update.py: Check out and build libc++ libc++abi on OS X, set deployment target.

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 456 matching lines @@
 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 deployment_target to 10.7.
+# TODO(thakis): Some bots are still on 10.6 (nacl...), so for now bundle
+# libc++.dylib.  Remove this once all bots are on 10.7+, then use
+# -DLLVM_ENABLE_LIBCXX=ON and 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}"

[Nico, 2015/06/09 23:30:34]

This is apparently no longer needed. A local --bootstrap build seems to work
without this. Probably a remnant from the configure/make days.

   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}/${LLVM_BOOTSTRAP_INSTALL_DIR}"
@@ skipping 214 matching lines @@
   # Run Chrome tool tests.
   ninja -C "${LLVM_BUILD_DIR}" cr-check-all
 fi
 if [[ -n "$run_tests" ]]; then
   # Run the LLVM and Clang tests.
   ninja -C "${LLVM_BUILD_DIR}" check-all
 fi
 
 # After everything is done, log success for this revision.
 echo "${PACKAGE_VERSION}" > "${STAMP_FILE}"