Auto merge of #99764 - matthiaskrgr:rollup-fawyb3m, r=matthiaskrgr

Rollup of 6 pull requests

Successful merges:

 - #99235 (rustdoc: Add support for `#[rustc_must_implement_one_of]`)
 - #99716 (remove useless mut from examples)
 - #99724 (Fix some broken link fragments.)
 - #99729 (Remove unused tuple fields)
 - #99757 (Make `transmute_copy` docs read better)
 - #99758 (remove useless `#[allow]` in a test)

Failed merges:

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

18 files changed, 66 insertions, 50 deletions

diff --git a/compiler/rustc_infer/src/infer/error_reporting/mod.rs b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
index be764cfe83b..39faed0bf36 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/mod.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
@@ -2412,9 +2412,9 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         #[derive(Debug)]
         enum SubOrigin<'hir> {
             GAT(&'hir hir::Generics<'hir>),
-            Impl(&'hir hir::Generics<'hir>),
-            Trait(&'hir hir::Generics<'hir>),
-            Fn(&'hir hir::Generics<'hir>),
+            Impl,
+            Trait,
+            Fn,
             Unknown,
         }
         let sub_origin = 'origin: {
@@ -2429,34 +2429,30 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                                         kind: hir::ImplItemKind::TyAlias(..),
                                         generics,
                                         ..
-                                    }) => SubOrigin::GAT(generics),
-                                    Node::ImplItem(hir::ImplItem {
-                                        kind: hir::ImplItemKind::Fn(..),
-                                        generics,
-                                        ..
-                                    }) => SubOrigin::Fn(generics),
-                                    Node::TraitItem(hir::TraitItem {
+                                    })
+                                    | Node::TraitItem(hir::TraitItem {
                                         kind: hir::TraitItemKind::Type(..),
                                         generics,
                                         ..
                                     }) => SubOrigin::GAT(generics),
-                                    Node::TraitItem(hir::TraitItem {
-                                        kind: hir::TraitItemKind::Fn(..),
-                                        generics,
+                                    Node::ImplItem(hir::ImplItem {
+                                        kind: hir::ImplItemKind::Fn(..),
                                         ..
-                                    }) => SubOrigin::Fn(generics),
-                                    Node::Item(hir::Item {
-                                        kind: hir::ItemKind::Trait(_, _, generics, _, _),
+                                    })
+                                    | Node::TraitItem(hir::TraitItem {
+                                        kind: hir::TraitItemKind::Fn(..),
                                         ..
-                                    }) => SubOrigin::Trait(generics),
+                                    })
+                                    | Node::Item(hir::Item {
+                                        kind: hir::ItemKind::Fn(..), ..
+                                    }) => SubOrigin::Fn,
                                     Node::Item(hir::Item {
-                                        kind: hir::ItemKind::Impl(hir::Impl { generics, .. }),
+                                        kind: hir::ItemKind::Trait(..),
                                         ..
-                                    }) => SubOrigin::Impl(generics),
+                                    }) => SubOrigin::Trait,
                                     Node::Item(hir::Item {
-                                        kind: hir::ItemKind::Fn(_, generics, _),
-                                        ..
-                                    }) => SubOrigin::Fn(generics),
+                                        kind: hir::ItemKind::Impl(..), ..
+                                    }) => SubOrigin::Impl,
                                     _ => continue,
                                 };
                             }
diff --git a/compiler/rustc_resolve/src/build_reduced_graph.rs b/compiler/rustc_resolve/src/build_reduced_graph.rs
index 6631470f219..e955a1798b7 100644
--- a/compiler/rustc_resolve/src/build_reduced_graph.rs
+++ b/compiler/rustc_resolve/src/build_reduced_graph.rs
@@ -524,7 +524,7 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
                         let crate_root = self.r.resolve_crate_root(source.ident);
                         let crate_name = match crate_root.kind {
                             ModuleKind::Def(.., name) => name,
-                            ModuleKind::Block(..) => unreachable!(),
+                            ModuleKind::Block => unreachable!(),
                         };
                         // HACK(eddyb) unclear how good this is, but keeping `$crate`
                         // in `source` breaks `src/test/ui/imports/import-crate-var.rs`,
@@ -936,7 +936,7 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
         if self.block_needs_anonymous_module(block) {
             let module = self.r.new_module(
                 Some(parent),
-                ModuleKind::Block(block.id),
+                ModuleKind::Block,
                 expansion.to_expn_id(),
                 block.span,
                 parent.no_implicit_prelude,
diff --git a/compiler/rustc_resolve/src/diagnostics.rs b/compiler/rustc_resolve/src/diagnostics.rs
index 8a655cbf384..0343e8d9b8e 100644
--- a/compiler/rustc_resolve/src/diagnostics.rs
+++ b/compiler/rustc_resolve/src/diagnostics.rs
@@ -163,7 +163,7 @@ impl<'a> Resolver<'a> {
 
