First red:
https://ci.chromium.org/buildbot/chromium.clang/ToTMac%20%28dbg%29/613

llvm range: 324173:324182

Probably this one:

------------------------------------------------------------------------
r324182 | ericwf | 2018-02-04 02:03:08 +0100 (Sun, 04 Feb 2018) | 14 lines

[libc++] Fix PR35491 - std::array of zero-size doesn't work with non-default constructible types.

Summary:
This patch fixes llvm.org/PR35491 and LWG2157  (https://cplusplus.github.io/LWG/issue2157)

The fix attempts to maintain ABI compatibility by replacing the array with a instance of `aligned_storage`.

Reviewers: mclow.lists, EricWF

Reviewed By: EricWF

Subscribers: lichray, cfe-commits

Differential Revision: https://reviews.llvm.org/D41223
------------------------------------------------------------------------

Actually, the error after r324182 was:

FAILED: obj/chrome/browser/media/router/discovery/discovery/safe_dial_device_description_parser.o 
export DEVELOPER_DIR=/b/c/b/ToTMac__dbg_/src/build/mac_files/Xcode.app;  ../../third_party/llvm-build/Release+Asserts/bin/clang++ -MMD -MF obj/chrome/browser/media/router/discovery/discovery/safe_dial_device_description_parser.o.d -DV8_DEPRECATION_WARNINGS -DNO_TCMALLOC -DFULL_SAFE_BROWSING -DSAFE_BROWSING_CSD -DSAFE_BROWSING_DB_LOCAL -DCHROMIUM_BUILD -DFIELDTRIAL_TESTING_ENABLED -DCR_XCODE_VERSION=0832 -DCR_CLANG_REVISION=\"324182\" -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -DCOMPONENT_BUILD -D__ASSERT_MACROS_DEFINE_VERSIONS_WITHOUT_UNDERSCORE=0 -D_DEBUG -DDYNAMIC_ANNOTATIONS_ENABLED=1 -DWTF_USE_DYNAMIC_ANNOTATIONS=1 -DWEBP_EXTERN=extern -DU_USING_ICU_NAMESPACE=0 -DU_ENABLE_DYLOAD=0 -DICU_UTIL_DATA_IMPL=ICU_UTIL_DATA_FILE -DUCHAR_TYPE=uint16_t -DGOOGLE_PROTOBUF_NO_RTTI -DGOOGLE_PROTOBUF_NO_STATIC_INITIALIZER -DHAVE_PTHREAD -DPROTOBUF_USE_DLLS -DBORINGSSL_SHARED_LIBRARY -DV8_USE_EXTERNAL_STARTUP_DATA -DLEVELDB_PLATFORM_CHROMIUM=1 -DSK_IGNORE_LINEONLY_AA_CONVEX_PATH_OPTS -DSK_HAS_PNG_LIBRARY -DSK_HAS_WEBP_LIBRARY -DSK_HAS_JPEG_LIBRARY -DSKIA_DLL -DGR_GL_IGNORE_ES3_MSAA=0 -DSK_SUPPORT_GPU=1 -DSK_BUILD_FOR_MAC -DUSING_V8_SHARED -DV8_ENABLE_CHECKS -DWEBRTC_NON_STATIC_TRACE_EVENT_HANDLERS=0 -DFEATURE_ENABLE_VOICEMAIL -DGTEST_RELATIVE_PATH -DWEBRTC_CHROMIUM_BUILD -DWEBRTC_POSIX -DWEBRTC_MAC -I../.. -Igen -I../../third_party/libwebp/src -I../../third_party/khronos -I../../gpu -I../../third_party/libyuv/include -I../../third_party/ced/src -I../../third_party/icu/source/common -I../../third_party/icu/source/i18n -I../../third_party/protobuf/src -Igen/protoc_out -I../../third_party/protobuf/src -I../../third_party/boringssl/src/include -I../../third_party/leveldatabase -I../../third_party/leveldatabase/src -I../../third_party/leveldatabase/src/include -I../../skia/config -I../../skia/ext -I../../third_party/skia/include/c -I../../third_party/skia/include/config -I../../third_party/skia/include/core -I../../third_party/skia/include/effects -I../../third_party/skia/include/encode -I../../third_party/skia/include/gpu -I../../third_party/skia/include/images -I../../third_party/skia/include/lazy -I../../third_party/skia/include/pathops -I../../third_party/skia/include/pdf -I../../third_party/skia/include/pipe -I../../third_party/skia/include/ports -I../../third_party/skia/include/utils -I../../third_party/vulkan/include -I../../third_party/skia/src/gpu -I../../third_party/skia/src/sksl -I../../third_party/libwebm/source -I../../third_party/WebKit -Igen/third_party/WebKit -I../../v8/include -Igen/v8/include -I../../third_party/webrtc_overrides -I../../third_party/webrtc -fno-strict-aliasing -fstack-protector-strong -Wno-builtin-macro-redefined -D__DATE__= -D__TIME__= -D__TIMESTAMP__= -fcolor-diagnostics -Xclang -mllvm -Xclang -instcombine-lower-dbg-declare=0 -no-canonical-prefixes -arch x86_64 -Wall -Werror -Wextra -Wthread-safety -Wunguarded-availability -Wno-missing-field-initializers -Wno-unused-parameter -Wno-c++11-narrowing -Wno-covered-switch-default -Wno-unneeded-internal-declaration -Wno-inconsistent-missing-override -Wno-undefined-var-template -Wno-nonportable-include-path -Wno-address-of-packed-member -Wno-unused-lambda-capture -Wno-user-defined-warnings -Wno-enum-compare-switch -Wno-tautological-unsigned-zero-compare -Wno-null-pointer-arithmetic -Wno-tautological-constant-compare -Wtautological-constant-out-of-range-compare -O0 -fno-omit-frame-pointer -gdwarf-2 -isysroot ../../build/mac_files/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk -mmacosx-version-min=10.9.0 -fvisibility=hidden -Wheader-hygiene -Wstring-conversion -Wtautological-overlap-compare -Wno-undefined-bool-conversion -Wno-tautological-undefined-compare -std=c++14 -stdlib=libc++ -fno-exceptions -fno-rtti -fvisibility-inlines-hidden -c ../../chrome/browser/media/router/discovery/dial/safe_dial_device_description_parser.cc -o obj/chrome/browser/media/router/discovery/discovery/safe_dial_device_description_parser.o
In file included from ../../chrome/browser/media/router/discovery/dial/safe_dial_device_description_parser.cc:5:
In file included from ../../chrome/browser/media/router/discovery/dial/safe_dial_device_description_parser.h:15:
In file included from ../../base/values.h:36:
In file included from ../../base/containers/span.h:11:
../../third_party/llvm-build/Release+Asserts/include/c++/v1/array:130:51: error: multiple overloads of '__data' instantiate to the same signature 'const char *const *(const std::__1::__array_traits<const char *const, 4>::_StorageT &)' (aka 'const char *const *(const char *const const (&)[4])')
  static _LIBCPP_CONSTEXPR_AFTER_CXX14 _Tp const* __data(const _StorageT& __store) {
                                                  ^
../../third_party/llvm-build/Release+Asserts/include/c++/v1/array:187:14: note: in instantiation of template class 'std::__1::__array_traits<const char *const, 4>' requested here
    typename _Traits::_StorageT __elems_;
             ^
../../chrome/browser/media/router/discovery/dial/safe_dial_device_description_parser.cc:86:62: note: in instantiation of template class 'std::__1::array<const char *const, 4>' requested here
  static constexpr std::array<const char* const, kArraySize> kNodeNames{
                                                             ^
../../third_party/llvm-build/Release+Asserts/include/c++/v1/array:125:45: note: previous declaration is here
  static _LIBCPP_CONSTEXPR_AFTER_CXX14 _Tp* __data(_StorageT& __store) {
                                            ^


