Auto merge of #77172 - jonas-schievink:rollup-a041rou, r=jonas-schievink

Rollup of 15 pull requests

Successful merges:

 - #75438 (Use adaptive SVG favicon for rustdoc like other rust sites)
 - #76304 (Make delegation methods of `std::net::IpAddr` unstably const)
 - #76724 (Allow a unique name to be assigned to dataflow graphviz output)
 - #76978 (Documented From impls in std/sync/mpsc/mod.rs)
 - #77044 (Liballoc bench vec use mem take not replace)
 - #77050 (Typo fix: "satsify" -> "satisfy")
 - #77074 (add array::from_ref)
 - #77078 (Don't use an if guard to check equality with a constant)
 - #77079 (Use `Self` in docs when possible)
 - #77081 (Merge two almost identical match arms)
 - #77121 (Updated html_root_url for compiler crates)
 - #77136 (Suggest `const_mut_refs`, not `const_fn` for mutable references in `const fn`)
 - #77160 (Suggest `const_fn_transmute`, not `const_fn`)
 - #77164 (Remove workaround for deref issue that no longer exists.)
 - #77165 (Followup to #76673)

Failed merges:

r? `@ghost`

76 files changed, 365 insertions, 214 deletions

diff --git a/compiler/rustc_apfloat/src/lib.rs b/compiler/rustc_apfloat/src/lib.rs
index ba3adc4a135..4a845fcb691 100644
--- a/compiler/rustc_apfloat/src/lib.rs
+++ b/compiler/rustc_apfloat/src/lib.rs
@@ -30,7 +30,7 @@
 //!
 //! This API is completely unstable and subject to change.
 
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![no_std]
 #![forbid(unsafe_code)]
 #![feature(nll)]
diff --git a/compiler/rustc_arena/src/lib.rs b/compiler/rustc_arena/src/lib.rs
index 32783951a31..b4bf31b1aba 100644
--- a/compiler/rustc_arena/src/lib.rs
+++ b/compiler/rustc_arena/src/lib.rs
@@ -8,7 +8,7 @@
 //! This crate implements several kinds of arena.
 
 #![doc(
-    html_root_url = "https://doc.rust-lang.org/nightly/",
+    html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/",
     test(no_crate_inject, attr(deny(warnings)))
 )]
 #![feature(dropck_eyepatch)]
diff --git a/compiler/rustc_ast/src/lib.rs b/compiler/rustc_ast/src/lib.rs
index 480a5d2f18e..6e47ff7d740 100644
--- a/compiler/rustc_ast/src/lib.rs
+++ b/compiler/rustc_ast/src/lib.rs
@@ -4,7 +4,10 @@
 //!
 //! This API is completely unstable and subject to change.
 
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/", test(attr(deny(warnings))))]
+#![doc(
+    html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/",
+    test(attr(deny(warnings)))
+)]
 #![feature(box_syntax)]
 #![feature(const_fn)] // For the `transmute` in `P::new`
 #![feature(const_fn_transmute)]
diff --git a/compiler/rustc_attr/src/builtin.rs b/compiler/rustc_attr/src/builtin.rs
index 9951c252001..1808eb270ba 100644
--- a/compiler/rustc_attr/src/builtin.rs
+++ b/compiler/rustc_attr/src/builtin.rs
@@ -301,7 +301,7 @@ where
                                                 .emit();
                                             };
                                             match issue.parse() {
-                                                Ok(num) if num == 0 => {
+                                                Ok(0) => {
                                                     emit_diag(
                                                         "`issue` must not be \"0\", \
                                                         use \"none\" instead",
diff --git a/compiler/rustc_builtin_macros/src/format_foreign.rs b/compiler/rustc_builtin_macros/src/format_foreign.rs
index b39423b86e7..ff81b5eca13 100644
--- a/compiler/rustc_builtin_macros/src/format_foreign.rs
+++ b/compiler/rustc_builtin_macros/src/format_foreign.rs
@@ -518,8 +518,7 @@ pub mod printf {
                         .and_then(|end| end.at_next_cp())
                         .map(|end| (next.slice_between(end).unwrap(), end));
                     let end = match end {
-                        Some(("32", end)) => end,
-                        Some(("64", end)) => end,
+                        Some(("32" | "64", end)) => end,
                         _ => next,
                     };
                     state = Type;
diff --git a/compiler/rustc_builtin_macros/src/lib.rs b/compiler/rustc_builtin_macros/src/lib.rs
index 87be6d1743a..97cadb913ca 100644
--- a/compiler/rustc_builtin_macros/src/lib.rs
+++ b/compiler/rustc_builtin_macros/src/lib.rs
@@ -1,7 +1,7 @@
 //! This crate contains implementations of built-in macros and other code generating facilities
 //! injecting code into the crate before it is lowered to HIR.
 
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(bool_to_option)]
 #![feature(crate_visibility_modifier)]
 #![feature(decl_macro)]
diff --git a/compiler/rustc_codegen_llvm/src/lib.rs b/compiler/rustc_codegen_llvm/src/lib.rs
index 2e2abe9fb30..456e9c7ce75 100644
--- a/compiler/rustc_codegen_llvm/src/lib.rs
+++ b/compiler/rustc_codegen_llvm/src/lib.rs
@@ -4,7 +4,7 @@
 //!
 //! This API is completely unstable and subject to change.
 
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(bool_to_option)]
 #![feature(const_cstr_unchecked)]
 #![feature(crate_visibility_modifier)]
diff --git a/compiler/rustc_codegen_ssa/src/lib.rs b/compiler/rustc_codegen_ssa/src/lib.rs
index a87ce1446ba..8568bd64f4c 100644
--- a/compiler/rustc_codegen_ssa/src/lib.rs
+++ b/compiler/rustc_codegen_ssa/src/lib.rs
@@ -1,4 +1,4 @@
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(bool_to_option)]
 #![feature(option_expect_none)]
 #![feature(box_patterns)]
diff --git a/compiler/rustc_data_structures/src/lib.rs b/compiler/rustc_data_structures/src/lib.rs
index 5990e94ab7e..9ded10e9c26 100644
--- a/compiler/rustc_data_structures/src/lib.rs
+++ b/compiler/rustc_data_structures/src/lib.rs
@@ -6,7 +6,7 @@
 //!
 //! This API is completely unstable and subject to change.
 
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![allow(incomplete_features)]
 #![feature(array_windows)]
 #![feature(control_flow_enum)]
diff --git a/compiler/rustc_driver/src/lib.rs b/compiler/rustc_driver/src/lib.rs
index 972e04fd101..7118437c0c8 100644
--- a/compiler/rustc_driver/src/lib.rs
+++ b/compiler/rustc_driver/src/lib.rs
@@ -4,7 +4,7 @@
 //!
 //! This API is completely unstable and subject to change.
 
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(nll)]
 #![feature(once_cell)]
 #![recursion_limit = "256"]
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index b16fe5603c1..2e8a4ef327a 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -2,7 +2,7 @@
 //!
 //! This module contains the code for creating and emitting diagnostics.
 
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(crate_visibility_modifier)]
 #![feature(backtrace)]
 #![feature(nll)]
diff --git a/compiler/rustc_graphviz/src/lib.rs b/compiler/rustc_graphviz/src/lib.rs
index 58db81bc1dc..76e33bed97f 100644
--- a/compiler/rustc_graphviz/src/lib.rs
+++ b/compiler/rustc_graphviz/src/lib.rs
@@ -272,7 +272,7 @@
 //! * [DOT language](http://www.graphviz.org/doc/info/lang.html)
 
 #![doc(
-    html_root_url = "https://doc.rust-lang.org/nightly/",
+    html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/",
     test(attr(allow(unused_variables), deny(warnings)))
 )]
 #![feature(nll)]
diff --git a/compiler/rustc_incremental/src/lib.rs b/compiler/rustc_incremental/src/lib.rs
index ad189138054..a80c4be3e93 100644
--- a/compiler/rustc_incremental/src/lib.rs
+++ b/compiler/rustc_incremental/src/lib.rs
@@ -1,6 +1,6 @@
 //! Support for serializing the dep-graph and reloading it.
 
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(in_band_lifetimes)]
 #![feature(nll)]
 #![recursion_limit = "256"]
diff --git a/compiler/rustc_infer/src/lib.rs b/compiler/rustc_infer/src/lib.rs
index 504b66bae73..ea9a4661348 100644
--- a/compiler/rustc_infer/src/lib.rs
+++ b/compiler/rustc_infer/src/lib.rs
@@ -12,7 +12,7 @@
 //!
 //! This API is completely unstable and subject to change.
 
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
diff --git a/compiler/rustc_lint/src/lib.rs b/compiler/rustc_lint/src/lib.rs
index b48592c103c..7f7472d9283 100644
--- a/compiler/rustc_lint/src/lib.rs
+++ b/compiler/rustc_lint/src/lib.rs
@@ -25,7 +25,7 @@
 //!
 //! This API is completely unstable and subject to change.
 
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![cfg_attr(test, feature(test))]
 #![feature(array_windows)]
 #![feature(bool_to_option)]
diff --git a/compiler/rustc_llvm/src/lib.rs b/compiler/rustc_llvm/src/lib.rs
index 9d23397ade0..a7a10b91b4e 100644
--- a/compiler/rustc_llvm/src/lib.rs
+++ b/compiler/rustc_llvm/src/lib.rs
@@ -1,6 +1,6 @@
 #![feature(nll)]
 #![feature(static_nobundle)]
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 
 // NOTE: This crate only exists to allow linking on mingw targets.
 
diff --git a/compiler/rustc_metadata/src/lib.rs b/compiler/rustc_metadata/src/lib.rs
index 85490f5f6e9..77766be7397 100644
--- a/compiler/rustc_metadata/src/lib.rs
+++ b/compiler/rustc_metadata/src/lib.rs
@@ -1,4 +1,4 @@
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(bool_to_option)]
 #![feature(core_intrinsics)]
 #![feature(crate_visibility_modifier)]
diff --git a/compiler/rustc_middle/src/lib.rs b/compiler/rustc_middle/src/lib.rs
index 74cb3c130b7..fa885ce2e7c 100644
--- a/compiler/rustc_middle/src/lib.rs
+++ b/compiler/rustc_middle/src/lib.rs
@@ -22,7 +22,7 @@
 //!
 //! This API is completely unstable and subject to change.
 
