Add x86_64-unknown-linux-musl build support

.travis.yml

@@ -42,6 +42,7 @@ matrix:
     - { <<: *linux, env: SKIP_TESTS=1 TARGET=mips64-unknown-linux-gnuabi64   }
     - { <<: *linux, env: SKIP_TESTS=1 TARGET=mips64el-unknown-linux-gnuabi64 }
     - { <<: *linux, env: SKIP_TESTS=1 TARGET=s390x-unknown-linux-gnu         }
+    - { os: linux, env: SKIP_TESTS=1 TARGET=x86_64-unknown-linux-musl        }
     - { <<: *linux, env: SKIP_TESTS=1 TARGET=arm-linux-androideabi           }
     - { <<: *linux, env: SKIP_TESTS=1 TARGET=armv7-linux-androideabi         }
     - { <<: *linux, env: SKIP_TESTS=1 TARGET=aarch64-linux-android           }

README.md

@@ -670,6 +670,7 @@ platform of your choice:
 - [x86_64-pc-windows-msvc](https://static.rust-lang.org/rustup/dist/x86_64-pc-windows-msvc/rustup-init.exe)<sup>[†](#vs2019)</sup>
 - [x86_64-unknown-freebsd](https://static.rust-lang.org/rustup/dist/x86_64-unknown-freebsd/rustup-init)
 - [x86_64-unknown-linux-gnu](https://static.rust-lang.org/rustup/dist/x86_64-unknown-linux-gnu/rustup-init)
+- [x86_64-unknown-linux-musl](https://static.rust-lang.org/rustup/dist/x86_64-unknown-linux-musl/rustup-init)
 - [x86_64-unknown-netbsd](https://static.rust-lang.org/rustup/dist/x86_64-unknown-netbsd/rustup-init)
 
 <a name="vs2019">†</a>

ci/docker/x86_64-unknown-linux-musl/Dockerfile

@@ -0,0 +1,13 @@
+FROM ubuntu:18.04
+
+RUN apt-get update && apt-get install -y \
+  musl-dev \
+  musl-tools \
+  curl \
+  ca-certificates \
+  perl \
+  make \
+  gcc
+
+RUN curl -L https://github.com/mozilla/sccache/releases/download/0.2.8/sccache-0.2.8-x86_64-unknown-linux-musl.tar.gz | tar xzf - \
+  && mv ./sccache-0.2.8-x86_64-unknown-linux-musl/sccache /usr/bin/sccache && rm -rf ./sccache-0.2.8-x86_64-unknown-linux-musl

rustup-init.sh

@@ -163,14 +163,18 @@ get_endianness() {
 }
 
 get_architecture() {
-    local _ostype _cputype _bitness _arch
+    local _ostype _cputype _bitness _arch _clibtype
     _ostype="$(uname -s)"
     _cputype="$(uname -m)"
+    _clibtype="gnu"
 
     if [ "$_ostype" = Linux ]; then
         if [ "$(uname -o)" = Android ]; then
             _ostype=Android
         fi
+        if [ "$(ldd --version 2>&1 | grep 'musl')" ]; then
+            _clibtype="musl"
+        fi
     fi
 
     if [ "$_ostype" = Darwin ] && [ "$_cputype" = i386 ]; then
@@ -187,7 +191,7 @@ get_architecture() {
             ;;
 
         Linux)
-            _ostype=unknown-linux-gnu
+            _ostype=unknown-linux-$_clibtype
             _bitness=$(get_bitness)
             ;;
 

src/dist/dist.rs

@@ -96,6 +96,13 @@ static LIST_ENVS: &[&str] = &[
     "musl",
 ];
 
+// Linux hosts don't indicate clib in uname, however binaries only
+// run on boxes with the same clib, as expected.
+#[cfg(all(not(windows), not(target_env = "musl")))]
+const TRIPLE_X86_64_UNKNOWN_LINUX: &str = "x86_64-unknown-linux-gnu";
+#[cfg(all(not(windows), target_env = "musl"))]
+const TRIPLE_X86_64_UNKNOWN_LINUX: &str = "x86_64-unknown-linux-musl";
+
 // MIPS platforms don't indicate endianness in uname, however binaries only
 // run on boxes with the same endianness, as expected.
 // Hence we could distinguish between the variants with compile-time cfg()
@@ -175,7 +182,7 @@ impl TargetTriple {
                 (_, b"aarch64") if cfg!(target_os = "android") => Some("aarch64-linux-android"),
                 (_, b"i686") if cfg!(target_os = "android") => Some("i686-linux-android"),
                 (_, b"x86_64") if cfg!(target_os = "android") => Some("x86_64-linux-android"),
-                (b"Linux", b"x86_64") => Some("x86_64-unknown-linux-gnu"),
+                (b"Linux", b"x86_64") => Some(TRIPLE_X86_64_UNKNOWN_LINUX),
                 (b"Linux", b"i686") => Some("i686-unknown-linux-gnu"),
                 (b"Linux", b"mips") => Some(TRIPLE_MIPS_UNKNOWN_LINUX_GNU),
                 (b"Linux", b"mips64") => Some(TRIPLE_MIPS64_UNKNOWN_LINUX_GNUABI64),