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authorbors <bors@rust-lang.org>2022-12-13 00:29:28 +0000
committerbors <bors@rust-lang.org>2022-12-13 00:29:28 +0000
commitb96d9e0e20adb7716aa32a56fe96fde15c75d517 (patch)
tree454f2841806010e5903bce4628eedcc1af27f35c
parented9749324aed9e97741abf569a022353e269a9df (diff)
parent5af04471aacadf650c23eed54b70fbe04e2230c2 (diff)
Auto merge of #105644 - matthiaskrgr:rollup-qc6hlzq, r=matthiaskrgr
Rollup of 8 pull requests

Successful merges:

 - #104864 (Account for item-local in inner scope for E0425)
 - #105332 (Point out the type of associated types in every method call of iterator chains)
 - #105620 (Remove unnecessary uses of `clone`)
 - #105625 (minor code cleanups)
 - #105629 (rustdoc: stop treating everything in a trait item as a method)
 - #105636 (Add check for local-storage value when changing "display line numbers" settings)
 - #105639 (rustdoc: remove `type="text/css" from stylesheet links)
 - #105640 (Adjust miri to still be optional)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
-rw-r--r--compiler/rustc_abi/src/lib.rs9
-rw-r--r--compiler/rustc_ast/src/token.rs2
-rw-r--r--compiler/rustc_ast_passes/src/feature_gate.rs2
-rw-r--r--compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs2
-rw-r--r--compiler/rustc_builtin_macros/src/alloc_error_handler.rs2
-rw-r--r--compiler/rustc_builtin_macros/src/concat_bytes.rs2
-rw-r--r--compiler/rustc_codegen_llvm/src/back/lto.rs2
-rw-r--r--compiler/rustc_data_structures/src/base_n.rs2
-rw-r--r--compiler/rustc_errors/src/diagnostic.rs8
-rw-r--r--compiler/rustc_errors/src/emitter.rs4
-rw-r--r--compiler/rustc_hir/src/hir.rs7
-rw-r--r--compiler/rustc_index/src/bit_set.rs2
-rw-r--r--compiler/rustc_infer/src/infer/error_reporting/nice_region_error/static_impl_trait.rs2
-rw-r--r--compiler/rustc_lexer/src/unescape.rs3
-rw-r--r--compiler/rustc_resolve/src/late.rs8
-rw-r--r--compiler/rustc_resolve/src/late/diagnostics.rs16
-rw-r--r--compiler/rustc_span/src/source_map.rs2
-rw-r--r--compiler/rustc_trait_selection/src/traits/error_reporting/method_chain.rs74
-rw-r--r--compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs7
-rw-r--r--compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs401
-rw-r--r--src/bootstrap/dist.rs56
-rw-r--r--src/librustdoc/formats/item_type.rs3
-rw-r--r--src/librustdoc/html/render/context.rs2
-rw-r--r--src/librustdoc/html/render/mod.rs3
-rw-r--r--src/librustdoc/html/render/print_item.rs3
-rw-r--r--src/librustdoc/html/static/js/main.js1
-rw-r--r--src/librustdoc/markdown.rs2
-rw-r--r--src/test/rustdoc-gui/docblock-code-block-line-number.goml2
-rw-r--r--src/test/rustdoc/toggle-trait-fn.rs7
-rw-r--r--src/test/ui/expr/malformed_closure/ruby_style_closure.stderr2
-rw-r--r--src/test/ui/generic-associated-types/issue-101020.stderr6
-rw-r--r--src/test/ui/issues/issue-20162.stderr6
-rw-r--r--src/test/ui/issues/issue-31173.rs3
-rw-r--r--src/test/ui/issues/issue-31173.stderr32
-rw-r--r--src/test/ui/issues/issue-33941.stderr6
-rw-r--r--src/test/ui/issues/issue-34334.stderr16
-rw-r--r--src/test/ui/issues/issue-66923-show-error-for-correct-call.stderr27
-rw-r--r--src/test/ui/iterators/collect-into-array.rs1
-rw-r--r--src/test/ui/iterators/collect-into-array.stderr6
-rw-r--r--src/test/ui/iterators/collect-into-slice.rs1
-rw-r--r--src/test/ui/iterators/collect-into-slice.stderr6
-rw-r--r--src/test/ui/iterators/invalid-iterator-chain.rs41
-rw-r--r--src/test/ui/iterators/invalid-iterator-chain.stderr176
-rw-r--r--src/test/ui/lazy-type-alias-impl-trait/branches.stderr6
-rw-r--r--src/test/ui/lazy-type-alias-impl-trait/recursion4.stderr12
-rw-r--r--src/test/ui/mismatched_types/method-help-unsatisfied-bound.stderr6
-rw-r--r--src/test/ui/never_type/feature-gate-never_type_fallback.stderr2
-rw-r--r--src/test/ui/not-clone-closure.stderr6
-rw-r--r--src/test/ui/on-unimplemented/sum.stderr26
-rw-r--r--src/test/ui/resolve/issue-104700-inner_scope.rs11
-rw-r--r--src/test/ui/resolve/issue-104700-inner_scope.stderr21
-rw-r--r--src/test/ui/rfc-2632-const-trait-impl/const-default-method-bodies.stderr6
-rw-r--r--src/test/ui/rfc-2632-const-trait-impl/cross-crate.gatednc.stderr6
-rw-r--r--src/test/ui/rfc-2632-const-trait-impl/cross-crate.stocknc.stderr6
-rw-r--r--src/test/ui/rfc-2632-const-trait-impl/default-method-body-is-const-same-trait-ck.stderr6
-rw-r--r--src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-2.yn.stderr6
-rw-r--r--src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-2.yy.stderr6
-rw-r--r--src/test/ui/suggestions/issue-71394-no-from-impl.stderr6
-rw-r--r--src/test/ui/traits/issue-97576.stderr6
-rw-r--r--src/test/ui/unsized/issue-71659.stderr6
60 files changed, 865 insertions, 244 deletions
diff --git a/compiler/rustc_abi/src/lib.rs b/compiler/rustc_abi/src/lib.rs
index 4ca59144b29..8c71332bfab 100644
--- a/compiler/rustc_abi/src/lib.rs
+++ b/compiler/rustc_abi/src/lib.rs
@@ -802,12 +802,9 @@ impl Integer {
     pub fn for_align<C: HasDataLayout>(cx: &C, wanted: Align) -> Option<Integer> {
         let dl = cx.data_layout();
 
-        for candidate in [I8, I16, I32, I64, I128] {
-            if wanted == candidate.align(dl).abi && wanted.bytes() == candidate.size().bytes() {
-                return Some(candidate);
-            }
-        }
-        None
+        [I8, I16, I32, I64, I128].into_iter().find(|&candidate| {
+            wanted == candidate.align(dl).abi && wanted.bytes() == candidate.size().bytes()
+        })
     }
 
     /// Find the largest integer with the given alignment or less.
diff --git a/compiler/rustc_ast/src/token.rs b/compiler/rustc_ast/src/token.rs
index c0cc4e79a3d..7b8c0d79a17 100644
--- a/compiler/rustc_ast/src/token.rs
+++ b/compiler/rustc_ast/src/token.rs
@@ -114,7 +114,7 @@ impl Lit {
                 if let NtExpr(expr) | NtLiteral(expr) = &**nt
                 && let ast::ExprKind::Lit(token_lit) = expr.kind =>
             {
-                Some(token_lit.clone())
+                Some(token_lit)
             }
             _ => None,
         }
diff --git a/compiler/rustc_ast_passes/src/feature_gate.rs b/compiler/rustc_ast_passes/src/feature_gate.rs
index 32f45f8b59e..039338f543c 100644
--- a/compiler/rustc_ast_passes/src/feature_gate.rs
+++ b/compiler/rustc_ast_passes/src/feature_gate.rs
@@ -630,7 +630,7 @@ fn check_incompatible_features(sess: &Session) {
             {
                 let spans = vec![f1_span, f2_span];
                 sess.struct_span_err(
-                    spans.clone(),
+                    spans,
                     &format!(
                         "features `{}` and `{}` are incompatible, using them at the same time \
                         is not allowed",
diff --git a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
index 5e3745f1735..5fb4dcf09f5 100644
--- a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
@@ -745,7 +745,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             err.span_suggestion_verbose(
                 span.shrink_to_hi(),
                 "consider cloning the value if the performance cost is acceptable",
-                ".clone()".to_string(),
+                ".clone()",
                 Applicability::MachineApplicable,
             );
         }
diff --git a/compiler/rustc_builtin_macros/src/alloc_error_handler.rs b/compiler/rustc_builtin_macros/src/alloc_error_handler.rs
index 95e38e4b053..dcf500ddbd3 100644
--- a/compiler/rustc_builtin_macros/src/alloc_error_handler.rs
+++ b/compiler/rustc_builtin_macros/src/alloc_error_handler.rs
@@ -32,7 +32,7 @@ pub fn expand(
             (item, true, ecx.with_def_site_ctxt(fn_kind.sig.span))
         } else {
             ecx.sess.parse_sess.span_diagnostic.span_err(item.span(), "alloc_error_handler must be a function");
-            return vec![orig_item.clone()];
+            return vec![orig_item];
         };
 
     // Generate a bunch of new items using the AllocFnFactory
diff --git a/compiler/rustc_builtin_macros/src/concat_bytes.rs b/compiler/rustc_builtin_macros/src/concat_bytes.rs
index 4c424ea430b..4f1a7d709ff 100644
--- a/compiler/rustc_builtin_macros/src/concat_bytes.rs
+++ b/compiler/rustc_builtin_macros/src/concat_bytes.rs
@@ -196,7 +196,7 @@ pub fn expand_concat_bytes(
         }
     }
     if !missing_literals.is_empty() {
-        let mut err = cx.struct_span_err(missing_literals.clone(), "expected a byte literal");
+        let mut err = cx.struct_span_err(missing_literals, "expected a byte literal");
         err.note("only byte literals (like `b\"foo\"`, `b's'`, and `[3, 4, 5]`) can be passed to `concat_bytes!()`");
         err.emit();
         return base::MacEager::expr(DummyResult::raw_expr(sp, true));
diff --git a/compiler/rustc_codegen_llvm/src/back/lto.rs b/compiler/rustc_codegen_llvm/src/back/lto.rs
index 551663bfbbd..e20dc906bce 100644
--- a/compiler/rustc_codegen_llvm/src/back/lto.rs
+++ b/compiler/rustc_codegen_llvm/src/back/lto.rs
@@ -210,7 +210,7 @@ pub(crate) fn run_thin(
 }
 
 pub(crate) fn prepare_thin(module: ModuleCodegen<ModuleLlvm>) -> (String, ThinBuffer) {
-    let name = module.name.clone();
+    let name = module.name;
     let buffer = ThinBuffer::new(module.module_llvm.llmod(), true);
     (name, buffer)
 }
diff --git a/compiler/rustc_data_structures/src/base_n.rs b/compiler/rustc_data_structures/src/base_n.rs
index 3c7bea27124..4567759c004 100644
--- a/compiler/rustc_data_structures/src/base_n.rs
+++ b/compiler/rustc_data_structures/src/base_n.rs
@@ -9,7 +9,7 @@ pub const MAX_BASE: usize = 64;
 pub const ALPHANUMERIC_ONLY: usize = 62;
 pub const CASE_INSENSITIVE: usize = 36;
 
-const BASE_64: &[u8; MAX_BASE as usize] =
+const BASE_64: &[u8; MAX_BASE] =
     b"0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ@$";
 