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(array_windows)]
 #![feature(backtrace)]
 #![feature(bool_to_option)]
diff --git a/compiler/rustc_middle/src/mir/terminator/mod.rs b/compiler/rustc_middle/src/mir/terminator/mod.rs
index fcfd648c2b7..8909f02270c 100644
--- a/compiler/rustc_middle/src/mir/terminator/mod.rs
+++ b/compiler/rustc_middle/src/mir/terminator/mod.rs
@@ -96,6 +96,8 @@ pub enum TerminatorKind<'tcx> {
     ///   P <- V
     /// }
     /// ```
+    ///
+    /// Note that DropAndReplace is eliminated as part of the `ElaborateDrops` pass.
     DropAndReplace {
         place: Place<'tcx>,
         value: Operand<'tcx>,
diff --git a/compiler/rustc_mir/src/borrow_check/mod.rs b/compiler/rustc_mir/src/borrow_check/mod.rs
index 64ad0627720..e4237482f47 100644
--- a/compiler/rustc_mir/src/borrow_check/mod.rs
+++ b/compiler/rustc_mir/src/borrow_check/mod.rs
@@ -205,6 +205,7 @@ fn do_mir_borrowck<'a, 'tcx>(
 
     let mut flow_inits = MaybeInitializedPlaces::new(tcx, &body, &mdpe)
         .into_engine(tcx, &body, def.did.to_def_id())
+        .pass_name("borrowck")
         .iterate_to_fixpoint()
         .into_results_cursor(&body);
 
@@ -264,12 +265,15 @@ fn do_mir_borrowck<'a, 'tcx>(
 
     let flow_borrows = Borrows::new(tcx, &body, regioncx.clone(), &borrow_set)
         .into_engine(tcx, &body, def.did.to_def_id())
+        .pass_name("borrowck")
         .iterate_to_fixpoint();
     let flow_uninits = MaybeUninitializedPlaces::new(tcx, &body, &mdpe)
         .into_engine(tcx, &body, def.did.to_def_id())
+        .pass_name("borrowck")
         .iterate_to_fixpoint();
     let flow_ever_inits = EverInitializedPlaces::new(tcx, &body, &mdpe)
         .into_engine(tcx, &body, def.did.to_def_id())
+        .pass_name("borrowck")
         .iterate_to_fixpoint();
 
     let movable_generator = match tcx.hir().get(id) {
diff --git a/compiler/rustc_mir/src/dataflow/framework/engine.rs b/compiler/rustc_mir/src/dataflow/framework/engine.rs
index 4084083bd99..f39c78f503d 100644
--- a/compiler/rustc_mir/src/dataflow/framework/engine.rs
+++ b/compiler/rustc_mir/src/dataflow/framework/engine.rs
@@ -84,6 +84,7 @@ where
     def_id: DefId,
     dead_unwinds: Option<&'a BitSet<BasicBlock>>,
     entry_sets: IndexVec<BasicBlock, A::Domain>,
+    pass_name: Option<&'static str>,
     analysis: A,
 
     /// Cached, cumulative transfer functions for each block.
@@ -174,6 +175,7 @@ where
             body,
             def_id,
             dead_unwinds: None,
+            pass_name: None,
             entry_sets,
             apply_trans_for_block,
         }
@@ -189,6 +191,15 @@ where
         self
     }
 
+    /// Adds an identifier to the graphviz output for this particular run of a dataflow analysis.
+    ///
+    /// Some analyses are run multiple times in the compilation pipeline. Give them a `pass_name`
+    /// to differentiate them. Otherwise, only the results for the latest run will be saved.
+    pub fn pass_name(mut self, name: &'static str) -> Self {
+        self.pass_name = Some(name);
+        self
+    }
+
     /// Computes the fixpoint for this dataflow problem and returns it.
     pub fn iterate_to_fixpoint(self) -> Results<'tcx, A>
     where
@@ -202,6 +213,7 @@ where
             mut entry_sets,
             tcx,
             apply_trans_for_block,
+            pass_name,
             ..
         } = self;
 
@@ -249,7 +261,7 @@ where
 
         let results = Results { analysis, entry_sets };
 
-        let res = write_graphviz_results(tcx, def_id, &body, &results);
+        let res = write_graphviz_results(tcx, def_id, &body, &results, pass_name);
         if let Err(e) = res {
             warn!("Failed to write graphviz dataflow results: {}", e);
         }
@@ -267,6 +279,7 @@ fn write_graphviz_results<A>(
     def_id: DefId,
     body: &mir::Body<'tcx>,
     results: &Results<'tcx, A>,
+    pass_name: Option<&'static str>,
 ) -> std::io::Result<()>
 where
     A: Analysis<'tcx>,
@@ -285,12 +298,17 @@ where
         None if tcx.sess.opts.debugging_opts.dump_mir_dataflow
             && dump_enabled(tcx, A::NAME, def_id) =>
         {
+            // FIXME: Use some variant of `pretty::dump_path` for this
             let mut path = PathBuf::from(&tcx.sess.opts.debugging_opts.dump_mir_dir);
 
+            let crate_name = tcx.crate_name(def_id.krate);
             let item_name = ty::print::with_forced_impl_filename_line(|| {
                 tcx.def_path(def_id).to_filename_friendly_no_crate()
             });
-            path.push(format!("rustc.{}.{}.dot", item_name, A::NAME));
+
+            let pass_name = pass_name.map(|s| format!(".{}", s)).unwrap_or_default();
+
+            path.push(format!("{}.{}.{}{}.dot", crate_name, item_name, A::NAME, pass_name));
             path
         }
 
diff --git a/compiler/rustc_mir/src/transform/check_consts/ops.rs b/compiler/rustc_mir/src/transform/check_consts/ops.rs
index e14dcf92b89..496e620dd9d 100644
--- a/compiler/rustc_mir/src/transform/check_consts/ops.rs
+++ b/compiler/rustc_mir/src/transform/check_consts/ops.rs
@@ -489,7 +489,14 @@ impl NonConstOp for Transmute {
     }
 
     fn emit_error(&self, ccx: &ConstCx<'_, '_>, span: Span) {
-        mcf_emit_error(ccx, span, "can only call `transmute` from const items, not `const fn`");
+        feature_err(
+            &ccx.tcx.sess.parse_sess,
+            sym::const_fn_transmute,
+            span,
+            &format!("`transmute` is not allowed in {}s", ccx.const_kind()),
+        )
+        .note("`transmute` is only allowed in constants and statics for now")
+        .emit();
     }
 }
 
@@ -535,6 +542,7 @@ impl NonConstOp for UnsizingCast {
     }
 }
 
+// Types that cannot appear in the signature or locals of a `const fn`.
 pub mod ty {
     use super::*;
 
@@ -548,7 +556,13 @@ pub mod ty {
         }
 
         fn emit_error(&self, ccx: &ConstCx<'_, '_>, span: Span) {
-            mcf_emit_error(ccx, span, "mutable references in const fn are unstable");
+            feature_err(
+                &ccx.tcx.sess.parse_sess,
+                sym::const_mut_refs,
+                span,
+                &format!("mutable references are not allowed in {}s", ccx.const_kind()),
+            )
+            .emit()
         }
     }
 
diff --git a/compiler/rustc_mir/src/transform/check_consts/validation.rs b/compiler/rustc_mir/src/transform/check_consts/validation.rs
index 7ea3c1d5a6f..dc28ba46d7c 100644
--- a/compiler/rustc_mir/src/transform/check_consts/validation.rs
+++ b/compiler/rustc_mir/src/transform/check_consts/validation.rs
@@ -59,6 +59,7 @@ impl Qualifs<'mir, 'tcx> {
             MaybeMutBorrowedLocals::mut_borrows_only(tcx, &body, param_env)
                 .unsound_ignore_borrow_on_drop()
                 .into_engine(tcx, &body, def_id.to_def_id())
+                .pass_name("const_qualification")
                 .iterate_to_fixpoint()
                 .into_results_cursor(&body)
         });
diff --git a/compiler/rustc_mir/src/transform/elaborate_drops.rs b/compiler/rustc_mir/src/transform/elaborate_drops.rs
index 5f193069356..a8b2ee5705f 100644
--- a/compiler/rustc_mir/src/transform/elaborate_drops.rs
+++ b/compiler/rustc_mir/src/transform/elaborate_drops.rs
@@ -44,6 +44,7 @@ impl<'tcx> MirPass<'tcx> for ElaborateDrops {
             let inits = MaybeInitializedPlaces::new(tcx, body, &env)
                 .into_engine(tcx, body, def_id)
                 .dead_unwinds(&dead_unwinds)
+                .pass_name("elaborate_drops")
                 .iterate_to_fixpoint()
                 .into_results_cursor(body);
 
@@ -51,6 +52,7 @@ impl<'tcx> MirPass<'tcx> for ElaborateDrops {
                 .mark_inactive_variants_as_uninit()
                 .into_engine(tcx, body, def_id)
                 .dead_unwinds(&dead_unwinds)
+                .pass_name("elaborate_drops")
                 .iterate_to_fixpoint()
                 .into_results_cursor(body);
 
@@ -83,6 +85,7 @@ fn find_dead_unwinds<'tcx>(
     let mut dead_unwinds = BitSet::new_empty(body.basic_blocks().len());
     let mut flow_inits = MaybeInitializedPlaces::new(tcx, body, &env)
         .into_engine(tcx, body, def_id)
+        .pass_name("find_dead_unwinds")
         .iterate_to_fixpoint()
         .into_results_cursor(body);
     for (bb, bb_data) in body.basic_blocks().iter_enumerated() {
diff --git a/compiler/rustc_mir/src/transform/generator.rs b/compiler/rustc_mir/src/transform/generator.rs
index 78cedec5020..1fffcf81515 100644
--- a/compiler/rustc_mir/src/transform/generator.rs
+++ b/compiler/rustc_mir/src/transform/generator.rs
@@ -467,8 +467,10 @@ fn locals_live_across_suspend_points(
 
     // Calculate the MIR locals which have been previously
     // borrowed (even if they are still active).
-    let borrowed_locals_results =
-        MaybeBorrowedLocals::all_borrows().into_engine(tcx, body_ref, def_id).iterate_to_fixpoint();
+    let borrowed_locals_results = MaybeBorrowedLocals::all_borrows()
+        .into_engine(tcx, body_ref, def_id)
+        .pass_name("generator")
+        .iterate_to_fixpoint();
 
     let mut borrowed_locals_cursor =
         dataflow::ResultsCursor::new(body_ref, &borrowed_locals_results);
@@ -484,6 +486,7 @@ fn locals_live_across_suspend_points(
     // Calculate the liveness of MIR locals ignoring borrows.
     let mut liveness = MaybeLiveLocals
         .into_engine(tcx, body_ref, def_id)
+        .pass_name("generator")
         .iterate_to_fixpoint()
         .into_results_cursor(body_ref);
 
diff --git a/compiler/rustc_mir/src/transform/remove_unneeded_drops.rs b/compiler/rustc_mir/src/transform/remove_unneeded_drops.rs
index f027f5e33a1..b9f29786c64 100644
--- a/compiler/rustc_mir/src/transform/remove_unneeded_drops.rs
+++ b/compiler/rustc_mir/src/transform/remove_unneeded_drops.rs
@@ -38,8 +38,7 @@ impl<'tcx> MirPass<'tcx> for RemoveUnneededDrops {
 impl<'a, 'tcx> Visitor<'tcx> for RemoveUnneededDropsOptimizationFinder<'a, 'tcx> {
     fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) {
         match terminator.kind {
-            TerminatorKind::Drop { place, target, .. }
-            | TerminatorKind::DropAndReplace { place, target, .. } => {
+            TerminatorKind::Drop { place, target, .. } => {
                 let ty = place.ty(self.body, self.tcx);
                 let needs_drop = ty.ty.needs_drop(self.tcx, self.tcx.param_env(self.def_id));
                 if !needs_drop {
diff --git a/compiler/rustc_parse_format/src/lib.rs b/compiler/rustc_parse_format/src/lib.rs
index cef632b1d8f..25e3e67e28e 100644
--- a/compiler/rustc_parse_format/src/lib.rs
+++ b/compiler/rustc_parse_format/src/lib.rs
@@ -5,7 +5,7 @@
 //! generated instead.
 
 #![doc(
-    html_root_url = "https://doc.rust-lang.org/nightly/",
+    html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/",
     html_playground_url = "https://play.rust-lang.org/",
     test(attr(deny(warnings)))
 )]
diff --git a/compiler/rustc_passes/src/lib.rs b/compiler/rustc_passes/src/lib.rs
index be4c542ec3a..c14d6aace87 100644
--- a/compiler/rustc_passes/src/lib.rs
+++ b/compiler/rustc_passes/src/lib.rs
@@ -4,7 +4,7 @@
 //!
 //! This API is completely unstable and subject to change.
 
