Auto merge of #90004 - pietroalbini:stable-next, r=pietroalbini1.56.0

Rust 1.56.0 stable release

This PR bumps 1.56.0 to the stable channel. This also includes a backport for:

* Latest changes to the release notes
* #89867

r? `@ghost`
cc `@rust-lang/release`

5 files changed, 228 insertions, 7 deletions

diff --git a/RELEASES.md b/RELEASES.md
index c0851a1506e..52d823d8aca 100644
--- a/RELEASES.md
+++ b/RELEASES.md
@@ -1,3 +1,185 @@
+Version 1.56.0 (2021-10-21)
+========================
+
+Language
+--------
+
+- [The 2021 Edition is now stable.][rust#88100]
+  See [the edition guide][rust-2021-edition-guide] for more details.
+- [The pattern in `binding @ pattern` can now also introduce new bindings.][rust#85305]
+- [Union field access is permitted in `const fn`.][rust#85769]
+
+[rust-2021-edition-guide]: https://doc.rust-lang.org/nightly/edition-guide/rust-2021/index.html
+
+Compiler
+--------
+
+- [Upgrade to LLVM 13.][rust#87570]
+- [Support memory, address, and thread sanitizers on aarch64-unknown-freebsd.][rust#88023]
+- [Allow specifying a deployment target version for all iOS targets][rust#87699]
+- [Warnings can be forced on with `--force-warn`.][rust#87472]
+  This feature is primarily intended for usage by `cargo fix`, rather than end users.
+- [Promote `aarch64-apple-ios-sim` to Tier 2\*.][rust#87760]
+- [Add `powerpc-unknown-freebsd` at Tier 3\*.][rust#87370]
+- [Add `riscv32imc-esp-espidf` at Tier 3\*.][rust#87666]
+
+\* Refer to Rust's [platform support page][platform-support-doc] for more
+information on Rust's tiered platform support.
+
+Libraries
+---------
+
+- [Allow writing of incomplete UTF-8 sequences via stdout/stderr on Windows.][rust#83342]
+  The Windows console still requires valid Unicode, but this change allows
+  splitting a UTF-8 character across multiple write calls. This allows, for
+  instance, programs that just read and write data buffers (e.g. copying a file
+  to stdout) without regard for Unicode or character boundaries.
+- [Prefer `AtomicU{64,128}` over Mutex for Instant backsliding protection.][rust#83093]
+  For this use case, atomics scale much better under contention.
+- [Implement `Extend<(A, B)>` for `(Extend<A>, Extend<B>)`][rust#85835]
+- [impl Default, Copy, Clone for std::io::Sink and std::io::Empty][rust#86744]
+- [`impl From<[(K, V); N]>` for all collections.][rust#84111]
+- [Remove `P: Unpin` bound on impl Future for Pin.][rust#81363]
+- [Treat invalid environment variable names as non-existent.][rust#86183]
+  Previously, the environment functions would panic if given a variable name
+  with an internal null character or equal sign (`=`). Now, these functions will
+  just treat such names as non-existent variables, since the OS cannot represent
+  the existence of a variable with such a name.
+
+Stabilised APIs
+---------------
+
+- [`std::os::unix::fs::chroot`]
+- [`UnsafeCell::raw_get`]
+- [`BufWriter::into_parts`]
+- [`core::panic::{UnwindSafe, RefUnwindSafe, AssertUnwindSafe}`]
+  These APIs were previously stable in `std`, but are now also available in `core`.
+- [`Vec::shrink_to`]
+- [`String::shrink_to`]
+- [`OsString::shrink_to`]
+- [`PathBuf::shrink_to`]
+- [`BinaryHeap::shrink_to`]
+- [`VecDeque::shrink_to`]
+- [`HashMap::shrink_to`]
+- [`HashSet::shrink_to`]
+
+These APIs are now usable in const contexts:
+
+- [`std::mem::transmute`]
+- [`[T]::first`][`slice::first`]
+- [`[T]::split_first`][`slice::split_first`]
+- [`[T]::last`][`slice::last`]
+- [`[T]::split_last`][`slice::split_last`]
+
+Cargo
+-----
+