 #[inline]
diff --git a/compiler/rustc_errors/src/diagnostic.rs b/compiler/rustc_errors/src/diagnostic.rs
index 06bb5edc090..585a54308c6 100644
--- a/compiler/rustc_errors/src/diagnostic.rs
+++ b/compiler/rustc_errors/src/diagnostic.rs
@@ -370,7 +370,11 @@ impl Diagnostic {
         self.set_span(after);
         for span_label in before.span_labels() {
             if let Some(label) = span_label.label {
-                self.span.push_span_label(after, label);
+                if span_label.is_primary {
+                    self.span.push_span_label(after, label);
+                } else {
+                    self.span.push_span_label(span_label.span, label);
+                }
             }
         }
         self
@@ -802,7 +806,7 @@ impl Diagnostic {
         debug_assert!(
             !(suggestions
                 .iter()
-                .flat_map(|suggs| suggs)
+                .flatten()
                 .any(|(sp, suggestion)| sp.is_empty() && suggestion.is_empty())),
             "Span must not be empty and have no suggestion"
         );
diff --git a/compiler/rustc_errors/src/emitter.rs b/compiler/rustc_errors/src/emitter.rs
index 4df2198fb0e..aaf0699f0dc 100644
--- a/compiler/rustc_errors/src/emitter.rs
+++ b/compiler/rustc_errors/src/emitter.rs
@@ -1308,7 +1308,7 @@ impl EmitterWriter {
         //                see how it *looks* with
         //                very *weird* formats
         //                see?
-        for &(ref text, ref style) in msg.iter() {
+        for (text, style) in msg.iter() {
             let text = self.translate_message(text, args);
             let lines = text.split('\n').collect::<Vec<_>>();
             if lines.len() > 1 {
@@ -1370,7 +1370,7 @@ impl EmitterWriter {
                 buffer.append(0, ": ", header_style);
                 label_width += 2;
             }
-            for &(ref text, _) in msg.iter() {
+            for (text, _) in msg.iter() {
                 let text = self.translate_message(text, args);
                 // Account for newlines to align output to its label.
                 for (line, text) in normalize_whitespace(&text).lines().enumerate() {
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index 8bc022e1e17..91825c29258 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/compiler/rustc_hir/src/hir.rs
@@ -548,12 +548,7 @@ impl<'hir> Generics<'hir> {
     }
 
     pub fn get_named(&self, name: Symbol) -> Option<&GenericParam<'hir>> {
-        for param in self.params {
-            if name == param.name.ident().name {
-                return Some(param);
-            }
-        }
-        None
+        self.params.iter().find(|&param| name == param.name.ident().name)
     }
 
     pub fn spans(&self) -> MultiSpan {
diff --git a/compiler/rustc_index/src/bit_set.rs b/compiler/rustc_index/src/bit_set.rs
index 777112442f0..686cb6dac49 100644
--- a/compiler/rustc_index/src/bit_set.rs
+++ b/compiler/rustc_index/src/bit_set.rs
@@ -209,7 +209,7 @@ impl<T: Idx> BitSet<T> {
             self.words[start_word_index] |= !(start_mask - 1);
             // And all trailing bits (i.e. from 0..=end) in the end word,
             // including the end.
-            self.words[end_word_index] |= end_mask | end_mask - 1;
+            self.words[end_word_index] |= end_mask | (end_mask - 1);
         } else {
             self.words[start_word_index] |= end_mask | (end_mask - start_mask);
         }
diff --git a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/static_impl_trait.rs b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/static_impl_trait.rs
index 09f9aa3c842..9bd2202d260 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/static_impl_trait.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/static_impl_trait.rs
@@ -330,7 +330,7 @@ pub fn suggest_new_region_bound(
                             Applicability::MaybeIncorrect,
                         );
                     }
-                    if let Some((param_span, param_ty)) = param.clone() {
+                    if let Some((param_span, ref param_ty)) = param {
                         err.span_suggestion_verbose(
                             param_span,
                             add_static_bound,
diff --git a/compiler/rustc_lexer/src/unescape.rs b/compiler/rustc_lexer/src/unescape.rs
index e405013dcab..87c44638a8d 100644
--- a/compiler/rustc_lexer/src/unescape.rs
+++ b/compiler/rustc_lexer/src/unescape.rs
@@ -204,14 +204,13 @@ fn scan_escape(chars: &mut Chars<'_>, is_byte: bool) -> Result<char, EscapeError
                         })?;
                     }
                     Some(c) => {
-                        let digit =
+                        let digit: u32 =
                             c.to_digit(16).ok_or(EscapeError::InvalidCharInUnicodeEscape)?;
                         n_digits += 1;
                         if n_digits > 6 {
                             // Stop updating value since we're sure that it's incorrect already.
                             continue;
                         }
-                        let digit = digit as u32;
                         value = value * 16 + digit;
                     }
                 };
diff --git a/compiler/rustc_resolve/src/late.rs b/compiler/rustc_resolve/src/late.rs
index cf3e5946053..5b7a00101e9 100644
--- a/compiler/rustc_resolve/src/late.rs
+++ b/compiler/rustc_resolve/src/late.rs
@@ -566,6 +566,9 @@ struct LateResolutionVisitor<'a, 'b, 'ast> {
     /// FIXME #4948: Reuse ribs to avoid allocation.
     ribs: PerNS<Vec<Rib<'a>>>,
 
+    /// Previous poped `rib`, only used for diagnostic.
+    last_block_rib: Option<Rib<'a>>,
+
     /// The current set of local scopes, for labels.
     label_ribs: Vec<Rib<'a, NodeId>>,
 
@@ -873,6 +876,8 @@ impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
                             // Ignore errors in function bodies if this is rustdoc
                             // Be sure not to set this until the function signature has been resolved.
                             let previous_state = replace(&mut this.in_func_body, true);
+                            // We only care block in the same function
+                            this.last_block_rib = None;
                             // Resolve the function body, potentially inside the body of an async closure
                             this.with_lifetime_rib(
                                 LifetimeRibKind::Elided(LifetimeRes::Infer),
@@ -1168,6 +1173,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
                 type_ns: vec![Rib::new(start_rib_kind)],
                 macro_ns: vec![Rib::new(start_rib_kind)],
             },
+            last_block_rib: None,
             label_ribs: Vec::new(),
             lifetime_ribs: Vec::new(),
             lifetime_elision_candidates: None,
@@ -3769,7 +3775,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
             self.ribs[ValueNS].pop();
             self.label_ribs.pop();
         }
-        self.ribs[ValueNS].pop();
+        self.last_block_rib = self.ribs[ValueNS].pop();
         if anonymous_module.is_some() {
             self.ribs[TypeNS].pop();
         }
diff --git a/compiler/rustc_resolve/src/late/diagnostics.rs b/compiler/rustc_resolve/src/late/diagnostics.rs
index d43983ea815..49bbe37ee43 100644
--- a/compiler/rustc_resolve/src/late/diagnostics.rs
+++ b/compiler/rustc_resolve/src/late/diagnostics.rs
@@ -623,6 +623,22 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
                 return (true, candidates);
             }
         }
+
+        // Try to find in last block rib
+        if let Some(rib) = &self.last_block_rib && let RibKind::NormalRibKind = rib.kind {
+            for (ident, &res) in &rib.bindings {
+                if let Res::Local(_) = res && path.len() == 1 &&
+                    ident.span.eq_ctxt(path[0].ident.span) &&
+                    ident.name == path[0].ident.name {
+                    err.span_help(
+                        ident.span,
+                        &format!("the binding `{}` is available in a different scope in the same function", path_str),
+                    );
+                    return (true, candidates);
+                }
+            }
+        }
+
         return (false, candidates);
     }
 
diff --git a/compiler/rustc_span/src/source_map.rs b/compiler/rustc_span/src/source_map.rs
index 43a31722707..a4e0f54d276 100644
--- a/compiler/rustc_span/src/source_map.rs
+++ b/compiler/rustc_span/src/source_map.rs
@@ -1150,7 +1150,7 @@ impl FilePathMapping {
             // NOTE: We are iterating over the mapping entries from last to first
             //       because entries specified later on the command line should
             //       take precedence.
-            for &(ref from, ref to) in mapping.iter().rev() {
+            for (from, to) in mapping.iter().rev() {
                 debug!("Trying to apply {from:?} => {to:?}");
 
                 if let Ok(rest) = path.strip_prefix(from) {
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/method_chain.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/method_chain.rs
new file mode 100644
index 00000000000..cb373d65772
--- /dev/null
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/method_chain.rs
@@ -0,0 +1,74 @@
+use crate::infer::InferCtxt;
+
+use rustc_middle::ty::error::TypeError;
+use rustc_middle::ty::relate::{self, Relate, RelateResult, TypeRelation};
+use rustc_middle::ty::{self, Ty, TyCtxt};
+
+pub struct CollectAllMismatches<'a, 'tcx> {
+    pub infcx: &'a InferCtxt<'tcx>,
+    pub param_env: ty::ParamEnv<'tcx>,
+    pub errors: Vec<TypeError<'tcx>>,
+}
+
+impl<'a, 'tcx> TypeRelation<'tcx> for CollectAllMismatches<'a, 'tcx> {
+    fn tag(&self) -> &'static str {
+        "CollectAllMismatches"
+    }
+    fn tcx(&self) -> TyCtxt<'tcx> {
+        self.infcx.tcx
+    }
+    fn intercrate(&self) -> bool {
+        false
+    }
+    fn param_env(&self) -> ty::ParamEnv<'tcx> {
+        self.param_env
+    }
+    fn a_is_expected(&self) -> bool {
+        true
+    } // irrelevant
+    fn mark_ambiguous(&mut self) {
+        bug!()
+    }
+    fn relate_with_variance<T: Relate<'tcx>>(
+        &mut self,
+        _: ty::Variance,
+        _: ty::VarianceDiagInfo<'tcx>,
+        a: T,
+        b: T,
+    ) -> RelateResult<'tcx, T> {
+        self.relate(a, b)
+    }
+    fn regions(
+        &mut self,
+        a: ty::Region<'tcx>,
+        _b: ty::Region<'tcx>,
+    ) -> RelateResult<'tcx, ty::Region<'tcx>> {
+        Ok(a)
+    }
+    fn tys(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>> {
+        if a == b || matches!(a.kind(), ty::Infer(_)) || matches!(b.kind(), ty::Infer(_)) {
+            return Ok(a);
+        }
+        relate::super_relate_tys(self, a, b).or_else(|e| {
+            self.errors.push(e);
+            Ok(a)
+        })
+    }
+    fn consts(
+        &mut self,
+        a: ty::Const<'tcx>,
+        b: ty::Const<'tcx>,
+    ) -> RelateResult<'tcx, ty::Const<'tcx>> {
+        if a == b {
+            return Ok(a);
+        }
+        relate::super_relate_consts(self, a, b) // could do something similar here for constants!
+    }
+    fn binders<T: Relate<'tcx>>(
+        &mut self,
+        a: ty::Binder<'tcx, T>,
+        b: ty::Binder<'tcx, T>,
+    ) -> RelateResult<'tcx, ty::Binder<'tcx, T>> {
+        Ok(a.rebind(self.relate(a.skip_binder(), b.skip_binder())?))
+    }
+}
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 82449a36b1d..30ff07ee6c3 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
@@ -1,4 +1,5 @@
 mod ambiguity;
+pub mod method_chain;
 pub mod on_unimplemented;
 pub mod suggestions;
 
@@ -536,7 +537,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
             |err| {
                 self.note_obligation_cause_code(
                     err,
-                    &predicate,
+                    predicate,
                     obligation.param_env,
                     obligation.cause.code(),
                     &mut vec![],
@@ -1587,7 +1588,7 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 {
                     self.note_obligation_cause_code(
                         &mut diag,
-                        &error.obligation.predicate,
+                        error.obligation.predicate,
                         error.obligation.param_env,
                         code,
                         &mut vec![],
@@ -2602,7 +2603,7 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
         if !self.maybe_note_obligation_cause_for_async_await(err, obligation) {
             self.note_obligation_cause_code(
                 err,
-                &obligation.predicate,
+                obligation.predicate,
                 obligation.param_env,
                 obligation.cause.code(),
                 &mut vec![],
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
index 9f5814a6bda..40c81025471 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
@@ -1,8 +1,9 @@
+// ignore-tidy-filelength
 use super::{DefIdOrName, Obligation, ObligationCause, ObligationCauseCode, PredicateObligation};
 
 use crate::autoderef::Autoderef;
 use crate::infer::InferCtxt;
-use crate::traits::NormalizeExt;
+use crate::traits::{NormalizeExt, ObligationCtxt};
 
 use hir::def::CtorOf;
 use hir::HirId;
@@ -22,17 +23,20 @@ use rustc_infer::infer::error_reporting::TypeErrCtxt;
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use rustc_infer::infer::{InferOk, LateBoundRegionConversionTime};
 use rustc_middle::hir::map;
+use rustc_middle::ty::error::TypeError::{self, Sorts};
+use rustc_middle::ty::relate::TypeRelation;
 use rustc_middle::ty::{
     self, suggest_arbitrary_trait_bound, suggest_constraining_type_param, AdtKind, DefIdTree,
-    GeneratorDiagnosticData, GeneratorInteriorTypeCause, Infer, InferTy, IsSuggestable,
-    ToPredicate, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeSuperFoldable, TypeVisitable,
+    GeneratorDiagnosticData, GeneratorInteriorTypeCause, Infer, InferTy, InternalSubsts,
+    IsSuggestable, ToPredicate, Ty, TyCtxt, TypeAndMut, TypeFoldable, TypeFolder,
+    TypeSuperFoldable, TypeVisitable, TypeckResults,
 };
-use rustc_middle::ty::{TypeAndMut, TypeckResults};
 use rustc_span::symbol::{sym, Ident, Symbol};
 use rustc_span::{BytePos, DesugaringKind, ExpnKind, Span, DUMMY_SP};
 use rustc_target::spec::abi;
-use std::fmt;
+use std::ops::Deref;
 
