default::default();
-
-    0
 }
diff --git a/src/test/ui/print_type_sizes/no_duplicates.rs b/src/test/ui/print_type_sizes/no_duplicates.rs
index e45e4794a35..2ec5d9e64bf 100644
--- a/src/test/ui/print_type_sizes/no_duplicates.rs
+++ b/src/test/ui/print_type_sizes/no_duplicates.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Z print-type-sizes
+// compile-flags: -Z print-type-sizes --crate-type=lib
 // build-pass
 // ignore-pass
 // ^-- needed because `--pass check` does not emit the output needed.
@@ -8,16 +8,12 @@
 // (even if multiple functions), it is only printed once in the
 // print-type-sizes output.
 
-#![feature(start)]
-
 pub struct SevenBytes([u8; 7]);
 
 pub fn f1() {
     let _s: SevenBytes = SevenBytes([0; 7]);
 }
 
-#[start]
-fn start(_: isize, _: *const *const u8) -> isize {
+pub fn test() {
     let _s: SevenBytes = SevenBytes([0; 7]);
-    0
 }
diff --git a/src/test/ui/print_type_sizes/packed.rs b/src/test/ui/print_type_sizes/packed.rs
index 269cc3cc282..5ddfe4bf4db 100644
--- a/src/test/ui/print_type_sizes/packed.rs
+++ b/src/test/ui/print_type_sizes/packed.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Z print-type-sizes
+// compile-flags: -Z print-type-sizes --crate-type=lib
 // build-pass
 // ignore-pass
 // ^-- needed because `--pass check` does not emit the output needed.
@@ -13,11 +13,10 @@
 // padding and overall computed sizes can be quite different.
 
 #![allow(dead_code)]
-#![feature(start)]
 
 #[derive(Default)]
 #[repr(packed)]
-struct Packed1 {
+pub struct Packed1 {
     a: u8,
     b: u8,
     g: i32,
@@ -28,7 +27,7 @@ struct Packed1 {
 
 #[derive(Default)]
 #[repr(packed(2))]
-struct Packed2 {
+pub struct Packed2 {
     a: u8,
     b: u8,
     g: i32,
@@ -40,7 +39,7 @@ struct Packed2 {
 #[derive(Default)]
 #[repr(packed(2))]
 #[repr(C)]
-struct Packed2C {
+pub struct Packed2C {
     a: u8,
     b: u8,
     g: i32,
@@ -50,7 +49,7 @@ struct Packed2C {
 }
 
 #[derive(Default)]
-struct Padded {
+pub struct Padded {
     a: u8,
     b: u8,
     g: i32,
@@ -58,12 +57,3 @@ struct Padded {
     h: i16,
     d: u8,
 }
-
-#[start]
-fn start(_: isize, _: *const *const u8) -> isize {
-    let _c: Packed1 = Default::default();
-    let _d: Packed2 = Default::default();
-    let _e: Packed2C = Default::default();
-    let _f: Padded = Default::default();
-    0
-}
diff --git a/src/test/ui/print_type_sizes/padding.rs b/src/test/ui/print_type_sizes/padding.rs
index d1acad16d7e..f41c677dc6c 100644
--- a/src/test/ui/print_type_sizes/padding.rs
+++ b/src/test/ui/print_type_sizes/padding.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Z print-type-sizes
+// compile-flags: -Z print-type-sizes --crate-type=lib
 // build-pass
 
 // This file illustrates how padding is handled: alignment
@@ -9,7 +9,6 @@
 // aligned (while on most it is 8-byte aligned) and so the resulting
 // padding and overall computed sizes can be quite different.
 
-#![feature(start)]
 #![allow(dead_code)]
 
 struct S {
@@ -27,8 +26,3 @@ enum E2 {
     A(i8, i32),
     B(S),
 }
-
-#[start]
-fn start(_: isize, _: *const *const u8) -> isize {
-    0
-}
diff --git a/src/test/ui/print_type_sizes/repr-align.rs b/src/test/ui/print_type_sizes/repr-align.rs
index 07544935b2f..0bd11ebc958 100644
--- a/src/test/ui/print_type_sizes/repr-align.rs
+++ b/src/test/ui/print_type_sizes/repr-align.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Z print-type-sizes
+// compile-flags: -Z print-type-sizes --crate-type=lib
 // build-pass
 // ignore-pass
 // ^-- needed because `--pass check` does not emit the output needed.
@@ -11,7 +11,7 @@
 // It avoids using u64/i64 because on some targets that is only 4-byte
 // aligned (while on most it is 8-byte aligned) and so the resulting
 // padding and overall computed sizes can be quite different.
-#![feature(start)]
+
 #![allow(dead_code)]
 
