Auto merge of #78028 - JohnTitor:rollup-jt3hikb, r=JohnTitor

Rollup of 10 pull requests

Successful merges:

 - #75209 (Suggest imports of unresolved macros)
 - #77547 (stabilize union with 'ManuallyDrop' fields and 'impl Drop for Union')
 - #77827 (Don't link to nightly primitives on stable channel)
 - #77855 (resolve: further improvements to "try using the enum's variant" diagnostic)
 - #77900 (Use fdatasync for File::sync_data on more OSes)
 - #77925 (Suggest minimal subset features in `incomplete_features` lint)
 - #77971 (Deny broken intra-doc links in linkchecker)
 - #77991 (Bump backtrace-rs)
 - #77992 (instrument-coverage: try our best to not ICE)
 - #78013 (Fix sidebar scroll on mobile devices)

Failed merges:

r? `@ghost`

154 files changed, 664 insertions, 272 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 5ca804cb739..0d2170a9927 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1744,6 +1744,10 @@ dependencies = [
 [[package]]
 name = "linkchecker"
 version = "0.1.0"
+dependencies = [
+ "once_cell",
+ "regex",
+]
 
 [[package]]
 name = "linked-hash-map"
diff --git a/compiler/rustc_error_codes/src/error_codes/E0660.md b/compiler/rustc_error_codes/src/error_codes/E0660.md
index fccd1b96f60..26d35f2620c 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0660.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0660.md
@@ -9,4 +9,4 @@ llvm_asm!("nop" "nop");
 Considering that this would be a long explanation, we instead recommend you
 take a look at the [`llvm_asm`] chapter of the Unstable book:
 
-[llvm_asm]: https://doc.rust-lang.org/stable/unstable-book/library-features/llvm-asm.html
+[`llvm_asm`]: https://doc.rust-lang.org/stable/unstable-book/library-features/llvm-asm.html
diff --git a/compiler/rustc_error_codes/src/error_codes/E0661.md b/compiler/rustc_error_codes/src/error_codes/E0661.md
index f1debee7a18..0b8ba7fbbed 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0661.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0661.md
@@ -10,4 +10,4 @@ llvm_asm!("nop" : "r"(a));
 Considering that this would be a long explanation, we instead recommend you
 take a look at the [`llvm_asm`] chapter of the Unstable book:
 
-[llvm_asm]: https://doc.rust-lang.org/stable/unstable-book/library-features/llvm-asm.html
+[`llvm_asm`]: https://doc.rust-lang.org/stable/unstable-book/library-features/llvm-asm.html
diff --git a/compiler/rustc_error_codes/src/error_codes/E0662.md b/compiler/rustc_error_codes/src/error_codes/E0662.md
index d4765f078b0..8c1bab8d041 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0662.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0662.md
@@ -13,4 +13,4 @@ llvm_asm!("xor %eax, %eax"
 Considering that this would be a long explanation, we instead recommend you
 take a look at the [`llvm_asm`] chapter of the Unstable book:
 
-[llvm_asm]: https://doc.rust-lang.org/stable/unstable-book/library-features/llvm-asm.html
+[`llvm_asm`]: https://doc.rust-lang.org/stable/unstable-book/library-features/llvm-asm.html
diff --git a/compiler/rustc_error_codes/src/error_codes/E0663.md b/compiler/rustc_error_codes/src/error_codes/E0663.md
index d5a85b275db..53ffd3373a5 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0663.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0663.md
@@ -13,4 +13,4 @@ llvm_asm!("xor %eax, %eax"
 Considering that this would be a long explanation, we instead recommend you
 take a look at the [`llvm_asm`] chapter of the Unstable book:
 
-[llvm_asm]: https://doc.rust-lang.org/stable/unstable-book/library-features/llvm-asm.html
+[`llvm_asm`]: https://doc.rust-lang.org/stable/unstable-book/library-features/llvm-asm.html
diff --git a/compiler/rustc_error_codes/src/error_codes/E0664.md b/compiler/rustc_error_codes/src/error_codes/E0664.md
index ce9c9491df3..f8e72cd330a 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0664.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0664.md
@@ -13,4 +13,4 @@ llvm_asm!("mov $$0x200, %eax"
 Considering that this would be a long explanation, we instead recommend you
 take a look at the [`llvm_asm`] chapter of the Unstable book:
 
-[llvm_asm]: https://doc.rust-lang.org/stable/unstable-book/library-features/llvm-asm.html
+[`llvm_asm`]: https://doc.rust-lang.org/stable/unstable-book/library-features/llvm-asm.html
diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index abd899e8db4..a7db9199665 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -2288,12 +2288,20 @@ impl EarlyLintPass for IncompleteFeatures {
                             n, n,
                         ));
                     }
+                    if HAS_MIN_FEATURES.contains(&name) {
+                        builder.help(&format!(
+                            "consider using `min_{}` instead, which is more stable and complete",
+                            name,
+                        ));
+                    }
                     builder.emit();
                 })
             });
     }
 }
 
+const HAS_MIN_FEATURES: &[Symbol] = &[sym::const_generics, sym::specialization];
+
 declare_lint! {
     /// The `invalid_value` lint detects creating a value that is not valid,
     /// such as a NULL reference.
diff --git a/compiler/rustc_mir/src/transform/instrument_coverage.rs b/compiler/rustc_mir/src/transform/instrument_coverage.rs
index babe10a0f14..6824c73ab60 100644
--- a/compiler/rustc_mir/src/transform/instrument_coverage.rs
+++ b/compiler/rustc_mir/src/transform/instrument_coverage.rs
@@ -22,9 +22,7 @@ use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::TyCtxt;
 use rustc_span::def_id::DefId;
 use rustc_span::source_map::original_sp;
-use rustc_span::{
-    BytePos, CharPos, FileName, Pos, RealFileName, SourceFile, Span, Symbol, SyntaxContext,
-};
+use rustc_span::{BytePos, CharPos, Pos, SourceFile, Span, Symbol, SyntaxContext};
 
 use std::cmp::Ordering;
 
@@ -549,13 +547,7 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
         let mir_body = &self.mir_body;
         let body_span = self.body_span();
         let source_file = source_map.lookup_source_file(body_span.lo());
-        let file_name = match &source_file.name {
-            FileName::Real(RealFileName::Named(path)) => Symbol::intern(&path.to_string_lossy()),
-            _ => bug!(
-                "source_file.name should be a RealFileName, but it was: {:?}",
-                source_file.name
-            ),
-        };
+        let file_name = Symbol::intern(&source_file.name.to_string());
 
         debug!("instrumenting {:?}, span: {}", def_id, source_map.span_to_string(body_span));
 
diff --git a/compiler/rustc_passes/src/stability.rs b/compiler/rustc_passes/src/stability.rs
index 1378b0d5705..c9497f2a5b2 100644
--- a/compiler/rustc_passes/src/stability.rs
+++ b/compiler/rustc_passes/src/stability.rs
@@ -13,15 +13,13 @@ use rustc_hir::{Generics, HirId, Item, StructField, TraitRef, Ty, TyKind, Varian
 use rustc_middle::hir::map::Map;
 use rustc_middle::middle::privacy::AccessLevels;
 use rustc_middle::middle::stability::{DeprecationEntry, Index};
-use rustc_middle::ty::query::Providers;
-use rustc_middle::ty::TyCtxt;
+use rustc_middle::ty::{self, query::Providers, TyCtxt};
 use rustc_session::lint;
 use rustc_session::lint::builtin::INEFFECTIVE_UNSTABLE_TRAIT_IMPL;
 use rustc_session::parse::feature_err;
 use rustc_session::Session;
 use rustc_span::symbol::{sym, Symbol};
-use rustc_span::Span;
-use rustc_trait_selection::traits::misc::can_type_implement_copy;
+use rustc_span::{Span, DUMMY_SP};
 
 use std::cmp::Ordering;
 use std::mem::replace;
@@ -711,27 +709,35 @@ impl Visitor<'tcx> for Checker<'tcx> {
             // so semi-randomly perform it here in stability.rs
             hir::ItemKind::Union(..) if !self.tcx.features().untagged_unions => {
                 let def_id = self.tcx.hir().local_def_id(item.hir_id);
-                let adt_def = self.tcx.adt_def(def_id);
                 let ty = self.tcx.type_of(def_id);
+                let (adt_def, substs) = match ty.kind() {
+                    ty::Adt(adt_def, substs) => (adt_def, substs),
+                    _ => bug!(),
+                };
 
-                if adt_def.has_dtor(self.tcx) {
-                    feature_err(
-                        &self.tcx.sess.parse_sess,
-                        sym::untagged_unions,
-                        item.span,
-                        "unions with `Drop` implementations are unstable",
-                    )
-                    .emit();
-                } else {
-                    let param_env = self.tcx.param_env(def_id);
-                    if can_type_implement_copy(self.tcx, param_env, ty).is_err() {
-                        feature_err(
-                            &self.tcx.sess.parse_sess,
-                            sym::untagged_unions,
-                            item.span,
-                            "unions with non-`Copy` fields are unstable",
-                        )
-                        .emit();
+                // Non-`Copy` fields are unstable, except for `ManuallyDrop`.
+                let param_env = self.tcx.param_env(def_id);
+                for field in &adt_def.non_enum_variant().fields {
+                    let field_ty = field.ty(self.tcx, substs);
+                    if !field_ty.ty_adt_def().map_or(false, |adt_def| adt_def.is_manually_drop())
+                        && !field_ty.is_copy_modulo_regions(self.tcx.at(DUMMY_SP), param_env)
+                    {
+                        if field_ty.needs_drop(self.tcx, param_env) {
+                            // Avoid duplicate error: This will error later anyway because fields
+                            // that need drop are not allowed.
+                            self.tcx.sess.delay_span_bug(
+                                item.span,
+                                "union should have been rejected due to potentially dropping field",
+                            );
+                        } else {
+                            feature_err(
+                                &self.tcx.sess.parse_sess,
+                                sym::untagged_unions,
+                                self.tcx.def_span(field.did),
+                                "unions with non-`Copy` fields other than `ManuallyDrop<T>` are unstable",
+                            )
+                            .emit();
+                        }
                     }
                 }
             }
diff --git a/compiler/rustc_resolve/src/diagnostics.rs b/compiler/rustc_resolve/src/diagnostics.rs
index 774a147c114..33ab09a8f42 100644
--- a/compiler/rustc_resolve/src/diagnostics.rs
+++ b/compiler/rustc_resolve/src/diagnostics.rs
@@ -922,6 +922,17 @@ impl<'a> Resolver<'a> {
         );
         self.add_typo_suggestion(err, suggestion, ident.span);
 
+        let import_suggestions = self.lookup_import_candidates(
+            ident,
+            Namespace::MacroNS,
+            parent_scope,
+            |res| match res {
+                Res::Def(DefKind::Macro(MacroKind::Bang), _) => true,
+                _ => false,
+            },
+        );
+        show_candidates(err, None, &import_suggestions, false, true);
+
         if macro_kind == MacroKind::Derive && (ident.name == sym::Send || ident.name == sym::Sync) {
             let msg = format!("unsafe traits like `{}` should be implemented explicitly", ident);
             err.span_note(ident.span, &msg);
diff --git a/compiler/rustc_resolve/src/late/diagnostics.rs b/compiler/rustc_resolve/src/late/diagnostics.rs
index bee05e77382..c24b383f3b8 100644
--- a/compiler/rustc_resolve/src/late/diagnostics.rs
+++ b/compiler/rustc_resolve/src/late/diagnostics.rs
@@ -1330,58 +1330,17 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
 
         let suggest_only_tuple_variants =
             matches!(source, PathSource::TupleStruct(..)) || source.is_call();
-        let mut suggestable_variants = if suggest_only_tuple_variants {
+        if suggest_only_tuple_variants {
             // Suggest only tuple variants regardless of whether they have fields and do not
             // suggest path with added parenthesis.
-            variants
+            let mut suggestable_variants = variants
                 .iter()
                 .filter(|(.., kind)| *kind == CtorKind::Fn)
                 .map(|(variant, ..)| path_names_to_string(variant))
-                .collect::<Vec<_>>()
-        } else {
-            variants
-                .iter()
-                .filter(|(_, def_id, kind)| {
-                    // Suggest only variants that have no fields (these can definitely
-                    // be constructed).
-                    let has_fields =
-                        self.r.field_names.get(&def_id).map(|f| f.is_empty()).unwrap_or(false);
-                    match kind {
-                        CtorKind::Const => true,
-                        CtorKind::Fn | CtorKind::Fictive if has_fields => true,
-                        _ => false,
-                    }
-                })
-                .map(|(variant, _, kind)| (path_names_to_string(variant), kind))
-                .map(|(variant_str, kind)| {
-                    // Add constructor syntax where appropriate.
-                    match kind {
-                        CtorKind::Const => variant_str,
-                        CtorKind::Fn => format!("({}())", variant_str),
-                        CtorKind::Fictive => format!("({} {{}})", variant_str),
-                    }
-                })
-                .collect::<Vec<_>>()
-        };
-
-        let non_suggestable_variant_count = variants.len() - suggestable_variants.len();
+                .collect::<Vec<_>>();
 
-        if !suggestable_variants.is_empty() {
-            let msg = if non_suggestable_variant_count == 0 && suggestable_variants.len() == 1 {
-                "try using the enum's variant"
-            } else {
-                "try using one of the enum's variants"
-            };
+            let non_suggestable_variant_count = variants.len() - suggestable_variants.len();
 
-            err.span_suggestions(
-                span,
-                msg,
-                suggestable_variants.drain(..),
-                Applicability::MaybeIncorrect,
-            );
-        }
-
-        if suggest_only_tuple_variants {
             let source_msg = if source.is_call() {
                 "to construct"
             } else if matches!(source, PathSource::TupleStruct(..)) {
@@ -1390,6 +1349,21 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
                 unreachable!()
             };
 