+- [Cargo supports specifying a minimum supported Rust version in Cargo.toml.][`rust-version`]
+  This has no effect at present on dependency version selection.
+  We encourage crates to specify their minimum supported Rust version, and we encourage CI systems
+  that support Rust code to include a crate's specified minimum version in the text matrix for that
+  crate by default.
+
+Compatibility notes
+-------------------
+
+- [Update to new argument parsing rules on Windows.][rust#87580]
+  This adjusts Rust's standard library to match the behavior of the standard
+  libraries for C/C++. The rules have changed slightly over time, and this PR
+  brings us to the latest set of rules (changed in 2008).
+- [Disallow the aapcs calling convention on aarch64][rust#88399]
+  This was already not supported by LLVM; this change surfaces this lack of
+  support with a better error message.
+- [Make `SEMICOLON_IN_EXPRESSIONS_FROM_MACROS` warn by default][rust#87385]
+- [Warn when an escaped newline skips multiple lines.][rust#87671]
+- [Calls to `libc::getpid` / `std::process::id` from `Command::pre_exec`
+   may return different values on glibc <= 2.24.][rust#81825]
+   Rust now invokes the `clone3` system call directly, when available, to use new functionality
+   available via that system call. Older versions of glibc cache the result of `getpid`, and only
+   update that cache when calling glibc's clone/fork functions, so a direct system call bypasses
+   that cache update. glibc 2.25 and newer no longer cache `getpid` for exactly this reason.
+
+Internal changes
+----------------
+These changes provide no direct user facing benefits, but represent significant
+improvements to the internals and overall performance of rustc
+and related tools.
+
+- [LLVM is compiled with PGO in published x86_64-unknown-linux-gnu artifacts.][rust#88069]
+  This improves the performance of most Rust builds.
+- [Unify representation of macros in internal data structures.][rust#88019]
+  This change fixes a host of bugs with the handling of macros by the compiler,
+  as well as rustdoc.
+
+[`std::os::unix::fs::chroot`]: https://doc.rust-lang.org/stable/std/os/unix/fs/fn.chroot.html
+[`Iterator::intersperse`]: https://doc.rust-lang.org/stable/std/iter/trait.Iterator.html#method.intersperse
+[`Iterator::intersperse_with`]: https://doc.rust-lang.org/stable/std/iter/trait.Iterator.html#method.intersperse
+[`UnsafeCell::raw_get`]: https://doc.rust-lang.org/stable/std/cell/struct.UnsafeCell.html#method.raw_get
+[`BufWriter::into_parts`]: https://doc.rust-lang.org/stable/std/io/struct.BufWriter.html#method.into_parts
+[`core::panic::{UnwindSafe, RefUnwindSafe, AssertUnwindSafe}`]: https://github.com/rust-lang/rust/pull/84662
+[`Vec::shrink_to`]: https://doc.rust-lang.org/stable/std/vec/struct.Vec.html#method.shrink_to
+[`String::shrink_to`]: https://doc.rust-lang.org/stable/std/string/struct.String.html#method.shrink_to
+[`OsString::shrink_to`]: https://doc.rust-lang.org/stable/std/ffi/struct.OsString.html#method.shrink_to
+[`PathBuf::shrink_to`]: https://doc.rust-lang.org/stable/std/path/struct.PathBuf.html#method.shrink_to
+[`BinaryHeap::shrink_to`]: https://doc.rust-lang.org/stable/std/collections/struct.BinaryHeap.html#method.shrink_to
+[`VecDeque::shrink_to`]: https://doc.rust-lang.org/stable/std/collections/struct.VecDeque.html#method.shrink_to
+[`HashMap::shrink_to`]: https://doc.rust-lang.org/stable/std/collections/hash_map/struct.HashMap.html#method.shrink_to
+[`HashSet::shrink_to`]: https://doc.rust-lang.org/stable/std/collections/hash_set/struct.HashSet.html#method.shrink_to
