Promote riscv64gc-unknown-linux-musl to tier 2

compiler/rustc_target/src/spec/targets/riscv64gc_unknown_linux_musl.rs

@@ -21,6 +21,7 @@ pub fn target() -> Target {
             llvm_abiname: "lp64d".into(),
             max_atomic_width: Some(64),
             supported_split_debuginfo: Cow::Borrowed(&[SplitDebuginfo::Off]),
+            crt_static_default: false,
             ..base::linux_musl::opts()
         },
     }

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

@@ -24,7 +24,8 @@ RUN apt-get update && apt-get build-dep -y clang llvm && apt-get install -y --no
   # Needed for apt-key to work:
   dirmngr \
   gpg-agent \
-  g++-9-arm-linux-gnueabi
+  g++-9-arm-linux-gnueabi \
+  g++-11-riscv64-linux-gnu
 
 RUN apt-key adv --batch --yes --keyserver keyserver.ubuntu.com --recv-keys 74DA7924C5513486
 RUN add-apt-repository -y 'deb https://apt.dilos.org/dilos dilos2 main'
@@ -73,6 +74,10 @@ RUN env \
     CC=arm-linux-gnueabi-gcc-9 CFLAGS="-march=armv7-a" \
     CXX=arm-linux-gnueabi-g++-9 CXXFLAGS="-march=armv7-a" \
     bash musl.sh armv7 && \
+    env \
+    CC=riscv64-linux-gnu-gcc-11 \
+    CXX=riscv64-linux-gnu-g++-11 \
+    bash musl.sh riscv64gc && \
     rm -rf /build/*
 
 WORKDIR /tmp
@@ -125,14 +130,19 @@ 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
+ENV TARGETS=$TARGETS,riscv64gc-unknown-linux-musl
 
 # As per https://bugs.launchpad.net/ubuntu/+source/gcc-defaults/+bug/1300211
 # we need asm in the search path for gcc-9 (for gnux32) but not in the search path of the
 # cross compilers.
 # Luckily one of the folders is /usr/local/include so symlink /usr/include/x86_64-linux-gnu/asm there
 RUN ln -s /usr/include/x86_64-linux-gnu/asm /usr/local/include/asm
 
+# musl-gcc can't find libgcc_s.so.1 since it doesn't use the standard search paths.
+RUN ln -s /usr/riscv64-linux-gnu/lib/libgcc_s.so.1 /usr/lib/gcc-cross/riscv64-linux-gnu/11/
+
 ENV RUST_CONFIGURE_ARGS --enable-extended --enable-lld --enable-llvm-bitcode-linker --disable-docs \
-  --musl-root-armv7=/musl-armv7
+  --musl-root-armv7=/musl-armv7 \
+  --musl-root-riscv64gc=/musl-riscv64gc
 
 ENV SCRIPT python3 ../x.py dist --host='' --target $TARGETS

src/doc/rustc/src/SUMMARY.md

@@ -66,6 +66,7 @@
     - [riscv32imac-unknown-xous-elf](platform-support/riscv32imac-unknown-xous-elf.md)
     - [riscv32*-unknown-none-elf](platform-support/riscv32-unknown-none-elf.md)
     - [riscv64gc-unknown-linux-gnu](platform-support/riscv64gc-unknown-linux-gnu.md)
+    - [riscv64gc-unknown-linux-musl](platform-support/riscv64gc-unknown-linux-musl.md)
     - [sparc-unknown-none-elf](./platform-support/sparc-unknown-none-elf.md)
     - [*-pc-windows-gnullvm](platform-support/pc-windows-gnullvm.md)
     - [\*-nto-qnx-\*](platform-support/nto-qnx.md)

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

@@ -98,6 +98,7 @@ target | notes
 `powerpc64-unknown-linux-gnu` | PPC64 Linux (kernel 3.2, glibc 2.17)
 `powerpc64le-unknown-linux-gnu` | PPC64LE Linux (kernel 3.10, glibc 2.17)
 [`riscv64gc-unknown-linux-gnu`](platform-support/riscv64gc-unknown-linux-gnu.md) | RISC-V Linux (kernel 4.20, glibc 2.29)
+[`riscv64gc-unknown-linux-musl`](platform-support/riscv64gc-unknown-linux-musl.md) | RISC-V Linux (kernel 4.20, musl 1.2.3)
 `s390x-unknown-linux-gnu` | S390x Linux (kernel 3.2, glibc 2.17)
 `x86_64-unknown-freebsd` | 64-bit FreeBSD
 `x86_64-unknown-illumos` | illumos
@@ -354,7 +355,6 @@ target | std | host | notes
 [`riscv64gc-unknown-hermit`](platform-support/hermit.md) | ✓ |   | RISC-V Hermit
 `riscv64gc-unknown-freebsd` |   |   | RISC-V FreeBSD
 `riscv64gc-unknown-fuchsia` |   |   | RISC-V Fuchsia
-`riscv64gc-unknown-linux-musl` |   |   | RISC-V Linux (kernel 4.20, musl 1.2.3)
 [`riscv64gc-unknown-netbsd`](platform-support/netbsd.md) | ✓ | ✓ | RISC-V NetBSD
 [`riscv64gc-unknown-openbsd`](platform-support/openbsd.md) | ✓ | ✓ | OpenBSD/riscv64
 [`riscv64-linux-android`](platform-support/android.md) |   |   | RISC-V 64-bit Android

src/doc/rustc/src/platform-support/riscv64gc-unknown-linux-musl.md

@@ -0,0 +1,47 @@
+# riscv64gc-unknown-linux-musl
+
+**Tier: 2**
+
+Target for RISC-V Linux programs using musl libc.
+
+## Target maintainers
+
+- [@Amanieu](https://github.com/Amanieu)
+- [@kraj](https://github.com/kraj)
+
+## Requirements
+
+Building the target itself requires a RISC-V compiler that is supported by `cc-rs`.
+
+## Building the target
+
+The target can be built by enabling it for a `rustc` build.
+
+```toml
+[build]
+target = ["riscv64gc-unknown-linux-musl"]
+```
+
+Make sure your C compiler is included in `$PATH`, then add it to the `config.toml`:
+
+```toml
+[target.riscv64gc-unknown-linux-musl]
+cc = "riscv64-linux-gnu-gcc"
+cxx = "riscv64-linux-gnu-g++"
+ar = "riscv64-linux-gnu-ar"
+linker = "riscv64-linux-gnu-gcc"
+```
+
+## Building Rust programs
+
+This target are distributed through `rustup`, and otherwise require no
+special configuration.
+
+## Cross-compilation
+
+This target can be cross-compiled from any host.
+
+## Testing
+
+This target can be tested as normal with `x.py` on a RISC-V host or via QEMU
+emulation.

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

@@ -141,6 +141,7 @@ static TARGETS: &[&str] = &[
     "riscv64gc-unknown-hermit",
     "riscv64gc-unknown-none-elf",
     "riscv64gc-unknown-linux-gnu",
+    "riscv64gc-unknown-linux-musl",
     "s390x-unknown-linux-gnu",
     "sparc64-unknown-linux-gnu",
     "sparcv9-sun-solaris",