+use super::method_chain::CollectAllMismatches;
 use super::InferCtxtPrivExt;
 use crate::infer::InferCtxtExt as _;
 use crate::traits::query::evaluate_obligation::InferCtxtExt as _;
@@ -292,13 +296,13 @@ pub trait TypeErrCtxtExt<'tcx> {
     fn note_obligation_cause_code<T>(
         &self,
         err: &mut Diagnostic,
-        predicate: &T,
+        predicate: T,
         param_env: ty::ParamEnv<'tcx>,
         cause_code: &ObligationCauseCode<'tcx>,
         obligated_types: &mut Vec<Ty<'tcx>>,
         seen_requirements: &mut FxHashSet<DefId>,
     ) where
-        T: fmt::Display + ToPredicate<'tcx>;
+        T: ToPredicate<'tcx>;
 
     /// Suggest to await before try: future? => future.await?
     fn suggest_await_before_try(
@@ -329,6 +333,23 @@ pub trait TypeErrCtxtExt<'tcx> {
         err: &mut Diagnostic,
         trait_pred: ty::PolyTraitPredicate<'tcx>,
     );
+    fn function_argument_obligation(
+        &self,
+        arg_hir_id: HirId,
+        err: &mut Diagnostic,
+        parent_code: &ObligationCauseCode<'tcx>,
+        param_env: ty::ParamEnv<'tcx>,
+        predicate: ty::Predicate<'tcx>,
+        call_hir_id: HirId,
+    );
+    fn point_at_chain(
+        &self,
+        expr: &hir::Expr<'_>,
+        typeck_results: &TypeckResults<'tcx>,
+        type_diffs: Vec<TypeError<'tcx>>,
+        param_env: ty::ParamEnv<'tcx>,
+        err: &mut Diagnostic,
+    );
 }
 
 fn predicate_constraint(generics: &hir::Generics<'_>, pred: ty::Predicate<'_>) -> (Span, String) {
@@ -2336,7 +2357,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
         debug!(?next_code);
         self.note_obligation_cause_code(
             err,
-            &obligation.predicate,
+            obligation.predicate,
             obligation.param_env,
             next_code.unwrap(),
             &mut Vec::new(),
@@ -2347,15 +2368,16 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
     fn note_obligation_cause_code<T>(
         &self,
         err: &mut Diagnostic,
-        predicate: &T,
+        predicate: T,
         param_env: ty::ParamEnv<'tcx>,
         cause_code: &ObligationCauseCode<'tcx>,
         obligated_types: &mut Vec<Ty<'tcx>>,
         seen_requirements: &mut FxHashSet<DefId>,
     ) where
-        T: fmt::Display + ToPredicate<'tcx>,
+        T: ToPredicate<'tcx>,
     {
         let tcx = self.tcx;
+        let predicate = predicate.to_predicate(tcx);
         match *cause_code {
             ObligationCauseCode::ExprAssignable
             | ObligationCauseCode::MatchExpressionArm { .. }
@@ -2390,12 +2412,11 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 err.note("only the last element of a tuple may have a dynamically sized type");
             }
             ObligationCauseCode::ProjectionWf(data) => {
-                err.note(&format!("required so that the projection `{}` is well-formed", data,));
+                err.note(&format!("required so that the projection `{data}` is well-formed"));
             }
             ObligationCauseCode::ReferenceOutlivesReferent(ref_ty) => {
                 err.note(&format!(
-                    "required so that reference `{}` does not outlive its referent",
-                    ref_ty,
+                    "required so that reference `{ref_ty}` does not outlive its referent"
                 ));
             }
             ObligationCauseCode::ObjectTypeBound(object_ty, region) => {
@@ -2689,7 +2710,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                     ensure_sufficient_stack(|| {
                         self.note_obligation_cause_code(
                             err,
-                            &parent_predicate,
+                            parent_predicate,
                             param_env,
                             &data.parent_code,
                             obligated_types,
@@ -2700,7 +2721,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                     ensure_sufficient_stack(|| {
                         self.note_obligation_cause_code(
                             err,
-                            &parent_predicate,
+                            parent_predicate,
                             param_env,
                             cause_code.peel_derives(),
                             obligated_types,
@@ -2809,7 +2830,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 ensure_sufficient_stack(|| {
                     self.note_obligation_cause_code(
                         err,
-                        &parent_predicate,
+                        parent_predicate,
                         param_env,
                         &data.parent_code,
                         obligated_types,
@@ -2824,7 +2845,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 ensure_sufficient_stack(|| {
                     self.note_obligation_cause_code(
                         err,
-                        &parent_predicate,
+                        parent_predicate,
                         param_env,
                         &data.parent_code,
                         obligated_types,
@@ -2837,43 +2858,14 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 call_hir_id,
                 ref parent_code,
             } => {
-                let hir = self.tcx.hir();
-                if let Some(Node::Expr(expr @ hir::Expr { kind: hir::ExprKind::Block(..), .. })) =
-                    hir.find(arg_hir_id)
-                {
-                    let parent_id = hir.get_parent_item(arg_hir_id);
-                    let typeck_results: &TypeckResults<'tcx> = match &self.typeck_results {
-                        Some(t) if t.hir_owner == parent_id => t,
-                        _ => self.tcx.typeck(parent_id.def_id),
-                    };
-                    let expr = expr.peel_blocks();
-                    let ty = typeck_results.expr_ty_adjusted_opt(expr).unwrap_or(tcx.ty_error());
-                    let span = expr.span;
-                    if Some(span) != err.span.primary_span() {
-                        err.span_label(
-                            span,
-                            if ty.references_error() {
-                                String::new()
-                            } else {
-                                format!("this tail expression is of type `{:?}`", ty)
-                            },
-                        );
-                    }
-                }
-                if let Some(Node::Expr(hir::Expr {
-                    kind:
-                        hir::ExprKind::Call(hir::Expr { span, .. }, _)
-                        | hir::ExprKind::MethodCall(
-                            hir::PathSegment { ident: Ident { span, .. }, .. },
-                            ..,
-                        ),
-                    ..
-                })) = hir.find(call_hir_id)
-                {
-                    if Some(*span) != err.span.primary_span() {
-                        err.span_label(*span, "required by a bound introduced by this call");
-                    }
-                }
+                self.function_argument_obligation(
+                    arg_hir_id,
+                    err,
+                    parent_code,
+                    param_env,
+                    predicate,
+                    call_hir_id,
+                );
                 ensure_sufficient_stack(|| {
                     self.note_obligation_cause_code(
                         err,
@@ -2888,9 +2880,8 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
             ObligationCauseCode::CompareImplItemObligation { trait_item_def_id, kind, .. } => {
                 let item_name = self.tcx.item_name(trait_item_def_id);
                 let msg = format!(
-                    "the requirement `{}` appears on the `impl`'s {kind} `{}` but not on the \
-                     corresponding trait's {kind}",
-                    predicate, item_name,
+                    "the requirement `{predicate}` appears on the `impl`'s {kind} \
+                     `{item_name}` but not on the corresponding trait's {kind}",
                 );
                 let sp = self
                     .tcx
@@ -2900,7 +2891,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 let mut assoc_span: MultiSpan = sp.into();
                 assoc_span.push_span_label(
                     sp,
-                    format!("this trait's {kind} doesn't have the requirement `{}`", predicate),
+                    format!("this trait's {kind} doesn't have the requirement `{predicate}`"),
                 );
                 if let Some(ident) = self
                     .tcx
@@ -2919,7 +2910,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
             }
             ObligationCauseCode::OpaqueReturnType(expr_info) => {
                 if let Some((expr_ty, expr_span)) = expr_info {
-                    let expr_ty = self.resolve_vars_if_possible(expr_ty);
+                    let expr_ty = with_forced_trimmed_paths!(self.ty_to_string(expr_ty));
                     err.span_label(
                         expr_span,
                         format!("return type was inferred to be `{expr_ty}` here"),
@@ -3099,6 +3090,298 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
             );
         }
     }
+    fn function_argument_obligation(
+        &self,
+        arg_hir_id: HirId,
+        err: &mut Diagnostic,
+        parent_code: &ObligationCauseCode<'tcx>,
+        param_env: ty::ParamEnv<'tcx>,
+        predicate: ty::Predicate<'tcx>,
+        call_hir_id: HirId,
+    ) {
+        let tcx = self.tcx;
+        let hir = tcx.hir();
+        if let Some(Node::Expr(expr)) = hir.find(arg_hir_id) {
+            let parent_id = hir.get_parent_item(arg_hir_id);
+            let typeck_results: &TypeckResults<'tcx> = match &self.typeck_results {
+                Some(t) if t.hir_owner == parent_id => t,
+                _ => self.tcx.typeck(parent_id.def_id),
+            };
+            if let hir::Expr { kind: hir::ExprKind::Block(..), .. } = expr {
+                let expr = expr.peel_blocks();
+                let ty = typeck_results.expr_ty_adjusted_opt(expr).unwrap_or(tcx.ty_error());
+                let span = expr.span;
+                if Some(span) != err.span.primary_span() {
+                    err.span_label(
+                        span,
+                        if ty.references_error() {
+                            String::new()
+                        } else {
+                            let ty = with_forced_trimmed_paths!(self.ty_to_string(ty));
+                            format!("this tail expression is of type `{ty}`")
+                        },
+                    );
+                }
+            }
+
+            // FIXME: visit the ty to see if there's any closure involved, and if there is,
+            // check whether its evaluated return type is the same as the one corresponding
+            // to an associated type (as seen from `trait_pred`) in the predicate. Like in
+            // trait_pred `S: Sum<<Self as Iterator>::Item>` and predicate `i32: Sum<&()>`
+            let mut type_diffs = vec![];
+
+            if let ObligationCauseCode::ExprBindingObligation(def_id, _, _, idx) = parent_code.deref()
+                && let predicates = self.tcx.predicates_of(def_id).instantiate_identity(self.tcx)
+                && let Some(pred) = predicates.predicates.get(*idx)
+                && let Ok(trait_pred) = pred.kind().try_map_bound(|pred| match pred {
+                    ty::PredicateKind::Clause(ty::Clause::Trait(trait_pred)) => Ok(trait_pred),
+                    _ => Err(()),
+                })
+            {
+                let mut c = CollectAllMismatches {
+                    infcx: self.infcx,
+                    param_env,
+                    errors: vec![],
+                };
+                if let Ok(trait_predicate) = predicate.kind().try_map_bound(|pred| match pred {
+                    ty::PredicateKind::Clause(ty::Clause::Trait(trait_pred)) => Ok(trait_pred),
+                    _ => Err(()),
+                }) {
+                    if let Ok(_) = c.relate(trait_pred, trait_predicate) {
+                        type_diffs = c.errors;
+                    }
+                }
+            }
+            if let hir::ExprKind::Path(hir::QPath::Resolved(None, path)) = expr.kind
+                && let hir::Path { res: hir::def::Res::Local(hir_id), .. } = path
+                && let Some(hir::Node::Pat(binding)) = self.tcx.hir().find(*hir_id)
+                && let parent_hir_id = self.tcx.hir().get_parent_node(binding.hir_id)
+                && let Some(hir::Node::Local(local)) = self.tcx.hir().find(parent_hir_id)
+                && let Some(binding_expr) = local.init
+            {
+                // If the expression we're calling on is a binding, we want to point at the
+                // `let` when talking about the type. Otherwise we'll point at every part
+                // of the method chain with the type.
+                self.point_at_chain(binding_expr, typeck_results, type_diffs, param_env, err);
+            } else {
+                self.point_at_chain(expr, typeck_results, type_diffs, param_env, err);
+            }
+        }
+        let call_node = hir.find(call_hir_id);
+        if let Some(Node::Expr(hir::Expr {
+            kind: hir::ExprKind::MethodCall(path, rcvr, ..), ..
+        })) = call_node
+        {
+            if Some(rcvr.span) == err.span.primary_span() {
+                err.replace_span_with(path.ident.span);
+            }
+        }
+        if let Some(Node::Expr(hir::Expr {
+            kind:
+                hir::ExprKind::Call(hir::Expr { span, .. }, _)
+                | hir::ExprKind::MethodCall(hir::PathSegment { ident: Ident { span, .. }, .. }, ..),
+            ..
+        })) = hir.find(call_hir_id)
+        {
+            if Some(*span) != err.span.primary_span() {
+                err.span_label(*span, "required by a bound introduced by this call");
+            }
+        }
+    }
+
+    fn point_at_chain(
+        &self,
+        expr: &hir::Expr<'_>,
+        typeck_results: &TypeckResults<'tcx>,
+        type_diffs: Vec<TypeError<'tcx>>,
+        param_env: ty::ParamEnv<'tcx>,
+        err: &mut Diagnostic,
+    ) {
+        let mut primary_spans = vec![];
+        let mut span_labels = vec![];
+
+        let tcx = self.tcx;
+
+        let mut assocs = vec![];
+        // We still want to point at the different methods even if there hasn't
+        // been a change of assoc type.
+        let mut call_spans = vec![];
+        let mut expr = expr;
+        let mut prev_ty = self.resolve_vars_if_possible(
+            typeck_results.expr_ty_adjusted_opt(expr).unwrap_or(tcx.ty_error()),
+        );
+        while let hir::ExprKind::MethodCall(_path_segment, rcvr_expr, _args, span) = expr.kind {
+            // Point at every method call in the chain with the resulting type.
+            // vec![1, 2, 3].iter().map(mapper).sum<i32>()
+            //               ^^^^^^ ^^^^^^^^^^^
+            expr = rcvr_expr;
+            let mut assocs_in_this_method = Vec::with_capacity(type_diffs.len());
+            call_spans.push(span);
+
+            let ocx = ObligationCtxt::new_in_snapshot(self.infcx);
+            for diff in &type_diffs {
+                let Sorts(expected_found) = diff else { continue; };
+                let ty::Projection(proj) = expected_found.expected.kind() else { continue; };
+
+                let origin =
+                    TypeVariableOrigin { kind: TypeVariableOriginKind::TypeInference, span };
+                let trait_def_id = proj.trait_def_id(self.tcx);
+                // Make `Self` be equivalent to the type of the call chain
+                // expression we're looking at now, so that we can tell what
+                // for example `Iterator::Item` is at this point in the chain.
+                let substs = InternalSubsts::for_item(self.tcx, trait_def_id, |param, _| {
+                    match param.kind {
+                        ty::GenericParamDefKind::Type { .. } => {
+                            if param.index == 0 {
+                                return prev_ty.into();
+                            }
+                        }
+                        ty::GenericParamDefKind::Lifetime
+                        | ty::GenericParamDefKind::Const { .. } => {}
+                    }
+                    self.var_for_def(span, param)
+                });
+                // This will hold the resolved type of the associated type, if the
+                // current expression implements the trait that associated type is
+                // in. For example, this would be what `Iterator::Item` is here.
+                let ty_var = self.infcx.next_ty_var(origin);
+                // This corresponds to `<ExprTy as Iterator>::Item = _`.
+                let trait_ref = ty::Binder::dummy(ty::PredicateKind::Clause(
+                    ty::Clause::Projection(ty::ProjectionPredicate {
+                        projection_ty: ty::ProjectionTy { substs, item_def_id: proj.item_def_id },
+                        term: ty_var.into(),
+                    }),
+                ));
+                // Add `<ExprTy as Iterator>::Item = _` obligation.
+                ocx.register_obligation(Obligation::misc(
+                    self.tcx,
+                    span,
+                    expr.hir_id,
+                    param_env,
+                    trait_ref,
+                ));
+                if ocx.select_where_possible().is_empty() {
+                    // `ty_var` now holds the type that `Item` is for `ExprTy`.
+                    let ty_var = self.resolve_vars_if_possible(ty_var);
+                    assocs_in_this_method.push(Some((span, (proj.item_def_id, ty_var))));
+                } else {
+                    // `<ExprTy as Iterator>` didn't select, so likely we've
+                    // reached the end of the iterator chain, like the originating
+                    // `Vec<_>`.
+                    // Keep the space consistent for later zipping.
+                    assocs_in_this_method.push(None);
+                }
+            }
+            assocs.push(assocs_in_this_method);
+            prev_ty = self.resolve_vars_if_possible(
+                typeck_results.expr_ty_adjusted_opt(expr).unwrap_or(tcx.ty_error()),
+            );
+
+            if let hir::ExprKind::Path(hir::QPath::Resolved(None, path)) = expr.kind
+                && let hir::Path { res: hir::def::Res::Local(hir_id), .. } = path
+                && let Some(hir::Node::Pat(binding)) = self.tcx.hir().find(*hir_id)
+                && let parent_hir_id = self.tcx.hir().get_parent_node(binding.hir_id)
+                && let Some(hir::Node::Local(local)) = self.tcx.hir().find(parent_hir_id)
+                && let Some(binding_expr) = local.init
+            {
+                // We've reached the root of the method call chain and it is a
+                // binding. Get the binding creation and try to continue the chain.
+                expr = binding_expr;
+            }
+        }
+        // We want the type before deref coercions, otherwise we talk about `&[_]`
+        // instead of `Vec<_>`.
+        if let Some(ty) = typeck_results.expr_ty_opt(expr) {
+            let ty = with_forced_trimmed_paths!(self.ty_to_string(ty));
+            // Point at the root expression
+            // vec![1, 2, 3].iter().map(mapper).sum<i32>()
+            // ^^^^^^^^^^^^^
+            span_labels.push((expr.span, format!("this expression has type `{ty}`")));
+        };
+        // Only show this if it is not a "trivial" expression (not a method
+        // chain) and there are associated types to talk about.
+        let mut assocs = assocs.into_iter().peekable();
+        while let Some(assocs_in_method) = assocs.next() {
+            let Some(prev_assoc_in_method) = assocs.peek() else {
+                for entry in assocs_in_method {
+                    let Some((span, (assoc, ty))) = entry else { continue; };
+                    if type_diffs.iter().any(|diff| {
+                        let Sorts(expected_found) = diff else { return false; };
+                        self.can_eq(param_env, expected_found.found, ty).is_ok()
+                    }) {
+                        // FIXME: this doesn't quite work for `Iterator::collect`
+                        // because we have `Vec<i32>` and `()`, but we'd want `i32`
+                        // to point at the `.into_iter()` call, but as long as we
+                        // still point at the other method calls that might have
+                        // introduced the issue, this is fine for now.
+                        primary_spans.push(span);
+                    }
+                    span_labels.push((
+                        span,
+                        with_forced_trimmed_paths!(format!(
+                            "`{}` is `{ty}` here",
+                            self.tcx.def_path_str(assoc),
+                        )),
+                    ));
+                }
+                break;
+            };
+            for (entry, prev_entry) in
+                assocs_in_method.into_iter().zip(prev_assoc_in_method.into_iter())
+            {
+                match (entry, prev_entry) {
+                    (Some((span, (assoc, ty))), Some((_, (_, prev_ty)))) => {
+                        let ty_str = with_forced_trimmed_paths!(self.ty_to_string(ty));
+
+                        let assoc = with_forced_trimmed_paths!(self.tcx.def_path_str(assoc));
+                        if ty != *prev_ty {
+                            if type_diffs.iter().any(|diff| {
+                                let Sorts(expected_found) = diff else { return false; };
+                                self.can_eq(param_env, expected_found.found, ty).is_ok()
+                            }) {
+                                primary_spans.push(span);
+                            }
+                            span_labels
+                                .push((span, format!("`{assoc}` changed to `{ty_str}` here")));
+                        } else {
+                            span_labels.push((span, format!("`{assoc}` remains `{ty_str}` here")));
+                        }
+                    }
+                    (Some((span, (assoc, ty))), None) => {
+                        span_labels.push((
+                            span,
+                            with_forced_trimmed_paths!(format!(
+                                "`{}` is `{}` here",
+                                self.tcx.def_path_str(assoc),
+                                self.ty_to_string(ty),
+                            )),
+                        ));
+                    }
+                    (None, Some(_)) | (None, None) => {}
+                }
+            }
+        }
+        for span in call_spans {
+            if span_labels.iter().find(|(s, _)| *s == span).is_none() {
+                // Ensure we are showing the entire chain, even if the assoc types
+                // haven't changed.
+                span_labels.push((span, String::new()));
+            }
+        }
+        if !primary_spans.is_empty() {
+            let mut multi_span: MultiSpan = primary_spans.into();
+            for (span, label) in span_labels {
+                multi_span.push_span_label(span, label);
+            }
+            err.span_note(
+                multi_span,
+                format!(
+                    "the method call chain might not have had the expected \
+                                     associated types",
+                ),
+            );
+        }
+    }
 }
 
