Clang update.sh: always clear CMake's cache, and only set MACOSX_DEPLOYMENT_TARGET when needed

tools/clang/scripts/update.sh

 #!/usr/bin/env bash
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # This script will check out llvm and clang into third_party/llvm and build it.
 
 # Do NOT CHANGE this if you don't know what you're doing -- see
 # https://code.google.com/p/chromium/wiki/UpdatingClang
 # Reverting problematic clang rolls is safe, though.
@@ skipping 333 matching lines @@
   CC="$gcc_toolchain/bin/gcc"
   CXX="$gcc_toolchain/bin/g++"
   # Set LD_LIBRARY_PATH to make auxiliary targets (tablegen, bootstrap compiler,
   # etc.) find the .so.
   export LD_LIBRARY_PATH="$(dirname $(${CXX} -print-file-name=libstdc++.so.6))"
 fi
 
 CFLAGS=""
 CXXFLAGS=""
 LDFLAGS=""
+
 # LLVM uses C++11 starting in llvm 3.5. On Linux, this means libstdc++4.7+ is
 # needed, on OS X it requires libc++. clang only automatically links to libc++
 # when targeting OS X 10.9+, so add stdlib=libc++ explicitly so clang can run on
 # OS X versions as old as 10.7.
 # TODO(thakis): Some bots are still on 10.6, so for now bundle libc++.dylib.
 # Remove this once all bots are on 10.7+, then use --enable-libcpp=yes and
-# change all MACOSX_DEPLOYMENT_TARGET values to 10.7.
+# change deployment_target to 10.7.
+deployment_target=""
+
 if [ "${OS}" = "Darwin" ]; then
   # When building on 10.9, /usr/include usually doesn't exist, and while
   # Xcode's clang automatically sets a sysroot, self-built clangs don't.
   CFLAGS="-isysroot $(xcrun --show-sdk-path)"
   CPPFLAGS="${CFLAGS}"
   CXXFLAGS="-stdlib=libc++ -nostdinc++ -I${ABS_LIBCXX_DIR}/include ${CFLAGS}"
+
+  if [[ -n "${bootstrap}" ]]; then
+    deployment_target=10.6
+  fi
 fi
 
 # Build bootstrap clang if requested.
 if [[ -n "${bootstrap}" ]]; then
   ABS_INSTALL_DIR="${PWD}/${LLVM_BOOTSTRAP_INSTALL_DIR}"
   echo "Building bootstrap compiler"
   mkdir -p "${LLVM_BOOTSTRAP_DIR}"
   pushd "${LLVM_BOOTSTRAP_DIR}"
 
   cmake -GNinja \
@@ skipping 63 matching lines @@
     -nodefaultlibs -current_version 1 -compatibility_version 1 \
     -lSystem -install_name @executable_path/libc++.dylib \
     -Wl,-unexported_symbols_list,${ABS_LIBCXX_DIR}/lib/libc++unexp.exp \
     -Wl,-force_symbols_not_weak_list,${ABS_LIBCXX_DIR}/lib/notweak.exp \
     -Wl,-force_symbols_weak_list,${ABS_LIBCXX_DIR}/lib/weak.exp
   ln -sf libc++.1.dylib libc++.dylib
   popd
   LDFLAGS+="-stdlib=libc++ -L${PWD}/libcxxbuild"
 fi
 
-if [[ ! -f ./CMakeCache.txt ]]; then
-  MACOSX_DEPLOYMENT_TARGET=10.6 cmake -GNinja \
-      -DCMAKE_BUILD_TYPE=Release \
-      -DLLVM_ENABLE_ASSERTIONS=ON \
-      -DLLVM_ENABLE_THREADS=OFF \
-      -DCMAKE_C_COMPILER="${CC}" \
-      -DCMAKE_CXX_COMPILER="${CXX}" \
-      -DCMAKE_C_FLAGS="${CFLAGS}" \
-      -DCMAKE_CXX_FLAGS="${CXXFLAGS}" \
-      -DCMAKE_EXE_LINKER_FLAGS="${LDFLAGS}" \
-      -DCMAKE_SHARED_LINKER_FLAGS="${LDFLAGS}" \
-      -DCMAKE_MODULE_LINKER_FLAGS="${LDFLAGS}" \
-      "${ABS_LLVM_DIR}"
-  env
-fi
+rm -fv CMakeCache.txt
+MACOSX_DEPLOYMENT_TARGET=${deployment_target} cmake -GNinja \
+    -DCMAKE_BUILD_TYPE=Release \
+    -DLLVM_ENABLE_ASSERTIONS=ON \
+    -DLLVM_ENABLE_THREADS=OFF \
+    -DCMAKE_C_COMPILER="${CC}" \
+    -DCMAKE_CXX_COMPILER="${CXX}" \
+    -DCMAKE_C_FLAGS="${CFLAGS}" \
+    -DCMAKE_CXX_FLAGS="${CXXFLAGS}" \
+    -DCMAKE_EXE_LINKER_FLAGS="${LDFLAGS}" \
+    -DCMAKE_SHARED_LINKER_FLAGS="${LDFLAGS}" \
+    -DCMAKE_MODULE_LINKER_FLAGS="${LDFLAGS}" \
+    "${ABS_LLVM_DIR}"
+env
 
 if [[ -n "${gcc_toolchain}" ]]; then
   # Copy in the right stdlibc++.so.6 so clang can start.
   mkdir -p lib
   cp -v "$(${CXX} ${CXXFLAGS} -print-file-name=libstdc++.so.6)" lib/
 fi
 