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(in_band_lifetimes)]
 #![feature(nll)]
 #![feature(or_patterns)]
diff --git a/compiler/rustc_plugin_impl/src/lib.rs b/compiler/rustc_plugin_impl/src/lib.rs
index 1eb65dd96ba..5bf4d300e9e 100644
--- a/compiler/rustc_plugin_impl/src/lib.rs
+++ b/compiler/rustc_plugin_impl/src/lib.rs
@@ -6,7 +6,7 @@
 //! feature](https://doc.rust-lang.org/nightly/unstable-book/language-features/plugin.html)
 //! of the Unstable Book for some examples.
 
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(nll)]
 #![recursion_limit = "256"]
 
diff --git a/compiler/rustc_privacy/src/lib.rs b/compiler/rustc_privacy/src/lib.rs
index c2de4cdbf0d..8d1b826ea35 100644
--- a/compiler/rustc_privacy/src/lib.rs
+++ b/compiler/rustc_privacy/src/lib.rs
@@ -1,4 +1,4 @@
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(in_band_lifetimes)]
 #![feature(nll)]
 #![recursion_limit = "256"]
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index 677cf27cde7..283db1404d0 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -8,7 +8,7 @@
 //!
 //! Type-relative name resolution (methods, fields, associated items) happens in `librustc_typeck`.
 
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(bool_to_option)]
 #![feature(crate_visibility_modifier)]
 #![feature(nll)]
diff --git a/compiler/rustc_save_analysis/src/lib.rs b/compiler/rustc_save_analysis/src/lib.rs
index 032d7cb3ed6..f6434689fec 100644
--- a/compiler/rustc_save_analysis/src/lib.rs
+++ b/compiler/rustc_save_analysis/src/lib.rs
@@ -1,4 +1,4 @@
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(nll)]
 #![feature(or_patterns)]
 #![recursion_limit = "256"]
diff --git a/compiler/rustc_serialize/src/lib.rs b/compiler/rustc_serialize/src/lib.rs
index 265b3b95e95..ed48fbf40ac 100644
--- a/compiler/rustc_serialize/src/lib.rs
+++ b/compiler/rustc_serialize/src/lib.rs
@@ -5,7 +5,7 @@ Core encoding and decoding interfaces.
 */
 
 #![doc(
-    html_root_url = "https://doc.rust-lang.org/nightly/",
+    html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/",
     html_playground_url = "https://play.rust-lang.org/",
     test(attr(allow(unused_variables), deny(warnings)))
 )]
diff --git a/compiler/rustc_span/src/lib.rs b/compiler/rustc_span/src/lib.rs
index 4b02a2d4076..96a6956a40c 100644
--- a/compiler/rustc_span/src/lib.rs
+++ b/compiler/rustc_span/src/lib.rs
@@ -4,7 +4,7 @@
 //!
 //! This API is completely unstable and subject to change.
 
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(array_windows)]
 #![feature(crate_visibility_modifier)]
 #![feature(const_fn)]
diff --git a/compiler/rustc_symbol_mangling/src/lib.rs b/compiler/rustc_symbol_mangling/src/lib.rs
index 296b40c4e39..75150a56c43 100644
--- a/compiler/rustc_symbol_mangling/src/lib.rs
+++ b/compiler/rustc_symbol_mangling/src/lib.rs
@@ -87,7 +87,7 @@
 //! virtually impossible. Thus, symbol hash generation exclusively relies on
 //! DefPaths which are much more robust in the face of changes to the code base.
 
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(never_type)]
 #![feature(nll)]
 #![feature(or_patterns)]
diff --git a/compiler/rustc_target/src/lib.rs b/compiler/rustc_target/src/lib.rs
index 5788e1e8385..fb747dfcbd3 100644
--- a/compiler/rustc_target/src/lib.rs
+++ b/compiler/rustc_target/src/lib.rs
@@ -7,7 +7,7 @@
 //! more 'stuff' here in the future. It does not have a dependency on
 //! LLVM.
 
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(bool_to_option)]
 #![feature(const_fn)]
 #![feature(const_panic)]
diff --git a/compiler/rustc_trait_selection/src/lib.rs b/compiler/rustc_trait_selection/src/lib.rs
index a53075448ed..ddeab340f38 100644
--- a/compiler/rustc_trait_selection/src/lib.rs
+++ b/compiler/rustc_trait_selection/src/lib.rs
@@ -10,7 +10,7 @@
 //!
 //! This API is completely unstable and subject to change.
 
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(drain_filter)]
diff --git a/compiler/rustc_ty/src/lib.rs b/compiler/rustc_ty/src/lib.rs
index 8dd6aa3c7fc..904c0062a92 100644
--- a/compiler/rustc_ty/src/lib.rs
+++ b/compiler/rustc_ty/src/lib.rs
@@ -4,7 +4,7 @@
 //!
 //! This API is completely unstable and subject to change.
 
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(nll)]
 #![recursion_limit = "256"]
 
diff --git a/compiler/rustc_typeck/src/lib.rs b/compiler/rustc_typeck/src/lib.rs
index 0e9f4476c20..84efb92582e 100644
--- a/compiler/rustc_typeck/src/lib.rs
+++ b/compiler/rustc_typeck/src/lib.rs
@@ -55,7 +55,7 @@ This API is completely unstable and subject to change.
 
 */
 
-#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
+#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![allow(non_camel_case_types)]
 #![feature(bool_to_option)]
 #![feature(box_syntax)]
diff --git a/library/alloc/benches/vec.rs b/library/alloc/benches/vec.rs
index b295342f361..687efa8e9e7 100644
--- a/library/alloc/benches/vec.rs
+++ b/library/alloc/benches/vec.rs
@@ -241,7 +241,7 @@ fn bench_extend_recycle(b: &mut Bencher) {
     let mut data = vec![0; 1000];
 
     b.iter(|| {
-        let tmp = std::mem::replace(&mut data, Vec::new());
+        let tmp = std::mem::take(&mut data);
         let mut to_extend = black_box(Vec::new());
         to_extend.extend(tmp.into_iter());
         data = black_box(to_extend);
@@ -500,7 +500,7 @@ fn bench_in_place_recycle(b: &mut Bencher) {
     let mut data = vec![0; 1000];
 
     b.iter(|| {
-        let tmp = std::mem::replace(&mut data, Vec::new());
+        let tmp = std::mem::take(&mut data);
         data = black_box(
             tmp.into_iter()
                 .enumerate()
@@ -520,7 +520,7 @@ fn bench_in_place_zip_recycle(b: &mut Bencher) {
     rng.fill_bytes(&mut subst[..]);
 
     b.iter(|| {
-        let tmp = std::mem::replace(&mut data, Vec::new());
+        let tmp = std::mem::take(&mut data);
         let mangled = tmp
             .into_iter()
             .zip(subst.iter().copied())
diff --git a/library/alloc/src/collections/binary_heap.rs b/library/alloc/src/collections/binary_heap.rs
index ea75fa21965..f2852b1cc2b 100644
--- a/library/alloc/src/collections/binary_heap.rs
+++ b/library/alloc/src/collections/binary_heap.rs
@@ -30,7 +30,7 @@
 //! // Explicitly implement the trait so the queue becomes a min-heap
 //! // instead of a max-heap.
 //! impl Ord for State {
-//!     fn cmp(&self, other: &State) -> Ordering {
+//!     fn cmp(&self, other: &Self) -> Ordering {
 //!         // Notice that the we flip the ordering on costs.
 //!         // In case of a tie we compare positions - this step is necessary
 //!         // to make implementations of `PartialEq` and `Ord` consistent.
@@ -41,7 +41,7 @@
 //!
 //! // `PartialOrd` needs to be implemented as well.
 //! impl PartialOrd for State {
-//!     fn partial_cmp(&self, other: &State) -> Option<Ordering> {
+//!     fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
 //!         Some(self.cmp(other))
 //!     }
 //! }
diff --git a/library/alloc/src/vec.rs b/library/alloc/src/vec.rs
index 8a9463cb518..c54b3aef95e 100644
--- a/library/alloc/src/vec.rs
+++ b/library/alloc/src/vec.rs
@@ -412,7 +412,7 @@ impl<T> Vec<T> {
     ///   (at least, it's highly likely to be incorrect if it wasn't).
     /// * `T` needs to have the same size and alignment as what `ptr` was allocated with.
     ///   (`T` having a less strict alignment is not sufficient, the alignment really
-    ///   needs to be equal to satsify the [`dealloc`] requirement that memory must be
+    ///   needs to be equal to satisfy the [`dealloc`] requirement that memory must be
     ///   allocated and deallocated with the same layout.)
     /// * `length` needs to be less than or equal to `capacity`.
     /// * `capacity` needs to be the capacity that the pointer was allocated with.
diff --git a/library/core/src/array/mod.rs b/library/core/src/array/mod.rs
index c1d3aca6fdd..966272ca115 100644
--- a/library/core/src/array/mod.rs
+++ b/library/core/src/array/mod.rs
@@ -19,6 +19,20 @@ mod iter;
 #[unstable(feature = "array_value_iter", issue = "65798")]
 pub use iter::IntoIter;
 
