Promote {aarch64,i686,x86_64}-unknown-uefi to Tier 2

MCP: rust-lang/compiler-team#555

Author: nicholasbishop

src/ci/docker/host-x86_64/dist-various-2/Dockerfile

@@ -118,6 +118,9 @@ 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
+ENV TARGETS=$TARGETS,aarch64-unknown-uefi
+ENV TARGETS=$TARGETS,i686-unknown-uefi
+ENV TARGETS=$TARGETS,x86_64-unknown-uefi
 
 # 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

src/doc/rustc/src/platform-support.md

@@ -128,6 +128,7 @@ target | std | notes
 [`aarch64-linux-android`](platform-support/android.md) | ✓ | ARM64 Android
 `aarch64-unknown-none-softfloat` | * | Bare ARM64, softfloat
 `aarch64-unknown-none` | * | Bare ARM64, hardfloat
+[`aarch64-unknown-uefi`](platform-support/unknown-uefi.md) | * | ARM64 UEFI
 [`arm-linux-androideabi`](platform-support/android.md) | ✓ | ARMv7 Android
 `arm-unknown-linux-musleabi` | ✓ | ARMv6 Linux with MUSL
 `arm-unknown-linux-musleabihf` | ✓ | ARMv6 Linux with MUSL, hardfloat
@@ -149,6 +150,7 @@ target | std | notes
 [`i686-linux-android`](platform-support/android.md) | ✓ | 32-bit x86 Android
 `i686-unknown-freebsd` | ✓ | 32-bit FreeBSD
 `i686-unknown-linux-musl` | ✓ | 32-bit Linux with MUSL
+[`i686-unknown-uefi`](platform-support/unknown-uefi.md) | * | 32-bit UEFI
 `mips-unknown-linux-musl` | ✓ | MIPS Linux with MUSL
 `mips64-unknown-linux-muslabi64` | ✓ | MIPS64 Linux, n64 ABI, MUSL
 `mips64el-unknown-linux-muslabi64` | ✓ | MIPS64 (LE) Linux, n64 ABI, MUSL
@@ -181,6 +183,7 @@ target | std | notes
 `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
+[`x86_64-unknown-uefi`](platform-support/unknown-uefi.md) | * | 64-bit UEFI
 
 [Fortanix ABI]: https://edp.fortanix.com/
 
@@ -213,7 +216,6 @@ target | std | host | notes
 [`aarch64-pc-windows-gnullvm`](platform-support/pc-windows-gnullvm.md) | ✓ | ✓ |
 `aarch64-unknown-freebsd` | ✓ | ✓ | ARM64 FreeBSD
 `aarch64-unknown-hermit` | ✓ |  | ARM64 HermitCore
-[`aarch64-unknown-uefi`](platform-support/unknown-uefi.md) | * |  | ARM64 UEFI
 `aarch64-unknown-linux-gnu_ilp32` | ✓ | ✓ | ARM64 Linux (ILP32 ABI)
 `aarch64-unknown-netbsd` | ✓ | ✓ |
 [`aarch64-unknown-openbsd`](platform-support/openbsd.md) | ✓ | ✓ | ARM64 OpenBSD
@@ -252,7 +254,6 @@ target | std | host | notes
 `i686-unknown-haiku` | ✓ | ✓ | 32-bit Haiku
 `i686-unknown-netbsd` | ✓ | ✓ | NetBSD/i386 with SSE2
 [`i686-unknown-openbsd`](platform-support/openbsd.md) | ✓ | ✓ | 32-bit OpenBSD
-[`i686-unknown-uefi`](platform-support/unknown-uefi.md) | * |  | 32-bit UEFI
 `i686-uwp-windows-gnu` | ? |  |
 `i686-uwp-windows-msvc` | ? |  |
 `i686-wrs-vxworks` | ? |  |
@@ -311,7 +312,6 @@ target | std | host | notes
 `x86_64-unknown-l4re-uclibc` | ? |  |
 `x86_64-unknown-none-linuxkernel` | * |  | Linux kernel modules
 [`x86_64-unknown-openbsd`](platform-support/openbsd.md) | ✓ | ✓ | 64-bit OpenBSD
-[`x86_64-unknown-uefi`](platform-support/unknown-uefi.md) | * |  | 64-bit UEFI
 `x86_64-uwp-windows-gnu` | ✓ |  |
 `x86_64-uwp-windows-msvc` | ✓ |  |
 `x86_64-wrs-vxworks` | ? |  |