 ninja
 
 STRIP_FLAGS=
 if [ "${OS}" = "Darwin" ]; then
   # See http://crbug.com/256342
   STRIP_FLAGS=-x
 
   cp libcxxbuild/libc++.1.dylib bin/
 fi
 strip ${STRIP_FLAGS} bin/clang
 popd
 
 # Build compiler-rt out-of-tree.
 mkdir -p "${COMPILER_RT_BUILD_DIR}"
 pushd "${COMPILER_RT_BUILD_DIR}"
 
-MACOSX_DEPLOYMENT_TARGET=10.6 cmake -GNinja \
+rm -fv CMakeCache.txt
+MACOSX_DEPLOYMENT_TARGET=${deployment_target} cmake -GNinja \
     -DCMAKE_BUILD_TYPE=Release \
     -DLLVM_ENABLE_ASSERTIONS=ON \
     -DLLVM_ENABLE_THREADS=OFF \
     -DCMAKE_C_COMPILER="${CC}" \
     -DCMAKE_CXX_COMPILER="${CXX}" \
     -DLLVM_CONFIG_PATH="${ABS_LLVM_BUILD_DIR}/bin/llvm-config" \
     "${ABS_COMPILER_RT_DIR}"
 
 ninja
 
@@ skipping 20 matching lines @@
       --system=linux-x86_64 \
       --stl=stlport
 
   # Android NDK r9d copies a broken unwind.h into the toolchain, see
   # http://crbug.com/357890
   rm -v "${LLVM_BUILD_DIR}"/android-toolchain/include/c++/*/unwind.h
 
   # Build ASan runtime for Android in a separate build tree.
   mkdir -p ${LLVM_BUILD_DIR}/android
   pushd ${LLVM_BUILD_DIR}/android
-  MACOSX_DEPLOYMENT_TARGET=10.6 cmake -GNinja \
+  rm -fv CMakeCache.txt
+  MACOSX_DEPLOYMENT_TARGET=${deployment_target} cmake -GNinja \
       -DCMAKE_BUILD_TYPE=Release \
       -DLLVM_ENABLE_ASSERTIONS=ON \
       -DLLVM_ENABLE_THREADS=OFF \
       -DCMAKE_C_COMPILER=${PWD}/../bin/clang \
       -DCMAKE_CXX_COMPILER=${PWD}/../bin/clang++ \
       -DLLVM_CONFIG_PATH=${PWD}/../bin/llvm-config \
       -DCMAKE_C_FLAGS="--target=arm-linux-androideabi --sysroot=${PWD}/../android-toolchain/sysroot -B${PWD}/../android-toolchain" \
       -DCMAKE_CXX_FLAGS="--target=arm-linux-androideabi --sysroot=${PWD}/../android-toolchain/sysroot -B${PWD}/../android-toolchain" \
       -DANDROID=1 \
       "${ABS_COMPILER_RT_DIR}"
   ninja clang_rt.asan-arm-android
 
   # And copy it into the main build tree.
   cp "$(find -name libclang_rt.asan-arm-android.so)" "${ABS_LLVM_CLANG_LIB_DIR}/lib/linux/"
   popd
 fi
 
 # Build Chrome-specific clang tools. Paths in this list should be relative to
 # tools/clang.
 TOOL_SRC_DIR="${PWD}/${THIS_DIR}/../"
 TOOL_BUILD_DIR="${ABS_LLVM_BUILD_DIR}/tools/clang/tools/chrome-extras"
 
 rm -rf "${TOOL_BUILD_DIR}"
 mkdir -p "${TOOL_BUILD_DIR}"
 pushd "${TOOL_BUILD_DIR}"
-MACOSX_DEPLOYMENT_TARGET=10.6 cmake -GNinja  \
+rm -fv CMakeCache.txt
+MACOSX_DEPLOYMENT_TARGET=${deployment_target} cmake -GNinja  \
     -DLLVM_BUILD_DIR="${ABS_LLVM_BUILD_DIR}" \
     -DLLVM_SRC_DIR="${ABS_LLVM_DIR}" \
     -DCMAKE_C_COMPILER="${CC}" \
     -DCMAKE_CXX_COMPILER="${CXX}" \
     -DCMAKE_C_FLAGS="${CFLAGS}" \
     -DCMAKE_CXX_FLAGS="${CXXFLAGS}" \
     -DCMAKE_EXE_LINKER_FLAGS="${LDFLAGS}" \
     -DCMAKE_SHARED_LINKER_FLAGS="${LDFLAGS}" \
     -DCMAKE_MODULE_LINKER_FLAGS="${LDFLAGS}" \
     -DCMAKE_INSTALL_PREFIX="${ABS_LLVM_BUILD_DIR}" \
     -DCHROMIUM_TOOLS="${chrome_tools}" \
     "${TOOL_SRC_DIR}"
 popd
 ninja -C "${TOOL_BUILD_DIR}" install
 
 if [[ -n "$run_tests" ]]; then
   # Run Chrome tool tests.
   ninja -C "${TOOL_BUILD_DIR}" check-all
   # Run the LLVM and Clang tests.
   ninja -C "${LLVM_BUILD_DIR}" check-all
 fi
 
 # After everything is done, log success for this revision.
 echo "${CLANG_AND_PLUGINS_REVISION}" > "${STAMP_FILE}"