         let container = match parent.kind {
             ModuleKind::Def(kind, _, _) => kind.descr(parent.def_id()),
-            ModuleKind::Block(..) => "block",
+            ModuleKind::Block => "block",
         };
 
         let old_noun = match old_binding.is_import() {
diff --git a/compiler/rustc_resolve/src/ident.rs b/compiler/rustc_resolve/src/ident.rs
index 0cc6d05d1d0..6e678288142 100644
--- a/compiler/rustc_resolve/src/ident.rs
+++ b/compiler/rustc_resolve/src/ident.rs
@@ -218,7 +218,7 @@ impl<'a> Resolver<'a> {
             return Some((self.expn_def_scope(ctxt.remove_mark()), None));
         }
 
-        if let ModuleKind::Block(..) = module.kind {
+        if let ModuleKind::Block = module.kind {
             return Some((module.parent.unwrap().nearest_item_scope(), None));
         }
 
@@ -333,7 +333,7 @@ impl<'a> Resolver<'a> {
             };
 
             match module.kind {
-                ModuleKind::Block(..) => {} // We can see through blocks
+                ModuleKind::Block => {} // We can see through blocks
                 _ => break,
             }
 
diff --git a/compiler/rustc_resolve/src/late/diagnostics.rs b/compiler/rustc_resolve/src/late/diagnostics.rs
index f979403e097..6b49c6b1ac6 100644
--- a/compiler/rustc_resolve/src/late/diagnostics.rs
+++ b/compiler/rustc_resolve/src/late/diagnostics.rs
@@ -1444,7 +1444,7 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
                     // Items from this module
                     self.r.add_module_candidates(module, &mut names, &filter_fn);
 
-                    if let ModuleKind::Block(..) = module.kind {
+                    if let ModuleKind::Block = module.kind {
                         // We can see through blocks
                     } else {
                         // Items from the prelude
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index 6945306a691..31d10008efb 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -437,7 +437,7 @@ enum ModuleKind {
     ///     f(); // Resolves to (1)
     /// }
     /// ```
-    Block(NodeId),
+    Block,
     /// Any module with a name.
     ///
     /// This could be:
@@ -454,7 +454,7 @@ impl ModuleKind {
     /// Get name of the module.
     pub fn name(&self) -> Option<Symbol> {
         match self {
-            ModuleKind::Block(..) => None,
+            ModuleKind::Block => None,
             ModuleKind::Def(.., name) => Some(*name),
         }
     }
@@ -530,7 +530,7 @@ impl<'a> ModuleData<'a> {
     ) -> Self {
         let is_foreign = match kind {
             ModuleKind::Def(_, def_id, _) => !def_id.is_local(),
-            ModuleKind::Block(_) => false,
+            ModuleKind::Block => false,
         };
         ModuleData {
             parent,
diff --git a/library/core/src/mem/mod.rs b/library/core/src/mem/mod.rs
index 6dc8563c421..234fa213da8 100644
--- a/library/core/src/mem/mod.rs
+++ b/library/core/src/mem/mod.rs
@@ -1000,7 +1000,7 @@ pub fn copy<T: Copy>(x: &T) -> T {
 ///
 /// This function will unsafely assume the pointer `src` is valid for [`size_of::<U>`][size_of]
 /// bytes by transmuting `&T` to `&U` and then reading the `&U` (except that this is done in a way
-/// that is correct even when `&U` makes stricter alignment requirements than `&T`). It will also
+/// that is correct even when `&U` has stricter alignment requirements than `&T`). It will also
 /// unsafely create a copy of the contained value instead of moving out of `src`.
 ///
 /// It is not a compile-time error if `T` and `U` have different sizes, but it
diff --git a/library/std/src/io/mod.rs b/library/std/src/io/mod.rs
index 18f7f6a35e9..96addbd1a05 100644
--- a/library/std/src/io/mod.rs
+++ b/library/std/src/io/mod.rs
@@ -898,7 +898,7 @@ pub trait Read {
     /// use std::fs::File;
     ///
     /// fn main() -> io::Result<()> {
-    ///     let mut f = File::open("foo.txt")?;
+    ///     let f = File::open("foo.txt")?;
     ///
     ///     for byte in f.bytes() {
     ///         println!("{}", byte.unwrap());
@@ -932,8 +932,8 @@ pub trait Read {
     /// use std::fs::File;
     ///
     /// fn main() -> io::Result<()> {
-    ///     let mut f1 = File::open("foo.txt")?;
-    ///     let mut f2 = File::open("bar.txt")?;
+    ///     let f1 = File::open("foo.txt")?;
+    ///     let f2 = File::open("bar.txt")?;
     ///
     ///     let mut handle = f1.chain(f2);
     ///     let mut buffer = String::new();
@@ -973,7 +973,7 @@ pub trait Read {
     /// use std::fs::File;
     ///
     /// fn main() -> io::Result<()> {
-    ///     let mut f = File::open("foo.txt")?;
+    ///     let f = File::open("foo.txt")?;
     ///     let mut buffer = [0; 5];
     ///
     ///     // read at most five bytes
diff --git a/src/doc/rustdoc/src/deprecated-features.md b/src/doc/rustdoc/src/deprecated-features.md
index 2bc6e8fc8ae..9438948af54 100644
--- a/src/doc/rustdoc/src/deprecated-features.md
+++ b/src/doc/rustdoc/src/deprecated-features.md
@@ -10,4 +10,4 @@ change in any release.
 