 /// Collect all the returned expressions within the input expression.
diff --git a/src/bootstrap/dist.rs b/src/bootstrap/dist.rs
index 2fef7f65827..3cb0eccd324 100644
--- a/src/bootstrap/dist.rs
+++ b/src/bootstrap/dist.rs
@@ -1470,7 +1470,7 @@ impl Step for Extended {
 
         let xform = |p: &Path| {
             let mut contents = t!(fs::read_to_string(p));
-            for tool in &["rust-demangler"] {
+            for tool in &["rust-demangler", "miri"] {
                 if !built_tools.contains(tool) {
                     contents = filter(&contents, tool);
                 }
@@ -1510,9 +1510,8 @@ impl Step for Extended {
             prepare("rust-std");
             prepare("rust-analysis");
             prepare("clippy");
-            prepare("miri");
             prepare("rust-analyzer");
-            for tool in &["rust-docs", "rust-demangler"] {
+            for tool in &["rust-docs", "rust-demangler", "miri"] {
                 if built_tools.contains(tool) {
                     prepare(tool);
                 }
@@ -1571,9 +1570,8 @@ impl Step for Extended {
             prepare("rust-docs");
             prepare("rust-std");
             prepare("clippy");
-            prepare("miri");
             prepare("rust-analyzer");
-            for tool in &["rust-demangler"] {
+            for tool in &["rust-demangler", "miri"] {
                 if built_tools.contains(tool) {
                     prepare(tool);
                 }
@@ -1710,23 +1708,25 @@ impl Step for Extended {
                         .arg(etc.join("msi/remove-duplicates.xsl")),
                 );
             }
-            builder.run(
-                Command::new(&heat)
-                    .current_dir(&exe)
-                    .arg("dir")
-                    .arg("miri")
-                    .args(&heat_flags)
-                    .arg("-cg")
-                    .arg("MiriGroup")
-                    .arg("-dr")
-                    .arg("Miri")
-                    .arg("-var")
-                    .arg("var.MiriDir")
-                    .arg("-out")
-                    .arg(exe.join("MiriGroup.wxs"))
-                    .arg("-t")
-                    .arg(etc.join("msi/remove-duplicates.xsl")),
-            );
+            if built_tools.contains("miri") {
+                builder.run(
+                    Command::new(&heat)
+                        .current_dir(&exe)
+                        .arg("dir")
+                        .arg("miri")
+                        .args(&heat_flags)
+                        .arg("-cg")
+                        .arg("MiriGroup")
+                        .arg("-dr")
+                        .arg("Miri")
+                        .arg("-var")
+                        .arg("var.MiriDir")
+                        .arg("-out")
+                        .arg(exe.join("MiriGroup.wxs"))
+                        .arg("-t")
+                        .arg(etc.join("msi/remove-duplicates.xsl")),
+                );
+            }
             builder.run(
                 Command::new(&heat)
                     .current_dir(&exe)
@@ -1774,7 +1774,6 @@ impl Step for Extended {
                     .arg("-dStdDir=rust-std")
                     .arg("-dAnalysisDir=rust-analysis")
                     .arg("-dClippyDir=clippy")
-                    .arg("-dMiriDir=miri")
                     .arg("-arch")
                     .arg(&arch)
                     .arg("-out")
@@ -1788,6 +1787,9 @@ impl Step for Extended {
                 if built_tools.contains("rust-analyzer") {
                     cmd.arg("-dRustAnalyzerDir=rust-analyzer");
                 }
+                if built_tools.contains("miri") {
+                    cmd.arg("-dMiriDir=miri");
+                }
                 if target.ends_with("windows-gnu") {
                     cmd.arg("-dGccDir=rust-mingw");
                 }
@@ -1801,7 +1803,9 @@ impl Step for Extended {
             candle("CargoGroup.wxs".as_ref());
             candle("StdGroup.wxs".as_ref());
             candle("ClippyGroup.wxs".as_ref());
-            candle("MiriGroup.wxs".as_ref());
+            if built_tools.contains("miri") {
+                candle("MiriGroup.wxs".as_ref());
+            }
             if built_tools.contains("rust-demangler") {
                 candle("RustDemanglerGroup.wxs".as_ref());
             }
@@ -1837,9 +1841,11 @@ impl Step for Extended {
                 .arg("StdGroup.wixobj")
                 .arg("AnalysisGroup.wixobj")
                 .arg("ClippyGroup.wixobj")
-                .arg("MiriGroup.wixobj")
                 .current_dir(&exe);
 