And then later, it became:

FAILED: obj/v8/test/cctest/cctest_sources/test-basic-block-profiler.o 
export DEVELOPER_DIR=/b/c/b/ToTMac__dbg_/src/build/mac_files/Xcode.app;  ../../third_party/llvm-build/Release+Asserts/bin/clang++ -MMD -MF obj/v8/test/cctest/cctest_sources/test-basic-block-profiler.o.d -DBUILDING_V8_SHARED -DV8_INTL_SUPPORT -DV8_DEPRECATION_WARNINGS -DNO_TCMALLOC -DFULL_SAFE_BROWSING -DSAFE_BROWSING_CSD -DSAFE_BROWSING_DB_LOCAL -DCHROMIUM_BUILD -DFIELDTRIAL_TESTING_ENABLED -DCR_XCODE_VERSION=0832 -DCR_CLANG_REVISION=\"324190\" -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -DCOMPONENT_BUILD -D__ASSERT_MACROS_DEFINE_VERSIONS_WITHOUT_UNDERSCORE=0 -D_DEBUG -DDYNAMIC_ANNOTATIONS_ENABLED=1 -DWTF_USE_DYNAMIC_ANNOTATIONS=1 -DUSING_V8_SHARED -DV8_ENABLE_CHECKS -DENABLE_DISASSEMBLER -DV8_TYPED_ARRAY_MAX_SIZE_IN_HEAP=64 -DOBJECT_PRINT -DVERIFY_HEAP -DV8_TRACE_MAPS -DV8_ENABLE_ALLOCATION_TIMEOUT -DV8_ENABLE_FORCE_SLOW_PATH -DV8_ENABLE_CHECKS -DV8_INTL_SUPPORT -DENABLE_HANDLE_ZAPPING -DV8_USE_SNAPSHOT -DV8_USE_EXTERNAL_STARTUP_DATA -DV8_CONCURRENT_MARKING -DV8_TARGET_ARCH_X64 -DDEBUG -DUSING_V8_BASE_SHARED -DUSING_V8_PLATFORM_SHARED -I../.. -Igen -I../../v8/include -Igen/v8/include -I../../v8 -I../../v8/include -fno-strict-aliasing -fstack-protector-strong -Wno-builtin-macro-redefined -D__DATE__= -D__TIME__= -D__TIMESTAMP__= -fcolor-diagnostics -Xclang -mllvm -Xclang -instcombine-lower-dbg-declare=0 -no-canonical-prefixes -arch x86_64 -Wall -Werror -Wextra -Wthread-safety -Wunguarded-availability -Wno-missing-field-initializers -Wno-unused-parameter -Wno-c++11-narrowing -Wno-covered-switch-default -Wno-unneeded-internal-declaration -Wno-inconsistent-missing-override -Wno-undefined-var-template -Wno-nonportable-include-path -Wno-address-of-packed-member -Wno-unused-lambda-capture -Wno-user-defined-warnings -Wno-enum-compare-switch -Wno-tautological-unsigned-zero-compare -Wno-null-pointer-arithmetic -Wno-tautological-constant-compare -Wtautological-constant-out-of-range-compare -fno-omit-frame-pointer -gdwarf-2 -isysroot ../../build/mac_files/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk -mmacosx-version-min=10.9.0 -fvisibility=hidden -Wheader-hygiene -Wstring-conversion -Wtautological-overlap-compare -Winconsistent-missing-override -Wno-implicit-fallthrough -Wunreachable-code -Wshorten-64-to-32 -O3 -Wno-undefined-bool-conversion -Wno-tautological-undefined-compare -std=c++14 -stdlib=libc++ -fno-exceptions -fno-rtti -fvisibility-inlines-hidden -c ../../v8/test/cctest/compiler/test-basic-block-profiler.cc -o obj/v8/test/cctest/cctest_sources/test-basic-block-profiler.o
In file included from ../../v8/test/cctest/compiler/test-basic-block-profiler.cc:5:
In file included from ../../v8/src/basic-block-profiler.h:13:
In file included from ../../v8/src/base/macros.h:12:
In file included from ../../v8/src/base/logging.h:15:
In file included from ../../v8/src/base/template-utils.h:8:
../../third_party/llvm-build/Release+Asserts/include/c++/v1/array:246:61: error: type 'typename _Traits::_StorageT' (aka 'std::__1::aligned_storage<2, 1>::type') does not provide a subscript operator
    reference operator[](size_type __n)             {return __elems_[__n];}
                                                            ^~~~~~~~ ~~~
../../v8/test/cctest/compiler/c-signature.h:58:34: note: in instantiation of member function 'std::__1::array<v8::internal::MachineType, 0>::operator[]' requested here
      CHECK_EQ(sig->GetParam(p), params[p]);
                                 ^
../../v8/test/cctest/compiler/call-tester.h:28:17: note: in instantiation of function template specialization 'v8::internal::compiler::CSignature::VerifyParams<>' requested here
    CSignature::VerifyParams<Params...>(csig_);
                ^
../../v8/test/cctest/compiler/codegen-tester.h:271:37: note: in instantiation of function template specialization 'v8::internal::compiler::CallHelper<int>::Call<>' requested here
    return static_cast<uint32_t>(T->Call());
                                    ^



There's a whole heap of changes that landed on Sunday, so I'm not sure what to revert.

Reverts are in r324309, but the bot doesn't seem to have cycled past that yet.

https://ci.chromium.org/buildbot/chromium.clang/ToTMac%20%28dbg%29/622 is green.