 In the past the most common use case for customizing passes was to omit the `strip-private` pass.
 You can do this more easily, and without risk of the pass being changed, by passing
-[`--document-private-items`](./unstable-features.md#--document-private-items).
+[`--document-private-items`](command-line-arguments.md#--document-private-items-show-items-that-are-not-public).
diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
index 30b3d6defb4..32b35007490 100644
--- a/src/doc/rustdoc/src/unstable-features.md
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -466,7 +466,7 @@ Note that the third item is the crate root, which in this case is undocumented.
 and is also accepted on stable toolchains.
 
 It can also be used with `--show-coverage`. Take a look at its
-[documentation](#--show-coverage-get-statistics-about-code-documentation-coverage) for more
+[documentation](#--show-coverage-calculate-the-percentage-of-items-with-documentation) for more
 information.
 
 ### `--enable-per-target-ignores`: allow `ignore-foo` style filters for doctests
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index c9ef4748a48..07237438a0d 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -1993,6 +1993,7 @@ fn clean_maybe_renamed_item<'tcx>(
             ItemKind::Trait(_, _, generics, bounds, item_ids) => {
                 let items =
                     item_ids.iter().map(|ti| cx.tcx.hir().trait_item(ti.id).clean(cx)).collect();
+
                 TraitItem(Trait {
                     def_id,
                     items,
diff --git a/src/librustdoc/html/render/print_item.rs b/src/librustdoc/html/render/print_item.rs
index 81cc12c9d55..dcd2eaac7ea 100644
--- a/src/librustdoc/html/render/print_item.rs
+++ b/src/librustdoc/html/render/print_item.rs
@@ -1,9 +1,5 @@
 use clean::AttributesExt;
 
-use std::cmp::Ordering;
-use std::fmt;
-use std::rc::Rc;
-
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_hir as hir;
 use rustc_hir::def::CtorKind;
@@ -15,6 +11,9 @@ use rustc_middle::ty::{Adt, TyCtxt};
 use rustc_span::hygiene::MacroKind;
 use rustc_span::symbol::{kw, sym, Symbol};
 use rustc_target::abi::{Layout, Primitive, TagEncoding, Variants};
+use std::cmp::Ordering;
+use std::fmt;
+use std::rc::Rc;
 
 use super::{
     collect_paths_for_type, document, ensure_trailing_slash, item_ty_to_section,
@@ -37,6 +36,7 @@ use crate::html::markdown::{HeadingOffset, MarkdownSummaryLine};
 use crate::html::url_parts_builder::UrlPartsBuilder;
 
 use askama::Template;
+use itertools::Itertools;
 
 const ITEM_TABLE_OPEN: &str = "<div class=\"item-table\">";
 const ITEM_TABLE_CLOSE: &str = "</div>";
@@ -539,6 +539,8 @@ fn item_trait(w: &mut Buffer, cx: &mut Context<'_>, it: &clean::Item, t: &clean:
     let count_types = required_types.len() + provided_types.len();
     let count_consts = required_consts.len() + provided_consts.len();
     let count_methods = required_methods.len() + provided_methods.len();
+    let must_implement_one_of_functions =
+        cx.tcx().trait_def(t.def_id).must_implement_one_of.clone();
 
     // Output the trait definition
     wrap_into_docblock(w, |w| {
@@ -784,13 +786,22 @@ fn item_trait(w: &mut Buffer, cx: &mut Context<'_>, it: &clean::Item, t: &clean:
     }
 
