使用 Ninja 使用 CMake 构建的 Unicode MFC 应用程序中未解决的 WinMain 错误

Question

这是一个显示此问题的最小项目。它由两个文件组成：CMakeLists.txt 和 hellomfc.cpp。

CMakeLists.txt

cmake_minimum_required(VERSION 3.18)
project(HelloMFC)
set(CMAKE_MFC_FLAG 2)
add_executable(HelloMFC WIN32 hellomfc.cpp)
target_compile_definitions(HelloMFC PRIVATE _AFXDLL _UNICODE UNICODE)

hellomfc.cpp

#include <afxwin.h>

class CMainFrame : public CFrameWnd {
public:
  CMainFrame() { Create(NULL, _T("Windows App")); }
};
class CApp : public CWinApp {
  CMainFrame *Frame;
  BOOL InitInstance() {
    Frame = new CMainFrame();
    m_pMainWnd = Frame;

    Frame->ShowWindow(SW_SHOW);
    Frame->UpdateWindow();

    return TRUE;
  }
};

CApp theApp;

对于此示例，我从 Visual Studio 2019 的开发人员命令提示符运行 CMake。

使用 Visual Studio 2019 生成器构建它没有问题：

C:\Users\rdeterre\Documents\hello-mfc\build-vs>cmake ..
-- Building for: Visual Studio 16 2019
-- The C compiler identification is MSVC 19.27.29111.0
-- The CXX compiler identification is MSVC 19.27.29111.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: C:/Program Files (x86)/Microsoft Visual Studio/2019/Professional/VC/Tools/MSVC/14.27.29110/bin/Hostx64/x64/cl.exe - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: C:/Program Files (x86)/Microsoft Visual Studio/2019/Professional/VC/Tools/MSVC/14.27.29110/bin/Hostx64/x64/cl.exe - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: C:/Users/rdeterre/Documents/hello-mfc/build-vs

C:\Users\rdeterre\Documents\hello-mfc\build-vs>cmake --build .
Microsoft (R) Build Engine version 16.7.0+b89cb5fde for .NET Framework
Copyright (C) Microsoft Corporation. All rights reserved.

  Checking Build System
  Building Custom Rule C:/Users/rdeterre/Documents/hello-mfc/CMakeLists.txt
  hellomfc.cpp
  _WIN32_WINNT not defined. Defaulting to _WIN32_WINNT_MAXVER (see WinSDKVer.h)
  HelloMFC.vcxproj -> C:\Users\rdeterre\Documents\hello-mfc\build-vs\Debug\HelloMFC.exe
  Building Custom Rule C:/Users/rdeterre/Documents/hello-mfc/CMakeLists.txt

但使用 ninja 生成器失败并出现“未解析符号 _WinMain@16”错误：

C:\Users\rdeterre\Documents\hello-mfc\build-ninja>cmake .. -GNinja
-- The C compiler identification is MSVC 19.27.29111.0
-- The CXX compiler identification is MSVC 19.27.29111.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: C:/Program Files (x86)/Microsoft Visual Studio/2019/Professional/VC/Tools/MSVC/14.27.29110/bin/Hostx86/x86/cl.exe - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: C:/Program Files (x86)/Microsoft Visual Studio/2019/Professional/VC/Tools/MSVC/14.27.29110/bin/Hostx86/x86/cl.exe - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: C:/Users/rdeterre/Documents/hello-mfc/build-ninja

C:\Users\rdeterre\Documents\hello-mfc\build-ninja>cmake --build .
[1/2] Building CXX object CMakeFiles\HelloMFC.dir\hellomfc.cpp.obj
_WIN32_WINNT not defined. Defaulting to _WIN32_WINNT_MAXVER (see WinSDKVer.h)
[2/2] Linking CXX executable HelloMFC.exe
FAILED: HelloMFC.exe
cmd.exe /C "cd . && C:\Users\rdeterre\scoop\apps\cmake\3.18.1\bin\cmake.exe -E vs_link_exe --intdir=CMakeFiles\HelloMFC.dir --rc=C:\PROGRA~2\WI3CF2~1\10\bin\100190~1.0\x86\rc.exe --mt=C:\PROGRA~2\WI3CF2~1\10\bin\100190~1.0\x86\mt.exe --manifests  -- C:\PROGRA~2\MICROS~1\2019\PROFES~1\VC\Tools\MSVC\1427~1.291\bin\Hostx86\x86\link.exe /nologo CMakeFiles\HelloMFC.dir\hellomfc.cpp.obj  /out:HelloMFC.exe /implib:HelloMFC.lib /pdb:HelloMFC.pdb /version:0.0 /machine:X86 /debug /INCREMENTAL /subsystem:windows  kernel32.lib user32.lib gdi32.lib winspool.lib shell32.lib ole32.lib oleaut32.lib uuid.lib comdlg32.lib advapi32.lib && cd ."
LINK Pass 1: command "C:\PROGRA~2\MICROS~1\2019\PROFES~1\VC\Tools\MSVC\1427~1.291\bin\Hostx86\x86\link.exe /nologo CMakeFiles\HelloMFC.dir\hellomfc.cpp.obj /out:HelloMFC.exe /implib:HelloMFC.lib /pdb:HelloMFC.pdb /version:0.0 /machine:X86 /debug /INCREMENTAL /subsystem:windows kernel32.lib user32.lib gdi32.lib winspool.lib shell32.lib ole32.lib oleaut32.lib uuid.lib comdlg32.lib advapi32.lib /MANIFEST /MANIFESTFILE:CMakeFiles\HelloMFC.dir/intermediate.manifest CMakeFiles\HelloMFC.dir/manifest.res" failed (exit code 1120) with the following output:
msvcrtd.lib(exe_winmain.obj) : error LNK2019: unresolved external symbol _WinMain@16 referenced in function "int __cdecl invoke_main(void)" (?invoke_main@@YAHXZ)
HelloMFC.exe : fatal error LNK1120: 1 unresolved externals
ninja: build stopped: subcommand failed.

请注意，在取出 _UNICODE UNICODE 编译定义时，构建对两个生成器都有效。但是，此特定项目需要 unicode 构建。

Answer 1

可能是CMake的一个bug，但是你可以显式指定应用入口点：

# CMakeLists.txt

...

target_link_options(${PROJECT_NAME} PRIVATE "/entry:wWinMainCRTStartup")

所以，它应该可以解决您的错误。