+/// Converts a reference to `T` into a reference to an array of length 1 (without copying).
+#[unstable(feature = "array_from_ref", issue = "77101")]
+pub fn from_ref<T>(s: &T) -> &[T; 1] {
+    // SAFETY: Converting `&T` to `&[T; 1]` is sound.
+    unsafe { &*(s as *const T).cast::<[T; 1]>() }
+}
+
+/// Converts a mutable reference to `T` into a mutable reference to an array of length 1 (without copying).
+#[unstable(feature = "array_from_ref", issue = "77101")]
+pub fn from_mut<T>(s: &mut T) -> &mut [T; 1] {
+    // SAFETY: Converting `&mut T` to `&mut [T; 1]` is sound.
+    unsafe { &mut *(s as *mut T).cast::<[T; 1]>() }
+}
+
 /// Utility trait implemented only on arrays of fixed size
 ///
 /// This trait can be used to implement other traits on fixed-size arrays
diff --git a/library/core/src/cmp.rs b/library/core/src/cmp.rs
index dde442aa7b5..ee79a94cc66 100644
--- a/library/core/src/cmp.rs
+++ b/library/core/src/cmp.rs
@@ -726,19 +726,19 @@ impl PartialOrd for Ordering {
 /// }
 ///
 /// impl PartialOrd for Person {
-///     fn partial_cmp(&self, other: &Person) -> Option<Ordering> {
+///     fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
 ///         Some(self.cmp(other))
 ///     }
 /// }
 ///
 /// impl Ord for Person {
-///     fn cmp(&self, other: &Person) -> Ordering {
+///     fn cmp(&self, other: &Self) -> Ordering {
 ///         self.height.cmp(&other.height)
 ///     }
 /// }
 ///
 /// impl PartialEq for Person {
-///     fn eq(&self, other: &Person) -> bool {
+///     fn eq(&self, other: &Self) -> bool {
 ///         self.height == other.height
 ///     }
 /// }
diff --git a/library/core/src/marker.rs b/library/core/src/marker.rs
index 9340b591ebd..cdf742057b7 100644
--- a/library/core/src/marker.rs
+++ b/library/core/src/marker.rs
@@ -643,9 +643,9 @@ macro_rules! impls {
 /// }
 ///
 /// impl<R: ResType> ExternalResource<R> {
-///     fn new() -> ExternalResource<R> {
+///     fn new() -> Self {
 ///         let size_of_res = mem::size_of::<R>();
-///         ExternalResource {
+///         Self {
 ///             resource_handle: foreign_lib::new(size_of_res),
 ///             resource_type: PhantomData,
 ///         }
diff --git a/library/core/src/ops/arith.rs b/library/core/src/ops/arith.rs
index bdf93baa1b8..19f86ced500 100644
--- a/library/core/src/ops/arith.rs
+++ b/library/core/src/ops/arith.rs
@@ -128,10 +128,10 @@ add_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f32 f64 }
 /// }
 ///
 /// impl Sub for Point {
-///     type Output = Point;
+///     type Output = Self;
 ///
-///     fn sub(self, other: Point) -> Point {
-///         Point {
+///     fn sub(self, other: Self) -> Self::Output {
+///         Self {
 ///             x: self.x - other.x,
 ///             y: self.y - other.y,
 ///         }
@@ -241,7 +241,7 @@ sub_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f32 f64 }
 ///         // Reduce to lowest terms by dividing by the greatest common
 ///         // divisor.
 ///         let gcd = gcd(numerator, denominator);
-///         Rational {
+///         Self {
 ///             numerator: numerator / gcd,
 ///             denominator: denominator / gcd,
 ///         }
@@ -255,7 +255,7 @@ sub_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f32 f64 }
 ///     fn mul(self, rhs: Self) -> Self {
 ///         let numerator = self.numerator * rhs.numerator;
 ///         let denominator = self.denominator * rhs.denominator;
-///         Rational::new(numerator, denominator)
+///         Self::new(numerator, denominator)
 ///     }
 /// }
 ///
@@ -291,7 +291,7 @@ sub_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f32 f64 }
 ///     type Output = Self;
 ///
 ///     fn mul(self, rhs: Scalar) -> Self::Output {
-///         Vector { value: self.value.iter().map(|v| v * rhs.value).collect() }
+///         Self { value: self.value.iter().map(|v| v * rhs.value).collect() }
 ///     }
 /// }
 ///
@@ -369,7 +369,7 @@ mul_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f32 f64 }
 ///         // Reduce to lowest terms by dividing by the greatest common
 ///         // divisor.
 ///         let gcd = gcd(numerator, denominator);
-///         Rational {
+///         Self {
 ///             numerator: numerator / gcd,
 ///             denominator: denominator / gcd,
 ///         }
@@ -387,7 +387,7 @@ mul_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f32 f64 }
 ///
 ///         let numerator = self.numerator * rhs.denominator;
 ///         let denominator = self.denominator * rhs.numerator;
-///         Rational::new(numerator, denominator)
+///         Self::new(numerator, denominator)
 ///     }
 /// }
 ///
@@ -423,7 +423,7 @@ mul_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f32 f64 }
 ///     type Output = Self;
 ///
 ///     fn div(self, rhs: Scalar) -> Self::Output {
-///         Vector { value: self.value.iter().map(|v| v / rhs.value).collect() }
+///         Self { value: self.value.iter().map(|v| v / rhs.value).collect() }
 ///     }
 /// }
 ///
@@ -515,7 +515,7 @@ div_impl_float! { f32 f64 }
 ///         let len = self.slice.len();
 ///         let rem = len % modulus;
 ///         let start = len - rem;
-///         SplitSlice {slice: &self.slice[start..]}
+///         Self {slice: &self.slice[start..]}
 ///     }
 /// }
 ///
@@ -615,7 +615,7 @@ rem_impl_float! { f32 f64 }
 /// }
 ///
 /// impl Neg for Sign {
-///     type Output = Sign;
+///     type Output = Self;
 ///
 ///     fn neg(self) -> Self::Output {
 ///         match self {
diff --git a/library/core/src/ops/bit.rs b/library/core/src/ops/bit.rs
index 3d71e0b0002..6120da50c3c 100644
--- a/library/core/src/ops/bit.rs
+++ b/library/core/src/ops/bit.rs
@@ -15,7 +15,7 @@
 /// }
 ///
 /// impl Not for Answer {
-///     type Output = Answer;
+///     type Output = Self;
 ///
 ///     fn not(self) -> Self::Output {
 ///         match self {
@@ -85,7 +85,7 @@ not_impl! { bool usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 }
 ///
 ///     // rhs is the "right-hand side" of the expression `a & b`
 ///     fn bitand(self, rhs: Self) -> Self::Output {
-///         Scalar(self.0 & rhs.0)
+///         Self(self.0 & rhs.0)
 ///     }
 /// }
 ///
@@ -106,10 +106,13 @@ not_impl! { bool usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 }
 /// impl BitAnd for BooleanVector {
 ///     type Output = Self;
 ///
-///     fn bitand(self, BooleanVector(rhs): Self) -> Self::Output {
-///         let BooleanVector(lhs) = self;
+///     fn bitand(self, Self(rhs): Self) -> Self::Output {
+///         let Self(lhs) = self;
 ///         assert_eq!(lhs.len(), rhs.len());
-///         BooleanVector(lhs.iter().zip(rhs.iter()).map(|(x, y)| *x && *y).collect())
+///         Self(lhs.iter()
+///                 .zip(rhs.iter())
+///                 .map(|(x, y)| *x && *y)
+///                 .collect())
 ///     }
 /// }
 ///
@@ -179,8 +182,8 @@ bitand_impl! { bool usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 }
 ///     type Output = Self;
 ///
 ///     // rhs is the "right-hand side" of the expression `a | b`
-///     fn bitor(self, rhs: Self) -> Self {
-///         Scalar(self.0 | rhs.0)
+///     fn bitor(self, rhs: Self) -> Self::Output {
+///         Self(self.0 | rhs.0)
 ///     }
 /// }
 ///
@@ -201,10 +204,10 @@ bitand_impl! { bool usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 }
 /// impl BitOr for BooleanVector {
 ///     type Output = Self;
 ///
-///     fn bitor(self, BooleanVector(rhs): Self) -> Self::Output {
-///         let BooleanVector(lhs) = self;
+///     fn bitor(self, Self(rhs): Self) -> Self::Output {
+///         let Self(lhs) = self;
 ///         assert_eq!(lhs.len(), rhs.len());
-///         BooleanVector(lhs.iter().zip(rhs.iter()).map(|(x, y)| *x || *y).collect())
+///         Self(lhs.iter().zip(rhs.iter()).map(|(x, y)| *x || *y).collect())
 ///     }
 /// }
 ///
@@ -275,7 +278,7 @@ bitor_impl! { bool usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 }
 ///
 ///     // rhs is the "right-hand side" of the expression `a ^ b`
 ///     fn bitxor(self, rhs: Self) -> Self::Output {
-///         Scalar(self.0 ^ rhs.0)
+///         Self(self.0 ^ rhs.0)
 ///     }
 /// }
 ///
@@ -296,13 +299,13 @@ bitor_impl! { bool usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 }
 /// impl BitXor for BooleanVector {
 ///     type Output = Self;
 ///
-///     fn bitxor(self, BooleanVector(rhs): Self) -> Self::Output {
-///         let BooleanVector(lhs) = self;
+///     fn bitxor(self, Self(rhs): Self) -> Self::Output {
+///         let Self(lhs) = self;
 ///         assert_eq!(lhs.len(), rhs.len());
-///         BooleanVector(lhs.iter()
-///                          .zip(rhs.iter())
-///                          .map(|(x, y)| (*x || *y) && !(*x && *y))
-///                          .collect())
+///         Self(lhs.iter()
+///                 .zip(rhs.iter())
+///                 .map(|(x, y)| (*x || *y) && !(*x && *y))
+///                 .collect())
 ///     }
 /// }
 ///
@@ -375,9 +378,9 @@ bitxor_impl! { bool usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 }
 /// impl Shl<Scalar> for Scalar {
 ///     type Output = Self;
 ///
-///     fn shl(self, Scalar(rhs): Self) -> Scalar {
-///         let Scalar(lhs) = self;
-///         Scalar(lhs << rhs)
+///     fn shl(self, Self(rhs): Self) -> Self::Output {
+///         let Self(lhs) = self;
+///         Self(lhs << rhs)
 ///     }
 /// }
 ///
@@ -400,10 +403,10 @@ bitxor_impl! { bool usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 }
 ///     fn shl(self, rhs: usize) -> Self::Output {
 ///         // Rotate the vector by `rhs` places.
 ///         let (a, b) = self.vec.split_at(rhs);
-///         let mut spun_vector: Vec<T> = vec![];
+///         let mut spun_vector = vec![];
 ///         spun_vector.extend_from_slice(b);
 ///         spun_vector.extend_from_slice(a);
-///         SpinVector { vec: spun_vector }
+///         Self { vec: spun_vector }
 ///     }
 /// }
 ///
@@ -493,9 +496,9 @@ shl_impl_all! { u8 u16 u32 u64 u128 usize i8 i16 i32 i64 isize i128 }
 /// impl Shr<Scalar> for Scalar {
 ///     type Output = Self;
 ///
-///     fn shr(self, Scalar(rhs): Self) -> Scalar {
-///         let Scalar(lhs) = self;
-///         Scalar(lhs >> rhs)
+///     fn shr(self, Self(rhs): Self) -> Self::Output {
+///         let Self(lhs) = self;
+///         Self(lhs >> rhs)
 ///     }
 /// }
 ///
@@ -518,10 +521,10 @@ shl_impl_all! { u8 u16 u32 u64 u128 usize i8 i16 i32 i64 isize i128 }
 ///     fn shr(self, rhs: usize) -> Self::Output {
 ///         // Rotate the vector by `rhs` places.
 ///         let (a, b) = self.vec.split_at(self.vec.len() - rhs);
-///         let mut spun_vector: Vec<T> = vec![];
+///         let mut spun_vector = vec![];
 ///         spun_vector.extend_from_slice(b);
 ///         spun_vector.extend_from_slice(a);
-///         SpinVector { vec: spun_vector }
+///         Self { vec: spun_vector }
 ///     }
 /// }
 ///
@@ -606,7 +609,7 @@ shr_impl_all! { u8 u16 u32 u64 u128 usize i8 i16 i32 i64 i128 isize }
 /// impl BitAndAssign for Scalar {
 ///     // rhs is the "right-hand side" of the expression `a &= b`
 ///     fn bitand_assign(&mut self, rhs: Self) {
-///         *self = Scalar(self.0 & rhs.0)
+///         *self = Self(self.0 & rhs.0)
 ///     }
 /// }
 ///
@@ -640,11 +643,11 @@ shr_impl_all! { u8 u16 u32 u64 u128 usize i8 i16 i32 i64 i128 isize }
 ///     // `rhs` is the "right-hand side" of the expression `a &= b`.
 ///     fn bitand_assign(&mut self, rhs: Self) {
 ///         assert_eq!(self.0.len(), rhs.0.len());
-///         *self = BooleanVector(self.0
-///                                   .iter()
-///                                   .zip(rhs.0.iter())
-///                                   .map(|(x, y)| *x && *y)
-///                                   .collect());
+///         *self = Self(self.0
+///                          .iter()
+///                          .zip(rhs.0.iter())
+///                          .map(|(x, y)| *x && *y)
+///                          .collect());
 ///     }
 /// }
 ///
diff --git a/library/core/src/ops/mod.rs b/library/core/src/ops/mod.rs
index 2a4186f9d5d..354ad6b7b73 100644
--- a/library/core/src/ops/mod.rs
+++ b/library/core/src/ops/mod.rs
@@ -49,18 +49,18 @@
 //! }
 //!
 //! impl Add for Point {
-//!     type Output = Point;
+//!     type Output = Self;
 //!
-//!     fn add(self, other: Point) -> Point {
-//!         Point {x: self.x + other.x, y: self.y + other.y}
+//!     fn add(self, other: Self) -> Self {
+//!         Self {x: self.x + other.x, y: self.y + other.y}
 //!     }
 //! }
 //!
 //! impl Sub for Point {
-//!     type Output = Point;
+//!     type Output = Self;
 //!
-//!     fn sub(self, other: Point) -> Point {
-//!         Point {x: self.x - other.x, y: self.y - other.y}
+//!     fn sub(self, other: Self) -> Self {
+//!         Self {x: self.x - other.x, y: self.y - other.y}
 //!     }
 //! }
 //!
diff --git a/library/core/src/slice/raw.rs b/library/core/src/slice/raw.rs
index a5811c5e472..09209306c9d 100644
--- a/library/core/src/slice/raw.rs
+++ b/library/core/src/slice/raw.rs
@@ -1,5 +1,6 @@
 //! Free functions to create `&[T]` and `&mut [T]`.
 
