Auto merge of #95798 - Dylan-DPC:rollup-51hx1wl, r=Dylan-DPC

Rollup of 7 pull requests

Successful merges:

 - #95102 (Add known-bug for #95034)
 - #95579 (Add `<[[T; N]]>::flatten{_mut}`)
 - #95634 (Mailmap update)
 - #95705 (Promote x86_64-unknown-none target to Tier 2 and distribute build artifacts)
 - #95761 (Kickstart the inner usage of `macro_metavar_expr`)
 - #95782 (Windows: Increase a pipe's buffer capacity to 64kb)
 - #95791 (hide an #[allow] directive from the Arc::new_cyclic doc example)

Failed merges:

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

6 files changed, 111 insertions, 8 deletions

diff --git a/src/ci/docker/host-x86_64/dist-various-2/Dockerfile b/src/ci/docker/host-x86_64/dist-various-2/Dockerfile
index e363c4f79f9..a045666ca8a 100644
--- a/src/ci/docker/host-x86_64/dist-various-2/Dockerfile
+++ b/src/ci/docker/host-x86_64/dist-various-2/Dockerfile
@@ -111,6 +111,7 @@ ENV TARGETS=$TARGETS,nvptx64-nvidia-cuda
 ENV TARGETS=$TARGETS,armv7-unknown-linux-gnueabi
 ENV TARGETS=$TARGETS,armv7-unknown-linux-musleabi
 ENV TARGETS=$TARGETS,i686-unknown-freebsd
+ENV TARGETS=$TARGETS,x86_64-unknown-none
 
 # As per https://bugs.launchpad.net/ubuntu/+source/gcc-defaults/+bug/1300211
 # we need asm in the search path for gcc-8 (for gnux32) but not in the search path of the
diff --git a/src/doc/rustc/src/platform-support.md b/src/doc/rustc/src/platform-support.md
index 8fc5a0d312b..32def67ed65 100644
--- a/src/doc/rustc/src/platform-support.md
+++ b/src/doc/rustc/src/platform-support.md
@@ -177,6 +177,7 @@ target | std | notes
 `x86_64-linux-android` | ✓ | 64-bit x86 Android
 `x86_64-pc-solaris` | ✓ | 64-bit Solaris 10/11, illumos
 `x86_64-unknown-linux-gnux32` | ✓ | 64-bit Linux (x32 ABI) (kernel 4.15, glibc 2.27)
+[`x86_64-unknown-none`](platform-support/x86_64-unknown-none.md) | * | Freestanding/bare-metal x86_64, softfloat
 `x86_64-unknown-redox` | ✓ | Redox OS
 
 [Fortanix ABI]: https://edp.fortanix.com/
@@ -291,7 +292,6 @@ target | std | host | notes
 `x86_64-unknown-haiku` | ✓ | ✓ | 64-bit Haiku
 `x86_64-unknown-hermit` | ✓ |  | HermitCore
 `x86_64-unknown-l4re-uclibc` | ? |  |
-[`x86_64-unknown-none`](platform-support/x86_64-unknown-none.md) | * |  | Freestanding/bare-metal x86_64, softfloat
 `x86_64-unknown-none-linuxkernel` | * |  | Linux kernel modules
 [`x86_64-unknown-openbsd`](platform-support/openbsd.md) | ✓ | ✓ | 64-bit OpenBSD
 `x86_64-unknown-uefi` | * |  | 64-bit UEFI
diff --git a/src/doc/rustc/src/platform-support/x86_64-unknown-none.md b/src/doc/rustc/src/platform-support/x86_64-unknown-none.md
index afcc48003b9..bd5fd1d0502 100644
--- a/src/doc/rustc/src/platform-support/x86_64-unknown-none.md
+++ b/src/doc/rustc/src/platform-support/x86_64-unknown-none.md
@@ -1,6 +1,6 @@
 # `x86_64-unknown-none`
 
-**Tier: 3**
+**Tier: 2**
 
 Freestanding/bare-metal x86-64 binaries in ELF format: firmware, kernels, etc.
 
@@ -32,7 +32,7 @@ You can change this using the `-C code-model=` option to rustc.
 On `x86_64-unknown-none`, `extern "C"` uses the [standard System V calling
 convention](https://gitlab.com/x86-psABIs/x86-64-ABI), without red zones.
 
-This target generated binaries in the ELF format. Any alternate formats or
+This target generates binaries in the ELF format. Any alternate formats or
 special considerations for binary layout will require linker options or linker
 scripts.
 
