Compiling with libc++

[Alberto Gonzalez]

Hello,

I have been trying to compile the v8 with libc++ but I have not been successful. I'm currently working with the latest verison of Xcode and my project is using some c++11 stuff. I have tried using the following:

export CXX="`which clang++` -std=c++11 -stdlib=libc++"
export LINK="`which clang++` -std=c++11 -stdlib=libc++"
export GYP_DEFINES="clang=1 mac_deployment_target=10.9"
make native

But when I try to use the library files are generated with my xcode project I'm getting linking errors such as:

Undefined symbols for architecture x86_64:
  "std::string::end() const", referenced from:
      v8::internal::compiler::operator<<(std::ostream&, v8::internal::compiler::Escaped const&) in libv8_base.a(graph-visualizer.o)
  "std::string::begin() const", referenced from:
      v8::internal::compiler::operator<<(std::ostream&, v8::internal::compiler::Escaped const&) in libv8_base.a(graph-visualizer.o)
  "std::string::c_str() const", referenced from:
      v8::internal::Object::ShortPrint(v8::internal::StringStream*) in libv8_base.a(objects.o)
      v8::internal::FlagList::argv() in libv8_base.a(flags.o)
      v8::internal::Logger::SharedLibraryEvent(std::string const&, unsigned long, unsigned long) in libv8_base.a(log.o)
      v8::internal::Logger::SetUp(v8::internal::Isolate*) in libv8_base.a(log.o)
      v8::internal::JavaScriptFrame::Print(v8::internal::StringStream*, v8::internal::StackFrame::PrintMode, int) const in libv8_base.a(frames.o)

Am I doing something wrong? or is there a different way to have the v8 project build on libc++?

Best Regards

Alberto Gonzalez Pacheco

[Ben Noordhuis]

It looks like it's not actually linking against libc++. Can you run
`make native V=1` and post the output of the link phase?

[Alberto Gonzalez]

I'm attaching the output of the build. I did notice something:


/usr/bin/clang++ -std=gnu++11 -stdlib=libc++ '-DU_USING_ICU_NAMESPACE=0' '-DHAVE_DLOPEN=0' '-DU_STATIC_IMPLEMENTATION' '-DV8_TARGET_ARCH_X64' '-DU_I18N_IMPLEMENTATION' '-DU_ENABLE_DYLOAD=0' -I../third_party/icu/source/common -I../third_party/icu/source/i18n  -O3 -gdwarf-2 -fstrict-aliasing -fvisibility=hidden -mmacosx-version-min=10.9 -arch x86_64 -Wall -Wendif-labels -W -Wno-unused-parameter -Wno-missing-field-initializers -Wno-deprecated-declarations -Wno-logical-op-parentheses -Wno-tautological-compare -Wno-return-type-c-linkage -std=gnu++0x -fno-exceptions -fvisibility-inlines-hidden -fno-threadsafe-statics -fno-strict-aliasing -MMD -MF /Users/kunashu/Development/libs/v8/out/native/.deps//Users/kunashu/Development/libs/v8/out/native/obj.target/icui18n/third_party/icu/source/i18n/numfmt.o.d.raw  -c -o /Users/kunashu/Development/libs/v8/out/native/obj.target/icui18n/third_party/icu/source/i18n/numfmt.o ../third_party/icu/source/i18n/numfmt.cpp

It looks like even do I specify -std=gnu++11 inside it also specifies another -std=gnu++0x

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Saludos,

Alberto Gonzalez

[Alberto Gonzalez]

So I think I found the solution. Since I'm using Xcode this works for me but I think there might be an alternative solution for command line. Here it is...

In the previous post, I mentioned that I noticed -std=gnu++0x when using V=1 while executing the make native command. (As suggested by Ben) I began to search for gnu++0x in all the files in the project. Within my search I found several files on the out folder with the following pattern  "*.native.mk". I changed them and than ran the build native, and I noticed they would be replaced by gnu++0x. So this was not working.

I then checked other files and noticed there was one in particular in the build folder "build/standalone.gypi". While going through the file I noticed there was a section called 'clang==1'. It was the same parameter I was setting GYP_DEFINES!! Inside there was CLANG_CXX_LANGUAGE_STANDARD which was set to gnu++0x. I changed the value to gnu++11. I also added a new parameter called CLANG_CXX_LIBRARY and set it with the value libc++.

When I ran the make native I noticed the flags -std=gnu++11 and -stdlib=libc++ which was nice. But this alone did not help with the make native to work. I went ahead and also ran

build/gyp_v8 -Dtarget_arch=x64

This actually changed the tools/gyp/v8.xcodeproj/project.pbxproj file to use those configs when adding the v8 project to my solution. When I hit build, I stopped getting the linking errors!!!! :D

Now, while searching other errors I was getting while running the sample code I found this:
https://code.google.com/p/v8/issues/detail?id=3627

Here I noticed that the poster was actually using

/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++

instead of using the 'which clang++' command which outputs /usr/bin/clang++.

It makes sense because you could say that these are two different compilers. I think that instead if I use:

export CXX="/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -std=c++11 -stdlib=libc++"
export LINK="`/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -std=c++11 -stdlib=libc++"

export GYP_DEFINES="clang=1 mac_deployment_target=10.9"
make native

I should not be getting the LINK errors!!!

So to summarize:

If you want the v8 xcode project to work:

• Change the value CLANG_CXX_LANGUAGE_STANDARD to gnu++11 in the build/standalone.gypi. (Or to the dialect used by your xcode project found in the Build Settings)
• Add CLANG_CXX_LIBRARY with value libc++ right under CLANG_CXX_LANGUAGE_STANDARD.
• Remember to modify it where it says 'clang==1'
• Then run build/gyp_v8 -Dtarget_arch=x64 (Or to the target arch of your preference)

If you want to build using the terminal using make:

• export the following variables and run make native:

export CXX="/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -std=c++11 -stdlib=libc++"
export LINK="`/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -std=c++11 -stdlib=libc++"

export GYP_DEFINES="clang=1 mac_deployment_target=10.9"
make native

• Note I haven't tested this method, but if I get a chance I will, or if someone could do this that would be great.

Well I hope this helps anyone in the future and have them compiling like a happy programmer! I know this will help my future self, since I tend to forget about these things :P

--
Saludos,

Alberto Gonzalez

[Sebastian Herrlinger]

Building on command line works fine for me on osx 10.9 with the following exports:

export CXX="/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -std=c++11 -stdlib=libc++"

export CC=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang

export CPP="/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -E"

export LINK="/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -std=c++11 -stdlib=libc++"

export CXX_host=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++

export CC_host=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang

export CPP_host="/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -E"

export LINK_host=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++

export GYP_DEFINES="clang=1 mac_deployment_target=10.8"

(Eventually adjust the path to your clang++ adn deployment target)