+            if built_tools.contains("miri") {
+                cmd.arg("MiriGroup.wixobj");
+            }
             if built_tools.contains("rust-analyzer") {
                 cmd.arg("RustAnalyzerGroup.wixobj");
             }
diff --git a/src/librustdoc/formats/item_type.rs b/src/librustdoc/formats/item_type.rs
index f21e60a64e0..2f1f4cbf359 100644
--- a/src/librustdoc/formats/item_type.rs
+++ b/src/librustdoc/formats/item_type.rs
@@ -177,6 +177,9 @@ impl ItemType {
             ItemType::TraitAlias => "traitalias",
         }
     }
+    pub(crate) fn is_method(&self) -> bool {
+        matches!(*self, ItemType::Method | ItemType::TyMethod)
+    }
 }
 
 impl fmt::Display for ItemType {
diff --git a/src/librustdoc/html/render/context.rs b/src/librustdoc/html/render/context.rs
index 73690c86f4f..d4d3e4f6ea7 100644
--- a/src/librustdoc/html/render/context.rs
+++ b/src/librustdoc/html/render/context.rs
@@ -637,7 +637,7 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
                             You need to enable Javascript be able to update your settings.\
                         </section>\
                      </noscript>\
-                     <link rel=\"stylesheet\" type=\"text/css\" \
+                     <link rel=\"stylesheet\" \
                          href=\"{static_root_path}{settings_css}\">\
                      <script defer src=\"{static_root_path}{settings_js}\"></script>",
                     static_root_path = page.get_static_root_path(),
diff --git a/src/librustdoc/html/render/mod.rs b/src/librustdoc/html/render/mod.rs
index 36d15ec3b86..80fbe9c1f06 100644
--- a/src/librustdoc/html/render/mod.rs
+++ b/src/librustdoc/html/render/mod.rs
@@ -1512,8 +1512,7 @@ fn render_impl(
 
         let toggled = !doc_buffer.is_empty();
         if toggled {
-            let method_toggle_class =
-                if item_type == ItemType::Method { " method-toggle" } else { "" };
+            let method_toggle_class = if item_type.is_method() { " method-toggle" } else { "" };
             write!(w, "<details class=\"rustdoc-toggle{}\" open><summary>", method_toggle_class);
         }
         match &*item.kind {
diff --git a/src/librustdoc/html/render/print_item.rs b/src/librustdoc/html/render/print_item.rs
index acbe3f22889..a7b57c373e3 100644
--- a/src/librustdoc/html/render/print_item.rs
+++ b/src/librustdoc/html/render/print_item.rs
@@ -732,7 +732,8 @@ fn item_trait(w: &mut Buffer, cx: &mut Context<'_>, it: &clean::Item, t: &clean:
         document(&mut content, cx, m, Some(t), HeadingOffset::H5);
         let toggled = !content.is_empty();
         if toggled {
-            write!(w, "<details class=\"rustdoc-toggle method-toggle\" open><summary>");
+            let method_toggle_class = if item_type.is_method() { " method-toggle" } else { "" };
+            write!(w, "<details class=\"rustdoc-toggle{method_toggle_class}\" open><summary>");
         }
         write!(w, "<section id=\"{}\" class=\"method has-srclink\">", id);
         render_rightside(w, cx, m, t, RenderMode::Normal);
diff --git a/src/librustdoc/html/static/js/main.js b/src/librustdoc/html/static/js/main.js
index 152116089c7..3f97e4e2e39 100644
--- a/src/librustdoc/html/static/js/main.js
+++ b/src/librustdoc/html/static/js/main.js
@@ -184,7 +184,6 @@ function browserSupportsHistoryApi() {
 function loadCss(cssUrl) {
     const link = document.createElement("link");
     link.href = cssUrl;
-    link.type = "text/css";
     link.rel = "stylesheet";
     document.getElementsByTagName("head")[0].appendChild(link);
 }
diff --git a/src/librustdoc/markdown.rs b/src/librustdoc/markdown.rs
index 044e051440c..5f4ad6d2aea 100644
--- a/src/librustdoc/markdown.rs
+++ b/src/librustdoc/markdown.rs
@@ -53,7 +53,7 @@ pub(crate) fn render<P: AsRef<Path>>(
 
     let mut css = String::new();
     for name in &options.markdown_css {
-        write!(css, r#"<link rel="stylesheet" type="text/css" href="{name}">"#)
+        write!(css, r#"<link rel="stylesheet" href="{name}">"#)
             .expect("Writing to a String can't fail");
     }
 
diff --git a/src/test/rustdoc-gui/docblock-code-block-line-number.goml b/src/test/rustdoc-gui/docblock-code-block-line-number.goml
index fec21ad35c3..b094c483876 100644
--- a/src/test/rustdoc-gui/docblock-code-block-line-number.goml
+++ b/src/test/rustdoc-gui/docblock-code-block-line-number.goml
@@ -33,7 +33,9 @@ assert-css: ("#settings", {"display": "block"})
 click: "input#line-numbers"
 wait-for: 100 // wait-for-false does not exist
 assert-false: "pre.example-line-numbers"
+assert-local-storage: {"rustdoc-line-numbers": "false" }
 
 // Finally, turn it on again.
 click: "input#line-numbers"
 wait-for: "pre.example-line-numbers"
+assert-local-storage: {"rustdoc-line-numbers": "true" }
diff --git a/src/test/rustdoc/toggle-trait-fn.rs b/src/test/rustdoc/toggle-trait-fn.rs
index e41422ce7c5..0a1f088b9ab 100644
--- a/src/test/rustdoc/toggle-trait-fn.rs
+++ b/src/test/rustdoc/toggle-trait-fn.rs
@@ -4,6 +4,8 @@
 // summary. Trait methods with no documentation should not be wrapped.
 //
 // @has foo/trait.Foo.html
+// @has - '//details[@class="rustdoc-toggle"]//summary//h4[@class="code-header"]' 'type Item'
+// @!has - '//details[@class="rustdoc-toggle"]//summary//h4[@class="code-header"]' 'type Item2'
 // @has -  '//details[@class="rustdoc-toggle method-toggle"]//summary//h4[@class="code-header"]' 'is_documented()'
 // @!has - '//details[@class="rustdoc-toggle method-toggle"]//summary//h4[@class="code-header"]' 'not_documented()'
 // @has -  '//details[@class="rustdoc-toggle method-toggle"]//*[@class="docblock"]' 'is_documented is documented'
@@ -11,6 +13,11 @@
 // @!has - '//details[@class="rustdoc-toggle method-toggle"]//summary//h4[@class="code-header"]' 'not_documented_optional()'
 // @has -  '//details[@class="rustdoc-toggle method-toggle"]//*[@class="docblock"]' 'is_documented_optional is documented'
 pub trait Foo {
+    /// is documented
+    type Item;
+
+    type Item2;
+
     fn not_documented();
 
     /// is_documented is documented
diff --git a/src/test/ui/expr/malformed_closure/ruby_style_closure.stderr b/src/test/ui/expr/malformed_closure/ruby_style_closure.stderr
index 759d79493a9..c7ed8e0de38 100644
--- a/src/test/ui/expr/malformed_closure/ruby_style_closure.stderr
+++ b/src/test/ui/expr/malformed_closure/ruby_style_closure.stderr
@@ -14,7 +14,7 @@ LL |       let p = Some(45).and_then({
 LL | |
 LL | |         |x| println!("doubling {}", x);
 LL | |         Some(x * 2)
-   | |         ----------- this tail expression is of type `std::option::Option<_>`
+   | |         ----------- this tail expression is of type `Option<_>`
 LL | |
 LL | |     });
    | |_____^ expected an `FnOnce<({integer},)>` closure, found `Option<_>`
diff --git a/src/test/ui/generic-associated-types/issue-101020.stderr b/src/test/ui/generic-associated-types/issue-101020.stderr
index b4e94cb83f7..422ac548427 100644
--- a/src/test/ui/generic-associated-types/issue-101020.stderr
+++ b/src/test/ui/generic-associated-types/issue-101020.stderr
@@ -1,10 +1,8 @@
 error[E0277]: the trait bound `for<'a> &'a mut (): Foo<&'a mut ()>` is not satisfied
-  --> $DIR/issue-101020.rs:31:5
+  --> $DIR/issue-101020.rs:31:22
    |
 LL |     (&mut EmptyIter).consume(());
-   |     ^^^^^^^^^^^^^^^^ ------- required by a bound introduced by this call
-   |     |
-   |     the trait `for<'a> Foo<&'a mut ()>` is not implemented for `&'a mut ()`
+   |                      ^^^^^^^ the trait `for<'a> Foo<&'a mut ()>` is not implemented for `&'a mut ()`
    |
 note: required for `&'a mut ()` to implement `for<'a> FuncInput<'a, &'a mut ()>`
   --> $DIR/issue-101020.rs:27:20
diff --git a/src/test/ui/issues/issue-20162.stderr b/src/test/ui/issues/issue-20162.stderr
index 3f9b3be9851..d70bf6e1d92 100644
--- a/src/test/ui/issues/issue-20162.stderr
+++ b/src/test/ui/issues/issue-20162.stderr
@@ -1,10 +1,8 @@
 error[E0277]: the trait bound `X: Ord` is not satisfied
-  --> $DIR/issue-20162.rs:5:5
+  --> $DIR/issue-20162.rs:5:7
    |
 LL |     b.sort();
-   |     ^ ---- required by a bound introduced by this call
-   |     |
-   |     the trait `Ord` is not implemented for `X`
+   |       ^^^^ the trait `Ord` is not implemented for `X`
    |
 note: required by a bound in `slice::<impl [T]>::sort`
   --> $SRC_DIR/alloc/src/slice.rs:LL:COL
diff --git a/src/test/ui/issues/issue-31173.rs b/src/test/ui/issues/issue-31173.rs
index 04efa27189b..f678df5b42b 100644
--- a/src/test/ui/issues/issue-31173.rs
+++ b/src/test/ui/issues/issue-31173.rs
@@ -4,12 +4,11 @@ pub fn get_tok(it: &mut IntoIter<u8>) {
     let mut found_e = false;
 
     let temp: Vec<u8> = it
-        //~^ ERROR to be an iterator that yields `&_`, but it yields `u8`
         .take_while(|&x| {
             found_e = true;
             false
         })
-        .cloned()
+        .cloned() //~ ERROR to be an iterator that yields `&_`, but it yields `u8`
         .collect(); //~ ERROR the method
 }
 
diff --git a/src/test/ui/issues/issue-31173.stderr b/src/test/ui/issues/issue-31173.stderr
index 58d9b564427..62d841f3789 100644
--- a/src/test/ui/issues/issue-31173.stderr
+++ b/src/test/ui/issues/issue-31173.stderr
@@ -1,16 +1,8 @@
-error[E0271]: expected `TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:8:21: 8:25]>` to be an iterator that yields `&_`, but it yields `u8`
-  --> $DIR/issue-31173.rs:6:25
-   |
-LL |       let temp: Vec<u8> = it
-   |  _________________________^
-LL | |
-LL | |         .take_while(|&x| {
-LL | |             found_e = true;
-LL | |             false
-LL | |         })
-   | |__________^ expected reference, found `u8`
-LL |           .cloned()
-   |            ------ required by a bound introduced by this call
+error[E0271]: expected `TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:7:21: 7:25]>` to be an iterator that yields `&_`, but it yields `u8`
+  --> $DIR/issue-31173.rs:11:10
+   |
+LL |         .cloned()
+   |          ^^^^^^ expected reference, found `u8`
    |
    = note: expected reference `&_`
                    found type `u8`
@@ -20,11 +12,11 @@ note: required by a bound in `cloned`
 LL |         Self: Sized + Iterator<Item = &'a T>,
    |                                ^^^^^^^^^^^^ required by this bound in `Iterator::cloned`
 
-error[E0599]: the method `collect` exists for struct `Cloned<TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:8:21: 8:25]>>`, but its trait bounds were not satisfied
-  --> $DIR/issue-31173.rs:13:10
+error[E0599]: the method `collect` exists for struct `Cloned<TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:7:21: 7:25]>>`, but its trait bounds were not satisfied
+  --> $DIR/issue-31173.rs:12:10
    |
 LL |         .collect();
-   |          ^^^^^^^ method cannot be called on `Cloned<TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:8:21: 8:25]>>` due to unsatisfied trait bounds
+   |          ^^^^^^^ 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
    |
   ::: $SRC_DIR/core/src/iter/adapters/take_while.rs:LL:COL
    |
@@ -37,10 +29,10 @@ LL | pub struct Cloned<I> {
    | -------------------- doesn't satisfy `_: Iterator`
    |
    = note: the following trait bounds were not satisfied:
-           `<TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:8:21: 8:25]> as Iterator>::Item = &_`
-           which is required by `Cloned<TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:8:21: 8:25]>>: Iterator`
-           `Cloned<TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:8:21: 8:25]>>: Iterator`
-           which is required by `&mut Cloned<TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:8:21: 8:25]>>: Iterator`
+           `<TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:7:21: 7:25]> as Iterator>::Item = &_`
+           which is required by `Cloned<TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:7:21: 7:25]>>: Iterator`
+           `Cloned<TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:7:21: 7:25]>>: Iterator`
+           which is required by `&mut Cloned<TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:7:21: 7:25]>>: Iterator`
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/issues/issue-33941.stderr b/src/test/ui/issues/issue-33941.stderr
index c28986a2985..73a9b786fe2 100644
--- a/src/test/ui/issues/issue-33941.stderr
+++ b/src/test/ui/issues/issue-33941.stderr
@@ -1,10 +1,8 @@
 error[E0271]: expected `std::collections::hash_map::Iter<'_, _, _>` to be an iterator that yields `&_`, but it yields `(&_, &_)`
-  --> $DIR/issue-33941.rs:6:14
+  --> $DIR/issue-33941.rs:6:36
    |
 LL |     for _ in HashMap::new().iter().cloned() {}
-   |              ^^^^^^^^^^^^^^^^^^^^^ ------ required by a bound introduced by this call
-   |              |
-   |              expected reference, found tuple
+   |                                    ^^^^^^ expected reference, found tuple
    |
    = note: expected reference `&_`
                   found tuple `(&_, &_)`
diff --git a/src/test/ui/issues/issue-34334.stderr b/src/test/ui/issues/issue-34334.stderr
index 3188cd80cca..b610e5c1366 100644
--- a/src/test/ui/issues/issue-34334.stderr
+++ b/src/test/ui/issues/issue-34334.stderr
@@ -13,15 +13,23 @@ LL |     let sr: Vec<(u32, _, _)> = vec![];
    |                            +
 