+            if !suggestable_variants.is_empty() {
+                let msg = if non_suggestable_variant_count == 0 && suggestable_variants.len() == 1 {
+                    format!("try {} the enum's variant", source_msg)
+                } else {
+                    format!("try {} one of the enum's variants", source_msg)
+                };
+
+                err.span_suggestions(
+                    span,
+                    &msg,
+                    suggestable_variants.drain(..),
+                    Applicability::MaybeIncorrect,
+                );
+            }
+
             // If the enum has no tuple variants..
             if non_suggestable_variant_count == variants.len() {
                 err.help(&format!("the enum has no tuple variants {}", source_msg));
@@ -1408,24 +1382,76 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
                 ));
             }
         } else {
-            let made_suggestion = non_suggestable_variant_count != variants.len();
-            if made_suggestion {
-                if non_suggestable_variant_count == 1 {
-                    err.help(
-                        "you might have meant to use the enum's other variant that has fields",
-                    );
-                } else if non_suggestable_variant_count >= 1 {
-                    err.help(
-                        "you might have meant to use one of the enum's other variants that \
-                         have fields",
-                    );
-                }
-            } else {
-                if non_suggestable_variant_count == 1 {
-                    err.help("you might have meant to use the enum's variant");
-                } else if non_suggestable_variant_count >= 1 {
-                    err.help("you might have meant to use one of the enum's variants");
+            let needs_placeholder = |def_id: DefId, kind: CtorKind| {
+                let has_no_fields =
+                    self.r.field_names.get(&def_id).map(|f| f.is_empty()).unwrap_or(false);
+                match kind {
+                    CtorKind::Const => false,
+                    CtorKind::Fn | CtorKind::Fictive if has_no_fields => false,
+                    _ => true,
                 }
+            };
+
+            let mut suggestable_variants = variants
+                .iter()
+                .filter(|(_, def_id, kind)| !needs_placeholder(*def_id, *kind))
+                .map(|(variant, _, kind)| (path_names_to_string(variant), kind))
+                .map(|(variant, kind)| match kind {
+                    CtorKind::Const => variant,
+                    CtorKind::Fn => format!("({}())", variant),
+                    CtorKind::Fictive => format!("({} {{}})", variant),
+                })
+                .collect::<Vec<_>>();
+
+            if !suggestable_variants.is_empty() {
+                let msg = if suggestable_variants.len() == 1 {
+                    "you might have meant to use the following enum variant"
+                } else {
+                    "you might have meant to use one of the following enum variants"
+                };
+
+                err.span_suggestions(
+                    span,
+                    msg,
+                    suggestable_variants.drain(..),
+                    Applicability::MaybeIncorrect,
+                );
+            }
+
+            let mut suggestable_variants_with_placeholders = variants
+                .iter()
+                .filter(|(_, def_id, kind)| needs_placeholder(*def_id, *kind))
+                .map(|(variant, _, kind)| (path_names_to_string(variant), kind))
+                .filter_map(|(variant, kind)| match kind {
+                    CtorKind::Fn => Some(format!("({}(/* fields */))", variant)),
+                    CtorKind::Fictive => Some(format!("({} {{ /* fields */ }})", variant)),
+                    _ => None,
+                })
+                .collect::<Vec<_>>();
+
+            if !suggestable_variants_with_placeholders.is_empty() {
+                let msg = match (
+                    suggestable_variants.is_empty(),
+                    suggestable_variants_with_placeholders.len(),
+                ) {
+                    (true, 1) => "the following enum variant is available",
+                    (true, _) => "the following enum variants are available",
+                    (false, 1) => "alternatively, the following enum variant is available",
+                    (false, _) => "alternatively, the following enum variants are also available",
+                };
+
+                err.span_suggestions(
+                    span,
+                    msg,
+                    suggestable_variants_with_placeholders.drain(..),
+                    Applicability::HasPlaceholders,
+                );
+            }
+        };
+
+        if def_id.is_local() {
+            if let Some(span) = self.def_span(def_id) {
+                err.span_note(span, "the enum is defined here");
             }
         }
     }
diff --git a/compiler/rustc_typeck/src/check/check.rs b/compiler/rustc_typeck/src/check/check.rs
index b9a5db47855..3d8653b4a6a 100644
--- a/compiler/rustc_typeck/src/check/check.rs
+++ b/compiler/rustc_typeck/src/check/check.rs
@@ -348,8 +348,7 @@ pub(super) fn check_union(tcx: TyCtxt<'_>, id: hir::HirId, span: Span) {
     check_packed(tcx, span, def);
 }
 
-/// When the `#![feature(untagged_unions)]` gate is active,
-/// check that the fields of the `union` does not contain fields that need dropping.
+/// Check that the fields of the `union` do not need dropping.
 pub(super) fn check_union_fields(tcx: TyCtxt<'_>, span: Span, item_def_id: LocalDefId) -> bool {
     let item_type = tcx.type_of(item_def_id);
     if let ty::Adt(def, substs) = item_type.kind() {
diff --git a/library/backtrace b/library/backtrace
-Subproject 893fbb23688e98376e54c26b59432a2966a8cc9
+Subproject a6dd47bd588c882e735675a1379d2b61719fa38
diff --git a/library/core/src/alloc/mod.rs b/library/core/src/alloc/mod.rs
index 6d09b4f0263..c61c19cc7d1 100644
--- a/library/core/src/alloc/mod.rs
+++ b/library/core/src/alloc/mod.rs
@@ -89,13 +89,11 @@ impl fmt::Display for AllocError {
 pub unsafe trait AllocRef {
     /// Attempts to allocate a block of memory.
     ///
-    /// On success, returns a [`NonNull<[u8]>`] meeting the size and alignment guarantees of `layout`.
+    /// On success, returns a [`NonNull<[u8]>`][NonNull] meeting the size and alignment guarantees of `layout`.
     ///
     /// The returned block may have a larger size than specified by `layout.size()`, and may or may
     /// not have its contents initialized.
     ///
-    /// [`NonNull<[u8]>`]: NonNull
-    ///
     /// # Errors
     ///
     /// Returning `Err` indicates that either memory is exhausted or `layout` does not meet
@@ -146,7 +144,7 @@ pub unsafe trait AllocRef {
 
     /// Attempts to extend the memory block.
     ///
-    /// Returns a new [`NonNull<[u8]>`] containing a pointer and the actual size of the allocated
+    /// Returns a new [`NonNull<[u8]>`][NonNull] containing a pointer and the actual size of the allocated
     /// memory. The pointer is suitable for holding data described by `new_layout`. To accomplish
     /// this, the allocator may extend the allocation referenced by `ptr` to fit the new layout.
     ///
@@ -158,8 +156,6 @@ pub unsafe trait AllocRef {
     /// If this method returns `Err`, then ownership of the memory block has not been transferred to
     /// this allocator, and the contents of the memory block are unaltered.
     ///
-    /// [`NonNull<[u8]>`]: NonNull
-    ///
     /// # Safety
     ///
     /// * `ptr` must denote a block of memory [*currently allocated*] via this allocator.
@@ -271,7 +267,7 @@ pub unsafe trait AllocRef {
 
     /// Attempts to shrink the memory block.
     ///
-    /// Returns a new [`NonNull<[u8]>`] containing a pointer and the actual size of the allocated
+    /// Returns a new [`NonNull<[u8]>`][NonNull] containing a pointer and the actual size of the allocated
     /// memory. The pointer is suitable for holding data described by `new_layout`. To accomplish
     /// this, the allocator may shrink the allocation referenced by `ptr` to fit the new layout.
     ///
@@ -283,8 +279,6 @@ pub unsafe trait AllocRef {
     /// If this method returns `Err`, then ownership of the memory block has not been transferred to
     /// this allocator, and the contents of the memory block are unaltered.
     ///
-    /// [`NonNull<[u8]>`]: NonNull
-    ///
     /// # Safety
     ///
     /// * `ptr` must denote a block of memory [*currently allocated*] via this allocator.
diff --git a/library/core/src/convert/mod.rs b/library/core/src/convert/mod.rs
index 2bfeb49b5fa..3f7110b34cc 100644
--- a/library/core/src/convert/mod.rs
+++ b/library/core/src/convert/mod.rs
@@ -134,6 +134,7 @@ pub const fn identity<T>(x: T) -> T {
 /// want to accept all references that can be converted to [`&str`] as an argument.
 /// Since both [`String`] and [`&str`] implement `AsRef<str>` we can accept both as input argument.
 ///
+/// [`&str`]: primitive@str
 /// [`Option<T>`]: Option
 /// [`Result<T, E>`]: Result
 /// [`Borrow`]: crate::borrow::Borrow
diff --git a/library/core/src/iter/traits/double_ended.rs b/library/core/src/iter/traits/double_ended.rs
index 16bee0e2eee..2253648ac2e 100644
--- a/library/core/src/iter/traits/double_ended.rs
+++ b/library/core/src/iter/traits/double_ended.rs
@@ -122,6 +122,9 @@ pub trait DoubleEndedIterator: Iterator {
     /// assert_eq!(iter.advance_back_by(0), Ok(()));
     /// assert_eq!(iter.advance_back_by(100), Err(1)); // only `&3` was skipped
     /// ```
+    ///
+    /// [`Ok(())`]: Ok
+    /// [`Err(k)`]: Err
     #[inline]
     #[unstable(feature = "iter_advance_by", reason = "recently added", issue = "77404")]
     fn advance_back_by(&mut self, n: usize) -> Result<(), usize> {
diff --git a/library/core/src/iter/traits/iterator.rs b/library/core/src/iter/traits/iterator.rs
index 813afcc0ec6..4af61111128 100644
--- a/library/core/src/iter/traits/iterator.rs
+++ b/library/core/src/iter/traits/iterator.rs
@@ -289,12 +289,12 @@ pub trait Iterator {
     /// This method will eagerly skip `n` elements by calling [`next`] up to `n`
     /// times until [`None`] is encountered.
     ///
-    /// `advance_by(n)` will return [`Ok(())`] if the iterator successfully advances by
-    /// `n` elements, or [`Err(k)`] if [`None`] is encountered, where `k` is the number
+    /// `advance_by(n)` will return [`Ok(())`][Ok] if the iterator successfully advances by
+    /// `n` elements, or [`Err(k)`][Err] if [`None`] is encountered, where `k` is the number
     /// of elements the iterator is advanced by before running out of elements (i.e. the
     /// length of the iterator). Note that `k` is always less than `n`.
     ///
-    /// Calling `advance_by(0)` does not consume any elements and always returns [`Ok(())`].
+    /// Calling `advance_by(0)` does not consume any elements and always returns [`Ok(())`][Ok].
     ///
     /// [`next`]: Iterator::next
     ///
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index 97f27566eb0..737a95b603b 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -131,7 +131,7 @@
 #![feature(transparent_unions)]
 #![feature(unboxed_closures)]
 #![feature(unsized_locals)]
-#![feature(untagged_unions)]
+#![cfg_attr(bootstrap, feature(untagged_unions))]
 #![feature(unwind_attributes)]
 #![feature(variant_count)]
 #![feature(tbm_target_feature)]
diff --git a/library/core/src/option.rs b/library/core/src/option.rs
index 9cb20a0afdc..825144e5a6f 100644
--- a/library/core/src/option.rs
+++ b/library/core/src/option.rs
@@ -687,6 +687,7 @@ impl<T> Option<T> {
     /// assert_eq!(Some(4).filter(is_even), Some(4));
     /// ```
     ///
+    /// [`Some(t)`]: Some
     #[inline]
     #[stable(feature = "option_filter", since = "1.27.0")]
     pub fn filter<P: FnOnce(&T) -> bool>(self, predicate: P) -> Self {
diff --git a/library/core/src/ptr/mod.rs b/library/core/src/ptr/mod.rs
index 92c4f2ccfe8..bca3be56ba5 100644
--- a/library/core/src/ptr/mod.rs
+++ b/library/core/src/ptr/mod.rs
@@ -229,6 +229,16 @@ pub(crate) struct FatPtr<T> {
     pub(crate) len: usize,
 }
 
+// Manual impl needed to avoid `T: Clone` bound.
+impl<T> Clone for FatPtr<T> {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+
+// Manual impl needed to avoid `T: Copy` bound.
+impl<T> Copy for FatPtr<T> {}
+
 /// Forms a raw slice from a pointer and a length.
 ///
 /// The `len` argument is the number of **elements**, not the number of bytes.
diff --git a/library/std/src/ffi/c_str.rs b/library/std/src/ffi/c_str.rs
index 13021738af1..6df4eb99259 100644
--- a/library/std/src/ffi/c_str.rs
+++ b/library/std/src/ffi/c_str.rs
@@ -1383,7 +1383,8 @@ impl CStr {
     /// [`U+FFFD REPLACEMENT CHARACTER`][U+FFFD] and return a
     /// [`Cow`]`::`[`Owned`]`(`[`String`]`)` with the result.
     ///
-    /// [`str`]: prim@str
+    /// [`str`]: primitive@str
+    /// [`&str`]: primitive@str
     /// [`Borrowed`]: Cow::Borrowed
     /// [`Owned`]: Cow::Owned
     /// [U+FFFD]: crate::char::REPLACEMENT_CHARACTER
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index 5224672adb2..30e7a7f3c3b 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -319,7 +319,7 @@
 #![feature(unsafe_block_in_unsafe_fn)]
 #![feature(unsafe_cell_get_mut)]
 #![feature(unsafe_cell_raw_get)]
-#![feature(untagged_unions)]
+#![cfg_attr(bootstrap, feature(untagged_unions))]
 #![feature(unwind_attributes)]
 #![feature(vec_into_raw_parts)]
 #![feature(wake_trait)]
diff --git a/library/std/src/sys/unix/fs.rs b/library/std/src/sys/unix/fs.rs
index 819e8ef1841..d27d6e2c565 100644
--- a/library/std/src/sys/unix/fs.rs
+++ b/library/std/src/sys/unix/fs.rs
@@ -787,11 +787,25 @@ impl File {
         unsafe fn os_datasync(fd: c_int) -> c_int {
             libc::fcntl(fd, libc::F_FULLFSYNC)
         }
-        #[cfg(target_os = "linux")]
+        #[cfg(any(
+            target_os = "freebsd",
+            target_os = "linux",
+            target_os = "android",
+            target_os = "netbsd",
+            target_os = "openbsd"
+        ))]
         unsafe fn os_datasync(fd: c_int) -> c_int {
             libc::fdatasync(fd)
         }
-        #[cfg(not(any(target_os = "macos", target_os = "ios", target_os = "linux")))]
+        #[cfg(not(any(
+            target_os = "android",
+            target_os = "freebsd",
+            target_os = "ios",
+            target_os = "linux",
+            target_os = "macos",
+            target_os = "netbsd",
+            target_os = "openbsd"
+        )))]
         unsafe fn os_datasync(fd: c_int) -> c_int {
             libc::fsync(fd)
         }
diff --git a/src/doc/embedded-book b/src/doc/embedded-book
-Subproject 79ab7776929c66db83203397958fa7037d5d9a3
+Subproject ca8169e69b479f615855d0eece7e318138fcfc0
diff --git a/src/doc/unstable-book/src/library-features/default-free-fn.md b/src/doc/unstable-book/src/library-features/default-free-fn.md
index 5dff73a94dd..d40a27dddf3 100644
--- a/src/doc/unstable-book/src/library-features/default-free-fn.md
+++ b/src/doc/unstable-book/src/library-features/default-free-fn.md
@@ -10,6 +10,8 @@ Adds a free `default()` function to the `std::default` module.  This function
 just forwards to [`Default::default()`], but may remove repetition of the word
 "default" from the call site.
 
