configure: Add options for separate musl roots

This allows using the `./configure` script to enable rustbuild to compile
multiple musl targets at once. We'll hopefully use this soon on our bots to
produce a bunch of targets.

Author: alexcrichton

configure

@@ -653,7 +653,12 @@ valopt arm-linux-androideabi-ndk "" "arm-linux-androideabi NDK standalone path"
 valopt armv7-linux-androideabi-ndk "" "armv7-linux-androideabi NDK standalone path"
 valopt aarch64-linux-android-ndk "" "aarch64-linux-android NDK standalone path"
 valopt nacl-cross-path  "" "NaCl SDK path (Pepper Canary is recommended). Must be absolute!"
-valopt musl-root "/usr/local" "MUSL root installation directory"
+valopt musl-root "/usr/local" "MUSL root installation directory (deprecated)"
+valopt musl-root-x86_64 "/usr/local" "x86_64-unknown-linux-musl install directory"
+valopt musl-root-i686 "/usr/local" "i686-unknown-linux-musl install directory"
+valopt musl-root-arm "/usr/local" "arm-unknown-linux-musleabi install directory"
+valopt musl-root-armhf "/usr/local" "arm-unknown-linux-musleabihf install directory"
+valopt musl-root-armv7 "/usr/local" "armv7-unknown-linux-musleabihf install directory"
 valopt extra-filename "" "Additional data that is hashed and passed to the -C extra-filename flag"
 
 if [ -e ${CFG_SRC_DIR}.git ]
@@ -1212,14 +1217,6 @@ do
             fi
             ;;
 
-
-        x86_64-*-musl | arm-*-musleabi)
-            if [ ! -f $CFG_MUSL_ROOT/lib/libc.a ]
-            then
-                err "musl libc $CFG_MUSL_ROOT/lib/libc.a not found"
-            fi
-            ;;
-
         *-msvc)
             # There are three builds of cmake on windows: MSVC, MinGW and Cygwin
             # The Cygwin build does not have generators for Visual Studio, so

src/bootstrap/config.rs

@@ -345,6 +345,36 @@ impl Config {
                 "CFG_MUSL_ROOT" if value.len() > 0 => {
                     self.musl_root = Some(PathBuf::from(value));
                 }
+                "CFG_MUSL_ROOT_X86_64" if value.len() > 0 => {
+                    let target = "x86_64-unknown-linux-musl".to_string();
+                    let target = self.target_config.entry(target)
+                                     .or_insert(Target::default());
+                    target.musl_root = Some(PathBuf::from(value));
+                }
+                "CFG_MUSL_ROOT_I686" if value.len() > 0 => {
+                    let target = "i686-unknown-linux-musl".to_string();
+                    let target = self.target_config.entry(target)
+                                     .or_insert(Target::default());
+                    target.musl_root = Some(PathBuf::from(value));
+                }
+                "CFG_MUSL_ROOT_ARM" if value.len() > 0 => {
+                    let target = "arm-unknown-linux-musleabi".to_string();
+                    let target = self.target_config.entry(target)
+                                     .or_insert(Target::default());
+                    target.musl_root = Some(PathBuf::from(value));
+                }
+                "CFG_MUSL_ROOT_ARMHF" if value.len() > 0 => {
+                    let target = "arm-unknown-linux-musleabihf".to_string();
+                    let target = self.target_config.entry(target)
+                                     .or_insert(Target::default());
+                    target.musl_root = Some(PathBuf::from(value));
+                }
+                "CFG_MUSL_ROOT_ARMV7" if value.len() > 0 => {
+                    let target = "armv7-unknown-linux-musleabihf".to_string();
+                    let target = self.target_config.entry(target)
+                                     .or_insert(Target::default());
+                    target.musl_root = Some(PathBuf::from(value));
+                }
                 "CFG_DEFAULT_AR" if value.len() > 0 => {
                     self.rustc_default_ar = Some(value.to_string());
                 }