在我的项目中使用v8.dll时解析外部符号
我是新的C ++项目。我可能不确定C ++项目的先决条件知识。
[我的环境]
- Windows 10
- Python 2.7.18
- 开发人员命令提示vs 2022
- Visual Studio 2022 Community
我目前正在散布将V8 Engine作为DLL并使用它。
我已将V8引擎构建为DLL Successfly，但使用它，我将面临“解析外部符号”错误。
详细信息：
error LNK2019: unresolved external symbol "class std::unique_ptr<class v8::Platform,struct std::default_delete<class v8::Platform> > __cdecl v8::platform::NewDefaultPlatform(int,enum v8::platform::IdleTaskSupport,enum v8::platform::InProcessStackDumping,class std::unique_ptr<class v8::TracingController,struct std::default_delete<class v8::TracingController> >)" (?NewDefaultPlatform@platform@v8@@YA?AV?$unique_ptr@VPlatform@v8@@U?$default_delete@VPlatform@v8@@@std@@@std@@HW4IdleTaskSupport@12@W4InProcessStackDumping@12@V?$unique_ptr@VTracingController@v8@@U?$default_delete@VTracingController@v8@@@std@@@4@@Z) referenced in function "public: __cdecl ezv8::Platform::Impl::Impl(void)" (??0Impl@Platform@ezv8@@QEAA@XZ)
我已经研究了C ++杂交和曲折行为的一些事情。
我注意到v8_libplatform.dll.lib文件包含以下其他类型的操纵符号。
?NewDefaultPlatform@platform@v8@@YA?AV?$unique_ptr@VPlatform@v8@@U?$default_delete@VPlatform@v8@@@__1@std@@@__1@std@@HW4IdleTaskSupport@12@W4InProcessStackDumping@12@V?$unique_ptr@VTracingController@v8@@U?$default_delete@VTracingController@v8@@@__1@std@@@45@@Z = ?NewDefaultPlatform@platform@v8@@YA?AV?$unique_ptr@VPlatform@v8@@U?$default_delete@VPlatform@v8@@@__1@std@@@__1@std@@HW4IdleTaskSupport@12@W4InProcessStackDumping@12@V?$unique_ptr@VTracingController@v8@@U?$default_delete@VTracingController@v8@@@__1@std@@@45@@Z (class std::__1::unique_ptr<class v8::Platform,struct std::__1::default_delete<class v8::Platform> > __cdecl v8::platform::NewDefaultPlatform(int,enum v8::platform::IdleTaskSupport,enum v8::platform::InProcessStackDumping,class std::__1::unique_ptr<class v8::TracingController,struct std::__1::default_delete<class v8::TracingController> >))
如您所见，.lib文件包含__ 1名称空间的符号。
我发现了为什么文件包含的原因。捆绑的clang编译器编译std带有内联命名空间__ 1的名称空间，但是我不确定我如何在没有__ 1内联命名空间的情况下更改编译。
有人知道如何改变编译器的行为吗？
I'm new to making C++ project. I may be not sure prerequisite knowledge of C++ project.
[My environment]
- Windows 10
- Python 2.7.18
- Developer Command Prompt for VS 2022
- Visual Studio 2022 Community
I'm currently straggling with making V8 engine as a DLL and using it.
I've built V8 engine as a DLL successfly but using it I'm facing "Unresolve exteranl symbols" error.
Details:
error LNK2019: unresolved external symbol "class std::unique_ptr<class v8::Platform,struct std::default_delete<class v8::Platform> > __cdecl v8::platform::NewDefaultPlatform(int,enum v8::platform::IdleTaskSupport,enum v8::platform::InProcessStackDumping,class std::unique_ptr<class v8::TracingController,struct std::default_delete<class v8::TracingController> >)" (?NewDefaultPlatform@platform@v8@@YA?AV?$unique_ptr@VPlatform@v8@@U?$default_delete@VPlatform@v8@@@std@@@std@@HW4IdleTaskSupport@12@W4InProcessStackDumping@12@V?$unique_ptr@VTracingController@v8@@U?$default_delete@VTracingController@v8@@@std@@@4@@Z) referenced in function "public: __cdecl ezv8::Platform::Impl::Impl(void)" (??0Impl@Platform@ezv8@@QEAA@XZ)
I've researched some thing that C++ mangling and compailer behaviours are.
I've noticed that the v8_libplatform.dll.lib file contains other type of mangled symbols like below.
