Fix GCC libc++abi build

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@286783 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 94a682c..537ae80 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -312,6 +312,9 @@
 add_target_flags_if(LIBCXX_TARGET_TRIPLE "-target ${LIBCXX_TARGET_TRIPLE}")
 add_target_flags_if(LIBCXX_SYSROOT "--sysroot=${LIBCXX_SYSROOT}")
 add_target_flags_if(LIBCXX_GCC_TOOLCHAIN "-gcc-toolchain ${LIBCXX_GCC_TOOLCHAIN}")
+if (LIBCXX_TARGET_TRIPLE)
+  set(TARGET_TRIPLE "${LIBCXX_TARGET_TRIPLE}")
+endif()
 
 # Configure compiler.
 include(config-ix)
diff --git a/test/libcxx/compiler.py b/test/libcxx/compiler.py
index cb8542c..24f7c36 100644
--- a/test/libcxx/compiler.py
+++ b/test/libcxx/compiler.py
@@ -193,6 +193,17 @@
                                          flags=flags)
         return rc == 0
 
+    def addFlagIfSupported(self, flag):
+        if isinstance(flag, list):
+            flags = list(flag)
+        else:
+            flags = [flag]
+        if self.hasCompileFlag(flags):
+            self.flags += flags
+            return True
+        else:
+            return False
+
     def addCompileFlagIfSupported(self, flag):
         if isinstance(flag, list):
             flags = list(flag)
diff --git a/test/libcxx/test/config.py b/test/libcxx/test/config.py
index 6549324..ada260b 100644
--- a/test/libcxx/test/config.py
+++ b/test/libcxx/test/config.py
@@ -83,6 +83,10 @@
         conf = self.get_lit_conf(name)
         if conf is None:
             return default
+        if isinstance(conf, bool):
+            return conf
+        if not isinstance(conf, str):
+            raise TypeError('expected bool or string')
         if conf.lower() in ('1', 'true'):
             return True
         if conf.lower() in ('', '0', 'false'):
@@ -375,7 +379,10 @@
         if gcc_toolchain:
             self.cxx.flags += ['-gcc-toolchain', gcc_toolchain]
         if self.use_target:
-            self.cxx.flags += ['-target', self.config.target_triple]
+            if not self.cxx.addFlagIfSupported(
+                    ['-target', self.config.target_triple]):
+                self.lit_config.warning('use_target is true but -target is '\
+                        'not supported by the compiler')
 
     def configure_compile_flags_header_includes(self):
         support_path = os.path.join(self.libcxx_src_root, 'test/support')
@@ -756,10 +763,12 @@
     def configure_triple(self):
         # Get or infer the target triple.
         self.config.target_triple = self.get_lit_conf('target_triple')
-        self.use_target = bool(self.config.target_triple)
+        self.use_target = self.get_lit_bool('use_target', False)
+        if self.use_target and self.config.target_triple:
+            self.lit_config.warning('use_target is true but no triple is specified')
         # If no target triple was given, try to infer it from the compiler
         # under test.
-        if not self.use_target:
+        if not self.config.target_triple:
             target_triple = self.cxx.getTriple()
             # Drop sub-major version components from the triple, because the
             # current XFAIL handling expects exact matches for feature checks.
diff --git a/test/lit.site.cfg.in b/test/lit.site.cfg.in
index 5344992..741e9c8 100644
--- a/test/lit.site.cfg.in
+++ b/test/lit.site.cfg.in
@@ -15,7 +15,9 @@
 config.sanitizer_library        = "@LIBCXX_SANITIZER_LIBRARY@"
 config.abi_library_path         = "@LIBCXX_CXX_ABI_LIBRARY_PATH@"
 config.configuration_variant    = "@LIBCXX_LIT_VARIANT@"
-config.target_triple            = "@LIBCXX_TARGET_TRIPLE@"
+config.host_triple              = "@LLVM_HOST_TRIPLE@"
+config.target_triple            = "@TARGET_TRIPLE@"
+config.use_target               = len("@LIBCXX_TARGET_TRIPLE@") > 0
 config.sysroot                  = "@LIBCXX_SYSROOT@"
 config.gcc_toolchain            = "@LIBCXX_GCC_TOOLCHAIN@"
 config.generate_coverage        = "@LIBCXX_GENERATE_COVERAGE@"