+[`Default::default()`]: https://doc.rust-lang.org/nightly/std/default/trait.Default.html#tymethod.default
+
 Here is an example:
 
 ```rust
diff --git a/src/librustdoc/clean/types.rs b/src/librustdoc/clean/types.rs
index 3b72cf5c4f9..32b3f69ecd4 100644
--- a/src/librustdoc/clean/types.rs
+++ b/src/librustdoc/clean/types.rs
@@ -14,6 +14,7 @@ use rustc_ast::{self as ast, AttrStyle};
 use rustc_ast::{FloatTy, IntTy, UintTy};
 use rustc_attr::{Stability, StabilityLevel};
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+use rustc_feature::UnstableFeatures;
 use rustc_hir as hir;
 use rustc_hir::def::Res;
 use rustc_hir::def_id::{CrateNum, DefId, LOCAL_CRATE};
@@ -679,9 +680,13 @@ impl Attributes {
                                     "../".repeat(depth)
                                 }
                                 Some(&(_, _, ExternalLocation::Remote(ref s))) => s.to_string(),
-                                Some(&(_, _, ExternalLocation::Unknown)) | None => {
-                                    String::from("https://doc.rust-lang.org/nightly")
-                                }
+                                Some(&(_, _, ExternalLocation::Unknown)) | None => String::from(
+                                    if UnstableFeatures::from_environment().is_nightly_build() {
+                                        "https://doc.rust-lang.org/nightly"
+                                    } else {
+                                        "https://doc.rust-lang.org"
+                                    },
+                                ),
                             };
                             // This is a primitive so the url is done "by hand".
                             let tail = fragment.find('#').unwrap_or_else(|| fragment.len());
diff --git a/src/librustdoc/html/static/main.js b/src/librustdoc/html/static/main.js
index 1b3eb2011af..67e50bba1f2 100644
--- a/src/librustdoc/html/static/main.js
+++ b/src/librustdoc/html/static/main.js
@@ -2716,10 +2716,6 @@ function defocusSearchBar() {
         };
     }
 
-    window.onresize = function() {
-        hideSidebar();
-    };
-
     if (main) {
         onEachLazy(main.getElementsByClassName("loading-content"), function(e) {
             e.remove();
diff --git a/src/test/ui/array-slice-vec/match_arr_unknown_len.stderr b/src/test/ui/array-slice-vec/match_arr_unknown_len.stderr
index 0ad05b3adeb..7c1a92c79d9 100644
--- a/src/test/ui/array-slice-vec/match_arr_unknown_len.stderr
+++ b/src/test/ui/array-slice-vec/match_arr_unknown_len.stderr
@@ -6,6 +6,7 @@ LL | #![feature(const_generics)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error[E0308]: mismatched types
   --> $DIR/match_arr_unknown_len.rs:6:9
diff --git a/src/test/ui/associated-types/defaults-specialization.stderr b/src/test/ui/associated-types/defaults-specialization.stderr
index 09a8c8f8a88..920f8322813 100644
--- a/src/test/ui/associated-types/defaults-specialization.stderr
+++ b/src/test/ui/associated-types/defaults-specialization.stderr
@@ -6,6 +6,7 @@ LL | #![feature(associated_type_defaults, specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0053]: method `make` has an incompatible type for trait
   --> $DIR/defaults-specialization.rs:19:18
diff --git a/src/test/ui/binding/const-param.stderr b/src/test/ui/binding/const-param.stderr
index 316fac62325..d3d06a2d834 100644
--- a/src/test/ui/binding/const-param.stderr
+++ b/src/test/ui/binding/const-param.stderr
@@ -6,6 +6,7 @@ LL | #![feature(const_generics)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error[E0158]: const parameters cannot be referenced in patterns
   --> $DIR/const-param.rs:7:9
diff --git a/src/test/ui/coherence/coherence-inherited-assoc-ty-cycle-err.stderr b/src/test/ui/coherence/coherence-inherited-assoc-ty-cycle-err.stderr
index 7e140480b77..f3edf1c350f 100644
--- a/src/test/ui/coherence/coherence-inherited-assoc-ty-cycle-err.stderr
+++ b/src/test/ui/coherence/coherence-inherited-assoc-ty-cycle-err.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0391]: cycle detected when building specialization graph of trait `Trait`
   --> $DIR/coherence-inherited-assoc-ty-cycle-err.rs:9:1
diff --git a/src/test/ui/const-generics/defaults/wrong-order.full.stderr b/src/test/ui/const-generics/defaults/wrong-order.full.stderr
index c51028d5b20..99f46309bf6 100644
--- a/src/test/ui/const-generics/defaults/wrong-order.full.stderr
+++ b/src/test/ui/const-generics/defaults/wrong-order.full.stderr
@@ -14,6 +14,7 @@ LL | #![cfg_attr(full, feature(const_generics))]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error: aborting due to previous error; 1 warning emitted
 
diff --git a/src/test/ui/const-generics/issues/issue-56445.full.stderr b/src/test/ui/const-generics/issues/issue-56445.full.stderr
index d853ec5015e..50e91418551 100644
--- a/src/test/ui/const-generics/issues/issue-56445.full.stderr
+++ b/src/test/ui/const-generics/issues/issue-56445.full.stderr
@@ -6,6 +6,7 @@ LL | #![cfg_attr(full, feature(const_generics))]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error[E0771]: use of non-static lifetime `'a` in const generic
   --> $DIR/issue-56445.rs:9:26
diff --git a/src/test/ui/const-generics/issues/issue-60818-struct-constructors.full.stderr b/src/test/ui/const-generics/issues/issue-60818-struct-constructors.full.stderr
index c03b7252a3c..cc014ea429d 100644
--- a/src/test/ui/const-generics/issues/issue-60818-struct-constructors.full.stderr
+++ b/src/test/ui/const-generics/issues/issue-60818-struct-constructors.full.stderr
@@ -6,6 +6,7 @@ LL | #![cfg_attr(full, feature(const_generics))]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/const-generics/issues/issue-61336-1.full.stderr b/src/test/ui/const-generics/issues/issue-61336-1.full.stderr
index f18728eabbb..3a9f819a626 100644
--- a/src/test/ui/const-generics/issues/issue-61336-1.full.stderr
+++ b/src/test/ui/const-generics/issues/issue-61336-1.full.stderr
@@ -6,6 +6,7 @@ LL | #![cfg_attr(full, feature(const_generics))]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/const-generics/issues/issue-61336-2.full.stderr b/src/test/ui/const-generics/issues/issue-61336-2.full.stderr
index ef6e60084a5..883ebbef3e8 100644
--- a/src/test/ui/const-generics/issues/issue-61336-2.full.stderr
+++ b/src/test/ui/const-generics/issues/issue-61336-2.full.stderr
@@ -6,6 +6,7 @@ LL | #![cfg_attr(full, feature(const_generics))]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error[E0277]: the trait bound `T: Copy` is not satisfied
   --> $DIR/issue-61336-2.rs:10:5
diff --git a/src/test/ui/const-generics/issues/issue-61336.full.stderr b/src/test/ui/const-generics/issues/issue-61336.full.stderr
index bdfdffd941d..3863da8da05 100644
--- a/src/test/ui/const-generics/issues/issue-61336.full.stderr
+++ b/src/test/ui/const-generics/issues/issue-61336.full.stderr
@@ -6,6 +6,7 @@ LL | #![cfg_attr(full, feature(const_generics))]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error[E0277]: the trait bound `T: Copy` is not satisfied
   --> $DIR/issue-61336.rs:10:5
diff --git a/src/test/ui/const-generics/issues/issue-61422.full.stderr b/src/test/ui/const-generics/issues/issue-61422.full.stderr
index ac6c378295d..294378a6690 100644
--- a/src/test/ui/const-generics/issues/issue-61422.full.stderr
+++ b/src/test/ui/const-generics/issues/issue-61422.full.stderr
@@ -6,6 +6,7 @@ LL | #![cfg_attr(full, feature(const_generics))]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/const-generics/issues/issue-61432.full.stderr b/src/test/ui/const-generics/issues/issue-61432.full.stderr
index 82b36de45a2..eec1b20254e 100644
--- a/src/test/ui/const-generics/issues/issue-61432.full.stderr
+++ b/src/test/ui/const-generics/issues/issue-61432.full.stderr
@@ -6,6 +6,7 @@ LL | #![cfg_attr(full, feature(const_generics))]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/const-generics/issues/issue-61747.full.stderr b/src/test/ui/const-generics/issues/issue-61747.full.stderr
index 3ccce5675fc..3a266c8e974 100644
--- a/src/test/ui/const-generics/issues/issue-61747.full.stderr
+++ b/src/test/ui/const-generics/issues/issue-61747.full.stderr
@@ -6,6 +6,7 @@ LL | #![cfg_attr(full, feature(const_generics))]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error: constant expression depends on a generic parameter
   --> $DIR/issue-61747.rs:8:23
diff --git a/src/test/ui/const-generics/occurs-check/unify-fixpoint.stderr b/src/test/ui/const-generics/occurs-check/unify-fixpoint.stderr
index 671f1103dcc..8a1462c59e8 100644
--- a/src/test/ui/const-generics/occurs-check/unify-fixpoint.stderr
+++ b/src/test/ui/const-generics/occurs-check/unify-fixpoint.stderr
@@ -6,6 +6,7 @@ LL | #![feature(const_generics)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error: constant expression depends on a generic parameter
   --> $DIR/unify-fixpoint.rs:9:32
diff --git a/src/test/ui/consts/trait_specialization.stderr b/src/test/ui/consts/trait_specialization.stderr
index 03da7d512e5..e80821cf46a 100644
--- a/src/test/ui/consts/trait_specialization.stderr
+++ b/src/test/ui/consts/trait_specialization.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/did_you_mean/bad-assoc-ty.rs b/src/test/ui/did_you_mean/bad-assoc-ty.rs
index e66b432ede2..99ebe84cd9d 100644
--- a/src/test/ui/did_you_mean/bad-assoc-ty.rs
+++ b/src/test/ui/did_you_mean/bad-assoc-ty.rs
@@ -68,7 +68,6 @@ enum N<F> where F: Fn() -> _ {
 
 union O<F> where F: Fn() -> _ {
 //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
-//~| ERROR unions with non-`Copy` fields are unstable
     foo: F,
 }
 
diff --git a/src/test/ui/did_you_mean/bad-assoc-ty.stderr b/src/test/ui/did_you_mean/bad-assoc-ty.stderr
index 4835d9ab107..ebc0883370b 100644
--- a/src/test/ui/did_you_mean/bad-assoc-ty.stderr
+++ b/src/test/ui/did_you_mean/bad-assoc-ty.stderr
@@ -57,19 +57,6 @@ LL | type J = ty!(u8);
    |
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0658]: unions with non-`Copy` fields are unstable
-  --> $DIR/bad-assoc-ty.rs:69:1
-   |
-LL | / union O<F> where F: Fn() -> _ {
-LL | |
-LL | |
-LL | |     foo: F,
-LL | | }
-   | |_^
-   |
-   = note: see issue #55149 <https://github.com/rust-lang/rust/issues/55149> for more information
-   = help: add `#![feature(untagged_unions)]` to the crate attributes to enable
-
 error[E0223]: ambiguous associated type
   --> $DIR/bad-assoc-ty.rs:1:10
    |
@@ -215,7 +202,7 @@ LL | union O<F, T> where F: Fn() -> T {
    |          ^^^                   ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/bad-assoc-ty.rs:75:29
+  --> $DIR/bad-assoc-ty.rs:74:29
    |
 LL | trait P<F> where F: Fn() -> _ {
    |                             ^ not allowed in type signatures
@@ -226,7 +213,7 @@ LL | trait P<F, T> where F: Fn() -> T {
    |          ^^^                   ^
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
-  --> $DIR/bad-assoc-ty.rs:80:38
+  --> $DIR/bad-assoc-ty.rs:79:38
    |
 LL |     fn foo<F>(_: F) where F: Fn() -> _ {}
    |                                      ^ not allowed in type signatures
@@ -236,7 +223,7 @@ help: use type parameters instead
 LL |     fn foo<F, T>(_: F) where F: Fn() -> T {}
    |             ^^^                         ^
 
-error: aborting due to 29 previous errors
+error: aborting due to 28 previous errors
 
-Some errors have detailed explanations: E0121, E0223, E0658.
+Some errors have detailed explanations: E0121, E0223.
 For more information about an error, try `rustc --explain E0121`.
diff --git a/src/test/ui/did_you_mean/issue-43871-enum-instead-of-variant.stderr b/src/test/ui/did_you_mean/issue-43871-enum-instead-of-variant.stderr
index e1325b789d2..bca493e67d5 100644
--- a/src/test/ui/did_you_mean/issue-43871-enum-instead-of-variant.stderr
+++ b/src/test/ui/did_you_mean/issue-43871-enum-instead-of-variant.stderr
@@ -2,7 +2,7 @@ error[E0423]: expected function, tuple struct or tuple variant, found enum `Opti
   --> $DIR/issue-43871-enum-instead-of-variant.rs:19:13
    |
 LL |     let x = Option(1);
-   |             ^^^^^^ help: try using one of the enum's variants: `std::option::Option::Some`
+   |             ^^^^^^ help: try to construct one of the enum's variants: `std::option::Option::Some`
    |
    = help: you might have meant to construct the enum's non-tuple variant
 
@@ -10,7 +10,7 @@ error[E0532]: expected tuple struct or tuple variant, found enum `Option`
   --> $DIR/issue-43871-enum-instead-of-variant.rs:21:12
    |
 LL |     if let Option(_) = x {
-   |            ^^^^^^ help: try using one of the enum's variants: `std::option::Option::Some`
+   |            ^^^^^^ help: try to match against one of the enum's variants: `std::option::Option::Some`
    |
    = help: you might have meant to match against the enum's non-tuple variant
 
@@ -18,9 +18,14 @@ error[E0532]: expected tuple struct or tuple variant, found enum `Example`
   --> $DIR/issue-43871-enum-instead-of-variant.rs:27:12
    |
 LL |     if let Example(_) = y {
-   |            ^^^^^^^ help: try using one of the enum's variants: `Example::Ex`
+   |            ^^^^^^^ help: try to match against one of the enum's variants: `Example::Ex`
    |
    = help: you might have meant to match against the enum's non-tuple variant
+note: the enum is defined here
+  --> $DIR/issue-43871-enum-instead-of-variant.rs:1:1
+   |
+LL | enum Example { Ex(String), NotEx }