+use crate::array;
 use crate::intrinsics::is_aligned_and_not_null;
 use crate::mem;
 use crate::ptr;
@@ -140,19 +141,11 @@ pub unsafe fn from_raw_parts_mut<'a, T>(data: *mut T, len: usize) -> &'a mut [T]
 /// Converts a reference to T into a slice of length 1 (without copying).
 #[stable(feature = "from_ref", since = "1.28.0")]
 pub fn from_ref<T>(s: &T) -> &[T] {
-    // SAFETY: a reference is guaranteed to be valid for reads. The returned
-    // reference cannot be mutated as it is an immutable reference.
-    // `mem::size_of::<T>()` cannot be larger than `isize::MAX`.
-    // Thus the call to `from_raw_parts` is safe.
-    unsafe { from_raw_parts(s, 1) }
+    array::from_ref(s)
 }
 
 /// Converts a reference to T into a slice of length 1 (without copying).
 #[stable(feature = "from_ref", since = "1.28.0")]
 pub fn from_mut<T>(s: &mut T) -> &mut [T] {
-    // SAFETY: a mutable reference is guaranteed to be valid for writes.
-    // The reference cannot be accessed by another pointer as it is an mutable reference.
-    // `mem::size_of::<T>()` cannot be larger than `isize::MAX`.
-    // Thus the call to `from_raw_parts_mut` is safe.
-    unsafe { from_raw_parts_mut(s, 1) }
+    array::from_mut(s)
 }
diff --git a/library/core/tests/array.rs b/library/core/tests/array.rs
index 5aba1a5d958..dbcea2747a0 100644
--- a/library/core/tests/array.rs
+++ b/library/core/tests/array.rs
@@ -1,4 +1,4 @@
-use core::array::{FixedSizeArray, IntoIter};
+use core::array::{self, FixedSizeArray, IntoIter};
 use core::convert::TryFrom;
 
 #[test]
@@ -20,6 +20,21 @@ fn fixed_size_array() {
 }
 
 #[test]
+fn array_from_ref() {
+    let value: String = "Hello World!".into();
+    let arr: &[String; 1] = array::from_ref(&value);
+    assert_eq!(&[value.clone()], arr);
+}
+
+#[test]
+fn array_from_mut() {
+    let mut value: String = "Hello World".into();
+    let arr: &mut [String; 1] = array::from_mut(&mut value);
+    arr[0].push_str("!");
+    assert_eq!(&value, "Hello World!");
+}
+
+#[test]
 fn array_try_from() {
     macro_rules! test {
         ($($N:expr)+) => {
diff --git a/library/core/tests/lib.rs b/library/core/tests/lib.rs
index 7e75c7cf47b..d8b36beb3e0 100644
--- a/library/core/tests/lib.rs
+++ b/library/core/tests/lib.rs
@@ -1,5 +1,6 @@
 #![feature(alloc_layout_extra)]
 #![feature(array_chunks)]
+#![feature(array_from_ref)]
 #![feature(array_methods)]
 #![feature(array_map)]
 #![feature(array_windows)]
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index 309657e7042..ac0075ad129 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -238,6 +238,7 @@
 #![feature(const_cstr_unchecked)]
 #![feature(const_fn_transmute)]
 #![feature(const_fn)]
+#![feature(const_ip)]
 #![feature(const_ipv6)]
 #![feature(const_raw_ptr_deref)]
 #![feature(const_ipv4)]
diff --git a/library/std/src/net/ip.rs b/library/std/src/net/ip.rs
index e2fc7edb87e..f01a7b72a65 100644
--- a/library/std/src/net/ip.rs
+++ b/library/std/src/net/ip.rs
@@ -148,8 +148,9 @@ impl IpAddr {
     /// assert_eq!(IpAddr::V4(Ipv4Addr::new(0, 0, 0, 0)).is_unspecified(), true);
     /// assert_eq!(IpAddr::V6(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 0)).is_unspecified(), true);
     /// ```
+    #[rustc_const_unstable(feature = "const_ip", issue = "76205")]
     #[stable(feature = "ip_shared", since = "1.12.0")]
-    pub fn is_unspecified(&self) -> bool {
+    pub const fn is_unspecified(&self) -> bool {
         match self {
             IpAddr::V4(ip) => ip.is_unspecified(),
             IpAddr::V6(ip) => ip.is_unspecified(),
@@ -169,8 +170,9 @@ impl IpAddr {
     /// assert_eq!(IpAddr::V4(Ipv4Addr::new(127, 0, 0, 1)).is_loopback(), true);
     /// assert_eq!(IpAddr::V6(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 0x1)).is_loopback(), true);
     /// ```
+    #[rustc_const_unstable(feature = "const_ip", issue = "76205")]
     #[stable(feature = "ip_shared", since = "1.12.0")]
-    pub fn is_loopback(&self) -> bool {
+    pub const fn is_loopback(&self) -> bool {
         match self {
             IpAddr::V4(ip) => ip.is_loopback(),
             IpAddr::V6(ip) => ip.is_loopback(),
@@ -192,7 +194,8 @@ impl IpAddr {
     /// assert_eq!(IpAddr::V4(Ipv4Addr::new(80, 9, 12, 3)).is_global(), true);
     /// assert_eq!(IpAddr::V6(Ipv6Addr::new(0, 0, 0x1c9, 0, 0, 0xafc8, 0, 0x1)).is_global(), true);
     /// ```
-    pub fn is_global(&self) -> bool {
+    #[rustc_const_unstable(feature = "const_ip", issue = "76205")]
+    pub const fn is_global(&self) -> bool {
         match self {
             IpAddr::V4(ip) => ip.is_global(),
             IpAddr::V6(ip) => ip.is_global(),
@@ -212,8 +215,9 @@ impl IpAddr {
     /// assert_eq!(IpAddr::V4(Ipv4Addr::new(224, 254, 0, 0)).is_multicast(), true);
     /// assert_eq!(IpAddr::V6(Ipv6Addr::new(0xff00, 0, 0, 0, 0, 0, 0, 0)).is_multicast(), true);
     /// ```
+    #[rustc_const_unstable(feature = "const_ip", issue = "76205")]
     #[stable(feature = "ip_shared", since = "1.12.0")]
-    pub fn is_multicast(&self) -> bool {
+    pub const fn is_multicast(&self) -> bool {
         match self {
             IpAddr::V4(ip) => ip.is_multicast(),
             IpAddr::V6(ip) => ip.is_multicast(),
@@ -238,7 +242,8 @@ impl IpAddr {
     ///     true
     /// );
     /// ```
-    pub fn is_documentation(&self) -> bool {
+    #[rustc_const_unstable(feature = "const_ip", issue = "76205")]
+    pub const fn is_documentation(&self) -> bool {
         match self {
             IpAddr::V4(ip) => ip.is_documentation(),
             IpAddr::V6(ip) => ip.is_documentation(),
diff --git a/library/std/src/net/ip/tests.rs b/library/std/src/net/ip/tests.rs
index 76a0ae8b945..d9fbdd1b5e7 100644
--- a/library/std/src/net/ip/tests.rs
+++ b/library/std/src/net/ip/tests.rs
@@ -918,3 +918,22 @@ fn ipv6_const() {
     const IP_V4: Option<Ipv4Addr> = IP_ADDRESS.to_ipv4();
     assert_eq!(IP_V4.unwrap(), Ipv4Addr::new(0, 0, 0, 1));
 }
+
+#[test]
+fn ip_const() {
+    // test that the methods of `IpAddr` are usable in a const context
+
+    const IP_ADDRESS: IpAddr = IpAddr::V4(Ipv4Addr::LOCALHOST);
+
+    const IS_UNSPECIFIED: bool = IP_ADDRESS.is_unspecified();
+    assert!(!IS_UNSPECIFIED);
+
+    const IS_LOOPBACK: bool = IP_ADDRESS.is_loopback();
+    assert!(IS_LOOPBACK);
+
+    const IS_GLOBAL: bool = IP_ADDRESS.is_global();
+    assert!(!IS_GLOBAL);
+
+    const IS_MULTICAST: bool = IP_ADDRESS.is_multicast();
+    assert!(!IS_MULTICAST);
+}
diff --git a/library/std/src/sync/mpsc/mod.rs b/library/std/src/sync/mpsc/mod.rs
index 073f969bbe2..dc13c9433f1 100644
--- a/library/std/src/sync/mpsc/mod.rs
+++ b/library/std/src/sync/mpsc/mod.rs
@@ -1531,6 +1531,11 @@ impl<T: Send> error::Error for TrySendError<T> {
 
 #[stable(feature = "mpsc_error_conversions", since = "1.24.0")]
 impl<T> From<SendError<T>> for TrySendError<T> {
+    /// Converts a `SendError<T>` into a `TrySendError<T>`.
+    ///
+    /// This conversion always returns a `TrySendError::Disconnected` containing the data in the `SendError<T>`.
+    ///
+    /// No data is allocated on the heap.
     fn from(err: SendError<T>) -> TrySendError<T> {
         match err {
             SendError(t) => TrySendError::Disconnected(t),
@@ -1576,6 +1581,11 @@ impl error::Error for TryRecvError {
 
 #[stable(feature = "mpsc_error_conversions", since = "1.24.0")]
 impl From<RecvError> for TryRecvError {
+    /// Converts a `RecvError` into a `TryRecvError`.
+    ///
+    /// This conversion always returns `TryRecvError::Disconnected`.
+    ///
+    /// No data is allocated on the heap.
     fn from(err: RecvError) -> TryRecvError {
         match err {
             RecvError => TryRecvError::Disconnected,
@@ -1606,6 +1616,11 @@ impl error::Error for RecvTimeoutError {
 
 #[stable(feature = "mpsc_error_conversions", since = "1.24.0")]
 impl From<RecvError> for RecvTimeoutError {
+    /// Converts a `RecvError` into a `RecvTimeoutError`.
+    ///
+    /// This conversion always returns `RecvTimeoutError::Disconnected`.
+    ///
+    /// No data is allocated on the heap.
     fn from(err: RecvError) -> RecvTimeoutError {
         match err {
             RecvError => RecvTimeoutError::Disconnected,
diff --git a/library/std/src/sys_common/remutex.rs b/library/std/src/sys_common/remutex.rs
index 360337c030b..162eab2388d 100644
--- a/library/std/src/sys_common/remutex.rs
+++ b/library/std/src/sys_common/remutex.rs
@@ -37,9 +37,7 @@ impl<T> RefUnwindSafe for ReentrantMutex<T> {}
 /// guarded data.
 #[must_use = "if unused the ReentrantMutex will immediately unlock"]
 pub struct ReentrantMutexGuard<'a, T: 'a> {
-    // funny underscores due to how Deref currently works (it disregards field
-    // privacy).
-    __lock: &'a ReentrantMutex<T>,
+    lock: &'a ReentrantMutex<T>,
 }
 
 impl<T> !marker::Send for ReentrantMutexGuard<'_, T> {}
@@ -129,7 +127,7 @@ impl<T: fmt::Debug + 'static> fmt::Debug for ReentrantMutex<T> {
 
 impl<'mutex, T> ReentrantMutexGuard<'mutex, T> {
     fn new(lock: &'mutex ReentrantMutex<T>) -> ReentrantMutexGuard<'mutex, T> {
-        ReentrantMutexGuard { __lock: lock }
+        ReentrantMutexGuard { lock }
     }
 }
 