 error[E0277]: a value of type `Vec<(u32, _, _)>` cannot be built from an iterator over elements of type `()`
-  --> $DIR/issue-34334.rs:5:33
+  --> $DIR/issue-34334.rs:5:87
    |
 LL |     let sr2: Vec<(u32, _, _)> = sr.iter().map(|(faction, th_sender, th_receiver)| {}).collect();
-   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ------- required by a bound introduced by this call
-   |                                 |
-   |                                 value of type `Vec<(u32, _, _)>` cannot be built from `std::iter::Iterator<Item=()>`
+   |                                                                                       ^^^^^^^ value of type `Vec<(u32, _, _)>` cannot be built from `std::iter::Iterator<Item=()>`
    |
    = help: the trait `FromIterator<()>` is not implemented for `Vec<(u32, _, _)>`
    = help: the trait `FromIterator<T>` is implemented for `Vec<T>`
+note: the method call chain might not have had the expected associated types
+  --> $DIR/issue-34334.rs:5:43
+   |
+LL |     let sr: Vec<(u32, _, _) = vec![];
+   |                               ------ this expression has type `Vec<(_, _, _)>`
+...
+LL |     let sr2: Vec<(u32, _, _)> = sr.iter().map(|(faction, th_sender, th_receiver)| {}).collect();
+   |                                    ------ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `Iterator::Item` changed to `()` here
+   |                                    |
+   |                                    `Iterator::Item` is `&(_, _, _)` here
 note: required by a bound in `collect`
   --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
    |
diff --git a/src/test/ui/issues/issue-66923-show-error-for-correct-call.stderr b/src/test/ui/issues/issue-66923-show-error-for-correct-call.stderr
index ce38c3320bb..c6352978613 100644
--- a/src/test/ui/issues/issue-66923-show-error-for-correct-call.stderr
+++ b/src/test/ui/issues/issue-66923-show-error-for-correct-call.stderr
@@ -1,13 +1,18 @@
 error[E0277]: a value of type `Vec<f64>` cannot be built from an iterator over elements of type `&f64`
-  --> $DIR/issue-66923-show-error-for-correct-call.rs:8:24
+  --> $DIR/issue-66923-show-error-for-correct-call.rs:8:39
    |
 LL |     let x2: Vec<f64> = x1.into_iter().collect();
-   |                        ^^^^^^^^^^^^^^ ------- required by a bound introduced by this call
-   |                        |
-   |                        value of type `Vec<f64>` cannot be built from `std::iter::Iterator<Item=&f64>`
+   |                                       ^^^^^^^ value of type `Vec<f64>` cannot be built from `std::iter::Iterator<Item=&f64>`
    |
    = help: the trait `FromIterator<&f64>` is not implemented for `Vec<f64>`
    = help: the trait `FromIterator<T>` is implemented for `Vec<T>`
+note: the method call chain might not have had the expected associated types
+  --> $DIR/issue-66923-show-error-for-correct-call.rs:8:27
+   |
+LL |     let x1: &[f64] = &v;
+   |                      -- this expression has type `&Vec<f64>`
+LL |     let x2: Vec<f64> = x1.into_iter().collect();
+   |                           ^^^^^^^^^^^ `Iterator::Item` is `&f64` here
 note: required by a bound in `collect`
   --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
    |
@@ -15,15 +20,21 @@ LL |     fn collect<B: FromIterator<Self::Item>>(self) -> B
    |                   ^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `Iterator::collect`
 
 error[E0277]: a value of type `Vec<f64>` cannot be built from an iterator over elements of type `&f64`
-  --> $DIR/issue-66923-show-error-for-correct-call.rs:12:14
+  --> $DIR/issue-66923-show-error-for-correct-call.rs:12:29
    |
 LL |     let x3 = x1.into_iter().collect::<Vec<f64>>();
-   |              ^^^^^^^^^^^^^^ ------- required by a bound introduced by this call
-   |              |
-   |              value of type `Vec<f64>` cannot be built from `std::iter::Iterator<Item=&f64>`
+   |                             ^^^^^^^ value of type `Vec<f64>` cannot be built from `std::iter::Iterator<Item=&f64>`
    |
    = help: the trait `FromIterator<&f64>` is not implemented for `Vec<f64>`
    = help: the trait `FromIterator<T>` is implemented for `Vec<T>`
+note: the method call chain might not have had the expected associated types
+  --> $DIR/issue-66923-show-error-for-correct-call.rs:12:17
+   |
+LL |     let x1: &[f64] = &v;
+   |                      -- this expression has type `&Vec<f64>`
+...
+LL |     let x3 = x1.into_iter().collect::<Vec<f64>>();
+   |                 ^^^^^^^^^^^ `Iterator::Item` is `&f64` here
 note: required by a bound in `collect`
   --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
    |
diff --git a/src/test/ui/iterators/collect-into-array.rs b/src/test/ui/iterators/collect-into-array.rs
index 4c424999b75..99d0d9bd735 100644
--- a/src/test/ui/iterators/collect-into-array.rs
+++ b/src/test/ui/iterators/collect-into-array.rs
@@ -3,5 +3,4 @@ fn main() {
     //~^ ERROR an array of type `[u32; 10]` cannot be built directly from an iterator
     //~| NOTE try collecting into a `Vec<{integer}>`, then using `.try_into()`
     //~| NOTE required by a bound in `collect`
-    //~| NOTE required by a bound introduced by this call
 }
diff --git a/src/test/ui/iterators/collect-into-array.stderr b/src/test/ui/iterators/collect-into-array.stderr
index 544b1da178a..7a07fed1fae 100644
--- a/src/test/ui/iterators/collect-into-array.stderr
+++ b/src/test/ui/iterators/collect-into-array.stderr
@@ -1,10 +1,8 @@
 error[E0277]: an array of type `[u32; 10]` cannot be built directly from an iterator
-  --> $DIR/collect-into-array.rs:2:31
+  --> $DIR/collect-into-array.rs:2:39
    |
 LL |     let whatever: [u32; 10] = (0..10).collect();
-   |                               ^^^^^^^ ------- required by a bound introduced by this call
-   |                               |
-   |                               try collecting into a `Vec<{integer}>`, then using `.try_into()`
+   |                                       ^^^^^^^ try collecting into a `Vec<{integer}>`, then using `.try_into()`
    |
    = help: the trait `FromIterator<{integer}>` is not implemented for `[u32; 10]`
 note: required by a bound in `collect`
diff --git a/src/test/ui/iterators/collect-into-slice.rs b/src/test/ui/iterators/collect-into-slice.rs
index 09832c260d0..5a8aacb1a6d 100644
--- a/src/test/ui/iterators/collect-into-slice.rs
+++ b/src/test/ui/iterators/collect-into-slice.rs
@@ -13,6 +13,5 @@ fn main() {
     //~| NOTE all local variables must have a statically known size
     //~| NOTE doesn't have a size known at compile-time
     //~| NOTE doesn't have a size known at compile-time
-    //~| NOTE required by a bound introduced by this call
     process_slice(&some_generated_vec);
 }
diff --git a/src/test/ui/iterators/collect-into-slice.stderr b/src/test/ui/iterators/collect-into-slice.stderr
index 65ef124a463..58da222e039 100644
--- a/src/test/ui/iterators/collect-into-slice.stderr
+++ b/src/test/ui/iterators/collect-into-slice.stderr
@@ -22,12 +22,10 @@ LL |     fn collect<B: FromIterator<Self::Item>>(self) -> B
    |                ^ required by this bound in `Iterator::collect`
 