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0423]: expected function, tuple struct or tuple variant, found enum `Void`
   --> $DIR/issue-43871-enum-instead-of-variant.rs:31:13
@@ -29,6 +34,11 @@ LL |     let y = Void();
    |             ^^^^
    |
    = help: the enum has no tuple variants to construct
+note: the enum is defined here
+  --> $DIR/issue-43871-enum-instead-of-variant.rs:3:1
+   |
+LL | enum Void {}
+   | ^^^^^^^^^^^^
 
 error[E0423]: expected function, tuple struct or tuple variant, found enum `ManyVariants`
   --> $DIR/issue-43871-enum-instead-of-variant.rs:33:13
@@ -38,6 +48,17 @@ LL |     let z = ManyVariants();
    |
    = help: the enum has no tuple variants to construct
    = help: you might have meant to construct one of the enum's non-tuple variants
+note: the enum is defined here
+  --> $DIR/issue-43871-enum-instead-of-variant.rs:5:1
+   |
+LL | / enum ManyVariants {
+LL | |     One,
+LL | |     Two,
+LL | |     Three,
+...  |
+LL | |     Ten,
+LL | | }
+   | |_^
 
 error: aborting due to 5 previous errors
 
diff --git a/src/test/ui/drop/dynamic-drop.rs b/src/test/ui/drop/dynamic-drop.rs
index ada61bf0df0..6d0cd101dbc 100644
--- a/src/test/ui/drop/dynamic-drop.rs
+++ b/src/test/ui/drop/dynamic-drop.rs
@@ -1,7 +1,7 @@
 // run-pass
 // ignore-wasm32-bare compiled with panic=abort by default
 
-#![feature(generators, generator_trait, untagged_unions)]
+#![feature(generators, generator_trait)]
 #![feature(bindings_after_at)]
 
 #![allow(unused_assignments)]
diff --git a/src/test/ui/dropck/dropck-union.rs b/src/test/ui/dropck/dropck-union.rs
index ef4d1b360b8..5a9965db5ed 100644
--- a/src/test/ui/dropck/dropck-union.rs
+++ b/src/test/ui/dropck/dropck-union.rs
@@ -1,5 +1,3 @@
-#![feature(untagged_unions)]
-
 use std::cell::Cell;
 use std::ops::Deref;
 use std::mem::ManuallyDrop;
diff --git a/src/test/ui/dropck/dropck-union.stderr b/src/test/ui/dropck/dropck-union.stderr
index 228744326f9..854e29385a8 100644
--- a/src/test/ui/dropck/dropck-union.stderr
+++ b/src/test/ui/dropck/dropck-union.stderr
@@ -1,5 +1,5 @@
 error[E0597]: `v` does not live long enough
-  --> $DIR/dropck-union.rs:39:18
+  --> $DIR/dropck-union.rs:37:18
    |
 LL |     v.0.set(Some(&v));
    |                  ^^ borrowed value does not live long enough
diff --git a/src/test/ui/empty/empty-macro-use.stderr b/src/test/ui/empty/empty-macro-use.stderr
index 8e3e06896ee..700f6616af4 100644
--- a/src/test/ui/empty/empty-macro-use.stderr
+++ b/src/test/ui/empty/empty-macro-use.stderr
@@ -3,6 +3,9 @@ error: cannot find macro `macro_two` in this scope
    |
 LL |     macro_two!();
    |     ^^^^^^^^^
+   |
+   = note: consider importing this macro:
+           two_macros::macro_two
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/error-codes/E0520.stderr b/src/test/ui/error-codes/E0520.stderr
index 1041ccee937..be7b95465a5 100644
--- a/src/test/ui/error-codes/E0520.stderr
+++ b/src/test/ui/error-codes/E0520.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0520]: `fly` specializes an item from a parent `impl`, but that item is not marked `default`
   --> $DIR/E0520.rs:17:5
diff --git a/src/test/ui/error-codes/E0730.stderr b/src/test/ui/error-codes/E0730.stderr
index f915f6edef5..356e4f36042 100644
--- a/src/test/ui/error-codes/E0730.stderr
+++ b/src/test/ui/error-codes/E0730.stderr
@@ -6,6 +6,7 @@ LL | #![feature(const_generics)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error[E0730]: cannot pattern-match on an array without a fixed length
   --> $DIR/E0730.rs:6:9
diff --git a/src/test/ui/error-codes/E0771.stderr b/src/test/ui/error-codes/E0771.stderr
index 60220be6b57..b184b599817 100644
--- a/src/test/ui/error-codes/E0771.stderr
+++ b/src/test/ui/error-codes/E0771.stderr
@@ -6,6 +6,7 @@ LL | #![feature(const_generics)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error[E0771]: use of non-static lifetime `'a` in const generic
   --> $DIR/E0771.rs:4:41
diff --git a/src/test/ui/feature-gates/feature-gate-untagged_unions.rs b/src/test/ui/feature-gates/feature-gate-untagged_unions.rs
index 9ee0e6f681d..f5f9631c3bc 100644
--- a/src/test/ui/feature-gates/feature-gate-untagged_unions.rs
+++ b/src/test/ui/feature-gates/feature-gate-untagged_unions.rs
@@ -1,3 +1,5 @@
+// ignore-tidy-linelength
+
 union U1 { // OK
     a: u8,
 }
@@ -6,15 +8,23 @@ union U2<T: Copy> { // OK
     a: T,
 }
 
-union U3 { //~ ERROR unions with non-`Copy` fields are unstable
+union U22<T> { // OK
+    a: std::mem::ManuallyDrop<T>,
+}
+
+union U3 {
     a: String, //~ ERROR unions may not contain fields that need dropping
 }
 
-union U4<T> { //~ ERROR unions with non-`Copy` fields are unstable
+union U32 { // field that does not drop but is not `Copy`, either -- this is the real feature gate test!
+    a: std::cell::RefCell<i32>, //~ ERROR unions with non-`Copy` fields other than `ManuallyDrop<T>` are unstable
+}
+
+union U4<T> {
     a: T, //~ ERROR unions may not contain fields that need dropping
 }
 
-union U5 { //~ ERROR unions with `Drop` implementations are unstable
+union U5 { // Having a drop impl is OK
     a: u8,
 }
 
diff --git a/src/test/ui/feature-gates/feature-gate-untagged_unions.stderr b/src/test/ui/feature-gates/feature-gate-untagged_unions.stderr
index 3a123ea1c93..ed973871b3f 100644
--- a/src/test/ui/feature-gates/feature-gate-untagged_unions.stderr
+++ b/src/test/ui/feature-gates/feature-gate-untagged_unions.stderr
@@ -1,61 +1,37 @@
-error[E0658]: unions with non-`Copy` fields are unstable
-  --> $DIR/feature-gate-untagged_unions.rs:9:1
+error[E0658]: unions with non-`Copy` fields other than `ManuallyDrop<T>` are unstable
+  --> $DIR/feature-gate-untagged_unions.rs:20:5
    |
-LL | / union U3 {
-LL | |     a: String,
-LL | | }
-   | |_^
-   |
-   = note: see issue #55149 <https://github.com/rust-lang/rust/issues/55149> for more information
-   = help: add `#![feature(untagged_unions)]` to the crate attributes to enable
-
-error[E0658]: unions with non-`Copy` fields are unstable
-  --> $DIR/feature-gate-untagged_unions.rs:13:1
-   |
-LL | / union U4<T> {
-LL | |     a: T,
-LL | | }
-   | |_^
-   |
-   = note: see issue #55149 <https://github.com/rust-lang/rust/issues/55149> for more information
-   = help: add `#![feature(untagged_unions)]` to the crate attributes to enable
-
-error[E0658]: unions with `Drop` implementations are unstable
-  --> $DIR/feature-gate-untagged_unions.rs:17:1
-   |
-LL | / union U5 {
-LL | |     a: u8,
-LL | | }
-   | |_^
+LL |     a: std::cell::RefCell<i32>,
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: see issue #55149 <https://github.com/rust-lang/rust/issues/55149> for more information
    = help: add `#![feature(untagged_unions)]` to the crate attributes to enable
 
 error[E0740]: unions may not contain fields that need dropping
-  --> $DIR/feature-gate-untagged_unions.rs:10:5
+  --> $DIR/feature-gate-untagged_unions.rs:16:5
    |
 LL |     a: String,
    |     ^^^^^^^^^
    |
 note: `std::mem::ManuallyDrop` can be used to wrap the type
-  --> $DIR/feature-gate-untagged_unions.rs:10:5
+  --> $DIR/feature-gate-untagged_unions.rs:16:5
    |
 LL |     a: String,
    |     ^^^^^^^^^
 
 error[E0740]: unions may not contain fields that need dropping
-  --> $DIR/feature-gate-untagged_unions.rs:14:5
+  --> $DIR/feature-gate-untagged_unions.rs:24:5
    |
 LL |     a: T,
    |     ^^^^
    |
 note: `std::mem::ManuallyDrop` can be used to wrap the type
-  --> $DIR/feature-gate-untagged_unions.rs:14:5
+  --> $DIR/feature-gate-untagged_unions.rs:24:5
    |
 LL |     a: T,
    |     ^^^^
 
-error: aborting due to 5 previous errors
+error: aborting due to 3 previous errors
 
 Some errors have detailed explanations: E0658, E0740.
 For more information about an error, try `rustc --explain E0658`.
diff --git a/src/test/ui/glob-resolve1.stderr b/src/test/ui/glob-resolve1.stderr
index 3c818f3ae48..cd128c1ea0b 100644
--- a/src/test/ui/glob-resolve1.stderr
+++ b/src/test/ui/glob-resolve1.stderr
@@ -24,7 +24,17 @@ error[E0423]: expected value, found enum `B`
   --> $DIR/glob-resolve1.rs:24:5
    |
 LL |     B;
-   |     ^ help: try using the enum's variant: `B::B1`
+   |     ^
+   |
+note: the enum is defined here
+  --> $DIR/glob-resolve1.rs:12:5
+   |
+LL |     pub enum B { B1 }
+   |     ^^^^^^^^^^^^^^^^^
+help: you might have meant to use the following enum variant
+   |
+LL |     B::B1;
+   |     ^^^^^
 
 error[E0425]: cannot find value `C` in this scope
   --> $DIR/glob-resolve1.rs:25:5
diff --git a/src/test/ui/hygiene/generic_params.stderr b/src/test/ui/hygiene/generic_params.stderr
index 4ca6d199835..6de36deb597 100644
--- a/src/test/ui/hygiene/generic_params.stderr
+++ b/src/test/ui/hygiene/generic_params.stderr
@@ -6,6 +6,7 @@ LL | #![feature(decl_macro, rustc_attrs, const_generics)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/hygiene/issue-61574-const-parameters.stderr b/src/test/ui/hygiene/issue-61574-const-parameters.stderr
index b351b8b73a0..3f85383eb33 100644
--- a/src/test/ui/hygiene/issue-61574-const-parameters.stderr
+++ b/src/test/ui/hygiene/issue-61574-const-parameters.stderr
@@ -6,6 +6,7 @@ LL | #![feature(const_generics)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/hygiene/no_implicit_prelude-2018.stderr b/src/test/ui/hygiene/no_implicit_prelude-2018.stderr
index f31b75238df..02ddc391f6e 100644
--- a/src/test/ui/hygiene/no_implicit_prelude-2018.stderr
+++ b/src/test/ui/hygiene/no_implicit_prelude-2018.stderr
@@ -3,6 +3,9 @@ error: cannot find macro `print` in this scope
    |
 LL |         print!();
    |         ^^^^^
+   |
+   = note: consider importing this macro:
+           std::print
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/hygiene/no_implicit_prelude.stderr b/src/test/ui/hygiene/no_implicit_prelude.stderr
index 3c0c0450774..843dee2478b 100644
--- a/src/test/ui/hygiene/no_implicit_prelude.stderr
+++ b/src/test/ui/hygiene/no_implicit_prelude.stderr
@@ -4,6 +4,9 @@ error: cannot find macro `panic` in this scope
 LL |         assert_eq!(0, 0);
    |         ^^^^^^^^^^^^^^^^^
    |
+   = note: consider importing one of these items:
+           core::panic
+           std::panic
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0433]: failed to resolve: use of undeclared type `Vec`
diff --git a/src/test/ui/impl-trait/equality-rpass.stderr b/src/test/ui/impl-trait/equality-rpass.stderr
index 1abf05dca82..11eeceba0ee 100644
--- a/src/test/ui/impl-trait/equality-rpass.stderr
+++ b/src/test/ui/impl-trait/equality-rpass.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/impl-trait/equality.stderr b/src/test/ui/impl-trait/equality.stderr
index cdaa61ac323..536a4726c6d 100644
--- a/src/test/ui/impl-trait/equality.stderr
+++ b/src/test/ui/impl-trait/equality.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0308]: mismatched types
   --> $DIR/equality.rs:15:5
diff --git a/src/test/ui/impl-trait/equality2.stderr b/src/test/ui/impl-trait/equality2.stderr
index 1780931efc5..1443b76048b 100644
--- a/src/test/ui/impl-trait/equality2.stderr
+++ b/src/test/ui/impl-trait/equality2.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0308]: mismatched types
   --> $DIR/equality2.rs:25:18
diff --git a/src/test/ui/issues/issue-35376.stderr b/src/test/ui/issues/issue-35376.stderr
index 06c31f3bae0..835277d408e 100644
--- a/src/test/ui/issues/issue-35376.stderr
+++ b/src/test/ui/issues/issue-35376.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/issues/issue-55380.stderr b/src/test/ui/issues/issue-55380.stderr
index 451beebd106..65e94d79670 100644
--- a/src/test/ui/issues/issue-55380.stderr
+++ b/src/test/ui/issues/issue-55380.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/issues/issue-59508-1.stderr b/src/test/ui/issues/issue-59508-1.stderr
index 5e97339f148..2a4ccda8929 100644
--- a/src/test/ui/issues/issue-59508-1.stderr
+++ b/src/test/ui/issues/issue-59508-1.stderr
@@ -12,6 +12,7 @@ LL | #![feature(const_generics)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error: aborting due to previous error; 1 warning emitted
 
diff --git a/src/test/ui/issues/issue-73427.stderr b/src/test/ui/issues/issue-73427.stderr
index 88d19943f02..4b5f65b3461 100644
--- a/src/test/ui/issues/issue-73427.stderr
+++ b/src/test/ui/issues/issue-73427.stderr
@@ -4,8 +4,18 @@ error[E0423]: expected value, found enum `A`
 LL |     A.foo();
    |     ^
    |
-   = help: you might have meant to use one of the enum's other variants that have fields
-help: try using one of the enum's variants
+note: the enum is defined here
+  --> $DIR/issue-73427.rs:1:1
+   |
+LL | / enum A {
+LL | |     StructWithFields { x: () },
+LL | |     TupleWithFields(()),
+LL | |     Struct {},
+LL | |     Tuple(),
+LL | |     Unit,
+LL | | }
+   | |_^
+help: you might have meant to use one of the following enum variants
    |
 LL |     (A::Struct {}).foo();
    |     ^^^^^^^^^^^^^^
@@ -13,6 +23,12 @@ LL |     (A::Tuple()).foo();
    |     ^^^^^^^^^^^^
 LL |     A::Unit.foo();
    |     ^^^^^^^
+help: the following enum variants are available
+   |
+LL |     (A::StructWithFields { /* fields */ }).foo();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     (A::TupleWithFields(/* fields */)).foo();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0423]: expected value, found enum `B`
   --> $DIR/issue-73427.rs:31:5
@@ -20,23 +36,69 @@ error[E0423]: expected value, found enum `B`