@@ -137,7 +135,7 @@ impl<T> Deref for ReentrantMutexGuard<'_, T> {
     type Target = T;
 
     fn deref(&self) -> &T {
-        &self.__lock.data
+        &self.lock.data
     }
 }
 
@@ -145,7 +143,7 @@ impl<T> Drop for ReentrantMutexGuard<'_, T> {
     #[inline]
     fn drop(&mut self) {
         unsafe {
-            self.__lock.inner.unlock();
+            self.lock.inner.unlock();
         }
     }
 }
diff --git a/src/librustdoc/html/layout.rs b/src/librustdoc/html/layout.rs
index 287c85b8c22..7239b3c5ba2 100644
--- a/src/librustdoc/html/layout.rs
+++ b/src/librustdoc/html/layout.rs
@@ -158,7 +158,9 @@ pub fn render<T: Print, S: Print>(
         keywords = page.keywords,
         favicon = if layout.favicon.is_empty() {
             format!(
-                r#"<link rel="shortcut icon" href="{static_root_path}favicon{suffix}.ico">"#,
+                r##"<link rel="icon" type="image/svg+xml" href="{static_root_path}favicon{suffix}.svg">
+<link rel="alternate icon" type="image/png" href="{static_root_path}favicon-16x16{suffix}.png">
+<link rel="alternate icon" type="image/png" href="{static_root_path}favicon-32x32{suffix}.png">"##,
                 static_root_path = static_root_path,
                 suffix = page.resource_suffix
             )
diff --git a/src/librustdoc/html/render/mod.rs b/src/librustdoc/html/render/mod.rs
index f095f67b54c..8b5ba7a239c 100644
--- a/src/librustdoc/html/render/mod.rs
+++ b/src/librustdoc/html/render/mod.rs
@@ -754,7 +754,9 @@ fn write_shared(
         write(cx.path("rust-logo.png"), static_files::RUST_LOGO)?;
     }
     if (*cx.shared).layout.favicon.is_empty() {
-        write(cx.path("favicon.ico"), static_files::RUST_FAVICON)?;
+        write(cx.path("favicon.svg"), static_files::RUST_FAVICON_SVG)?;
+        write(cx.path("favicon-16x16.png"), static_files::RUST_FAVICON_PNG_16)?;
+        write(cx.path("favicon-32x32.png"), static_files::RUST_FAVICON_PNG_32)?;
     }
     write(cx.path("brush.svg"), static_files::BRUSH_SVG)?;
     write(cx.path("wheel.svg"), static_files::WHEEL_SVG)?;
diff --git a/src/librustdoc/html/static/favicon-16x16.png b/src/librustdoc/html/static/favicon-16x16.png
new file mode 100644
index 00000000000..7cfe6c13550
--- /dev/null
+++ b/src/librustdoc/html/static/favicon-16x16.png
Binary files differdiff --git a/src/librustdoc/html/static/favicon-32x32.png b/src/librustdoc/html/static/favicon-32x32.png
new file mode 100644
index 00000000000..5109c1de8be
--- /dev/null
+++ b/src/librustdoc/html/static/favicon-32x32.png
Binary files differdiff --git a/src/librustdoc/html/static/favicon.ico b/src/librustdoc/html/static/favicon.ico
deleted file mode 100644
index b8ad23769ac..00000000000
--- a/src/librustdoc/html/static/favicon.ico
+++ /dev/null
Binary files differdiff --git a/src/librustdoc/html/static/favicon.svg b/src/librustdoc/html/static/favicon.svg
new file mode 100644
index 00000000000..8b34b511989
--- /dev/null
+++ b/src/librustdoc/html/static/favicon.svg
@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?><!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd"><svg width="100%" height="100%" viewBox="0 0 32 32" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" xml:space="preserve" xmlns:serif="http://www.serif.com/" style="fill-rule:evenodd;clip-rule:evenodd;stroke-linecap:round;stroke-linejoin:round;">
+<defs>
+  <style type="text/css"><![CDATA[
+    #logo {
+      fill-rule: nonzero;
+    }
+    #logo-teeth {
+      stroke: #000000;
+      stroke-width: 0.92px;
+    }
+    @media (prefers-color-scheme: dark) {
+      #logo {
+        fill: #FFFFFF;
+        fill-rule: nonzero;
+      }
+      #logo-teeth {
+        fill: #FFFFFF;
+        stroke: #FFFFFF;
+        stroke-width: 0.92px;
+      }
+    }
+  ]]></style>
+</defs>
+<path id="logo" d="M15.993,1.54c-7.972,0 -14.461,6.492 -14.461,14.462c0,7.969 6.492,14.461 14.461,14.461c7.97,0 14.462,-6.492 14.462,-14.461c0,-7.97 -6.492,-14.462 -14.462,-14.462Zm-0.021,1.285c0.511,0.013 0.924,0.439 0.924,0.951c0,0.522 -0.43,0.952 -0.952,0.952c-0.522,0 -0.951,-0.43 -0.951,-0.952c0,0 0,0 0,0c0,-0.522 0.429,-0.952 0.951,-0.952c0.01,0 0.019,0.001 0.028,0.001Zm2.178,1.566c3.379,0.633 6.313,2.723 8.016,5.709l-1.123,2.533c-0.193,0.438 0.006,0.952 0.44,1.147l2.16,0.958c0.067,0.675 0.076,1.355 0.025,2.031l-1.202,0c-0.12,0 -0.169,0.08 -0.169,0.196l0,0.551c0,1.297 -0.731,1.582 -1.373,1.652c-0.612,0.07 -1.288,-0.257 -1.374,-0.63c-0.361,-2.029 -0.961,-2.46 -1.909,-3.21c1.178,-0.746 2.401,-1.85 2.401,-3.325c0,-1.594 -1.092,-2.597 -1.835,-3.09c-1.046,-0.688 -2.203,-0.826 -2.515,-0.826l-12.421,0c1.717,-1.918 4.02,-3.218 6.55,-3.696l1.466,1.536c0.33,0.346 0.878,0.361 1.223,0.028l1.64,-1.564Zm-13.522,7.043c0.511,0.015 0.924,0.44 0.924,0.951c0,0.522 -0.43,0.952 -0.952,0.952c-0.522,0 -0.951,-0.43 -0.951,-0.952c0,0 0,0 0,0c0,-0.522 0.429,-0.951 0.951,-0.951c0.009,0 0.019,0 0.028,0Zm22.685,0.043c0.511,0.015 0.924,0.44 0.924,0.951c0,0.522 -0.43,0.952 -0.952,0.952c-0.522,0 -0.951,-0.43 -0.951,-0.952c0,0 0,0 0,0c0,-0.522 0.429,-0.952 0.951,-0.952c0.01,0 0.019,0 0.028,0.001Zm-20.892,0.153l1.658,0l0,7.477l-3.347,0c-0.414,-1.452 -0.542,-2.97 -0.38,-4.47l2.05,-0.912c0.438,-0.195 0.637,-0.706 0.441,-1.144l-0.422,-0.951Zm6.92,0.079l3.949,0c0.205,0 1.441,0.236 1.441,1.163c0,0.768 -0.948,1.043 -1.728,1.043l-3.665,0l0.003,-2.206Zm0,5.373l3.026,0c0.275,0 1.477,0.079 1.86,1.615c0.119,0.471 0.385,2.007 0.566,2.499c0.18,0.551 0.911,1.652 1.691,1.652l4.938,0c-0.331,0.444 -0.693,0.863 -1.083,1.255l-2.01,-0.432c-0.468,-0.101 -0.93,0.199 -1.031,0.667l-0.477,2.228c-3.104,1.406 -6.672,1.389 -9.762,-0.046l-0.478,-2.228c-0.101,-0.468 -0.56,-0.767 -1.028,-0.667l-1.967,0.423c-0.365,-0.377 -0.704,-0.778 -1.016,-1.2l9.567,0c0.107,0 0.181,-0.018 0.181,-0.119l0,-3.384c0,-0.097 -0.074,-0.119 -0.181,-0.119l-2.799,0l0.003,-2.144Zm-4.415,7.749c0.512,0.015 0.924,0.44 0.924,0.951c0,0.522 -0.429,0.952 -0.951,0.952c-0.522,0 -0.952,-0.43 -0.952,-0.952c0,0 0,0 0,0c0,-0.522 0.43,-0.952 0.952,-0.952c0.009,0 0.018,0.001 0.027,0.001Zm14.089,0.043c0.511,0.015 0.924,0.439 0.923,0.951c0,0.522 -0.429,0.952 -0.951,0.952c-0.522,0 -0.951,-0.43 -0.951,-0.952c0,0 0,0 0,0c0,-0.522 0.429,-0.952 0.951,-0.952c0.009,0 0.018,0 0.028,0.001Z"/><path id="logo-teeth" d="M29.647,16.002c0,7.49 -6.163,13.653 -13.654,13.653c-7.49,0 -13.654,-6.163 -13.654,-13.653c0,-7.491 6.164,-13.654 13.654,-13.654c7.491,0 13.654,6.163 13.654,13.654Zm-0.257,-1.319l2.13,1.319l-2.13,1.318l1.83,1.71l-2.344,0.878l1.463,2.035l-2.475,0.404l1.04,2.282l-2.506,-0.089l0.575,2.442l-2.441,-0.576l0.089,2.506l-2.283,-1.04l-0.403,2.475l-2.035,-1.462l-0.878,2.343l-1.71,-1.829l-1.319,2.129l-1.318,-2.129l-1.71,1.829l-0.878,-2.343l-2.035,1.462l-0.404,-2.475l-2.282,1.04l0.089,-2.506l-2.442,0.576l0.575,-2.442l-2.505,0.089l1.04,-2.282l-2.475,-0.404l1.462,-2.035l-2.343,-0.878l1.829,-1.71l-2.129,-1.318l2.129,-1.319l-1.829,-1.71l2.343,-0.878l-1.462,-2.035l2.475,-0.404l-1.04,-2.282l2.505,0.089l-0.575,-2.441l2.442,0.575l-0.089,-2.506l2.282,1.04l0.404,-2.475l2.035,1.463l0.878,-2.344l1.71,1.83l1.318,-2.13l1.319,2.13l1.71,-1.83l0.878,2.344l2.035,-1.463l0.403,2.475l2.283,-1.04l-0.089,2.506l2.441,-0.575l-0.575,2.441l2.506,-0.089l-1.04,2.282l2.475,0.404l-1.463,2.035l2.344,0.878l-1.83,1.71Z"/></svg>
diff --git a/src/librustdoc/html/static_files.rs b/src/librustdoc/html/static_files.rs
index 6bd7e53cdfb..213c7f3aab8 100644
--- a/src/librustdoc/html/static_files.rs
+++ b/src/librustdoc/html/static_files.rs
@@ -53,8 +53,10 @@ pub static LICENSE_MIT: &[u8] = include_bytes!("static/LICENSE-MIT.txt");
 
 /// The contents of `rust-logo.png`, the default icon of the documentation.
 pub static RUST_LOGO: &[u8] = include_bytes!("static/rust-logo.png");
-/// The contents of `favicon.ico`, the default favicon of the documentation.
-pub static RUST_FAVICON: &[u8] = include_bytes!("static/favicon.ico");
+/// The default documentation favicons (SVG and PNG fallbacks)
+pub static RUST_FAVICON_SVG: &[u8] = include_bytes!("static/favicon.svg");
+pub static RUST_FAVICON_PNG_16: &[u8] = include_bytes!("static/favicon-16x16.png");
+pub static RUST_FAVICON_PNG_32: &[u8] = include_bytes!("static/favicon-32x32.png");
 
