MSVC下CMake子模块无法解析项目依赖 提示无法打开include文件错误

核心问题点 #

• 子目录加载顺序错误：顶层CMake中先对主目标Neon链接solvers依赖，之后才执行add_subdirectory(solvers)加载子模块。CMake是顺序执行的，处理Neon的链接逻辑时solvers目标还未被定义，其自身的依赖传播规则完全不生效。
• 依赖传播修饰符缺失：solvers库的target_link_libraries没有指定PUBLIC修饰符，默认按PRIVATE处理。Eigen和IGL的头文件目录只会被添加到solvers的私有编译选项中，但你对外暴露的LinearElastic.h头文件内直接引用了Eigen类型，所有引用该头的目标（包括主程序）都需要能访问Eigen头目录，PRIVATE修饰符无法满足这个要求。
• 语法错误：顶层CMake的target_include_directories中${PROJECT_SOURCE_DIR}}/include多了一个多余的右大括号；solvers子目录CMake的最后一行export命令缺少右括号，会导致配置阶段直接报错。
• 未定义安装路径变量：solvers安装逻辑中使用的INSTALL_INCLUDE_DIR变量未提前定义，安装时会出现路径错误。

修复步骤 #

1. 修正顶层CMake顺序和语法 #

cmake_minimum_required(VERSION 3.19)
project(Neon LANGUAGES CXX)

set(CMAKE_CXX_STANDARD 17)
# 引入标准安装路径定义，子模块可复用
include(GNUInstallDirs)
set(INSTALL_INCLUDE_DIR ${CMAKE_INSTALL_INCLUDEDIR})

list(PREPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake)

option(LIBIGL_WITH_OPENGL "Use OpenGL" ON)
option(LIBIGL_WITH_OPENGL_GLFW "Use GLFW" ON)
option(LIBIGL_WITH_OPENGL_GLFW_IMGUI "Use ImGui" ON)
include(libigl)

find_package(Boost REQUIRED COMPONENTS unit_test_framework)

# 先加载子目录，再定义主目标
add_subdirectory(solvers)

add_executable(Neon src/main.cpp)

# 修正多余的右大括号
target_include_directories(${PROJECT_NAME} PUBLIC
        $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>
        $<INSTALL_INTERFACE:include>)

target_link_libraries(Neon PUBLIC Eigen3::Eigen igl::core igl::opengl_glfw solvers)

2. 修正solvers子目录CMake #

project(solvers)

add_library(${PROJECT_NAME} SHARED src/LinearElastic.cpp)

target_include_directories(${PROJECT_NAME}
        PUBLIC
        $<INSTALL_INTERFACE:include>
        $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
        PRIVATE
        ${CMAKE_CURRENT_SOURCE_DIR}/src)

install(TARGETS ${PROJECT_NAME} EXPORT ${PROJECT_NAME}Config
        ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
        LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
        RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})

# 添加PUBLIC修饰符，让Eigen/IGL的头目录可以传播到依赖solvers的目标
target_link_libraries(${PROJECT_NAME} PUBLIC igl::core Eigen3::Eigen)

install(DIRECTORY include/ DESTINATION "${INSTALL_INCLUDE_DIR}")
install(EXPORT ${PROJECT_NAME}Config DESTINATION share/${PROJECT_NAME}/cmake)
# 补全右括号
export(TARGETS ${PROJECT_NAME} FILE ${PROJECT_NAME}Config.cmake)

3. 清理缓存重新构建 #

删除原有构建目录和CMakeCache.txt，重新执行cmake配置和构建命令即可解决头文件找不到的问题。

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