 LL |     B.foo();
    |     ^
    |
-   = help: you might have meant to use one of the enum's variants
+note: the enum is defined here
+  --> $DIR/issue-73427.rs:9:1
+   |
+LL | / enum B {
+LL | |     StructWithFields { x: () },
+LL | |     TupleWithFields(()),
+LL | | }
+   | |_^
+help: the following enum variants are available
+   |
+LL |     (B::StructWithFields { /* fields */ }).foo();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     (B::TupleWithFields(/* fields */)).foo();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0423]: expected value, found enum `C`
   --> $DIR/issue-73427.rs:33:5
    |
 LL |     C.foo();
-   |     ^ help: try using one of the enum's variants: `C::Unit`
+   |     ^
+   |
+note: the enum is defined here
+  --> $DIR/issue-73427.rs:14:1
+   |
+LL | / enum C {
+LL | |     StructWithFields { x: () },
+LL | |     TupleWithFields(()),
+LL | |     Unit,
+LL | | }
+   | |_^
+help: you might have meant to use the following enum variant
+   |
+LL |     C::Unit.foo();
+   |     ^^^^^^^
+help: the following enum variants are available
    |
-   = help: you might have meant to use one of the enum's other variants that have fields
+LL |     (C::StructWithFields { /* fields */ }).foo();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     (C::TupleWithFields(/* fields */)).foo();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0423]: expected value, found enum `D`
   --> $DIR/issue-73427.rs:35:5
    |
 LL |     D.foo();
-   |     ^ help: try using one of the enum's variants: `D::Unit`
+   |     ^
+   |
+note: the enum is defined here
+  --> $DIR/issue-73427.rs:20:1
+   |
+LL | / enum D {
+LL | |     TupleWithFields(()),
+LL | |     Unit,
+LL | | }
+   | |_^
+help: you might have meant to use the following enum variant
    |
-   = help: you might have meant to use the enum's other variant that has fields
+LL |     D::Unit.foo();
+   |     ^^^^^^^
+help: the following enum variant is available
+   |
+LL |     (D::TupleWithFields(/* fields */)).foo();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0423]: expected function, tuple struct or tuple variant, found enum `A`
   --> $DIR/issue-73427.rs:40:13
@@ -45,7 +107,18 @@ LL |     let x = A(3);
    |             ^
    |
    = help: you might have meant to construct one of the enum's non-tuple variants
-help: try using one of the enum's variants
+note: the enum is defined here
+  --> $DIR/issue-73427.rs:1:1
+   |
+LL | / enum A {
+LL | |     StructWithFields { x: () },
+LL | |     TupleWithFields(()),
+LL | |     Struct {},
+LL | |     Tuple(),
+LL | |     Unit,
+LL | | }
+   | |_^
+help: try to construct one of the enum's variants
    |
 LL |     let x = A::TupleWithFields(3);
    |             ^^^^^^^^^^^^^^^^^^
@@ -59,7 +132,18 @@ LL |     if let A(3) = x { }
    |            ^
    |
    = help: you might have meant to match against one of the enum's non-tuple variants
-help: try using one of the enum's variants
+note: the enum is defined here
+  --> $DIR/issue-73427.rs:1:1
+   |
+LL | / enum A {
+LL | |     StructWithFields { x: () },
+LL | |     TupleWithFields(()),
+LL | |     Struct {},
+LL | |     Tuple(),
+LL | |     Unit,
+LL | | }
+   | |_^
+help: try to match against one of the enum's variants
    |
 LL |     if let A::TupleWithFields(3) = x { }
    |            ^^^^^^^^^^^^^^^^^^
diff --git a/src/test/ui/macros/macro-use-wrong-name.stderr b/src/test/ui/macros/macro-use-wrong-name.stderr
index 74fb519cc82..888fb913fb7 100644
--- a/src/test/ui/macros/macro-use-wrong-name.stderr
+++ b/src/test/ui/macros/macro-use-wrong-name.stderr
@@ -8,6 +8,9 @@ LL |     macro_two!();
    |
 LL | macro_rules! macro_one { () => ("one") }
    | ---------------------- similarly named macro `macro_one` defined here
+   |
+   = note: consider importing this macro:
+           two_macros::macro_two
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/missing/missing-macro-use.stderr b/src/test/ui/missing/missing-macro-use.stderr
index 711e249d2bc..ced062269df 100644
--- a/src/test/ui/missing/missing-macro-use.stderr
+++ b/src/test/ui/missing/missing-macro-use.stderr
@@ -3,6 +3,9 @@ error: cannot find macro `macro_two` in this scope
    |
 LL |     macro_two!();
    |     ^^^^^^^^^
+   |
+   = note: consider importing this macro:
+           two_macros::macro_two
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/overlap-doesnt-conflict-with-specialization.stderr b/src/test/ui/overlap-doesnt-conflict-with-specialization.stderr
index 16df31ba2a8..fca98662708 100644
--- a/src/test/ui/overlap-doesnt-conflict-with-specialization.stderr
+++ b/src/test/ui/overlap-doesnt-conflict-with-specialization.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/parser/assoc-static-semantic-fail.stderr b/src/test/ui/parser/assoc-static-semantic-fail.stderr
index bc3054c3e30..7ae092cee67 100644
--- a/src/test/ui/parser/assoc-static-semantic-fail.stderr
+++ b/src/test/ui/parser/assoc-static-semantic-fail.stderr
@@ -170,6 +170,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error: aborting due to 24 previous errors; 1 warning emitted
 
diff --git a/src/test/ui/parser/default.stderr b/src/test/ui/parser/default.stderr
index dea35666f37..5b763ae72f5 100644
--- a/src/test/ui/parser/default.stderr
+++ b/src/test/ui/parser/default.stderr
@@ -31,6 +31,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0046]: not all trait items implemented, missing: `foo`
   --> $DIR/default.rs:22:1
diff --git a/src/test/ui/parser/trait-item-with-defaultness-fail-semantic.stderr b/src/test/ui/parser/trait-item-with-defaultness-fail-semantic.stderr
index e8ff93f6323..cdc9ee8d9e7 100644
--- a/src/test/ui/parser/trait-item-with-defaultness-fail-semantic.stderr
+++ b/src/test/ui/parser/trait-item-with-defaultness-fail-semantic.stderr
@@ -54,6 +54,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error: aborting due to 6 previous errors; 1 warning emitted
 
diff --git a/src/test/ui/polymorphization/const_parameters/closures.stderr b/src/test/ui/polymorphization/const_parameters/closures.stderr
index 266b6e62afd..63335586b76 100644
--- a/src/test/ui/polymorphization/const_parameters/closures.stderr
+++ b/src/test/ui/polymorphization/const_parameters/closures.stderr
@@ -6,6 +6,7 @@ LL | #![feature(const_generics, rustc_attrs)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error: item has unused generic parameters
   --> $DIR/closures.rs:19:19
diff --git a/src/test/ui/polymorphization/const_parameters/functions.stderr b/src/test/ui/polymorphization/const_parameters/functions.stderr
index e379e32c1fc..c976a5b62aa 100644
--- a/src/test/ui/polymorphization/const_parameters/functions.stderr
+++ b/src/test/ui/polymorphization/const_parameters/functions.stderr
@@ -6,6 +6,7 @@ LL | #![feature(const_generics, rustc_attrs)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error: item has unused generic parameters
   --> $DIR/functions.rs:15:8
diff --git a/src/test/ui/polymorphization/generators.stderr b/src/test/ui/polymorphization/generators.stderr
index c59055ba9d6..b2b32db045d 100644
--- a/src/test/ui/polymorphization/generators.stderr
+++ b/src/test/ui/polymorphization/generators.stderr
@@ -6,6 +6,7 @@ LL | #![feature(const_generics, generators, generator_trait, rustc_attrs)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error: item has unused generic parameters
   --> $DIR/generators.rs:36:5
diff --git a/src/test/ui/reject-specialized-drops-8142.stderr b/src/test/ui/reject-specialized-drops-8142.stderr
index f819faa2789..eac24617533 100644
--- a/src/test/ui/reject-specialized-drops-8142.stderr
+++ b/src/test/ui/reject-specialized-drops-8142.stderr
@@ -1,15 +1,3 @@
-error[E0367]: `Drop` impl requires `AddsBnd: Bound` but the union it is implemented for does not
-  --> $DIR/reject-specialized-drops-8142.rs:67:21
-   |
-LL | impl<AddsBnd:Copy + Bound> Drop for Union<AddsBnd> { fn drop(&mut self) { } } // REJECT
-   |                     ^^^^^
-   |
-note: the implementor must specify the same requirement
-  --> $DIR/reject-specialized-drops-8142.rs:21:1
-   |
-LL | union Union<T: Copy> { f: T }
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
 error[E0367]: `Drop` impl requires `'adds_bnd: 'al` but the struct it is implemented for does not
   --> $DIR/reject-specialized-drops-8142.rs:23:20
    |
@@ -145,6 +133,18 @@ note: the implementor must specify the same requirement
 LL | struct TupleStruct<T>(T);
    | ^^^^^^^^^^^^^^^^^^^^^^^^^
 
+error[E0367]: `Drop` impl requires `AddsBnd: Bound` but the union it is implemented for does not
+  --> $DIR/reject-specialized-drops-8142.rs:67:21
+   |
+LL | impl<AddsBnd:Copy + Bound> Drop for Union<AddsBnd> { fn drop(&mut self) { } } // REJECT
+   |                     ^^^^^
+   |
+note: the implementor must specify the same requirement
+  --> $DIR/reject-specialized-drops-8142.rs:21:1
+   |
+LL | union Union<T: Copy> { f: T }
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
 error: aborting due to 11 previous errors
 
 Some errors have detailed explanations: E0308, E0366, E0367, E0495.
diff --git a/src/test/ui/resolve/issue-65035-static-with-parent-generics.stderr b/src/test/ui/resolve/issue-65035-static-with-parent-generics.stderr
index 7f8151db06f..5de8eb21582 100644
--- a/src/test/ui/resolve/issue-65035-static-with-parent-generics.stderr
+++ b/src/test/ui/resolve/issue-65035-static-with-parent-generics.stderr
@@ -48,6 +48,7 @@ LL | #![feature(const_generics)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 error: aborting due to 5 previous errors; 1 warning emitted
 
diff --git a/src/test/ui/resolve/privacy-enum-ctor.stderr b/src/test/ui/resolve/privacy-enum-ctor.stderr
index 77429f800f1..807dadf417b 100644
--- a/src/test/ui/resolve/privacy-enum-ctor.stderr
+++ b/src/test/ui/resolve/privacy-enum-ctor.stderr
@@ -2,17 +2,57 @@ error[E0423]: expected value, found enum `n::Z`
   --> $DIR/privacy-enum-ctor.rs:23:9
    |
 LL |         n::Z;
-   |         ^^^^ help: try using one of the enum's variants: `m::Z::Unit`
+   |         ^^^^
    |
-   = help: you might have meant to use one of the enum's other variants that have fields
+note: the enum is defined here
+  --> $DIR/privacy-enum-ctor.rs:11:9
+   |
+LL | /         pub(in m) enum Z {
+LL | |             Fn(u8),
+LL | |             Struct {
+LL | |                 s: u8,
+LL | |             },
+LL | |             Unit,
+LL | |         }
+   | |_________^
+help: you might have meant to use the following enum variant
+   |
+LL |         m::Z::Unit;
+   |         ^^^^^^^^^^
+help: the following enum variants are available
+   |
+LL |         (m::Z::Fn(/* fields */));
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^
+LL |         (m::Z::Struct { /* fields */ });
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0423]: expected value, found enum `Z`
   --> $DIR/privacy-enum-ctor.rs:25:9
    |
 LL |         Z;
-   |         ^ help: try using one of the enum's variants: `m::Z::Unit`
+   |         ^
+   |
+note: the enum is defined here
+  --> $DIR/privacy-enum-ctor.rs:11:9
    |
-   = help: you might have meant to use one of the enum's other variants that have fields
+LL | /         pub(in m) enum Z {
+LL | |             Fn(u8),
+LL | |             Struct {
+LL | |                 s: u8,
+LL | |             },
+LL | |             Unit,
+LL | |         }
+   | |_________^
+help: you might have meant to use the following enum variant
+   |
+LL |         m::Z::Unit;
+   |         ^^^^^^^^^^
+help: the following enum variants are available
+   |
+LL |         (m::Z::Fn(/* fields */));
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^
+LL |         (m::Z::Struct { /* fields */ });
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0423]: expected value, found struct variant `Z::Struct`
   --> $DIR/privacy-enum-ctor.rs:29:20
@@ -34,11 +74,27 @@ LL |     fn f() {
 LL |     let _: E = m::E;
    |                ^^^^
    |
-   = help: you might have meant to use one of the enum's other variants that have fields
-help: try using one of the enum's variants
+note: the enum is defined here
+  --> $DIR/privacy-enum-ctor.rs:2:5
+   |
+LL | /     pub enum E {
+LL | |         Fn(u8),
+LL | |         Struct {
+LL | |             s: u8,
+LL | |         },
+LL | |         Unit,
+LL | |     }
+   | |_____^
+help: you might have meant to use the following enum variant
    |
 LL |     let _: E = E::Unit;
    |                ^^^^^^^
+help: the following enum variants are available
+   |
+LL |     let _: E = (E::Fn(/* fields */));
+   |                ^^^^^^^^^^^^^^^^^^^^^
+LL |     let _: E = (E::Struct { /* fields */ });
+   |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 help: a function with a similar name exists
    |
 LL |     let _: E = m::f;
@@ -67,11 +123,27 @@ error[E0423]: expected value, found enum `E`
 LL |     let _: E = E;
    |                ^
    |
-   = help: you might have meant to use one of the enum's other variants that have fields
-help: try using one of the enum's variants
+note: the enum is defined here
+  --> $DIR/privacy-enum-ctor.rs:2:5
+   |
+LL | /     pub enum E {
+LL | |         Fn(u8),
+LL | |         Struct {
+LL | |             s: u8,
+LL | |         },
+LL | |         Unit,
+LL | |     }
+   | |_____^
+help: you might have meant to use the following enum variant
    |