?NewDefaultPlatform@platform@v8@@YA?AV?$unique_ptr@VPlatform@v8@@U?$default_delete@VPlatform@v8@@@__1@std@@@__1@std@@HW4IdleTaskSupport@12@W4InProcessStackDumping@12@V?$unique_ptr@VTracingController@v8@@U?$default_delete@VTracingController@v8@@@__1@std@@@45@@Z = ?NewDefaultPlatform@platform@v8@@YA?AV?$unique_ptr@VPlatform@v8@@U?$default_delete@VPlatform@v8@@@__1@std@@@__1@std@@HW4IdleTaskSupport@12@W4InProcessStackDumping@12@V?$unique_ptr@VTracingController@v8@@U?$default_delete@VTracingController@v8@@@__1@std@@@45@@Z (class std::__1::unique_ptr<class v8::Platform,struct std::__1::default_delete<class v8::Platform> > __cdecl v8::platform::NewDefaultPlatform(int,enum v8::platform::IdleTaskSupport,enum v8::platform::InProcessStackDumping,class std::__1::unique_ptr<class v8::TracingController,struct std::__1::default_delete<class v8::TracingController> >))
As you can see, the .lib file contains the symbol with __1 namespace.
I found out why the file contains that. A bundled clang compiler compiles std namespace with inline namespace __1 but I'm not sure that how I can change compililng without __1 inline namespace.
Does anyone know how to change the compiler behaviour?
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我自己解决了这个问题。 （但是我还有其他构建中的其他错误。）
问题是我必须在
gn args中添加一个标志“ is_clang = false”到MSV。如果添加了标志，则V8工具将使用安装的CL.EXE编译这些代码。
I resolved this problem myself. (But I get still other erros in building.)
What the problem is that I have to add a flag "is_clang = false" to
gn argsbecause the clang that is bound v8 will compile other type of manglings to MSVS.If I added the flag then v8 tools will compile these code with cl.exe you installed.
我的链接问题与
v8 :: Platform :: NewDefaultPlatform（）函数以及其他一些其他方法（例如v8 :: context :: scope :: scope :: scope（），v8 :: context :: scope ::〜scope（）等。原因与名称杂交无关，它看起来像clang-cl（默认情况下在Windows Platform在V8/Chromium中使用）使用与CL相同的名称。所有这些方法均在标题文件中定义，因此它们实际上是嵌入式的，并且Clang-Cl使用/ZC：dllexportinlines-编译器选项，该选项不会从DLL中导出inlines（请参阅 https://reviews.llvm.org/d51340?id=172304？id = 172304很久以前提出了添加
/zc的请求：dllextortinlines选项已很久以前提出： https://develovelercommunity.visualstudio.com/t/implement-zcdllexportinlines-aka-fvisibility-inlin/374754 仍然不支持它。因此，我看不到在没有修改V8/Chromium标头文件的情况下使用Microsoft CL编译器的V8 DLL（这永远不好）。可以将V8构建为静态库，也可以将Clang-Cl用作自定义构建工具。
至于使用
is_clang = falsegn参数的构建v8，我想知道这是否可能是可能的。有许多编译器选项，例如-wno-unused-const-variable或-wno-unused功能，这些 不受cl的支持，但在GN构建文件中无条件添加。我记得几年前，可以使用CL建造铬，但这是吗？I had exactly the same linking issue with
v8::platform::NewDefaultPlatform()function, as well as some other methods likev8::Context::Scope::Scope(),v8::Context::Scope::~Scope()and so on. And the cause wasn't related with name mangling, it looks like clang-cl (used in v8/chromium by default on Windows platforms) uses the same name mangling as cl does. All these methods are defined in header files so they're effectively inlines, and clang-cl uses/Zc:DllexportInlines-compiler option which doesn't export inlines from DLLs (see https://reviews.llvm.org/D51340?id=172304 for details).A request for adding
/Zc:DllexportInlinesoption to cl compiler was raised a long time ago: https://developercommunity.visualstudio.com/t/implement-zcdllexportinlines-aka-fvisibility-inlin/374754 , but as of now, cl version 19.34.31937 still doesn't support it.So I can see no way using v8 DLLs with Microsoft's cl compiler without modifying v8/chromium header files (which is never good). One can build v8 as static libraries, or use clang-cl as a custom build tool.
As for building v8 without clang using
is_clang=falsegn argument, I wonder if it's actually possible. There are many compiler options like-Wno-unused-const-variableor-Wno-unused-functionwhich aren't supported by cl but added unconditionally in gn build files. I remember years ago it was possible to build chromium using cl, but is it now?