Windows下add_custom_target编译报错：无法找到指定路径

问题 #

将应用从Linux移植到Windows时遇到编译错误，通过CMake构建mupdf Git子模块（该子模块用Makefile构建），CMake代码如下：

# Configure variables for building mupdf
elseif(WIN32)
    set(MUPDF_OUTPUT "${PROJECT_SOURCE_DIR}/libs/mupdf/platform/win32/x64/Release/mupdfcpp64.lib" PARENT_SCOPE)
    set(MUPDF_OUTPUT "${PROJECT_SOURCE_DIR}/libs/mupdf/platform/win32/x64/Release/mupdfcpp64.lib")
    set(MUPDF_BUILD_COMMAND "python scripts/mupdfwrap.py --venv -b -j 0 m01")
endif()


add_custom_command(
    OUTPUT ${MUPDF_OUTPUT}
    WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}/libs/mupdf
    COMMAND ${MUPDF_BUILD_COMMAND}
    COMMENT "Building mupdf (This takes a while) ..."
    BYPRODUCTS ${MUPDF_OUTPUT}
)

add_custom_target(mupdf ALL
   DEPENDS ${MUPDF_OUTPUT}
)



# Build
add_library(application
                SHARED
                    ${application_SRC}
)

# Make sure to build mupdf before the application
add_dependencies(application mupdf)

构建时输出错误：

-- Configuring done (0.7s)
-- Generating done (0.5s)
-- Build files have been written to: C:/Users/prtnp/Librum/build
Change Dir: 'C:/Users/prtnp/Librum/build'

Run Build Command(s): "C:/Program Files (x86)/Microsoft Visual Studio/2019/Community/MSBuild/Current/Bin/MSBuild.exe" ALL_BUILD.vcxproj /p:Configuration=Debug /p:Platform=x64 /p:VisualStudioVersion=16.0 /v:n
Microsoft (R) Build Engine, version 16.11.2+f32259642 for .NET Framework
Copyright (C) Microsoft Corporation. All rights reserved.

The build started on 07/22/2023 at 16:08:38.
Project "C:\Users\prtnp\Librum\build\ALL_BUILD.vcxproj" on node "1" (default targets).
The project "C:\Users\prtnp\Librum\build\ALL_BUILD.vcxproj" (1) is building "C:\Users\prtnp\Librum\build\ZERO_CHECK.vcxproj" (2) on node "1" (default targets).
InitializeBuildStatus:
  Creating "x64\Debug\ZERO_CHECK\ZERO_CHECK.tlog\unsuccessfulbuild" because "AlwaysCreate" was specified.
CustomBuild:
  All outputs are up-to-date.
  1>Checking Build System
FinalizeBuildStatus:
  Deleting file "x64\Debug\ZERO_CHECK\ZERO_CHECK.tlog\unsuccessfulbuild".
  Touching "x64\Debug\ZERO_CHECK\ZERO_CHECK.tlog\ZERO_CHECK.lastbuildstate".
The project "C:\Users\prtnp\Librum\build\ZERO_CHECK.vcxproj" is complete (default targets).

The project "C:\Users\prtnp\Librum\build\ALL_BUILD.vcxproj" (1) is building "C:\Users\prtnp\Librum\build\src\application\mupdf.vcxproj" (3) on node "1" (default targets).
InitializeBuildStatus:
  Touching "x64\Debug\mupdf\mupdf.tlog\unsuccessfulbuild".
CustomBuild:
  "Building mupdf (This takes a while) ..."
  The system cannot find the path specified.
C:\Program Files (x86)\Microsoft Visual Studio\2019/Community/MSBuild/Microsoft/VC/v160/Microsoft.CppCommon.targets(241,5): error MSB8066: The custom build for "C:\Users\prtnp\Librum\build\CMakeFiles\8e03d71809f012c9d6e5459fc00784b2\mupdfcpp64.lib.rule;C:\Users\prtnp\Librum\build\CMakeFiles\5736ecdae8f9a33915df7c26a6ac3c00\mupdf.rule" exited with code 3. [C:\Users\prtnp\Librum\build\src\application\mupdf.vcxproj]
The project "C:\Users\prtnp\Librum\build\src\application\mupdf.vcxproj" is complete (default targets) -- ERROR.

The project "C:\Users\prtnp\Librum\build\ALL_BUILD.vcxproj" is complete (default targets) -- ERROR.

Build failed.

"C:\Users\prtnp\Librum\build\ALL_BUILD.vcxproj" (default target) (1) ->
"C:\Users\prtnp\Librum\build\src\application\mupdf.vcxproj" (default target) (3) ->
(CustomBuild target) ->
  C:\Program Files (x86)\Microsoft Visual Studio\2019/Community/MSBuild/Microsoft/VC/v160/Microsoft.CppCommon.targets(241,5): error MSB8066: The custom build for "C:\Users\prtnp\Librum\build\CMakeFiles\8e03d71809f012c9d6e5459fc00784b2\mupdfcpp64.lib.rule;C:\Users\prtnp\Librum\build\CMakeFiles\5736ecdae8f9a33915df7c26a6ac3c00\mupdf.rule" exited with code 3. [C:\Users\prtnp\Librum\build\src\application\mupdf.vcxproj]

    0 Warning(s)
    1 Error(s)

Time Elapsed 00:00:01.28

手动在指定工作目录执行${MUPDF_BUILD_COMMAND}可正常运行，CMake命令为：

cmake -G "Visual Studio 16 2019" -DCMAKE_BUILD_TYPE=Debug -DCMAKE_PREFIX_PATH=C:\\Qt\\6.5.2\\msvc2019_64 ..

可能的原因及解决办法 #

• 命令参数解析问题：Windows下CMake如果用字符串包裹整个命令，可能无法正确拆分参数。将MUPDF_BUILD_COMMAND改为列表形式，去掉外层引号：

  set(MUPDF_BUILD_COMMAND python scripts/mupdfwrap.py --venv -b -j 0 m01)
  

  让CMake自动处理参数拆分，避免空格或特殊字符导致的路径识别错误。

• Python路径环境问题：手动执行时环境变量能找到Python，但MSBuild运行时可能未加载完整用户环境。指定Python绝对路径：

  set(MUPDF_BUILD_COMMAND "C:/Python39/python.exe" scripts/mupdfwrap.py --venv -b -j 0 m01)
  

  替换为你实际的Python安装路径。

• 构建配置不匹配：当前CMake指定Debug配置，但MUPDF_OUTPUT指向Release目录，导致MSBuild构建时路径不匹配。根据CMAKE_BUILD_TYPE动态设置输出路径：

  if(CMAKE_BUILD_TYPE STREQUAL "Debug")
      set(MUPDF_OUTPUT "${PROJECT_SOURCE_DIR}/libs/mupdf/platform/win32/x64/Debug/mupdfcpp64.lib")
  else()
      set(MUPDF_OUTPUT "${PROJECT_SOURCE_DIR}/libs/mupdf/platform/win32/x64/Release/mupdfcpp64.lib")
  endif()
  set(MUPDF_OUTPUT "${PROJECT_SOURCE_DIR}/libs/mupdf/platform/win32/x64/${CMAKE_BUILD_TYPE}/mupdfcpp64.lib" PARENT_SCOPE)
  

• 工作目录验证：添加日志确认工作目录是否正确：

  message(STATUS "MUPDF working directory: ${PROJECT_SOURCE_DIR}/libs/mupdf")
  

  检查CMake配置阶段输出的路径是否存在。

内容的提问来源于stack exchange，提问作者Creapermann