 LL |     let _: E = E::Unit;
    |                ^^^^^^^
+help: the following enum variants are available
+   |
+LL |     let _: E = (E::Fn(/* fields */));
+   |                ^^^^^^^^^^^^^^^^^^^^^
+LL |     let _: E = (E::Struct { /* fields */ });
+   |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 help: consider importing one of these items instead
    |
 LL | use std::f32::consts::E;
@@ -112,9 +184,29 @@ error[E0423]: expected value, found enum `m::n::Z`
   --> $DIR/privacy-enum-ctor.rs:57:16
    |
 LL |     let _: Z = m::n::Z;
-   |                ^^^^^^^ help: try using one of the enum's variants: `m::Z::Unit`
+   |                ^^^^^^^
+   |
+note: the enum is defined here
+  --> $DIR/privacy-enum-ctor.rs:11:9
+   |
+LL | /         pub(in m) enum Z {
+LL | |             Fn(u8),
+LL | |             Struct {
+LL | |                 s: u8,
+LL | |             },
+LL | |             Unit,
+LL | |         }
+   | |_________^
+help: you might have meant to use the following enum variant
+   |
+LL |     let _: Z = m::Z::Unit;
+   |                ^^^^^^^^^^
+help: the following enum variants are available
    |
-   = help: you might have meant to use one of the enum's other variants that have fields
+LL |     let _: Z = (m::Z::Fn(/* fields */));
+   |                ^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     let _: Z = (m::Z::Struct { /* fields */ });
+   |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0412]: cannot find type `Z` in this scope
   --> $DIR/privacy-enum-ctor.rs:61:12
diff --git a/src/test/ui/rfc-2497-if-let-chains/disallowed-positions.stderr b/src/test/ui/rfc-2497-if-let-chains/disallowed-positions.stderr
index d38a3aba46f..bd39650702c 100644
--- a/src/test/ui/rfc-2497-if-let-chains/disallowed-positions.stderr
+++ b/src/test/ui/rfc-2497-if-let-chains/disallowed-positions.stderr
@@ -507,6 +507,7 @@ LL | #![feature(const_generics)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 warning: the feature `let_chains` is incomplete and may not be safe to use and/or cause compiler crashes
   --> $DIR/disallowed-positions.rs:22:12
diff --git a/src/test/ui/self/self-in-typedefs.rs b/src/test/ui/self/self-in-typedefs.rs
index 3b1eb9e1dfa..81e557d53a6 100644
--- a/src/test/ui/self/self-in-typedefs.rs
+++ b/src/test/ui/self/self-in-typedefs.rs
@@ -1,7 +1,4 @@
 // build-pass (FIXME(62277): could be check-pass?)
-
-#![feature(untagged_unions)]
-
 #![allow(dead_code)]
 
 use std::mem::ManuallyDrop;
diff --git a/src/test/ui/specialization/assoc-ty-graph-cycle.stderr b/src/test/ui/specialization/assoc-ty-graph-cycle.stderr
index 250f48f8e59..17da34caa70 100644
--- a/src/test/ui/specialization/assoc-ty-graph-cycle.stderr
+++ b/src/test/ui/specialization/assoc-ty-graph-cycle.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/cross-crate-defaults.stderr b/src/test/ui/specialization/cross-crate-defaults.stderr
index f18bc99d739..e368c2e73b6 100644
--- a/src/test/ui/specialization/cross-crate-defaults.stderr
+++ b/src/test/ui/specialization/cross-crate-defaults.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/deafult-associated-type-bound-1.stderr b/src/test/ui/specialization/deafult-associated-type-bound-1.stderr
index 337972ea2b7..4ca3d831198 100644
--- a/src/test/ui/specialization/deafult-associated-type-bound-1.stderr
+++ b/src/test/ui/specialization/deafult-associated-type-bound-1.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0277]: the trait bound `str: Clone` is not satisfied
   --> $DIR/deafult-associated-type-bound-1.rs:19:5
diff --git a/src/test/ui/specialization/deafult-associated-type-bound-2.stderr b/src/test/ui/specialization/deafult-associated-type-bound-2.stderr
index 8c9da81d277..2bc14dbe3b2 100644
--- a/src/test/ui/specialization/deafult-associated-type-bound-2.stderr
+++ b/src/test/ui/specialization/deafult-associated-type-bound-2.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0277]: can't compare `&'static B` with `B`
   --> $DIR/deafult-associated-type-bound-2.rs:16:5
diff --git a/src/test/ui/specialization/deafult-generic-associated-type-bound.stderr b/src/test/ui/specialization/deafult-generic-associated-type-bound.stderr
index f145b90f216..b5a1877ea19 100644
--- a/src/test/ui/specialization/deafult-generic-associated-type-bound.stderr
+++ b/src/test/ui/specialization/deafult-generic-associated-type-bound.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: the feature `generic_associated_types` is incomplete and may not be safe to use and/or cause compiler crashes
   --> $DIR/deafult-generic-associated-type-bound.rs:4:12
diff --git a/src/test/ui/specialization/defaultimpl/allowed-cross-crate.stderr b/src/test/ui/specialization/defaultimpl/allowed-cross-crate.stderr
index 1b50329719d..d8b9c48c72e 100644
--- a/src/test/ui/specialization/defaultimpl/allowed-cross-crate.stderr
+++ b/src/test/ui/specialization/defaultimpl/allowed-cross-crate.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/defaultimpl/out-of-order.stderr b/src/test/ui/specialization/defaultimpl/out-of-order.stderr
index deae021a891..9ca915686e8 100644
--- a/src/test/ui/specialization/defaultimpl/out-of-order.stderr
+++ b/src/test/ui/specialization/defaultimpl/out-of-order.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/defaultimpl/overlap-projection.stderr b/src/test/ui/specialization/defaultimpl/overlap-projection.stderr
index 46899ca9954..31d0e6e3882 100644
--- a/src/test/ui/specialization/defaultimpl/overlap-projection.stderr
+++ b/src/test/ui/specialization/defaultimpl/overlap-projection.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/defaultimpl/projection.stderr b/src/test/ui/specialization/defaultimpl/projection.stderr
index 8629c6c52d4..2d5c80d05f0 100644
--- a/src/test/ui/specialization/defaultimpl/projection.stderr
+++ b/src/test/ui/specialization/defaultimpl/projection.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/defaultimpl/specialization-no-default.stderr b/src/test/ui/specialization/defaultimpl/specialization-no-default.stderr
index 7958eddbeba..3f1a5495e21 100644
--- a/src/test/ui/specialization/defaultimpl/specialization-no-default.stderr
+++ b/src/test/ui/specialization/defaultimpl/specialization-no-default.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0520]: `foo` specializes an item from a parent `impl`, but that item is not marked `default`
   --> $DIR/specialization-no-default.rs:20:5
diff --git a/src/test/ui/specialization/defaultimpl/specialization-trait-item-not-implemented-rpass.stderr b/src/test/ui/specialization/defaultimpl/specialization-trait-item-not-implemented-rpass.stderr
index dc377dd10c8..163c93550fb 100644
--- a/src/test/ui/specialization/defaultimpl/specialization-trait-item-not-implemented-rpass.stderr
+++ b/src/test/ui/specialization/defaultimpl/specialization-trait-item-not-implemented-rpass.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/defaultimpl/specialization-trait-item-not-implemented.stderr b/src/test/ui/specialization/defaultimpl/specialization-trait-item-not-implemented.stderr
index 9d1eca1d6af..250f0017bea 100644
--- a/src/test/ui/specialization/defaultimpl/specialization-trait-item-not-implemented.stderr
+++ b/src/test/ui/specialization/defaultimpl/specialization-trait-item-not-implemented.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0046]: not all trait items implemented, missing: `foo_two`
   --> $DIR/specialization-trait-item-not-implemented.rs:18:1
diff --git a/src/test/ui/specialization/defaultimpl/specialization-trait-not-implemented.stderr b/src/test/ui/specialization/defaultimpl/specialization-trait-not-implemented.stderr
index 6b8e559bc36..fb623c97f42 100644
--- a/src/test/ui/specialization/defaultimpl/specialization-trait-not-implemented.stderr
+++ b/src/test/ui/specialization/defaultimpl/specialization-trait-not-implemented.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0599]: no method named `foo_one` found for struct `MyStruct` in the current scope
   --> $DIR/specialization-trait-not-implemented.rs:22:29
diff --git a/src/test/ui/specialization/defaultimpl/specialization-wfcheck.stderr b/src/test/ui/specialization/defaultimpl/specialization-wfcheck.stderr
index dcac310ed06..57b90c457cb 100644
--- a/src/test/ui/specialization/defaultimpl/specialization-wfcheck.stderr
+++ b/src/test/ui/specialization/defaultimpl/specialization-wfcheck.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0277]: the trait bound `U: Eq` is not satisfied
   --> $DIR/specialization-wfcheck.rs:7:17
diff --git a/src/test/ui/specialization/defaultimpl/validation.stderr b/src/test/ui/specialization/defaultimpl/validation.stderr
index 2449849725f..cbf0cef5e74 100644
--- a/src/test/ui/specialization/defaultimpl/validation.stderr
+++ b/src/test/ui/specialization/defaultimpl/validation.stderr
@@ -16,6 +16,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error: impls of auto traits cannot be default
   --> $DIR/validation.rs:9:21
diff --git a/src/test/ui/specialization/issue-36804.stderr b/src/test/ui/specialization/issue-36804.stderr
index 744d8820424..783a38e6bdc 100644
--- a/src/test/ui/specialization/issue-36804.stderr
+++ b/src/test/ui/specialization/issue-36804.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/issue-38091-2.stderr b/src/test/ui/specialization/issue-38091-2.stderr
index a314c26ad14..bd5ed498d92 100644
--- a/src/test/ui/specialization/issue-38091-2.stderr
+++ b/src/test/ui/specialization/issue-38091-2.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0275]: overflow evaluating the requirement `i32: Check`
    |
diff --git a/src/test/ui/specialization/issue-38091.stderr b/src/test/ui/specialization/issue-38091.stderr
index 6be0f26849f..97e5775ab54 100644
--- a/src/test/ui/specialization/issue-38091.stderr
+++ b/src/test/ui/specialization/issue-38091.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0277]: the trait bound `(): Valid` is not satisfied
   --> $DIR/issue-38091.rs:12:5
diff --git a/src/test/ui/specialization/issue-39448.stderr b/src/test/ui/specialization/issue-39448.stderr
index f3bb69b8f71..98e49b1bab3 100644
--- a/src/test/ui/specialization/issue-39448.stderr
+++ b/src/test/ui/specialization/issue-39448.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0275]: overflow evaluating the requirement `T: FromA<U>`
   --> $DIR/issue-39448.rs:45:13
diff --git a/src/test/ui/specialization/issue-39618.stderr b/src/test/ui/specialization/issue-39618.stderr
index d40d17d8f71..77a45806edb 100644
--- a/src/test/ui/specialization/issue-39618.stderr
+++ b/src/test/ui/specialization/issue-39618.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/issue-50452.stderr b/src/test/ui/specialization/issue-50452.stderr
index c01817e0b27..2f05c41346f 100644
--- a/src/test/ui/specialization/issue-50452.stderr
+++ b/src/test/ui/specialization/issue-50452.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/issue-52050.stderr b/src/test/ui/specialization/issue-52050.stderr
index a7564ced055..27070f8e4a1 100644
--- a/src/test/ui/specialization/issue-52050.stderr
+++ b/src/test/ui/specialization/issue-52050.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0119]: conflicting implementations of trait `IntoPyDictPointer` for type `()`:
   --> $DIR/issue-52050.rs:28:1
diff --git a/src/test/ui/specialization/issue-63716-parse-async.stderr b/src/test/ui/specialization/issue-63716-parse-async.stderr
index 43620e1ba51..cde17872d6b 100644
--- a/src/test/ui/specialization/issue-63716-parse-async.stderr
+++ b/src/test/ui/specialization/issue-63716-parse-async.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/issue-70442.stderr b/src/test/ui/specialization/issue-70442.stderr
index f71e4c7dd1c..5ee82e9915b 100644
--- a/src/test/ui/specialization/issue-70442.stderr
+++ b/src/test/ui/specialization/issue-70442.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/non-defaulted-item-fail.stderr b/src/test/ui/specialization/non-defaulted-item-fail.stderr
index eae045b92c0..85ccbd809b0 100644
--- a/src/test/ui/specialization/non-defaulted-item-fail.stderr
+++ b/src/test/ui/specialization/non-defaulted-item-fail.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization, associated_type_defaults)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0520]: `Ty` specializes an item from a parent `impl`, but that item is not marked `default`
   --> $DIR/non-defaulted-item-fail.rs:30:5
diff --git a/src/test/ui/specialization/specialization-allowed-cross-crate.stderr b/src/test/ui/specialization/specialization-allowed-cross-crate.stderr
index 7d087545725..9605bd08935 100644
--- a/src/test/ui/specialization/specialization-allowed-cross-crate.stderr
+++ b/src/test/ui/specialization/specialization-allowed-cross-crate.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/specialization-assoc-fns.stderr b/src/test/ui/specialization/specialization-assoc-fns.stderr
index b12738604ea..a7c0661a825 100644
--- a/src/test/ui/specialization/specialization-assoc-fns.stderr
+++ b/src/test/ui/specialization/specialization-assoc-fns.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/specialization-basics.stderr b/src/test/ui/specialization/specialization-basics.stderr
index ad00cd81df1..afb2af3803f 100644
--- a/src/test/ui/specialization/specialization-basics.stderr