+[`std::mem::transmute`]: https://doc.rust-lang.org/stable/std/mem/fn.transmute.html
+[`slice::first`]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.first
+[`slice::split_first`]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.split_first
+[`slice::last`]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.last
+[`slice::split_last`]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.split_last
+[`rust-version`]: https://doc.rust-lang.org/nightly/cargo/reference/manifest.html#the-rust-version-field
+[rust#87671]: https://github.com/rust-lang/rust/pull/87671
+[rust#86183]: https://github.com/rust-lang/rust/pull/86183
+[rust#87385]: https://github.com/rust-lang/rust/pull/87385
+[rust#88100]: https://github.com/rust-lang/rust/pull/88100
+[rust#86860]: https://github.com/rust-lang/rust/pull/86860
+[rust#84039]: https://github.com/rust-lang/rust/pull/84039
+[rust#86492]: https://github.com/rust-lang/rust/pull/86492
+[rust#88363]: https://github.com/rust-lang/rust/pull/88363
+[rust#85305]: https://github.com/rust-lang/rust/pull/85305
+[rust#87832]: https://github.com/rust-lang/rust/pull/87832
+[rust#88069]: https://github.com/rust-lang/rust/pull/88069
+[rust#87472]: https://github.com/rust-lang/rust/pull/87472
+[rust#87699]: https://github.com/rust-lang/rust/pull/87699
+[rust#87570]: https://github.com/rust-lang/rust/pull/87570
+[rust#88023]: https://github.com/rust-lang/rust/pull/88023
+[rust#87760]: https://github.com/rust-lang/rust/pull/87760
+[rust#87370]: https://github.com/rust-lang/rust/pull/87370
+[rust#87580]: https://github.com/rust-lang/rust/pull/87580
+[rust#83342]: https://github.com/rust-lang/rust/pull/83342
+[rust#83093]: https://github.com/rust-lang/rust/pull/83093
+[rust#88177]: https://github.com/rust-lang/rust/pull/88177
+[rust#88548]: https://github.com/rust-lang/rust/pull/88548
+[rust#88551]: https://github.com/rust-lang/rust/pull/88551
+[rust#88299]: https://github.com/rust-lang/rust/pull/88299
+[rust#88220]: https://github.com/rust-lang/rust/pull/88220
+[rust#85835]: https://github.com/rust-lang/rust/pull/85835
+[rust#86879]: https://github.com/rust-lang/rust/pull/86879
+[rust#86744]: https://github.com/rust-lang/rust/pull/86744
+[rust#84662]: https://github.com/rust-lang/rust/pull/84662
+[rust#86593]: https://github.com/rust-lang/rust/pull/86593
+[rust#81050]: https://github.com/rust-lang/rust/pull/81050
+[rust#81363]: https://github.com/rust-lang/rust/pull/81363
+[rust#84111]: https://github.com/rust-lang/rust/pull/84111
+[rust#85769]: https://github.com/rust-lang/rust/pull/85769#issuecomment-854363720
+[rust#88490]: https://github.com/rust-lang/rust/pull/88490
+[rust#88269]: https://github.com/rust-lang/rust/pull/88269
+[rust#84176]: https://github.com/rust-lang/rust/pull/84176
+[rust#88399]: https://github.com/rust-lang/rust/pull/88399
+[rust#88227]: https://github.com/rust-lang/rust/pull/88227
+[rust#88200]: https://github.com/rust-lang/rust/pull/88200
+[rust#82776]: https://github.com/rust-lang/rust/pull/82776
+[rust#88077]: https://github.com/rust-lang/rust/pull/88077
+[rust#87728]: https://github.com/rust-lang/rust/pull/87728
+[rust#87050]: https://github.com/rust-lang/rust/pull/87050
+[rust#87619]: https://github.com/rust-lang/rust/pull/87619
+[rust#81825]: https://github.com/rust-lang/rust/pull/81825#issuecomment-808406918
+[rust#88019]: https://github.com/rust-lang/rust/pull/88019
+[rust#87666]: https://github.com/rust-lang/rust/pull/87666
+
 Version 1.55.0 (2021-09-09)
 ============================
 