src/doc/rustc/src/platform-support/unknown-uefi.md

@@ -1,6 +1,6 @@
 # `*-unknown-uefi`
 
-**Tier: 3**
+**Tier: 2**
 
 Unified Extensible Firmware Interface (UEFI) targets for application, driver,
 and core UEFI binaries.
@@ -72,28 +72,14 @@ target = ["x86_64-unknown-uefi"]
 
 ## 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 rust for UEFI targets" above), or build your own copy of `core` by
-using `build-std`, `cargo-buildx`, or similar.
-
-A native build with the unstable `build-std`-feature can be achieved via:
-
-```sh
-cargo +nightly build \
-    -Zbuild-std=core,compiler_builtins \
-    -Zbuild-std-features=compiler-builtins-mem \
-    --target x86_64-unknown-uefi
-```
-
-Alternatively, you can install `cargo-xbuild` via
-`cargo install --force cargo-xbuild` and build for the UEFI targets via:
+Starting with Rust 1.67, precompiled artifacts are provided via
+`rustup`. For example, to use `x86_64-unknown-uefi`:
 
 ```sh
-cargo \
-    +nightly \
-    xbuild \
-    --target x86_64-unknown-uefi
+# install cross-compile toolchain
+rustup target add x86_64-unknown-uefi
+# target flag may be used with any cargo or rustc command
+cargo build --target x86_64-unknown-uefi
 ```
 
 ## Testing
@@ -167,18 +153,10 @@ The following code is a valid UEFI application returning immediately upon
 execution with an exit code of 0. A panic handler is provided. This is executed
 by rust on panic. For simplicity, we simply end up in an infinite loop.
 
-Note that as of rust-1.31.0, all features used here are stabilized. No unstable
-features are required, nor do we rely on nightly compilers. However, if you do
-not compile rustc for the UEFI targets, you need a nightly compiler to support
-the `-Z build-std` flag.
-
 This example can be compiled as binary crate via `cargo`:
 
 ```sh
-cargo +nightly build \
-    -Zbuild-std=core,compiler_builtins \
-    -Zbuild-std-features=compiler-builtins-mem \
-    --target x86_64-unknown-uefi
+cargo build --target x86_64-unknown-uefi
 ```
 
 ```rust,ignore (platform-specific,eh-personality-is-unstable)

src/tools/build-manifest/src/main.rs

@@ -64,6 +64,7 @@ static TARGETS: &[&str] = &[
     "aarch64-unknown-none",
     "aarch64-unknown-none-softfloat",
     "aarch64-unknown-redox",
+    "aarch64-unknown-uefi",
     "arm-linux-androideabi",
     "arm-unknown-linux-gnueabi",
     "arm-unknown-linux-gnueabihf",
@@ -99,6 +100,7 @@ static TARGETS: &[&str] = &[
     "i686-unknown-freebsd",
     "i686-unknown-linux-gnu",
     "i686-unknown-linux-musl",
+    "i686-unknown-uefi",
     "m68k-unknown-linux-gnu",
     "mips-unknown-linux-gnu",
     "mips-unknown-linux-musl",
@@ -155,6 +157,7 @@ static TARGETS: &[&str] = &[
     "x86_64-unknown-none",
     "x86_64-unknown-redox",
     "x86_64-unknown-hermit",
+    "x86_64-unknown-uefi",
 ];
 
 /// This allows the manifest to contain rust-docs for hosts that don't build