 error[E0277]: a slice of type `[i32]` cannot be built since `[i32]` has no definite size
-  --> $DIR/collect-into-slice.rs:6:30
+  --> $DIR/collect-into-slice.rs:6:38
    |
 LL |     let some_generated_vec = (0..10).collect();
-   |                              ^^^^^^^ ------- required by a bound introduced by this call
-   |                              |
-   |                              try explicitly collecting into a `Vec<{integer}>`
+   |                                      ^^^^^^^ try explicitly collecting into a `Vec<{integer}>`
    |
    = help: the trait `FromIterator<{integer}>` is not implemented for `[i32]`
 note: required by a bound in `collect`
diff --git a/src/test/ui/iterators/invalid-iterator-chain.rs b/src/test/ui/iterators/invalid-iterator-chain.rs
new file mode 100644
index 00000000000..87116e49245
--- /dev/null
+++ b/src/test/ui/iterators/invalid-iterator-chain.rs
@@ -0,0 +1,41 @@
+fn main() {
+    let scores = vec![(0, 0)]
+        .iter()
+        .map(|(a, b)| {
+            a + b;
+        });
+    println!("{}", scores.sum::<i32>()); //~ ERROR E0277
+    println!(
+        "{}",
+        vec![0, 1]
+            .iter()
+            .map(|x| x * 2)
+            .map(|x| x as f64)
+            .map(|x| x as i64)
+            .filter(|x| *x > 0)
+            .map(|x| { x + 1 })
+            .map(|x| { x; })
+            .sum::<i32>(), //~ ERROR E0277
+    );
+    println!(
+        "{}",
+        vec![0, 1]
+            .iter()
+            .map(|x| x * 2)
+            .map(|x| x as f64)
+            .filter(|x| *x > 0.0)
+            .map(|x| { x + 1.0 })
+            .sum::<i32>(), //~ ERROR E0277
+    );
+    println!("{}", vec![0, 1].iter().map(|x| { x; }).sum::<i32>()); //~ ERROR E0277
+    println!("{}", vec![(), ()].iter().sum::<i32>()); //~ ERROR E0277
+    let a = vec![0];
+    let b = a.into_iter();
+    let c = b.map(|x| x + 1);
+    let d = c.filter(|x| *x > 10 );
+    let e = d.map(|x| {
+        x + 1;
+    });
+    let f = e.filter(|_| false);
+    let g: Vec<i32> = f.collect(); //~ ERROR E0277
+}
diff --git a/src/test/ui/iterators/invalid-iterator-chain.stderr b/src/test/ui/iterators/invalid-iterator-chain.stderr
new file mode 100644
index 00000000000..49651b20fb1
--- /dev/null
+++ b/src/test/ui/iterators/invalid-iterator-chain.stderr
@@ -0,0 +1,176 @@
+error[E0277]: a value of type `i32` cannot be made by summing an iterator over elements of type `()`
+  --> $DIR/invalid-iterator-chain.rs:7:27
+   |
+LL |     println!("{}", scores.sum::<i32>());
+   |                           ^^^ value of type `i32` cannot be made by summing a `std::iter::Iterator<Item=()>`
+   |
+   = help: the trait `Sum<()>` is not implemented for `i32`
+   = help: the following other types implement trait `Sum<A>`:
+             <i32 as Sum<&'a i32>>
+             <i32 as Sum>
+note: the method call chain might not have had the expected associated types
+  --> $DIR/invalid-iterator-chain.rs:4:10
+   |
+LL |       let scores = vec![(0, 0)]
+   |                    ------------ this expression has type `Vec<({integer}, {integer})>`
+LL |           .iter()
+   |            ------ `Iterator::Item` is `&({integer}, {integer})` here
+LL |           .map(|(a, b)| {
+   |  __________^
+LL | |             a + b;
+LL | |         });
+   | |__________^ `Iterator::Item` changed to `()` here
+note: required by a bound in `std::iter::Iterator::sum`
+  --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
+   |
+LL |         S: Sum<Self::Item>,
+   |            ^^^^^^^^^^^^^^^ required by this bound in `Iterator::sum`
+
+error[E0277]: a value of type `i32` cannot be made by summing an iterator over elements of type `()`
+  --> $DIR/invalid-iterator-chain.rs:18:14
+   |
+LL |             .sum::<i32>(),
+   |              ^^^ value of type `i32` cannot be made by summing a `std::iter::Iterator<Item=()>`
+   |
+   = help: the trait `Sum<()>` is not implemented for `i32`
+   = help: the following other types implement trait `Sum<A>`:
+             <i32 as Sum<&'a i32>>
+             <i32 as Sum>
+note: the method call chain might not have had the expected associated types
+  --> $DIR/invalid-iterator-chain.rs:12:14
+   |
+LL |         vec![0, 1]
+   |         ---------- this expression has type `Vec<{integer}>`
+LL |             .iter()
+   |              ------ `Iterator::Item` is `&{integer}` here
+LL |             .map(|x| x * 2)
+   |              ^^^^^^^^^^^^^^ `Iterator::Item` changed to `{integer}` here
+LL |             .map(|x| x as f64)
+   |              ----------------- `Iterator::Item` changed to `f64` here
+LL |             .map(|x| x as i64)
+   |              ----------------- `Iterator::Item` changed to `i64` here
+LL |             .filter(|x| *x > 0)
+   |              ------------------ `Iterator::Item` remains `i64` here
+LL |             .map(|x| { x + 1 })
+   |              ------------------ `Iterator::Item` remains `i64` here
+LL |             .map(|x| { x; })
+   |              ^^^^^^^^^^^^^^^ `Iterator::Item` changed to `()` here
+note: required by a bound in `std::iter::Iterator::sum`
+  --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
+   |
+LL |         S: Sum<Self::Item>,
+   |            ^^^^^^^^^^^^^^^ required by this bound in `Iterator::sum`
+
+error[E0277]: a value of type `i32` cannot be made by summing an iterator over elements of type `f64`
+  --> $DIR/invalid-iterator-chain.rs:28:14
+   |
+LL |             .sum::<i32>(),
+   |              ^^^ value of type `i32` cannot be made by summing a `std::iter::Iterator<Item=f64>`
+   |
+   = help: the trait `Sum<f64>` is not implemented for `i32`
+   = help: the following other types implement trait `Sum<A>`:
+             <i32 as Sum<&'a i32>>
+             <i32 as Sum>
+note: the method call chain might not have had the expected associated types
+  --> $DIR/invalid-iterator-chain.rs:24:14
+   |
+LL |         vec![0, 1]
+   |         ---------- this expression has type `Vec<{integer}>`
+LL |             .iter()
+   |              ------ `Iterator::Item` is `&{integer}` here
+LL |             .map(|x| x * 2)
+   |              ^^^^^^^^^^^^^^ `Iterator::Item` changed to `{integer}` here
+LL |             .map(|x| x as f64)
+   |              ^^^^^^^^^^^^^^^^^ `Iterator::Item` changed to `f64` here
+LL |             .filter(|x| *x > 0.0)
+   |              -------------------- `Iterator::Item` remains `f64` here
+LL |             .map(|x| { x + 1.0 })
+   |              -------------------- `Iterator::Item` remains `f64` here
+note: required by a bound in `std::iter::Iterator::sum`
+  --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
+   |
+LL |         S: Sum<Self::Item>,
+   |            ^^^^^^^^^^^^^^^ required by this bound in `Iterator::sum`
+
+error[E0277]: a value of type `i32` cannot be made by summing an iterator over elements of type `()`
+  --> $DIR/invalid-iterator-chain.rs:30:54
+   |
+LL |     println!("{}", vec![0, 1].iter().map(|x| { x; }).sum::<i32>());
+   |                                                      ^^^ value of type `i32` cannot be made by summing a `std::iter::Iterator<Item=()>`
+   |
+   = help: the trait `Sum<()>` is not implemented for `i32`
+   = help: the following other types implement trait `Sum<A>`:
+             <i32 as Sum<&'a i32>>
+             <i32 as Sum>
+note: the method call chain might not have had the expected associated types
+  --> $DIR/invalid-iterator-chain.rs:30:38
+   |
+LL |     println!("{}", vec![0, 1].iter().map(|x| { x; }).sum::<i32>());
+   |                    ---------- ------ ^^^^^^^^^^^^^^^ `Iterator::Item` changed to `()` here
+   |                    |          |
+   |                    |          `Iterator::Item` is `&{integer}` here
+   |                    this expression has type `Vec<{integer}>`
+note: required by a bound in `std::iter::Iterator::sum`
+  --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
+   |
+LL |         S: Sum<Self::Item>,
+   |            ^^^^^^^^^^^^^^^ required by this bound in `Iterator::sum`
+
+error[E0277]: a value of type `i32` cannot be made by summing an iterator over elements of type `&()`
+  --> $DIR/invalid-iterator-chain.rs:31:40
+   |
+LL |     println!("{}", vec![(), ()].iter().sum::<i32>());
+   |                                        ^^^ value of type `i32` cannot be made by summing a `std::iter::Iterator<Item=&()>`
+   |
+   = help: the trait `Sum<&()>` is not implemented for `i32`
+   = help: the following other types implement trait `Sum<A>`:
+             <i32 as Sum<&'a i32>>
+             <i32 as Sum>
+note: the method call chain might not have had the expected associated types
+  --> $DIR/invalid-iterator-chain.rs:31:33
+   |
+LL |     println!("{}", vec![(), ()].iter().sum::<i32>());
+   |                    ------------ ^^^^^^ `Iterator::Item` is `&()` here
+   |                    |
+   |                    this expression has type `Vec<()>`
+note: required by a bound in `std::iter::Iterator::sum`
+  --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
+   |
+LL |         S: Sum<Self::Item>,
+   |            ^^^^^^^^^^^^^^^ required by this bound in `Iterator::sum`
+
+error[E0277]: a value of type `Vec<i32>` cannot be built from an iterator over elements of type `()`
+  --> $DIR/invalid-iterator-chain.rs:40:25
+   |
+LL |     let g: Vec<i32> = f.collect();
+   |                         ^^^^^^^ value of type `Vec<i32>` cannot be built from `std::iter::Iterator<Item=()>`
+   |
+   = help: the trait `FromIterator<()>` is not implemented for `Vec<i32>`
+   = help: the trait `FromIterator<T>` is implemented for `Vec<T>`
+note: the method call chain might not have had the expected associated types
+  --> $DIR/invalid-iterator-chain.rs:36:15
+   |
+LL |       let a = vec![0];
+   |               ------- this expression has type `Vec<{integer}>`
+LL |       let b = a.into_iter();
+   |                 ----------- `Iterator::Item` is `{integer}` here
+LL |       let c = b.map(|x| x + 1);
+   |                 -------------- `Iterator::Item` remains `{integer}` here
+LL |       let d = c.filter(|x| *x > 10 );
+   |                 -------------------- `Iterator::Item` remains `{integer}` here
+LL |       let e = d.map(|x| {
+   |  _______________^
+LL | |         x + 1;
+LL | |     });
+   | |______^ `Iterator::Item` changed to `()` here
+LL |       let f = e.filter(|_| false);
+   |                 ----------------- `Iterator::Item` remains `()` here
+note: required by a bound in `collect`
+  --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
+   |
+LL |     fn collect<B: FromIterator<Self::Item>>(self) -> B
+   |                   ^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `Iterator::collect`
+
+error: aborting due to 6 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/lazy-type-alias-impl-trait/branches.stderr b/src/test/ui/lazy-type-alias-impl-trait/branches.stderr
index 5a46027dd52..c66069c4d25 100644
--- a/src/test/ui/lazy-type-alias-impl-trait/branches.stderr
+++ b/src/test/ui/lazy-type-alias-impl-trait/branches.stderr
@@ -1,10 +1,8 @@
 error[E0277]: a value of type `Bar` cannot be built from an iterator over elements of type `_`
-  --> $DIR/branches.rs:19:9
+  --> $DIR/branches.rs:19:28
    |
 LL |         std::iter::empty().collect()
-   |         ^^^^^^^^^^^^^^^^^^ ------- required by a bound introduced by this call
-   |         |
-   |         value of type `Bar` cannot be built from `std::iter::Iterator<Item=_>`
+   |                            ^^^^^^^ value of type `Bar` cannot be built from `std::iter::Iterator<Item=_>`
    |
    = help: the trait `FromIterator<_>` is not implemented for `Bar`
 note: required by a bound in `collect`
diff --git a/src/test/ui/lazy-type-alias-impl-trait/recursion4.stderr b/src/test/ui/lazy-type-alias-impl-trait/recursion4.stderr
index a4b4968b7d2..a92c3a6809e 100644
--- a/src/test/ui/lazy-type-alias-impl-trait/recursion4.stderr
+++ b/src/test/ui/lazy-type-alias-impl-trait/recursion4.stderr
@@ -1,10 +1,8 @@
 error[E0277]: a value of type `Foo` cannot be built from an iterator over elements of type `_`
-  --> $DIR/recursion4.rs:10:9
+  --> $DIR/recursion4.rs:10:28
    |
 LL |     x = std::iter::empty().collect();
-   |         ^^^^^^^^^^^^^^^^^^ ------- required by a bound introduced by this call
-   |         |
-   |         value of type `Foo` cannot be built from `std::iter::Iterator<Item=_>`
+   |                            ^^^^^^^ value of type `Foo` cannot be built from `std::iter::Iterator<Item=_>`
    |
    = help: the trait `FromIterator<_>` is not implemented for `Foo`
 note: required by a bound in `collect`
@@ -14,12 +12,10 @@ LL |     fn collect<B: FromIterator<Self::Item>>(self) -> B
    |                   ^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `Iterator::collect`
 
 error[E0277]: a value of type `impl Debug` cannot be built from an iterator over elements of type `_`
-  --> $DIR/recursion4.rs:19:9
+  --> $DIR/recursion4.rs:19:28
    |
 LL |     x = std::iter::empty().collect();
-   |         ^^^^^^^^^^^^^^^^^^ ------- required by a bound introduced by this call
-   |         |
-   |         value of type `impl Debug` cannot be built from `std::iter::Iterator<Item=_>`
+   |                            ^^^^^^^ value of type `impl Debug` cannot be built from `std::iter::Iterator<Item=_>`
    |
    = help: the trait `FromIterator<_>` is not implemented for `impl Debug`
 note: required by a bound in `collect`
diff --git a/src/test/ui/mismatched_types/method-help-unsatisfied-bound.stderr b/src/test/ui/mismatched_types/method-help-unsatisfied-bound.stderr
index 36748fae13c..c2515c40b1d 100644
--- a/src/test/ui/mismatched_types/method-help-unsatisfied-bound.stderr
+++ b/src/test/ui/mismatched_types/method-help-unsatisfied-bound.stderr
@@ -1,10 +1,8 @@
 error[E0277]: `Foo` doesn't implement `Debug`
-  --> $DIR/method-help-unsatisfied-bound.rs:5:5
+  --> $DIR/method-help-unsatisfied-bound.rs:5:7
    |
 LL |     a.unwrap();
-   |     ^ ------ required by a bound introduced by this call
-   |     |
-   |     `Foo` cannot be formatted using `{:?}`
+   |       ^^^^^^ `Foo` cannot be formatted using `{:?}`
    |
    = help: the trait `Debug` is not implemented for `Foo`
    = note: add `#[derive(Debug)]` to `Foo` or manually `impl Debug for Foo`
diff --git a/src/test/ui/never_type/feature-gate-never_type_fallback.stderr b/src/test/ui/never_type/feature-gate-never_type_fallback.stderr
index 6dc039fc35d..2db1cc4b776 100644
--- a/src/test/ui/never_type/feature-gate-never_type_fallback.stderr
+++ b/src/test/ui/never_type/feature-gate-never_type_fallback.stderr
@@ -5,7 +5,7 @@ LL |     foo(panic!())
    |     --- ^^^^^^^^
    |     |   |
    |     |   the trait `T` is not implemented for `()`
-   |     |   this tail expression is of type `_`
+   |     |   this tail expression is of type `()`
    |     required by a bound introduced by this call
    |
 note: required by a bound in `foo`
diff --git a/src/test/ui/not-clone-closure.stderr b/src/test/ui/not-clone-closure.stderr
index f61ee661bb7..37d94cf0ebd 100644
--- a/src/test/ui/not-clone-closure.stderr
+++ b/src/test/ui/not-clone-closure.stderr
@@ -1,13 +1,11 @@
 error[E0277]: the trait bound `S: Clone` is not satisfied in `[closure@$DIR/not-clone-closure.rs:7:17: 7:24]`
-  --> $DIR/not-clone-closure.rs:11:17
+  --> $DIR/not-clone-closure.rs:11:23
    |
 LL |     let hello = move || {
    |                 ------- within this `[closure@$DIR/not-clone-closure.rs:7:17: 7:24]`
 ...
 LL |     let hello = hello.clone();
-   |                 ^^^^^ ----- required by a bound introduced by this call
-   |                 |
-   |                 within `[closure@$DIR/not-clone-closure.rs:7:17: 7:24]`, the trait `Clone` is not implemented for `S`
+   |                       ^^^^^ within `[closure@$DIR/not-clone-closure.rs:7:17: 7:24]`, the trait `Clone` is not implemented for `S`
    |
 note: required because it's used within this closure
   --> $DIR/not-clone-closure.rs:7:17
diff --git a/src/test/ui/on-unimplemented/sum.stderr b/src/test/ui/on-unimplemented/sum.stderr
index c3103671178..70706541ad6 100644
--- a/src/test/ui/on-unimplemented/sum.stderr
+++ b/src/test/ui/on-unimplemented/sum.stderr
@@ -1,15 +1,20 @@
 error[E0277]: a value of type `i32` cannot be made by summing an iterator over elements of type `&()`
-  --> $DIR/sum.rs:4:5
+  --> $DIR/sum.rs:4:25
    |
 LL |     vec![(), ()].iter().sum::<i32>();
-   |     ^^^^^^^^^^^^^^^^^^^ --- required by a bound introduced by this call
-   |     |
-   |     value of type `i32` cannot be made by summing a `std::iter::Iterator<Item=&()>`
+   |                         ^^^ value of type `i32` cannot be made by summing a `std::iter::Iterator<Item=&()>`
    |
    = help: the trait `Sum<&()>` is not implemented for `i32`
    = help: the following other types implement trait `Sum<A>`:
              <i32 as Sum<&'a i32>>
              <i32 as Sum>
+note: the method call chain might not have had the expected associated types
+  --> $DIR/sum.rs:4:18
+   |
+LL |     vec![(), ()].iter().sum::<i32>();
+   |     ------------ ^^^^^^ `Iterator::Item` is `&()` here
+   |     |
+   |     this expression has type `Vec<()>`
 note: required by a bound in `std::iter::Iterator::sum`
   --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
    |
@@ -17,17 +22,22 @@ LL |         S: Sum<Self::Item>,
    |            ^^^^^^^^^^^^^^^ required by this bound in `Iterator::sum`
 