 /// The built-in themes given to every documentation site.
 pub mod themes {
diff --git a/src/test/ui/consts/const-mut-refs/feature-gate-const_mut_refs.rs b/src/test/ui/consts/const-mut-refs/feature-gate-const_mut_refs.rs
index f31543af590..ce9be4ac5c2 100644
--- a/src/test/ui/consts/const-mut-refs/feature-gate-const_mut_refs.rs
+++ b/src/test/ui/consts/const-mut-refs/feature-gate-const_mut_refs.rs
@@ -2,7 +2,7 @@ fn main() {
     foo(&mut 5);
 }
 
-const fn foo(x: &mut i32) -> i32 { //~ ERROR mutable references in const fn
+const fn foo(x: &mut i32) -> i32 { //~ ERROR mutable references
     *x + 1
 
 }
diff --git a/src/test/ui/consts/const-mut-refs/feature-gate-const_mut_refs.stderr b/src/test/ui/consts/const-mut-refs/feature-gate-const_mut_refs.stderr
index 83e050c7a5c..3f9bd37053a 100644
--- a/src/test/ui/consts/const-mut-refs/feature-gate-const_mut_refs.stderr
+++ b/src/test/ui/consts/const-mut-refs/feature-gate-const_mut_refs.stderr
@@ -1,12 +1,12 @@
-error[E0723]: mutable references in const fn are unstable
+error[E0658]: mutable references are not allowed in constant functions
   --> $DIR/feature-gate-const_mut_refs.rs:5:14
    |
 LL | const fn foo(x: &mut i32) -> i32 {
    |              ^
    |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
+   = note: see issue #57349 <https://github.com/rust-lang/rust/issues/57349> for more information
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0723`.
+For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/consts/const_let_assign3.stderr b/src/test/ui/consts/const_let_assign3.stderr
index 785d9c8c2a5..15badea0037 100644
--- a/src/test/ui/consts/const_let_assign3.stderr
+++ b/src/test/ui/consts/const_let_assign3.stderr
@@ -1,11 +1,11 @@
-error[E0723]: mutable references in const fn are unstable
+error[E0658]: mutable references are not allowed in constant functions
   --> $DIR/const_let_assign3.rs:8:18
    |
 LL |     const fn foo(&mut self, x: u32) {
    |                  ^^^^^^^^^
    |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
+   = note: see issue #57349 <https://github.com/rust-lang/rust/issues/57349> for more information
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error[E0764]: mutable references are not allowed in constants
   --> $DIR/const_let_assign3.rs:16:5
@@ -29,5 +29,5 @@ LL |     *y = 42;
 
 error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0019, E0723, E0764.
+Some errors have detailed explanations: E0019, E0658, E0764.
 For more information about an error, try `rustc --explain E0019`.
diff --git a/src/test/ui/consts/min_const_fn/min_const_fn.rs b/src/test/ui/consts/min_const_fn/min_const_fn.rs
index 5dd70acb6ff..336d754b06a 100644
--- a/src/test/ui/consts/min_const_fn/min_const_fn.rs
+++ b/src/test/ui/consts/min_const_fn/min_const_fn.rs
@@ -37,26 +37,26 @@ impl<T> Foo<T> {
     const fn into_inner(self) -> T { self.0 } //~ destructors cannot be evaluated
     const fn get(&self) -> &T { &self.0 }
     const fn get_mut(&mut self) -> &mut T { &mut self.0 }
-    //~^ mutable references in const fn are unstable
+    //~^ mutable references
 }
 impl<'a, T> Foo<T> {
     const fn new_lt(t: T) -> Self { Foo(t) }
     const fn into_inner_lt(self) -> T { self.0 } //~ destructors cannot be evaluated
     const fn get_lt(&'a self) -> &T { &self.0 }
     const fn get_mut_lt(&'a mut self) -> &mut T { &mut self.0 }
-    //~^ mutable references in const fn are unstable
+    //~^ mutable references
 }
 impl<T: Sized> Foo<T> {
     const fn new_s(t: T) -> Self { Foo(t) }
     const fn into_inner_s(self) -> T { self.0 } //~ ERROR destructors
     const fn get_s(&self) -> &T { &self.0 }
     const fn get_mut_s(&mut self) -> &mut T { &mut self.0 }
-    //~^ mutable references in const fn are unstable
+    //~^ mutable references
 }
 impl<T: ?Sized> Foo<T> {
     const fn get_sq(&self) -> &T { &self.0 }
     const fn get_mut_sq(&mut self) -> &mut T { &mut self.0 }
-    //~^ mutable references in const fn are unstable
+    //~^ mutable references
 }
 
 
@@ -99,7 +99,7 @@ const fn foo30_2_with_unsafe(x: *mut u32) -> usize { unsafe { x as usize } }
 //~^ ERROR casting pointers to integers
 const fn foo30_6() -> bool { let x = true; x }
 const fn inc(x: &mut i32) { *x += 1 }
-//~^ ERROR mutable references in const fn are unstable
+//~^ ERROR mutable references
 
 // ok
 const fn foo36(a: bool, b: bool) -> bool { a && b }
diff --git a/src/test/ui/consts/min_const_fn/min_const_fn.stderr b/src/test/ui/consts/min_const_fn/min_const_fn.stderr
index d4498f061c6..c96500e38ec 100644
--- a/src/test/ui/consts/min_const_fn/min_const_fn.stderr
+++ b/src/test/ui/consts/min_const_fn/min_const_fn.stderr
@@ -6,14 +6,14 @@ LL |     const fn into_inner(self) -> T { self.0 }
    |                         |
    |                         constant functions cannot evaluate destructors
 
-error[E0723]: mutable references in const fn are unstable
+error[E0658]: mutable references are not allowed in constant functions
   --> $DIR/min_const_fn.rs:39:36
    |
 LL |     const fn get_mut(&mut self) -> &mut T { &mut self.0 }
    |                                    ^^^^^^
    |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
+   = note: see issue #57349 <https://github.com/rust-lang/rust/issues/57349> for more information
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error[E0493]: destructors cannot be evaluated at compile-time
   --> $DIR/min_const_fn.rs:44:28
@@ -23,14 +23,14 @@ LL |     const fn into_inner_lt(self) -> T { self.0 }
    |                            |
    |                            constant functions cannot evaluate destructors
 
-error[E0723]: mutable references in const fn are unstable
+error[E0658]: mutable references are not allowed in constant functions
   --> $DIR/min_const_fn.rs:46:42
    |
 LL |     const fn get_mut_lt(&'a mut self) -> &mut T { &mut self.0 }
    |                                          ^^^^^^
    |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
+   = note: see issue #57349 <https://github.com/rust-lang/rust/issues/57349> for more information
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error[E0493]: destructors cannot be evaluated at compile-time
   --> $DIR/min_const_fn.rs:51:27
@@ -40,23 +40,23 @@ LL |     const fn into_inner_s(self) -> T { self.0 }
    |                           |
    |                           constant functions cannot evaluate destructors
 
-error[E0723]: mutable references in const fn are unstable
+error[E0658]: mutable references are not allowed in constant functions
   --> $DIR/min_const_fn.rs:53:38
    |
 LL |     const fn get_mut_s(&mut self) -> &mut T { &mut self.0 }
    |                                      ^^^^^^
    |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
+   = note: see issue #57349 <https://github.com/rust-lang/rust/issues/57349> for more information
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
-error[E0723]: mutable references in const fn are unstable
+error[E0658]: mutable references are not allowed in constant functions
   --> $DIR/min_const_fn.rs:58:39
    |
 LL |     const fn get_mut_sq(&mut self) -> &mut T { &mut self.0 }
    |                                       ^^^^^^
    |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
+   = note: see issue #57349 <https://github.com/rust-lang/rust/issues/57349> for more information
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error[E0723]: trait bounds other than `Sized` on const fn parameters are unstable
   --> $DIR/min_const_fn.rs:76:16
@@ -164,14 +164,14 @@ LL | const fn foo30_2_with_unsafe(x: *mut u32) -> usize { unsafe { x as usize }
    = note: see issue #51910 <https://github.com/rust-lang/rust/issues/51910> for more information
    = help: add `#![feature(const_raw_ptr_to_usize_cast)]` to the crate attributes to enable
 
-error[E0723]: mutable references in const fn are unstable
+error[E0658]: mutable references are not allowed in constant functions
   --> $DIR/min_const_fn.rs:101:14
    |
 LL | const fn inc(x: &mut i32) { *x += 1 }
    |              ^
    |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
+   = note: see issue #57349 <https://github.com/rust-lang/rust/issues/57349> for more information
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error[E0723]: trait bounds other than `Sized` on const fn parameters are unstable
   --> $DIR/min_const_fn.rs:110:6
diff --git a/src/test/ui/consts/min_const_fn/mutable_borrow.rs b/src/test/ui/consts/min_const_fn/mutable_borrow.rs
index 89acfea6ed8..580b1d50f77 100644
--- a/src/test/ui/consts/min_const_fn/mutable_borrow.rs
+++ b/src/test/ui/consts/min_const_fn/mutable_borrow.rs
@@ -1,6 +1,6 @@
 const fn mutable_ref_in_const() -> u8 {
     let mut a = 0;
-    let b = &mut a; //~ ERROR mutable references in const fn
+    let b = &mut a; //~ ERROR mutable references
     *b
 }
 
@@ -9,7 +9,7 @@ struct X;
 impl X {
     const fn inherent_mutable_ref_in_const() -> u8 {
         let mut a = 0;
-        let b = &mut a; //~ ERROR mutable references in const fn
+        let b = &mut a; //~ ERROR mutable references
         *b
     }
 }
diff --git a/src/test/ui/consts/min_const_fn/mutable_borrow.stderr b/src/test/ui/consts/min_const_fn/mutable_borrow.stderr
index f5a3c168a86..4e5cdbb18aa 100644
--- a/src/test/ui/consts/min_const_fn/mutable_borrow.stderr
+++ b/src/test/ui/consts/min_const_fn/mutable_borrow.stderr
@@ -1,21 +1,21 @@
-error[E0723]: mutable references in const fn are unstable
+error[E0658]: mutable references are not allowed in constant functions
   --> $DIR/mutable_borrow.rs:3:9
    |
 LL |     let b = &mut a;
    |         ^
    |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
+   = note: see issue #57349 <https://github.com/rust-lang/rust/issues/57349> for more information
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
-error[E0723]: mutable references in const fn are unstable
+error[E0658]: mutable references are not allowed in constant functions
   --> $DIR/mutable_borrow.rs:12:13
    |
 LL |         let b = &mut a;
    |             ^
    |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
+   = note: see issue #57349 <https://github.com/rust-lang/rust/issues/57349> for more information
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0723`.
+For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/feature-gates/feature-gate-const_fn_transmute.rs b/src/test/ui/feature-gates/feature-gate-const_fn_transmute.rs
index 981680b5d1f..9007e501bc2 100644
--- a/src/test/ui/feature-gates/feature-gate-const_fn_transmute.rs
+++ b/src/test/ui/feature-gates/feature-gate-const_fn_transmute.rs
@@ -6,33 +6,33 @@ struct Foo(u32);
 const TRANSMUTED_U32: u32 = unsafe { mem::transmute(Foo(3)) };
 
 const fn transmute_fn() -> u32 { unsafe { mem::transmute(Foo(3)) } }
-//~^ ERROR can only call `transmute` from const items, not `const fn`
+//~^ ERROR `transmute`
 
 const fn transmute_fn_intrinsic() -> u32 { unsafe { std::intrinsics::transmute(Foo(3)) } }
-//~^ ERROR can only call `transmute` from const items, not `const fn`
+//~^ ERROR `transmute`
 
 const fn transmute_fn_core_intrinsic() -> u32 { unsafe { core::intrinsics::transmute(Foo(3)) } }
-//~^ ERROR can only call `transmute` from const items, not `const fn`
+//~^ ERROR `transmute`
 
