Handle env and llvm-target for musl

Further changes needed for musl to work.
env needs to be set to "musl" for unwinding work properly.
Also the llvm target should end with "-musl" and not "-gnu".

classes/rust-common.bbclass

@@ -11,8 +11,27 @@ RUSTLIB_DEP ?= "libstd-rs"
 RUST_TARGET_PATH = "${STAGING_LIBDIR_NATIVE}/rustlib"
 RUST_PANIC_STRATEGY ?= "unwind"
 
-# Responsible for taking Yocto triples and converting it to Rust triples
+# Native builds are not effected by TCLIBC. Without this, rust-native
+# thinks it's "target" (i.e. x86_64-linux) is a musl target.
+RUST_LIBC = "${TCLIBC}"
+RUST_LIBC_class-native = "glibc"
 
+def determine_libc(d, thing):
+    '''Determine which libc something should target'''
+
+    # BUILD is never musl, TARGET may be musl or glibc,
+    # HOST could be musl, but only if a compiler is built to be run on
+    # target in which case HOST_SYS != BUILD_SYS.
+    if thing == 'TARGET':
+        libc = d.getVar('RUST_LIBC')
+    elif thing == 'BUILD' and (d.getVar('HOST_SYS') != d.getVar('BUILD_SYS')):
+        libc = d.getVar('RUST_LIBC')
+    else:
+        libc = d.getVar('RUST_LIBC_class-native')
+
+    return libc
+
+# Responsible for taking Yocto triples and converting it to Rust triples
 def rust_base_triple(d, thing):
     '''
     Mangle bitbake's *_SYS into something that rust might support (see
@@ -25,7 +44,7 @@ def rust_base_triple(d, thing):
     # All the Yocto targets are Linux and are 'unknown'
     vendor = "-unknown"
     os = d.getVar('{}_OS'.format(thing))
-    libc = d.getVar('TCLIBC')
+    libc = determine_libc(d, thing)
 
     # Prefix with a dash and convert glibc -> gnu
     if libc == "glibc":

recipes-devtools/rust/rust.inc

@@ -142,39 +142,39 @@ TARGET_C_INT_WIDTH[arm] = "32"
 MAX_ATOMIC_WIDTH[arm] = "64"
 FEATURES[arm] = "+v6,+vfp2"
 
-## aarch64-unknown-linux-gnu
+## aarch64-unknown-linux-{gnu, musl}
 DATA_LAYOUT[aarch64] = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
-LLVM_TARGET[aarch64] = "aarch64-unknown-linux-gnu"
+LLVM_TARGET[aarch64] = "${RUST_TARGET_SYS}"
 TARGET_ENDIAN[aarch64] = "little"
 TARGET_POINTER_WIDTH[aarch64] = "64"
 TARGET_C_INT_WIDTH[aarch64] = "32"
 MAX_ATOMIC_WIDTH[aarch64] = "128"
 
-## x86_64-unknown-linux-gnu
+## x86_64-unknown-linux-{gnu, musl}
 DATA_LAYOUT[x86_64] = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
-LLVM_TARGET[x86_64] = "x86_64-unknown-linux-gnu"
+LLVM_TARGET[x86_64] = "${RUST_TARGET_SYS}"
 TARGET_ENDIAN[x86_64] = "little"
 TARGET_POINTER_WIDTH[x86_64] = "64"
 TARGET_C_INT_WIDTH[x86_64] = "32"
 MAX_ATOMIC_WIDTH[x86_64] = "64"
 
-## i686-unknown-linux-gnu
+## i686-unknown-linux-{gnu, musl}
 DATA_LAYOUT[i686] = "e-m:e-p:32:32-f64:32:64-f80:32-n8:16:32-S128"
-LLVM_TARGET[i686] = "i686-unknown-linux-gnu"
+LLVM_TARGET[i686] = "${RUST_TARGET_SYS}"
 TARGET_ENDIAN[i686] = "little"
 TARGET_POINTER_WIDTH[i686] = "32"
 TARGET_C_INT_WIDTH[i686] = "32"
 MAX_ATOMIC_WIDTH[i686] = "64"
 
-## XXX: a bit of a hack so qemux86 builds, clone of i686-unknown-linux-gnu above
+## XXX: a bit of a hack so qemux86 builds, clone of i686-unknown-linux-{gnu, musl} above
 DATA_LAYOUT[i586] = "e-m:e-p:32:32-f64:32:64-f80:32-n8:16:32-S128"
-LLVM_TARGET[i586] = "i586-unknown-linux-gnu"
+LLVM_TARGET[i586] = "${RUST_TARGET_SYS}"
 TARGET_ENDIAN[i586] = "little"
 TARGET_POINTER_WIDTH[i586] = "32"
 TARGET_C_INT_WIDTH[i586] = "32"
 MAX_ATOMIC_WIDTH[i586] = "64"
 
-## mips-unknown-linux-gnu
+## mips-unknown-linux-{gnu, musl}
 DATA_LAYOUT[mips] = "E-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32-S64"
 LLVM_TARGET[mips] = "${RUST_TARGET_SYS}"
 TARGET_ENDIAN[mips] = "big"
@@ -182,7 +182,7 @@ TARGET_POINTER_WIDTH[mips] = "32"
 TARGET_C_INT_WIDTH[mips] = "32"
 MAX_ATOMIC_WIDTH[mips] = "32"
 
-## mipsel-unknown-linux-gnu
+## mipsel-unknown-linux-{gnu, musl}
 DATA_LAYOUT[mipsel] = "e-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32-S64"
 LLVM_TARGET[mipsel] = "${RUST_TARGET_SYS}"
 TARGET_ENDIAN[mipsel] = "little"
@@ -267,7 +267,10 @@ def rust_gen_target(d, thing, wd):
     tspec['target-endian'] = d.getVarFlag('TARGET_ENDIAN', arch)
     tspec['arch'] = arch_to_rust_target_arch(arch)
     tspec['os'] = "linux"
-    tspec['env'] = "gnu"
+    if "musl" in tspec['llvm-target']:
+        tspec['env'] = "musl"
+    else:
+        tspec['env'] = "gnu"
     tspec['vendor'] = "unknown"
     tspec['target-family'] = "unix"
     tspec['linker'] = "{}{}gcc".format(d.getVar('CCACHE'), prefix)