 error[E0277]: a value of type `i32` cannot be made by multiplying all elements of type `&()` from an iterator
-  --> $DIR/sum.rs:7:5
+  --> $DIR/sum.rs:7:25
    |
 LL |     vec![(), ()].iter().product::<i32>();
-   |     ^^^^^^^^^^^^^^^^^^^ ------- required by a bound introduced by this call
-   |     |
-   |     value of type `i32` cannot be made by multiplying all elements from a `std::iter::Iterator<Item=&()>`
+   |                         ^^^^^^^ value of type `i32` cannot be made by multiplying all elements from a `std::iter::Iterator<Item=&()>`
    |
    = help: the trait `Product<&()>` is not implemented for `i32`
    = help: the following other types implement trait `Product<A>`:
              <i32 as Product<&'a i32>>
              <i32 as Product>
+note: the method call chain might not have had the expected associated types
+  --> $DIR/sum.rs:7:18
+   |
+LL |     vec![(), ()].iter().product::<i32>();
+   |     ------------ ^^^^^^ `Iterator::Item` is `&()` here
+   |     |
+   |     this expression has type `Vec<()>`
 note: required by a bound in `std::iter::Iterator::product`
   --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
    |
diff --git a/src/test/ui/resolve/issue-104700-inner_scope.rs b/src/test/ui/resolve/issue-104700-inner_scope.rs
new file mode 100644
index 00000000000..e8f28c113e3
--- /dev/null
+++ b/src/test/ui/resolve/issue-104700-inner_scope.rs
@@ -0,0 +1,11 @@
+fn main() {
+    let foo = 1;
+    {
+        let bar = 2;
+        let test_func = |x| x > 3;
+    }
+    if bar == 2 { //~ ERROR cannot find value
+        println!("yes");
+    }
+    test_func(1); //~ ERROR cannot find function
+}
diff --git a/src/test/ui/resolve/issue-104700-inner_scope.stderr b/src/test/ui/resolve/issue-104700-inner_scope.stderr
new file mode 100644
index 00000000000..051b234fc72
--- /dev/null
+++ b/src/test/ui/resolve/issue-104700-inner_scope.stderr
@@ -0,0 +1,21 @@
+error[E0425]: cannot find value `bar` in this scope
+  --> $DIR/issue-104700-inner_scope.rs:7:8
+   |
+LL |     if bar == 2 {
+   |        ^^^
+   |
+help: the binding `bar` is available in a different scope in the same function
+  --> $DIR/issue-104700-inner_scope.rs:4:13
+   |
+LL |         let bar = 2;
+   |             ^^^
+
+error[E0425]: cannot find function `test_func` in this scope
+  --> $DIR/issue-104700-inner_scope.rs:10:5
+   |
+LL |     test_func(1);
+   |     ^^^^^^^^^ not found in this scope
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0425`.
diff --git a/src/test/ui/rfc-2632-const-trait-impl/const-default-method-bodies.stderr b/src/test/ui/rfc-2632-const-trait-impl/const-default-method-bodies.stderr
index c64930db9be..f9d0d1f7875 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/const-default-method-bodies.stderr
+++ b/src/test/ui/rfc-2632-const-trait-impl/const-default-method-bodies.stderr
@@ -1,10 +1,8 @@
 error[E0277]: the trait bound `NonConstImpl: ~const ConstDefaultFn` is not satisfied
-  --> $DIR/const-default-method-bodies.rs:24:5
+  --> $DIR/const-default-method-bodies.rs:24:18
    |
 LL |     NonConstImpl.a();
-   |     ^^^^^^^^^^^^ - required by a bound introduced by this call
-   |     |
-   |     the trait `~const ConstDefaultFn` is not implemented for `NonConstImpl`
+   |                  ^ the trait `~const ConstDefaultFn` is not implemented for `NonConstImpl`
    |
 note: the trait `ConstDefaultFn` is implemented for `NonConstImpl`, but that implementation is not `const`
   --> $DIR/const-default-method-bodies.rs:24:5
diff --git a/src/test/ui/rfc-2632-const-trait-impl/cross-crate.gatednc.stderr b/src/test/ui/rfc-2632-const-trait-impl/cross-crate.gatednc.stderr
index 925ae53e324..633b7cc255a 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/cross-crate.gatednc.stderr
+++ b/src/test/ui/rfc-2632-const-trait-impl/cross-crate.gatednc.stderr
@@ -1,10 +1,8 @@
 error[E0277]: the trait bound `cross_crate::NonConst: ~const cross_crate::MyTrait` is not satisfied
-  --> $DIR/cross-crate.rs:17:5
+  --> $DIR/cross-crate.rs:17:14
    |
 LL |     NonConst.func();
-   |     ^^^^^^^^ ---- required by a bound introduced by this call
-   |     |
-   |     the trait `~const cross_crate::MyTrait` is not implemented for `cross_crate::NonConst`
+   |              ^^^^ the trait `~const cross_crate::MyTrait` is not implemented for `cross_crate::NonConst`
    |
 note: the trait `cross_crate::MyTrait` is implemented for `cross_crate::NonConst`, but that implementation is not `const`
   --> $DIR/cross-crate.rs:17:5
diff --git a/src/test/ui/rfc-2632-const-trait-impl/cross-crate.stocknc.stderr b/src/test/ui/rfc-2632-const-trait-impl/cross-crate.stocknc.stderr
index 11db0c2b8f2..9e97d3f1137 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/cross-crate.stocknc.stderr
+++ b/src/test/ui/rfc-2632-const-trait-impl/cross-crate.stocknc.stderr
@@ -1,10 +1,8 @@
 error[E0277]: the trait bound `cross_crate::NonConst: cross_crate::MyTrait` is not satisfied
-  --> $DIR/cross-crate.rs:17:5
+  --> $DIR/cross-crate.rs:17:14
    |
 LL |     NonConst.func();
-   |     ^^^^^^^^ ---- required by a bound introduced by this call
-   |     |
-   |     the trait `~const cross_crate::MyTrait` is not implemented for `cross_crate::NonConst`
+   |              ^^^^ the trait `~const cross_crate::MyTrait` is not implemented for `cross_crate::NonConst`
    |
 note: the trait `cross_crate::MyTrait` is implemented for `cross_crate::NonConst`, but that implementation is not `const`
   --> $DIR/cross-crate.rs:17:5
diff --git a/src/test/ui/rfc-2632-const-trait-impl/default-method-body-is-const-same-trait-ck.stderr b/src/test/ui/rfc-2632-const-trait-impl/default-method-body-is-const-same-trait-ck.stderr
index c2c16921c2e..21ecddaffbb 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/default-method-body-is-const-same-trait-ck.stderr
+++ b/src/test/ui/rfc-2632-const-trait-impl/default-method-body-is-const-same-trait-ck.stderr
@@ -1,10 +1,8 @@
 error[E0277]: the trait bound `(): ~const Tr` is not satisfied
-  --> $DIR/default-method-body-is-const-same-trait-ck.rs:8:9
+  --> $DIR/default-method-body-is-const-same-trait-ck.rs:8:12
    |
 LL |         ().a()
-   |         ^^ - required by a bound introduced by this call
-   |         |
-   |         the trait `~const Tr` is not implemented for `()`
+   |            ^ the trait `~const Tr` is not implemented for `()`
    |
 note: the trait `Tr` is implemented for `()`, but that implementation is not `const`
   --> $DIR/default-method-body-is-const-same-trait-ck.rs:8:9
diff --git a/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-2.yn.stderr b/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-2.yn.stderr
index b52eb2c0332..13fc719f28c 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-2.yn.stderr
+++ b/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-2.yn.stderr
@@ -1,10 +1,8 @@
 error[E0277]: the trait bound `T: ~const Foo` is not satisfied
-  --> $DIR/super-traits-fail-2.rs:15:5
+  --> $DIR/super-traits-fail-2.rs:15:7
    |
 LL |     x.a();
-   |     ^ - required by a bound introduced by this call
-   |     |
-   |     the trait `~const Foo` is not implemented for `T`
+   |       ^ the trait `~const Foo` is not implemented for `T`
    |
 note: the trait `Foo` is implemented for `T`, but that implementation is not `const`
   --> $DIR/super-traits-fail-2.rs:15:5
diff --git a/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-2.yy.stderr b/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-2.yy.stderr
index b52eb2c0332..13fc719f28c 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-2.yy.stderr
+++ b/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-2.yy.stderr
@@ -1,10 +1,8 @@
 error[E0277]: the trait bound `T: ~const Foo` is not satisfied
-  --> $DIR/super-traits-fail-2.rs:15:5
+  --> $DIR/super-traits-fail-2.rs:15:7
    |
 LL |     x.a();
-   |     ^ - required by a bound introduced by this call
-   |     |
-   |     the trait `~const Foo` is not implemented for `T`
+   |       ^ the trait `~const Foo` is not implemented for `T`
    |
 note: the trait `Foo` is implemented for `T`, but that implementation is not `const`
   --> $DIR/super-traits-fail-2.rs:15:5
diff --git a/src/test/ui/suggestions/issue-71394-no-from-impl.stderr b/src/test/ui/suggestions/issue-71394-no-from-impl.stderr
index 684db23e135..a5e6f5b5ffc 100644
--- a/src/test/ui/suggestions/issue-71394-no-from-impl.stderr
+++ b/src/test/ui/suggestions/issue-71394-no-from-impl.stderr
@@ -1,10 +1,8 @@
 error[E0277]: the trait bound `&[i8]: From<&[u8]>` is not satisfied
-  --> $DIR/issue-71394-no-from-impl.rs:3:20
+  --> $DIR/issue-71394-no-from-impl.rs:3:25
    |
 LL |     let _: &[i8] = data.into();
-   |                    ^^^^ ---- required by a bound introduced by this call
-   |                    |
-   |                    the trait `From<&[u8]>` is not implemented for `&[i8]`
+   |                         ^^^^ the trait `From<&[u8]>` is not implemented for `&[i8]`
    |
    = help: the following other types implement trait `From<T>`:
              <[T; LANES] as From<Simd<T, LANES>>>
diff --git a/src/test/ui/traits/issue-97576.stderr b/src/test/ui/traits/issue-97576.stderr
index 146d38d076a..9062a0fab63 100644
--- a/src/test/ui/traits/issue-97576.stderr
+++ b/src/test/ui/traits/issue-97576.stderr
@@ -1,10 +1,8 @@
 error[E0277]: the trait bound `String: From<impl ToString>` is not satisfied
-  --> $DIR/issue-97576.rs:8:18
+  --> $DIR/issue-97576.rs:8:22
    |
 LL |             bar: bar.into(),
-   |                  ^^^ ---- required by a bound introduced by this call
-   |                  |
-   |                  the trait `From<impl ToString>` is not implemented for `String`
+   |                      ^^^^ the trait `From<impl ToString>` is not implemented for `String`
    |
    = note: required for `impl ToString` to implement `Into<String>`
 
diff --git a/src/test/ui/unsized/issue-71659.stderr b/src/test/ui/unsized/issue-71659.stderr
index 50060e53a49..d7b95f55769 100644
--- a/src/test/ui/unsized/issue-71659.stderr
+++ b/src/test/ui/unsized/issue-71659.stderr
@@ -1,10 +1,8 @@
 error[E0277]: the trait bound `dyn Foo: CastTo<[i32]>` is not satisfied
-  --> $DIR/issue-71659.rs:30:13
+  --> $DIR/issue-71659.rs:30:15
    |
 LL |     let x = x.cast::<[i32]>();
-   |             ^ ---- required by a bound introduced by this call
-   |             |
-   |             the trait `CastTo<[i32]>` is not implemented for `dyn Foo`
+   |               ^^^^ the trait `CastTo<[i32]>` is not implemented for `dyn Foo`
    |
 note: required by a bound in `Cast::cast`
   --> $DIR/issue-71659.rs:19:15