+++ b/src/test/ui/specialization/specialization-basics.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/specialization-cross-crate.stderr b/src/test/ui/specialization/specialization-cross-crate.stderr
index 7481eed796d..c69130c0aef 100644
--- a/src/test/ui/specialization/specialization-cross-crate.stderr
+++ b/src/test/ui/specialization/specialization-cross-crate.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/specialization-default-methods.stderr b/src/test/ui/specialization/specialization-default-methods.stderr
index 4fa19adad06..ef6365ed31f 100644
--- a/src/test/ui/specialization/specialization-default-methods.stderr
+++ b/src/test/ui/specialization/specialization-default-methods.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/specialization-default-projection.stderr b/src/test/ui/specialization/specialization-default-projection.stderr
index 456eb6d5ca5..445bc1646f0 100644
--- a/src/test/ui/specialization/specialization-default-projection.stderr
+++ b/src/test/ui/specialization/specialization-default-projection.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0308]: mismatched types
   --> $DIR/specialization-default-projection.rs:21:5
diff --git a/src/test/ui/specialization/specialization-default-types.stderr b/src/test/ui/specialization/specialization-default-types.stderr
index 5acfb53e206..5ba38facee0 100644
--- a/src/test/ui/specialization/specialization-default-types.stderr
+++ b/src/test/ui/specialization/specialization-default-types.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0308]: mismatched types
   --> $DIR/specialization-default-types.rs:15:9
diff --git a/src/test/ui/specialization/specialization-no-default.stderr b/src/test/ui/specialization/specialization-no-default.stderr
index bb8b2a6c98e..711c1fda149 100644
--- a/src/test/ui/specialization/specialization-no-default.stderr
+++ b/src/test/ui/specialization/specialization-no-default.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0520]: `foo` specializes an item from a parent `impl`, but that item is not marked `default`
   --> $DIR/specialization-no-default.rs:20:5
diff --git a/src/test/ui/specialization/specialization-on-projection.stderr b/src/test/ui/specialization/specialization-on-projection.stderr
index d91668d10c5..d051ffe0a02 100644
--- a/src/test/ui/specialization/specialization-on-projection.stderr
+++ b/src/test/ui/specialization/specialization-on-projection.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/specialization-out-of-order.stderr b/src/test/ui/specialization/specialization-out-of-order.stderr
index a17f9f11a3f..785ec29239b 100644
--- a/src/test/ui/specialization/specialization-out-of-order.stderr
+++ b/src/test/ui/specialization/specialization-out-of-order.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/specialization-overlap-negative.stderr b/src/test/ui/specialization/specialization-overlap-negative.stderr
index 6141174ba8c..552b04a6019 100644
--- a/src/test/ui/specialization/specialization-overlap-negative.stderr
+++ b/src/test/ui/specialization/specialization-overlap-negative.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0751]: found both positive and negative implementation of trait `std::marker::Send` for type `TestType<_>`:
   --> $DIR/specialization-overlap-negative.rs:9:1
diff --git a/src/test/ui/specialization/specialization-overlap-projection.stderr b/src/test/ui/specialization/specialization-overlap-projection.stderr
index 6f1a594bacb..c92db73074d 100644
--- a/src/test/ui/specialization/specialization-overlap-projection.stderr
+++ b/src/test/ui/specialization/specialization-overlap-projection.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/specialization-overlap.stderr b/src/test/ui/specialization/specialization-overlap.stderr
index cf0f186a183..7e5c96ac1c8 100644
--- a/src/test/ui/specialization/specialization-overlap.stderr
+++ b/src/test/ui/specialization/specialization-overlap.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0119]: conflicting implementations of trait `Foo` for type `std::vec::Vec<_>`:
   --> $DIR/specialization-overlap.rs:5:1
diff --git a/src/test/ui/specialization/specialization-polarity.stderr b/src/test/ui/specialization/specialization-polarity.stderr
index c44af22b8e6..be013552f5d 100644
--- a/src/test/ui/specialization/specialization-polarity.stderr
+++ b/src/test/ui/specialization/specialization-polarity.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0751]: found both positive and negative implementation of trait `Foo` for type `u8`:
   --> $DIR/specialization-polarity.rs:10:1
diff --git a/src/test/ui/specialization/specialization-projection-alias.stderr b/src/test/ui/specialization/specialization-projection-alias.stderr
index 0c3659a8f7a..6d2bca5d2df 100644
--- a/src/test/ui/specialization/specialization-projection-alias.stderr
+++ b/src/test/ui/specialization/specialization-projection-alias.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/specialization-projection.stderr b/src/test/ui/specialization/specialization-projection.stderr
index c5c86f5108e..0f1ecf5e379 100644
--- a/src/test/ui/specialization/specialization-projection.stderr
+++ b/src/test/ui/specialization/specialization-projection.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/specialization-super-traits.stderr b/src/test/ui/specialization/specialization-super-traits.stderr
index 05bdfd40136..165703d6365 100644
--- a/src/test/ui/specialization/specialization-super-traits.stderr
+++ b/src/test/ui/specialization/specialization-super-traits.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/specialization-translate-projections-with-lifetimes.stderr b/src/test/ui/specialization/specialization-translate-projections-with-lifetimes.stderr
index 6284dd8f3f7..d30f7af2cbd 100644
--- a/src/test/ui/specialization/specialization-translate-projections-with-lifetimes.stderr
+++ b/src/test/ui/specialization/specialization-translate-projections-with-lifetimes.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/specialization-translate-projections-with-params.stderr b/src/test/ui/specialization/specialization-translate-projections-with-params.stderr
index b17794173c5..1762248f695 100644
--- a/src/test/ui/specialization/specialization-translate-projections-with-params.stderr
+++ b/src/test/ui/specialization/specialization-translate-projections-with-params.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/specialization/specialization-translate-projections.stderr b/src/test/ui/specialization/specialization-translate-projections.stderr
index fbb28e60640..94a0e79dd56 100644
--- a/src/test/ui/specialization/specialization-translate-projections.stderr
+++ b/src/test/ui/specialization/specialization-translate-projections.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/traits/negative-impls/negative-default-impls.stderr b/src/test/ui/traits/negative-impls/negative-default-impls.stderr
index 50e74373b53..ceb86559d85 100644
--- a/src/test/ui/traits/negative-impls/negative-default-impls.stderr
+++ b/src/test/ui/traits/negative-impls/negative-default-impls.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0750]: negative impls cannot be default impls
   --> $DIR/negative-default-impls.rs:9:1
diff --git a/src/test/ui/traits/negative-impls/negative-specializes-negative.stderr b/src/test/ui/traits/negative-impls/negative-specializes-negative.stderr
index 8b536de3786..9a846143d3d 100644
--- a/src/test/ui/traits/negative-impls/negative-specializes-negative.stderr
+++ b/src/test/ui/traits/negative-impls/negative-specializes-negative.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/traits/negative-impls/negative-specializes-positive-item.stderr b/src/test/ui/traits/negative-impls/negative-specializes-positive-item.stderr
index 89ef15e89ac..77b4373a273 100644
--- a/src/test/ui/traits/negative-impls/negative-specializes-positive-item.stderr
+++ b/src/test/ui/traits/negative-impls/negative-specializes-positive-item.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0751]: found both positive and negative implementation of trait `MyTrait` for type `u32`:
   --> $DIR/negative-specializes-positive-item.rs:11:1
diff --git a/src/test/ui/traits/negative-impls/negative-specializes-positive.stderr b/src/test/ui/traits/negative-impls/negative-specializes-positive.stderr
index e45d5a251ab..e5dc81b3eb7 100644
--- a/src/test/ui/traits/negative-impls/negative-specializes-positive.stderr
+++ b/src/test/ui/traits/negative-impls/negative-specializes-positive.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0751]: found both positive and negative implementation of trait `MyTrait` for type `u32`:
   --> $DIR/negative-specializes-positive.rs:7:1
diff --git a/src/test/ui/traits/negative-impls/positive-specializes-negative.stderr b/src/test/ui/traits/negative-impls/positive-specializes-negative.stderr
index 49c16d47404..c091bc81da3 100644
--- a/src/test/ui/traits/negative-impls/positive-specializes-negative.stderr
+++ b/src/test/ui/traits/negative-impls/positive-specializes-negative.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 error[E0751]: found both positive and negative implementation of trait `MyTrait` for type `u32`:
   --> $DIR/positive-specializes-negative.rs:7:1
diff --git a/src/test/ui/transmute-specialization.stderr b/src/test/ui/transmute-specialization.stderr
index 02315051d30..a0ea72415a1 100644
--- a/src/test/ui/transmute-specialization.stderr
+++ b/src/test/ui/transmute-specialization.stderr
@@ -6,6 +6,7 @@ LL | #![feature(specialization)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/transmute/main.rs b/src/test/ui/transmute/main.rs
index ea233a47a78..cb46fc5ec46 100644
--- a/src/test/ui/transmute/main.rs
+++ b/src/test/ui/transmute/main.rs
@@ -1,9 +1,6 @@
 // normalize-stderr-32bit: "`&str` \(64 bits\)" -> "`&str` ($$STR bits)"
 // normalize-stderr-64bit: "`&str` \(128 bits\)" -> "`&str` ($$STR bits)"
 
-
-
-#![feature(untagged_unions)]
 use std::mem::transmute;
 
 pub trait TypeConstructor<'a> {
diff --git a/src/test/ui/transmute/main.stderr b/src/test/ui/transmute/main.stderr
index 4e781318329..f48562094a4 100644
--- a/src/test/ui/transmute/main.stderr
+++ b/src/test/ui/transmute/main.stderr
@@ -1,5 +1,5 @@
 error[E0512]: cannot transmute between types of different sizes, or dependently-sized types
-  --> $DIR/main.rs:16:5
+  --> $DIR/main.rs:13:5
    |
 LL |     transmute(x)
    |     ^^^^^^^^^
@@ -7,7 +7,7 @@ LL |     transmute(x)
    = note: `<C as TypeConstructor>::T` does not have a fixed size
 
 error[E0512]: cannot transmute between types of different sizes, or dependently-sized types
-  --> $DIR/main.rs:20:17
+  --> $DIR/main.rs:17:17
    |
 LL |     let x: u8 = transmute(10u16);
    |                 ^^^^^^^^^
@@ -16,7 +16,7 @@ LL |     let x: u8 = transmute(10u16);
    = note: target type: `u8` (8 bits)
 
 error[E0512]: cannot transmute between types of different sizes, or dependently-sized types
-  --> $DIR/main.rs:24:17
+  --> $DIR/main.rs:21:17
    |
 LL |     let x: u8 = transmute("test");
    |                 ^^^^^^^^^
@@ -25,7 +25,7 @@ LL |     let x: u8 = transmute("test");
    = note: target type: `u8` (8 bits)
 
 error[E0512]: cannot transmute between types of different sizes, or dependently-sized types
-  --> $DIR/main.rs:29:18
+  --> $DIR/main.rs:26:18
    |
 LL |     let x: Foo = transmute(10);
    |                  ^^^^^^^^^
diff --git a/src/test/ui/type-alias-impl-trait/assoc-type-const.stderr b/src/test/ui/type-alias-impl-trait/assoc-type-const.stderr
index e0c1b023861..c5b22f0026d 100644
--- a/src/test/ui/type-alias-impl-trait/assoc-type-const.stderr
+++ b/src/test/ui/type-alias-impl-trait/assoc-type-const.stderr
@@ -6,6 +6,7 @@ LL | #![feature(const_generics)]
    |
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
+   = help: consider using `min_const_generics` instead, which is more stable and complete
 
 warning: 1 warning emitted
 
diff --git a/src/test/ui/union/union-align.rs b/src/test/ui/union/union-align.rs
index edd83a51169..1340ae43cd6 100644
--- a/src/test/ui/union/union-align.rs
+++ b/src/test/ui/union/union-align.rs
@@ -1,8 +1,6 @@
 // run-pass
 #![allow(dead_code)]
 
-#![feature(untagged_unions)]
-
 use std::mem::{size_of, size_of_val, align_of, align_of_val};
 
 #[repr(align(16))]
@@ -35,6 +33,7 @@ mod hybrid {
     use std::mem::{size_of, align_of};
 
     #[repr(align(16))]
+    #[derive(Copy, Clone)]
     struct S1 {
         a: u16,
         b: u8,
diff --git a/src/test/ui/union/union-copy.rs b/src/test/ui/union/union-copy.rs
index 8318f96940e..5c3f8d90898 100644
--- a/src/test/ui/union/union-copy.rs
+++ b/src/test/ui/union/union-copy.rs
@@ -1,5 +1,3 @@
-#![feature(untagged_unions)]
-
 #[derive(Clone)]
 union U {
     a: u8
@@ -7,7 +5,7 @@ union U {
 
 #[derive(Clone)]
 union W {
-    a: String
+    a: std::mem::ManuallyDrop<String>
 }
 
 impl Copy for U {} // OK
diff --git a/src/test/ui/union/union-copy.stderr b/src/test/ui/union/union-copy.stderr
index a875ff660f9..0f47bae7f0f 100644
--- a/src/test/ui/union/union-copy.stderr
+++ b/src/test/ui/union/union-copy.stderr
@@ -1,8 +1,8 @@
 error[E0204]: the trait `Copy` may not be implemented for this type
-  --> $DIR/union-copy.rs:14:6
+  --> $DIR/union-copy.rs:12:6
    |
-LL |     a: String
-   |     --------- this field does not implement `Copy`
+LL |     a: std::mem::ManuallyDrop<String>
+   |     --------------------------------- this field does not implement `Copy`
 ...