     // Output the documentation for each function individually
-    if !required_methods.is_empty() {
+    if !required_methods.is_empty() || must_implement_one_of_functions.is_some() {
         write_small_section_header(
             w,
             "required-methods",
             "Required Methods",
             "<div class=\"methods\">",
         );
+
+        if let Some(list) = must_implement_one_of_functions.as_deref() {
+            write!(
+                w,
+                "<div class=\"stab must_implement\">At least one of the `{}` methods is required.</div>",
+                list.iter().join("`, `")
+            );
+        }
+
         for m in required_methods {
             trait_item(w, cx, m, it);
         }
diff --git a/src/librustdoc/html/static/css/themes/ayu.css b/src/librustdoc/html/static/css/themes/ayu.css
index 7ff8063904a..c42cac59bd6 100644
--- a/src/librustdoc/html/static/css/themes/ayu.css
+++ b/src/librustdoc/html/static/css/themes/ayu.css
@@ -205,11 +205,13 @@ details.rustdoc-toggle > summary::before {
 
 /* Created this empty rule to satisfy the theme checks. */
 .stab.empty-impl {}
+.stab.must_implement {}
 
 .stab.unstable,
 .stab.deprecated,
 .stab.portability,
-.stab.empty-impl {
+.stab.empty-impl,
+.stab.must_implement {
 	color: #c5c5c5;
 	background: #314559 !important;
 	border-style: none !important;
diff --git a/src/librustdoc/html/static/css/themes/dark.css b/src/librustdoc/html/static/css/themes/dark.css
index 8e753f57682..62d9eaa02e6 100644
--- a/src/librustdoc/html/static/css/themes/dark.css
+++ b/src/librustdoc/html/static/css/themes/dark.css
@@ -180,6 +180,7 @@ details.rustdoc-toggle > summary::before {
 .stab.empty-impl { background: #FFF5D6; border-color: #FFC600; color: #2f2f2f; }
 .stab.unstable { background: #FFF5D6; border-color: #FFC600; color: #2f2f2f; }
 .stab.deprecated { background: #ffc4c4; border-color: #db7b7b; color: #2f2f2f; }
+.stab.must_implement { background: #F3DFFF; border-color: #b07bdb; color: #2f2f2f; }
 .stab.portability { background: #F3DFFF; border-color: #b07bdb; color: #2f2f2f; }
 .stab.portability > code { background: none; }
 
diff --git a/src/librustdoc/html/static/css/themes/light.css b/src/librustdoc/html/static/css/themes/light.css
index 40d965c39c3..b751acff152 100644
--- a/src/librustdoc/html/static/css/themes/light.css
+++ b/src/librustdoc/html/static/css/themes/light.css
@@ -163,6 +163,7 @@ details.rustdoc-toggle > summary::before {
 .stab.empty-impl { background: #FFF5D6; border-color: #FFC600; }
 .stab.unstable { background: #FFF5D6; border-color: #FFC600; }
 .stab.deprecated { background: #ffc4c4; border-color: #db7b7b; }
+.stab.must_implement { background: #F3DFFF; border-color: #b07bdb; }
 .stab.portability { background: #F3DFFF; border-color: #b07bdb; }
 .stab.portability > code { background: none; }
 
diff --git a/src/test/rustdoc/must_implement_one_of.rs b/src/test/rustdoc/must_implement_one_of.rs
new file mode 100644
index 00000000000..1f1dd5d5796
--- /dev/null
+++ b/src/test/rustdoc/must_implement_one_of.rs
@@ -0,0 +1,10 @@
+#![crate_name = "c"]
+#![feature(rustc_attrs)]
+
+#[rustc_must_implement_one_of(a, b)]
+// @matches c/trait.Trait.html '//*[@class="stab must_implement"]' \
+//      'At least one of the `a`, `b` methods is required.$'
+pub trait Trait {
+    fn a() {}
+    fn b() {}
+}
diff --git a/src/test/ui/issues/issue-30371.rs b/src/test/ui/issues/issue-30371.rs
index 58521b95cf6..a1ae9a36bc1 100644
--- a/src/test/ui/issues/issue-30371.rs
+++ b/src/test/ui/issues/issue-30371.rs
@@ -1,6 +1,5 @@
 // run-pass
 #![allow(unreachable_code)]
-#![allow(unused_mut)] // rust-lang/rust#54586
 #![deny(unused_variables)]
 
 fn main() {
diff --git a/src/tools/linkchecker/main.rs b/src/tools/linkchecker/main.rs
index c9b1649200d..a7c78d80ccd 100644
--- a/src/tools/linkchecker/main.rs
+++ b/src/tools/linkchecker/main.rs
@@ -348,11 +348,6 @@ impl Checker {
                     return;
                 }
 
-                // These appear to be broken in mdbook right now?
-                if fragment.starts_with('-') {
-                    return;
-                }
-
                 parse_ids(&mut target_ids.borrow_mut(), &pretty_path, target_source, report);
 
                 if target_ids.borrow().contains(*fragment) {