@@ -49,15 +49,19 @@ target = ["x86_64-unknown-none"]
 
 ## Building Rust programs
 
-Rust does not yet ship pre-compiled artifacts for this target. To compile for
-this target, you will either need to build Rust with the target enabled (see
-"Building the target" above), or build your own copy of `core` by using
-`build-std` or similar.
+Starting with Rust 1.62, precompiled artifacts are provided via `rustup`:
+
+```text
+# install cross-compile toolchain
+rustup target add x86_64-unknown-none
+# target flag may be used with any cargo or rustc command
+cargo build --target x86_64-unknown-none
+```
 
 ## Testing
 
 As `x86_64-unknown-none` supports a variety of different environments and does
-not support `std`, this target does not support running the Rust testsuite.
+not support `std`, this target does not support running the Rust test suite.
 
 ## Cross-compilation toolchains and C code
 
diff --git a/src/test/ui/hrtb/issue-94034.rs b/src/test/ui/hrtb/issue-94034.rs
new file mode 100644
index 00000000000..5239e5db11c
--- /dev/null
+++ b/src/test/ui/hrtb/issue-94034.rs
@@ -0,0 +1,96 @@
+// known-bug
+// failure-status: 101
+// compile-flags: --edition=2021 --crate-type=lib
+// rustc-env:RUST_BACKTRACE=0
+
+// normalize-stderr-test "thread 'rustc' panicked.*" -> "thread 'rustc' panicked"
+// normalize-stderr-test "note:.*RUST_BACKTRACE=1.*\n" -> ""
+// normalize-stderr-test "\nerror: internal compiler error.*\n\n" -> ""
+// normalize-stderr-test "note:.*unexpectedly panicked.*\n\n" -> ""
+// normalize-stderr-test "note: we would appreciate a bug report.*\n\n" -> ""
+// normalize-stderr-test "note: compiler flags.*\n\n" -> ""
+// normalize-stderr-test "note: rustc.*running on.*\n\n" -> ""
+// normalize-stderr-test "query stack during panic:\n" -> ""
+// normalize-stderr-test "we're just showing a limited slice of the query stack\n" -> ""
+// normalize-stderr-test "end of query stack\n" -> ""
+// normalize-stderr-test "#.*\n" -> ""
+
+// This should not ICE.
+
+use std::{
+    future::Future,
+    marker::PhantomData,
+    pin::Pin,
+    task::{Context, Poll},
+};
+
+mod object {
+    use super::*;
+
+    pub trait Object<'a> {
+        type Error;
+        type Future: Future<Output = Self>;
+        fn create() -> Self::Future;
+    }
+
+    impl<'a> Object<'a> for u8 {
+        type Error = ();
+        type Future = Pin<Box<dyn Future<Output = Self>>>;
+        fn create() -> Self::Future {
+            unimplemented!()
+        }
+    }
+
+    impl<'a, E, A: Object<'a, Error = E>> Object<'a> for (A,) {
+        type Error = ();
+        type Future = CustomFut<'a, E, A>;
+        fn create() -> Self::Future {
+            unimplemented!()
+        }
+    }
+
+    pub struct CustomFut<'f, E, A: Object<'f, Error = E>> {
+        ph: PhantomData<(A::Future,)>,
+    }
+
+    impl<'f, E, A: Object<'f, Error = E>> Future for CustomFut<'f, E, A> {
+        type Output = (A,);
+        fn poll(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Self::Output> {
+            unimplemented!()
+        }
+    }
+}
+
+mod async_fn {
+    use super::*;
+
+    pub trait AsyncFn {
+        type Future: Future<Output = ()>;
+        fn call(&self) -> Self::Future;
+    }
+
+    impl<F, Fut> AsyncFn for F
+    where
+        F: Fn() -> Fut,
+        Fut: Future<Output = ()>,
+    {
+        type Future = Fut;
+        fn call(&self) -> Self::Future {
+            (self)()
+        }
+    }
+}
+
+pub async fn test() {
+    use self::{async_fn::AsyncFn, object::Object};
+
+    async fn create<T: Object<'static>>() {
+        T::create().await;
+    }
+
+    async fn call_async_fn(inner: impl AsyncFn) {
+        inner.call().await;
+    }
+
+    call_async_fn(create::<(u8,)>).await;
+}
diff --git a/src/test/ui/hrtb/issue-94034.stderr b/src/test/ui/hrtb/issue-94034.stderr
new file mode 100644
index 00000000000..1d8329142fc
--- /dev/null
+++ b/src/test/ui/hrtb/issue-94034.stderr
@@ -0,0 +1 @@
+thread 'rustc' panicked
diff --git a/src/tools/build-manifest/src/main.rs b/src/tools/build-manifest/src/main.rs
index c682879e323..a1dfbef0601 100644
--- a/src/tools/build-manifest/src/main.rs
+++ b/src/tools/build-manifest/src/main.rs
@@ -152,6 +152,7 @@ static TARGETS: &[&str] = &[
     "x86_64-unknown-linux-gnux32",
     "x86_64-unknown-linux-musl",
     "x86_64-unknown-netbsd",
+    "x86_64-unknown-none",
     "x86_64-unknown-redox",
     "x86_64-unknown-hermit",
 ];