 const unsafe fn unsafe_transmute_fn() -> u32 { mem::transmute(Foo(3)) }
-//~^ ERROR can only call `transmute` from const items, not `const fn`
+//~^ ERROR `transmute`
 
 const unsafe fn unsafe_transmute_fn_intrinsic() -> u32 { std::intrinsics::transmute(Foo(3)) }
-//~^ ERROR can only call `transmute` from const items, not `const fn`
+//~^ ERROR `transmute`
 
 const unsafe fn unsafe_transmute_fn_core_intrinsic() -> u32 { core::intrinsics::transmute(Foo(3)) }
-//~^ ERROR can only call `transmute` from const items, not `const fn`
+//~^ ERROR `transmute`
 
 const fn safe_transmute_fn() -> u32 { mem::transmute(Foo(3)) }
-//~^ ERROR can only call `transmute` from const items, not `const fn`
+//~^ ERROR `transmute`
 //~| ERROR call to unsafe function is unsafe and requires unsafe function or block
 
 const fn safe_transmute_fn_intrinsic() -> u32 { std::intrinsics::transmute(Foo(3)) }
-//~^ ERROR can only call `transmute` from const items, not `const fn`
+//~^ ERROR `transmute`
 //~| ERROR call to unsafe function is unsafe and requires unsafe function or block
 
 const fn safe_transmute_fn_core_intrinsic() -> u32 { core::intrinsics::transmute(Foo(3)) }
-//~^ ERROR can only call `transmute` from const items, not `const fn`
+//~^ ERROR `transmute`
 //~| ERROR call to unsafe function is unsafe and requires unsafe function or block
 
 fn main() {}
diff --git a/src/test/ui/feature-gates/feature-gate-const_fn_transmute.stderr b/src/test/ui/feature-gates/feature-gate-const_fn_transmute.stderr
index 44430fd577d..08ba14dc40e 100644
--- a/src/test/ui/feature-gates/feature-gate-const_fn_transmute.stderr
+++ b/src/test/ui/feature-gates/feature-gate-const_fn_transmute.stderr
@@ -1,83 +1,92 @@
-error[E0723]: can only call `transmute` from const items, not `const fn`
+error[E0658]: `transmute` is not allowed in constant functions
   --> $DIR/feature-gate-const_fn_transmute.rs:8:43
    |
 LL | const fn transmute_fn() -> u32 { unsafe { mem::transmute(Foo(3)) } }
    |                                           ^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
+   = note: see issue #53605 <https://github.com/rust-lang/rust/issues/53605> for more information
+   = help: add `#![feature(const_fn_transmute)]` to the crate attributes to enable
+   = note: `transmute` is only allowed in constants and statics for now
 
-error[E0723]: can only call `transmute` from const items, not `const fn`
+error[E0658]: `transmute` is not allowed in constant functions
   --> $DIR/feature-gate-const_fn_transmute.rs:11:53
    |
 LL | const fn transmute_fn_intrinsic() -> u32 { unsafe { std::intrinsics::transmute(Foo(3)) } }
    |                                                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
+   = note: see issue #53605 <https://github.com/rust-lang/rust/issues/53605> for more information
+   = help: add `#![feature(const_fn_transmute)]` to the crate attributes to enable
+   = note: `transmute` is only allowed in constants and statics for now
 
-error[E0723]: can only call `transmute` from const items, not `const fn`
+error[E0658]: `transmute` is not allowed in constant functions
   --> $DIR/feature-gate-const_fn_transmute.rs:14:58
    |
 LL | const fn transmute_fn_core_intrinsic() -> u32 { unsafe { core::intrinsics::transmute(Foo(3)) } }
    |                                                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
+   = note: see issue #53605 <https://github.com/rust-lang/rust/issues/53605> for more information
+   = help: add `#![feature(const_fn_transmute)]` to the crate attributes to enable
+   = note: `transmute` is only allowed in constants and statics for now
 
-error[E0723]: can only call `transmute` from const items, not `const fn`
+error[E0658]: `transmute` is not allowed in constant functions
   --> $DIR/feature-gate-const_fn_transmute.rs:17:48
    |
 LL | const unsafe fn unsafe_transmute_fn() -> u32 { mem::transmute(Foo(3)) }
    |                                                ^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
+   = note: see issue #53605 <https://github.com/rust-lang/rust/issues/53605> for more information
+   = help: add `#![feature(const_fn_transmute)]` to the crate attributes to enable
+   = note: `transmute` is only allowed in constants and statics for now
 
-error[E0723]: can only call `transmute` from const items, not `const fn`
+error[E0658]: `transmute` is not allowed in constant functions
   --> $DIR/feature-gate-const_fn_transmute.rs:20:58
    |
 LL | const unsafe fn unsafe_transmute_fn_intrinsic() -> u32 { std::intrinsics::transmute(Foo(3)) }
    |                                                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
+   = note: see issue #53605 <https://github.com/rust-lang/rust/issues/53605> for more information
+   = help: add `#![feature(const_fn_transmute)]` to the crate attributes to enable
+   = note: `transmute` is only allowed in constants and statics for now
 
-error[E0723]: can only call `transmute` from const items, not `const fn`
+error[E0658]: `transmute` is not allowed in constant functions
   --> $DIR/feature-gate-const_fn_transmute.rs:23:63
    |
 LL | const unsafe fn unsafe_transmute_fn_core_intrinsic() -> u32 { core::intrinsics::transmute(Foo(3)) }
    |                                                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
+   = note: see issue #53605 <https://github.com/rust-lang/rust/issues/53605> for more information
+   = help: add `#![feature(const_fn_transmute)]` to the crate attributes to enable
+   = note: `transmute` is only allowed in constants and statics for now
 
-error[E0723]: can only call `transmute` from const items, not `const fn`
+error[E0658]: `transmute` is not allowed in constant functions
   --> $DIR/feature-gate-const_fn_transmute.rs:26:39
    |
 LL | const fn safe_transmute_fn() -> u32 { mem::transmute(Foo(3)) }
    |                                       ^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
+   = note: see issue #53605 <https://github.com/rust-lang/rust/issues/53605> for more information
+   = help: add `#![feature(const_fn_transmute)]` to the crate attributes to enable
+   = note: `transmute` is only allowed in constants and statics for now
 
-error[E0723]: can only call `transmute` from const items, not `const fn`
+error[E0658]: `transmute` is not allowed in constant functions
   --> $DIR/feature-gate-const_fn_transmute.rs:30:49
    |
 LL | const fn safe_transmute_fn_intrinsic() -> u32 { std::intrinsics::transmute(Foo(3)) }
    |                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
+   = note: see issue #53605 <https://github.com/rust-lang/rust/issues/53605> for more information
+   = help: add `#![feature(const_fn_transmute)]` to the crate attributes to enable
+   = note: `transmute` is only allowed in constants and statics for now
 
-error[E0723]: can only call `transmute` from const items, not `const fn`
+error[E0658]: `transmute` is not allowed in constant functions
   --> $DIR/feature-gate-const_fn_transmute.rs:34:54
    |
 LL | const fn safe_transmute_fn_core_intrinsic() -> u32 { core::intrinsics::transmute(Foo(3)) }
    |                                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
+   = note: see issue #53605 <https://github.com/rust-lang/rust/issues/53605> for more information
+   = help: add `#![feature(const_fn_transmute)]` to the crate attributes to enable
+   = note: `transmute` is only allowed in constants and statics for now
 
 error[E0133]: call to unsafe function is unsafe and requires unsafe function or block
   --> $DIR/feature-gate-const_fn_transmute.rs:26:39
@@ -105,5 +114,5 @@ LL | const fn safe_transmute_fn_core_intrinsic() -> u32 { core::intrinsics::tran
 
 error: aborting due to 12 previous errors
 
-Some errors have detailed explanations: E0133, E0723.
+Some errors have detailed explanations: E0133, E0658.
 For more information about an error, try `rustc --explain E0133`.
diff --git a/src/test/ui/internal/internal-unstable-const.rs b/src/test/ui/internal/internal-unstable-const.rs
index b923bc22f6e..554c67be4e0 100644
--- a/src/test/ui/internal/internal-unstable-const.rs
+++ b/src/test/ui/internal/internal-unstable-const.rs
@@ -8,7 +8,7 @@
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_const_stable(feature = "rust1", since = "1.0.0")]
 pub const fn foo() -> i32 {
-    unsafe { std::mem::transmute(4u32) } //~ ERROR can only call `transmute` from const items
+    unsafe { std::mem::transmute(4u32) } //~ ERROR `transmute`
 }
 
 fn main() {}
diff --git a/src/test/ui/internal/internal-unstable-const.stderr b/src/test/ui/internal/internal-unstable-const.stderr
index 9626df23ec3..adfb8dc3691 100644
--- a/src/test/ui/internal/internal-unstable-const.stderr
+++ b/src/test/ui/internal/internal-unstable-const.stderr
@@ -1,12 +1,13 @@
-error[E0723]: can only call `transmute` from const items, not `const fn`
+error[E0658]: `transmute` is not allowed in constant functions
   --> $DIR/internal-unstable-const.rs:11:14
    |
 LL |     unsafe { std::mem::transmute(4u32) }
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
+   = note: see issue #53605 <https://github.com/rust-lang/rust/issues/53605> for more information
+   = help: add `#![feature(const_fn_transmute)]` to the crate attributes to enable
+   = note: `transmute` is only allowed in constants and statics for now
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0723`.
+For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/unsafe/ranged_ints2_const.stderr b/src/test/ui/unsafe/ranged_ints2_const.stderr
index d508d07791d..1a6bcd36ee1 100644
--- a/src/test/ui/unsafe/ranged_ints2_const.stderr
+++ b/src/test/ui/unsafe/ranged_ints2_const.stderr
@@ -1,20 +1,20 @@
-error[E0723]: mutable references in const fn are unstable
+error[E0658]: mutable references are not allowed in constant functions
   --> $DIR/ranged_ints2_const.rs:11:9
    |
 LL |     let y = &mut x.0;
    |         ^
    |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
+   = note: see issue #57349 <https://github.com/rust-lang/rust/issues/57349> for more information
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
-error[E0723]: mutable references in const fn are unstable
+error[E0658]: mutable references are not allowed in constant functions
   --> $DIR/ranged_ints2_const.rs:18:9
    |
 LL |     let y = unsafe { &mut x.0 };
    |         ^
    |
-   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
-   = help: add `#![feature(const_fn)]` to the crate attributes to enable
+   = note: see issue #57349 <https://github.com/rust-lang/rust/issues/57349> for more information
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error[E0133]: mutation of layout constrained field is unsafe and requires unsafe function or block
   --> $DIR/ranged_ints2_const.rs:11:13
@@ -26,5 +26,5 @@ LL |     let y = &mut x.0;
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0133, E0723.
+Some errors have detailed explanations: E0133, E0658.
 For more information about an error, try `rustc --explain E0133`.
diff --git a/src/tools/clippy/clippy_lints/src/redundant_clone.rs b/src/tools/clippy/clippy_lints/src/redundant_clone.rs
index 57a45e628db..1615f192370 100644
--- a/src/tools/clippy/clippy_lints/src/redundant_clone.rs
+++ b/src/tools/clippy/clippy_lints/src/redundant_clone.rs
@@ -87,6 +87,7 @@ impl<'tcx> LateLintPass<'tcx> for RedundantClone {
 
         let maybe_storage_live_result = MaybeStorageLive
             .into_engine(cx.tcx, mir, def_id.to_def_id())
+            .pass_name("redundant_clone")
             .iterate_to_fixpoint()
             .into_results_cursor(mir);
         let mut possible_borrower = {