@@ -4985,7 +5167,7 @@ Libraries
 - [Upgrade to Unicode 10.0.0][42999]
 - [Reimplemented `{f32, f64}::{min, max}` in Rust instead of using CMath.][42430]
 - [Skip the main thread's manual stack guard on Linux][43072]
-- [Iterator::nth for `ops::{Range, RangeFrom}` is now done in O(1) time][43077]
+- [Iterator::nth for `ops::{Range, RangeFrom}` is now done in *O*(1) time][43077]
 - [`#[repr(align(N))]` attribute max number is now 2^31 - 1.][43097] This was
   previously 2^15.
 - [`{OsStr, Path}::Display` now avoids allocations where possible][42613]
@@ -8288,7 +8470,7 @@ Libraries
   algorithm][s].
 * [`std::io::copy` allows `?Sized` arguments][cc].
 * The `Windows`, `Chunks`, and `ChunksMut` iterators over slices all
-  [override `count`, `nth` and `last` with an O(1)
+  [override `count`, `nth` and `last` with an *O*(1)
   implementation][it].
 * [`Default` is implemented for arrays up to `[T; 32]`][d].
 * [`IntoRawFd` has been added to the Unix-specific prelude,
@@ -8810,7 +8992,7 @@ Libraries
 * The `Default` implementation for `Arc` [no longer requires `Sync +
   Send`][arc].
 * [The `Iterator` methods `count`, `nth`, and `last` have been
-  overridden for slices to have O(1) performance instead of O(n)][si].
+  overridden for slices to have *O*(1) performance instead of *O*(*n*)][si].
 * Incorrect handling of paths on Windows has been improved in both the
   compiler and the standard library.
 * [`AtomicPtr` gained a `Default` implementation][ap].
diff --git a/src/ci/channel b/src/ci/channel
index 65b2df87f7d..2bf5ad0447d 100644
--- a/src/ci/channel
+++ b/src/ci/channel
@@ -1 +1 @@
-beta
+stable
diff --git a/src/librustdoc/visit_ast.rs b/src/librustdoc/visit_ast.rs
index 897b9140fc8..5082a14da2c 100644
--- a/src/librustdoc/visit_ast.rs
+++ b/src/librustdoc/visit_ast.rs
@@ -86,13 +86,21 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
         // the rexport defines the path that a user will actually see. Accordingly,
         // we add the rexport as an item here, and then skip over the original
         // definition in `visit_item()` below.
+        //
+        // We also skip `#[macro_export] macro_rules!` that have already been inserted,
+        // it can happen if within the same module a `#[macro_export] macro_rules!`
+        // is declared but also a reexport of itself producing two exports of the same
+        // macro in the same module.
+        let mut inserted = FxHashSet::default();
         for export in self.cx.tcx.module_exports(CRATE_DEF_ID).unwrap_or(&[]) {
             if let Res::Def(DefKind::Macro(_), def_id) = export.res {
                 if let Some(local_def_id) = def_id.as_local() {
                     if self.cx.tcx.has_attr(def_id, sym::macro_export) {
-                        let hir_id = self.cx.tcx.hir().local_def_id_to_hir_id(local_def_id);
-                        let item = self.cx.tcx.hir().expect_item(hir_id);
-                        top_level_module.items.push((item, None));
+                        if inserted.insert(def_id) {
+                            let hir_id = self.cx.tcx.hir().local_def_id_to_hir_id(local_def_id);
+                            let item = self.cx.tcx.hir().expect_item(hir_id);
+                            top_level_module.items.push((item, None));
+                        }
                     }
                 }
             }
diff --git a/src/test/rustdoc-json/reexport/macro.rs b/src/test/rustdoc-json/reexport/macro.rs
new file mode 100644
index 00000000000..b86614ffbad
--- /dev/null
+++ b/src/test/rustdoc-json/reexport/macro.rs
@@ -0,0 +1,17 @@
+// edition:2018
+
+#![no_core]
+#![feature(no_core)]
+
+// @count macro.json "$.index[*][?(@.name=='macro')].inner.items[*]" 2
+
+// @set repro_id = macro.json "$.index[*][?(@.name=='repro')].id"
+// @has - "$.index[*][?(@.name=='macro')].inner.items[*]" $repro_id
+#[macro_export]
+macro_rules! repro {
+    () => {};
+}
+
+// @set repro2_id = macro.json "$.index[*][?(@.inner.name=='repro2')].id"
+// @has - "$.index[*][?(@.name=='macro')].inner.items[*]" $repro2_id
+pub use crate::repro as repro2;
diff --git a/src/test/rustdoc/issue-89852.rs b/src/test/rustdoc/issue-89852.rs
new file mode 100644
index 00000000000..45544dbeea6
--- /dev/null
+++ b/src/test/rustdoc/issue-89852.rs
@@ -0,0 +1,14 @@
+// edition:2018
+
+#![no_core]
+#![feature(no_core)]
+
+// @matches 'issue_89852/sidebar-items.js' '"repro"'
+// @!matches 'issue_89852/sidebar-items.js' '"repro".*"repro"'
+
+#[macro_export]
+macro_rules! repro {
+    () => {};
+}
+
+pub use crate::repro as repro2;