 #[repr(align(16))]
@@ -24,15 +24,9 @@ enum E {
 }
 
 #[derive(Default)]
-struct S {
+pub struct S {
     a: i32,
     b: i32,
     c: A,
     d: i8,
 }
-
-#[start]
-fn start(_: isize, _: *const *const u8) -> isize {
-    let _s: S = Default::default();
-    0
-}
diff --git a/src/test/ui/print_type_sizes/repr_int_c.rs b/src/test/ui/print_type_sizes/repr_int_c.rs
index b8067c112ee..6b103776a30 100644
--- a/src/test/ui/print_type_sizes/repr_int_c.rs
+++ b/src/test/ui/print_type_sizes/repr_int_c.rs
@@ -1,10 +1,9 @@
-// compile-flags: -Z print-type-sizes
+// compile-flags: -Z print-type-sizes --crate-type=lib
 // build-pass
 
 // This test makes sure that the tag is not grown for `repr(C)` or `repr(u8)`
 // variants (see https://github.com/rust-lang/rust/issues/50098 for the original bug).
 
-#![feature(start)]
 #![allow(dead_code)]
 
 #[repr(C, u8)]
@@ -18,8 +17,3 @@ enum Repru8 {
     A(u16),
     B,
 }
-
-#[start]
-fn start(_: isize, _: *const *const u8) -> isize {
-    0
-}
diff --git a/src/test/ui/print_type_sizes/uninhabited.rs b/src/test/ui/print_type_sizes/uninhabited.rs
index 06a62db4ebb..86fab7b500a 100644
--- a/src/test/ui/print_type_sizes/uninhabited.rs
+++ b/src/test/ui/print_type_sizes/uninhabited.rs
@@ -1,14 +1,12 @@
-// compile-flags: -Z print-type-sizes
+// compile-flags: -Z print-type-sizes --crate-type=lib
 // build-pass
 // ignore-pass
 // ^-- needed because `--pass check` does not emit the output needed.
 //     FIXME: consider using an attribute instead of side-effects.
 
 #![feature(never_type)]
-#![feature(start)]
 
-#[start]
-fn start(_: isize, _: *const *const u8) -> isize {
+pub fn test() {
     let _x: Option<!> = None;
     let _y: Result<u32, !> = Ok(42);
     let _z: Result<!, !> = loop {};
diff --git a/src/test/ui/print_type_sizes/variants.rs b/src/test/ui/print_type_sizes/variants.rs
index 6c8553cc23d..5a302052026 100644
--- a/src/test/ui/print_type_sizes/variants.rs
+++ b/src/test/ui/print_type_sizes/variants.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Z print-type-sizes
+// compile-flags: -Z print-type-sizes --crate-type=lib
 // build-pass
 
 // This file illustrates two things:
@@ -9,8 +9,6 @@
 // 2. For an enum, the print-type-sizes output will also include the
 //    size of each variant.
 
-#![feature(start)]
-
 pub struct SevenBytes([u8;  7]);
 pub struct FiftyBytes([u8; 50]);
 
@@ -18,9 +16,3 @@ pub enum Enum {
     Small(SevenBytes),
     Large(FiftyBytes),
 }
-
-#[start]
-fn start(_: isize, _: *const *const u8) -> isize {
-    let _e: Enum;
-    0
-}
diff --git a/src/test/ui/print_type_sizes/zero-sized-fields.rs b/src/test/ui/print_type_sizes/zero-sized-fields.rs
index e02a33109e5..09415824d5d 100644
--- a/src/test/ui/print_type_sizes/zero-sized-fields.rs
+++ b/src/test/ui/print_type_sizes/zero-sized-fields.rs
@@ -1,12 +1,10 @@
-// compile-flags: -Z print-type-sizes
+// compile-flags: -Z print-type-sizes --crate-type=lib
 // build-pass
 // ignore-pass
 
 // At one point, zero-sized fields such as those in this file were causing
 // incorrect output from `-Z print-type-sizes`.
 
-#![feature(start)]
-
 struct S1 {
     x: u32,
     y: u32,
@@ -28,8 +26,7 @@ struct S5<TagW, TagZ> {
     tagz: TagZ,
 }
 
-#[start]
-fn start(_: isize, _: *const *const u8) -> isize {
+pub fn test() {
     let _s1: S1 = S1 { x: 0, y: 0, tag: () };
 
     let _s5: S5<(), Empty> = S5 {
@@ -43,5 +40,4 @@ fn start(_: isize, _: *const *const u8) -> isize {
         z: 4,
         tagz: Empty {},
     };
-    0
 }