 LL | impl Copy for W {}
    |      ^^^^
diff --git a/src/test/ui/union/union-derive-clone.rs b/src/test/ui/union/union-derive-clone.rs
index 8126980604a..753a9f74d03 100644
--- a/src/test/ui/union/union-derive-clone.rs
+++ b/src/test/ui/union/union-derive-clone.rs
@@ -1,5 +1,3 @@
-#![feature(untagged_unions)]
-
 use std::mem::ManuallyDrop;
 
 #[derive(Clone)] //~ ERROR the trait bound `U1: Copy` is not satisfied
diff --git a/src/test/ui/union/union-derive-clone.stderr b/src/test/ui/union/union-derive-clone.stderr
index 7a59f539c37..e18f457a8b6 100644
--- a/src/test/ui/union/union-derive-clone.stderr
+++ b/src/test/ui/union/union-derive-clone.stderr
@@ -1,5 +1,5 @@
 error[E0277]: the trait bound `U1: Copy` is not satisfied
-  --> $DIR/union-derive-clone.rs:5:10
+  --> $DIR/union-derive-clone.rs:3:10
    |
 LL | #[derive(Clone)]
    |          ^^^^^ the trait `Copy` is not implemented for `U1`
@@ -12,7 +12,7 @@ LL | pub struct AssertParamIsCopy<T: Copy + ?Sized> {
    = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0599]: no method named `clone` found for union `U5<CloneNoCopy>` in the current scope
-  --> $DIR/union-derive-clone.rs:37:15
+  --> $DIR/union-derive-clone.rs:35:15
    |
 LL | union U5<T> {
    | -----------
diff --git a/src/test/ui/union/union-derive-eq.rs b/src/test/ui/union/union-derive-eq.rs
index ac5808e4361..e689f8c27d7 100644
--- a/src/test/ui/union/union-derive-eq.rs
+++ b/src/test/ui/union/union-derive-eq.rs
@@ -1,5 +1,3 @@
-#![feature(untagged_unions)]
-
 #[derive(Eq)] // OK
 union U1 {
     a: u8,
@@ -7,7 +5,7 @@ union U1 {
 
 impl PartialEq for U1 { fn eq(&self, rhs: &Self) -> bool { true } }
 
-#[derive(PartialEq)]
+#[derive(PartialEq, Copy, Clone)]
 struct PartialEqNotEq;
 
 #[derive(Eq)]
diff --git a/src/test/ui/union/union-derive-eq.stderr b/src/test/ui/union/union-derive-eq.stderr
index c4d437c6cdd..0591d12d598 100644
--- a/src/test/ui/union/union-derive-eq.stderr
+++ b/src/test/ui/union/union-derive-eq.stderr
@@ -1,5 +1,5 @@
 error[E0277]: the trait bound `PartialEqNotEq: Eq` is not satisfied
-  --> $DIR/union-derive-eq.rs:15:5
+  --> $DIR/union-derive-eq.rs:13:5
    |
 LL |     a: PartialEqNotEq,
    |     ^^^^^^^^^^^^^^^^^ the trait `Eq` is not implemented for `PartialEqNotEq`
diff --git a/src/test/ui/union/union-derive-rpass.rs b/src/test/ui/union/union-derive-rpass.rs
index b2f7ae679fd..db18a81c1f6 100644
--- a/src/test/ui/union/union-derive-rpass.rs
+++ b/src/test/ui/union/union-derive-rpass.rs
@@ -4,8 +4,6 @@
 
 // Some traits can be derived for unions.
 
-#![feature(untagged_unions)]
-
 #[derive(
     Copy,
     Clone,
diff --git a/src/test/ui/union/union-drop-assign.rs b/src/test/ui/union/union-drop-assign.rs
index f1511b0a601..215666bdd9d 100644
--- a/src/test/ui/union/union-drop-assign.rs
+++ b/src/test/ui/union/union-drop-assign.rs
@@ -3,8 +3,6 @@
 
 // Drop works for union itself.
 
-#![feature(untagged_unions)]
-
 use std::mem::ManuallyDrop;
 
 struct S;
diff --git a/src/test/ui/union/union-drop.rs b/src/test/ui/union/union-drop.rs
index 4df3ed50282..9edf5827511 100644
--- a/src/test/ui/union/union-drop.rs
+++ b/src/test/ui/union/union-drop.rs
@@ -4,8 +4,7 @@
 
 // Drop works for union itself.
 
-#![feature(untagged_unions)]
-
+#[derive(Copy, Clone)]
 struct S;
 
 union U {
diff --git a/src/test/ui/union/union-generic-rpass.rs b/src/test/ui/union/union-generic-rpass.rs
index eb169c516d2..69837f31cab 100644
--- a/src/test/ui/union/union-generic-rpass.rs
+++ b/src/test/ui/union/union-generic-rpass.rs
@@ -1,8 +1,6 @@
 // run-pass
 #![allow(dead_code)]
 
-#![feature(untagged_unions)]
-
 use std::mem::ManuallyDrop;
 
 union MaybeItem<T: Iterator> {
@@ -16,7 +14,7 @@ union U<A, B> where A: Copy, B: Copy {
 }
 
 unsafe fn union_transmute<A, B>(a: A) -> B where A: Copy, B: Copy {
-    U { a: a }.b
+    U { a }.b
 }
 
 fn main() {
diff --git a/src/test/ui/union/union-manuallydrop-rpass.rs b/src/test/ui/union/union-manuallydrop-rpass.rs
index a43a5050865..977d12f1086 100644
--- a/src/test/ui/union/union-manuallydrop-rpass.rs
+++ b/src/test/ui/union/union-manuallydrop-rpass.rs
@@ -1,4 +1,3 @@
-#![feature(untagged_unions)]
 #![allow(dead_code)]
 // run-pass
 
diff --git a/src/test/ui/union/union-nodrop.rs b/src/test/ui/union/union-nodrop.rs
index 59282bec59b..bc58c5995cb 100644
--- a/src/test/ui/union/union-nodrop.rs
+++ b/src/test/ui/union/union-nodrop.rs
@@ -1,7 +1,5 @@
 // run-pass
 
-#![feature(untagged_unions)]
-
 #![allow(dead_code)]
 
 use std::mem::needs_drop;
diff --git a/src/test/ui/union/union-overwrite.rs b/src/test/ui/union/union-overwrite.rs
index 8234beb74a8..399ed9ae458 100644
--- a/src/test/ui/union/union-overwrite.rs
+++ b/src/test/ui/union/union-overwrite.rs
@@ -1,5 +1,4 @@
 // run-pass
-#![feature(untagged_unions)]
 
 #[repr(C)]
 #[derive(Copy, Clone)]
diff --git a/src/test/ui/union/union-packed.rs b/src/test/ui/union/union-packed.rs
index ceb35d94656..9cde44c06bd 100644
--- a/src/test/ui/union/union-packed.rs
+++ b/src/test/ui/union/union-packed.rs
@@ -2,8 +2,6 @@
 #![allow(dead_code)]
 #![allow(non_snake_case)]
 
-#![feature(untagged_unions)]
-
 use std::mem::{size_of, size_of_val, align_of, align_of_val};
 
 struct S {
@@ -118,6 +116,7 @@ mod hybrid {
     use std::mem::{size_of, align_of};
 
     #[repr(packed)]
+    #[derive(Copy, Clone)]
     struct S1 {
         a: u16,
         b: u8,
diff --git a/src/test/ui/union/union-unsafe.rs b/src/test/ui/union/union-unsafe.rs
index 8535cbd019c..10f0c467560 100644
--- a/src/test/ui/union/union-unsafe.rs
+++ b/src/test/ui/union/union-unsafe.rs
@@ -1,4 +1,3 @@
-#![feature(untagged_unions)]
 use std::mem::ManuallyDrop;
 
 union U1 {
diff --git a/src/test/ui/union/union-unsafe.stderr b/src/test/ui/union/union-unsafe.stderr
index e020dab63f8..b50d9e17506 100644
--- a/src/test/ui/union/union-unsafe.stderr
+++ b/src/test/ui/union/union-unsafe.stderr
@@ -1,5 +1,5 @@
 error[E0133]: assignment to non-`Copy` union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:22:5
+  --> $DIR/union-unsafe.rs:21:5
    |
 LL |     u3.a = ManuallyDrop::new(T::default());
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ assignment to non-`Copy` union field
@@ -7,7 +7,7 @@ LL |     u3.a = ManuallyDrop::new(T::default());
    = note: the previous content of the field will be dropped, which causes undefined behavior if the field was not properly initialized
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:23:6
+  --> $DIR/union-unsafe.rs:22:6
    |
 LL |     *u3.a = T::default();
    |      ^^^^ access to union field
@@ -15,7 +15,7 @@ LL |     *u3.a = T::default();
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:29:6
+  --> $DIR/union-unsafe.rs:28:6
    |
 LL |     *u3.a = T::default();
    |      ^^^^ access to union field
@@ -23,7 +23,7 @@ LL |     *u3.a = T::default();
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:37:13
+  --> $DIR/union-unsafe.rs:36:13
    |
 LL |     let a = u1.a;
    |             ^^^^ access to union field
@@ -31,7 +31,7 @@ LL |     let a = u1.a;
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:40:14
+  --> $DIR/union-unsafe.rs:39:14
    |
 LL |     let U1 { a } = u1;
    |              ^ access to union field
@@ -39,7 +39,7 @@ LL |     let U1 { a } = u1;
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:41:20
+  --> $DIR/union-unsafe.rs:40:20
    |
 LL |     if let U1 { a: 12 } = u1 {}
    |                    ^^ access to union field
@@ -47,7 +47,7 @@ LL |     if let U1 { a: 12 } = u1 {}
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: assignment to non-`Copy` union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:45:5
+  --> $DIR/union-unsafe.rs:44:5
    |
 LL |     u2.a = ManuallyDrop::new(String::from("new"));
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ assignment to non-`Copy` union field
@@ -55,7 +55,7 @@ LL |     u2.a = ManuallyDrop::new(String::from("new"));
    = note: the previous content of the field will be dropped, which causes undefined behavior if the field was not properly initialized
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:46:6
+  --> $DIR/union-unsafe.rs:45:6
    |
 LL |     *u2.a = String::from("new");
    |      ^^^^ access to union field
@@ -63,7 +63,7 @@ LL |     *u2.a = String::from("new");
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:50:6
+  --> $DIR/union-unsafe.rs:49:6
    |
 LL |     *u3.a = 1;
    |      ^^^^ access to union field
@@ -71,7 +71,7 @@ LL |     *u3.a = 1;
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: assignment to non-`Copy` union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:53:5
+  --> $DIR/union-unsafe.rs:52:5
    |
 LL |     u3.a = ManuallyDrop::new(String::from("new"));
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ assignment to non-`Copy` union field
@@ -79,7 +79,7 @@ LL |     u3.a = ManuallyDrop::new(String::from("new"));
    = note: the previous content of the field will be dropped, which causes undefined behavior if the field was not properly initialized
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:54:6
+  --> $DIR/union-unsafe.rs:53:6
    |
 LL |     *u3.a = String::from("new");
    |      ^^^^ access to union field
diff --git a/src/tools/cargo b/src/tools/cargo
-Subproject 12db56cdedbc2c26a9aa18f994c0188cdcc67df
+Subproject 79b397d72c557eb6444a2ba0dc00a211a226a35
diff --git a/src/tools/linkchecker/Cargo.toml b/src/tools/linkchecker/Cargo.toml
index 0994cd20662..e5d870c039d 100644
--- a/src/tools/linkchecker/Cargo.toml
+++ b/src/tools/linkchecker/Cargo.toml
@@ -7,3 +7,7 @@ edition = "2018"
 [[bin]]
 name = "linkchecker"
 path = "main.rs"
+
+[dependencies]
+regex = "1"
+once_cell = "1"
diff --git a/src/tools/linkchecker/main.rs b/src/tools/linkchecker/main.rs
index 4fe493a850d..f213944e0ab 100644
--- a/src/tools/linkchecker/main.rs
+++ b/src/tools/linkchecker/main.rs
@@ -21,6 +21,9 @@ use std::fs;
 use std::path::{Component, Path, PathBuf};
 use std::rc::Rc;
 
+use once_cell::sync::Lazy;
+use regex::Regex;
+
 use crate::Redirect::*;
 
 // Add linkcheck exceptions here
@@ -50,6 +53,44 @@ const LINKCHECK_EXCEPTIONS: &[(&str, &[&str])] = &[
     ("alloc/collections/btree_set/struct.BTreeSet.html", &["#insert-and-complex-keys"]),
 ];
 
+#[rustfmt::skip]
+const INTRA_DOC_LINK_EXCEPTIONS: &[(&str, &[&str])] = &[
+    // This will never have links that are not in other pages.
+    // To avoid repeating the exceptions twice, an empty list means all broken links are allowed.
+    ("reference/print.html", &[]),
+    // All the reference 'links' are actually ENBF highlighted as code
+    ("reference/comments.html", &[
+         "/</code> <code>!",
+         "*</code> <code>!",
+    ]),
+    ("reference/identifiers.html", &[
+         "a</code>-<code>z</code> <code>A</code>-<code>Z",
+         "a</code>-<code>z</code> <code>A</code>-<code>Z</code> <code>0</code>-<code>9</code> <code>_",
+         "a</code>-<code>z</code> <code>A</code>-<code>Z</code>] [<code>a</code>-<code>z</code> <code>A</code>-<code>Z</code> <code>0</code>-<code>9</code> <code>_",
+    ]),
+    ("reference/tokens.html", &[
+         "0</code>-<code>1",
+         "0</code>-<code>7",
+         "0</code>-<code>9",
+         "0</code>-<code>9",
+         "0</code>-<code>9</code> <code>a</code>-<code>f</code> <code>A</code>-<code>F",
+    ]),
+    ("reference/notation.html", &[
+         "b</code> <code>B",
+         "a</code>-<code>z",
+    ]),
+    // This is being used in the sense of 'inclusive range', not a markdown link
+    ("core/ops/struct.RangeInclusive.html", &["begin</code>, <code>end"]),
+    ("std/ops/struct.RangeInclusive.html", &["begin</code>, <code>end"]),
+    ("core/slice/trait.SliceIndex.html", &["begin</code>, <code>end"]),
+    ("alloc/slice/trait.SliceIndex.html", &["begin</code>, <code>end"]),
+    ("std/slice/trait.SliceIndex.html", &["begin</code>, <code>end"]),
+
+];
+
+static BROKEN_INTRA_DOC_LINK: Lazy<Regex> =
+    Lazy::new(|| Regex::new(r#"\[<code>(.*)</code>\]"#).unwrap());
+
 macro_rules! t {
     ($e:expr) => {
         match $e {
@@ -138,6 +179,14 @@ fn walk(cache: &mut Cache, root: &Path, dir: &Path, errors: &mut bool) {
     }
 }
 
+fn is_intra_doc_exception(file: &Path, link: &str) -> bool {
+    if let Some(entry) = INTRA_DOC_LINK_EXCEPTIONS.iter().find(|&(f, _)| file.ends_with(f)) {
+        entry.1.is_empty() || entry.1.contains(&link)
+    } else {
+        false
+    }
+}
+
 fn is_exception(file: &Path, link: &str) -> bool {
     if let Some(entry) = LINKCHECK_EXCEPTIONS.iter().find(|&(f, _)| file.ends_with(f)) {
         entry.1.contains(&link)
@@ -292,6 +341,19 @@ fn check(cache: &mut Cache, root: &Path, file: &Path, errors: &mut bool) -> Opti
             }
         }
     });
+
+    // Search for intra-doc links that rustdoc didn't warn about
+    // FIXME(#77199, 77200) Rustdoc should just warn about these directly.
+    // NOTE: only looks at one line at a time; in practice this should find most links
+    for (i, line) in contents.lines().enumerate() {
+        for broken_link in BROKEN_INTRA_DOC_LINK.captures_iter(line) {
+            if !is_intra_doc_exception(file, &broken_link[1]) {
+                *errors = true;
+                print!("{}:{}: broken intra-doc link - ", pretty_file.display(), i + 1);
+                println!("{}", &broken_link[0]);
+            }
+        }
+    }
     Some(pretty_file)
 }