Some fixed to build_clang.sh including ability to use libc++

scripts/build_clang.sh

@@ -1,19 +1,44 @@
 #!/bin/sh
 
+BUILD_DIR=${BUILD_DIR:-build}
+
+args() {
+  for flag in "$@"; do
+    case "$flag" in
+      --no-update)
+        NOUPDATE=1
+        ;;
+      --use-libc++)
+        LIBCPP=1
+        ;;
+      *)
+        echo Unknown parameter $flag
+        exit 1
+    esac
+    shift
+  done
+}
+args "$@"
+
+LIBCPP_CXX_FLAGS="-std=c++11 -stdlib=libc++"
+CXXFLAGS="${CXXFLAGS} ${LIBCPP:+$LIBCPP_CXX_FLAGS}"
+
 # Default to Clang.
 if [ "$CC" == "gcc" ]; then
 	CXX=g++
 else
 	CC=clang
 	CXX=clang++
+    CFLAGS="${CFLAGS} -fcolor-diagnostics"
+    CXXFLAGS="${CXXFLAGS} -fcolor-diagnostics"
 fi
 
 # Use the 'ninja' build tool by default, but allow 'make' for the non-ninja.
 if [ "$MAKE" == "make" ]; then
-	GENERATOR="-G 'Unix Makefiles'"
+	GENERATOR="Unix Makefiles"
 else
 	MAKE="ninja"
-	GENERATOR="-G Ninja"
+	GENERATOR="Ninja"
 fi
 
 # If we don't have an LLVM directory, go get one. If we do, update it.
@@ -22,7 +47,7 @@ if [ ! -d llvm ]; then
   cd llvm/tools
   git clone http://github.com/CTSRD-TESLA/clang
   cd ../../
-elif [ "$1" != "--no-update" ]; then
+elif [ -z "$NOUPDATE" ]; then
   cd llvm
   git pull
   cd tools/clang
@@ -31,16 +56,17 @@ elif [ "$1" != "--no-update" ]; then
 fi
 
 # Build out of tree.
-mkdir -p build
-cd build
+mkdir -p "$BUILD_DIR"
+cd "$BUILD_DIR"
 
 if [ -f CMakeCache.txt ]; then
 	# CMake has already been run. No need to explicitly run it again: its
 	# previously-generated makefiles will take care of that if needed.
 	:
 else
-	cmake $GENERATOR \
+	cmake -G "$GENERATOR" \
 		-D CMAKE_C_COMPILER=${CC} -D CMAKE_CXX_COMPILER=${CXX} \
+        -D CMAKE_C_FLAGS="${CFLAGS}" -D CMAKE_CXX_FLAGS="${CXXFLAGS}" \
 		../llvm
 fi