Disable custom libcxx on mac fuzzer builds

build/config/sanitizers/sanitizers.gni

 # Copyright 2015 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.
 
 import("//build/config/chrome_build.gni")
 import("//build/toolchain/toolchain.gni")
 
 declare_args() {
   # Compile for Address Sanitizer to find memory bugs.
   is_asan = false
@@ skipping 121 matching lines @@
 
 # Args that are in turn dependent on other args must be in a separate
 # declare_args block. User overrides are only applied at the end of a
 # declare_args block.
 declare_args() {
   # Use libc++ (buildtools/third_party/libc++ and
   # buildtools/third_party/libc++abi) instead of stdlibc++ as standard library.
   # This is intended to be used for instrumented builds.
   use_custom_libcxx =
       (is_asan && is_linux && !is_chromeos) || is_tsan || is_msan || is_ubsan ||
-      is_ubsan_security || use_libfuzzer || use_afl
+      is_ubsan_security || (use_libfuzzer && !is_mac) || use_afl

[Tom Anderson, 2017/06/02 20:27:40]

Should this entire thing be wrapped in "is_linux && !is_chromeos"?

[Nico, 2017/06/02 20:38:35]

I think we use it on android too.

 
   # Enable -fsanitize-coverage.
   use_sanitizer_coverage =
       use_libfuzzer || use_afl || sanitizer_coverage_flags != ""
 
   # Detect overflow/underflow for global objects.
   #
   # Mac: http://crbug.com/352073
   asan_globals = !is_mac
 }
@@ skipping 41 matching lines @@
 assert(!is_debug || !(is_msan || is_ubsan || is_ubsan_null || is_ubsan_vptr),
        "Sanitizers should generally be used in release (set is_debug=false).")
 
 assert(!is_msan || (is_linux && current_cpu == "x64"),
        "MSan currently only works on 64-bit Linux and ChromeOS builds.")
 
 # ASAN build on Windows is not working in debug mode. Intercepting memory
 # allocation functions is hard on Windows and not yet implemented in LLVM.
 assert(!is_win || !is_debug || !is_asan,
        "ASan on Windows doesn't work in debug (set is_debug=false).")