如何限制CMake组件的依赖传递（单项目多Target场景）

我正在优化一个以Conan作为依赖管理工具的CMake项目，原项目是可执行文件myExecutable，依赖多个Conan库。为了共享部分头文件与依赖，我拆分出两个新Target：静态库myLib和仅头文件组件iface，myExecutable依赖这两个Target。

我希望其他项目链接myproject::myLib时，不会自动引入绑定在iface的INTERFACE作用域下的Boost、OpenSSL、MyOtherLib等依赖，但目前CMake与Conan未区分这种依赖关系。

我已尝试通过CMake的install指令解决头文件安装问题，也在Conan的package_info中配置组件信息，设置myLib的requires为空，但均无效果——链接myproject::myLib仍会引入所有依赖。

当前环境：GCC 14.2、CMake 3.26、Conan 1.65.0。请问是否可在单个CMake项目与Conan文件中实现这种依赖传递隔离，无需将Target拆分为独立项目？

现有代码片段 #

CMakeLists.txt #

project(myProject)

// ...

// 查找Conan安装的依赖
find_package(Boost CONFIG REQUIRED)
find_package(OpenSSL CONFIG REQUIRED)
find_package(MyOtherLib CONFIG REQUIRED)

// 主可执行文件Target
add_executable(myExecutable
  one.cpp
  two.cpp
)

// 新静态库Target
add_library(myLib STATIC)
target_sources(myLib
  PRIVATE
    lib/myLib/threeLib.cpp
  PUBLIC
    FILE_SET libHeaders
    TYPE HEADERS
    BASE_DIRS lib/myLib/include
    FILES
      lib/myLib/threeLib.h
)
target_link_libraries(myLib PRIVATE boost::boost)

// 新仅头文件组件Target
add_library(iface INTERFACE)
target_sources(iface
  INTERFACE
    FILE_SET ifaceHeaders
    TYPE HEADERS
    BASE_DIRS include
    FILES
      include/fourHeader.h
      include/fiveHeader.h
)
target_link_libraries(iface
  INTERFACE
    boost::boost
    openssl::openssl
    myotherlib::myotherlib
)

// 可执行文件依赖这两个库/组件
target_link_libraries(myExecutable 
  PRIVATE 
    iface
    myLib
)
// ...

conanfile.py #

# 相关导入
class myProject(ConanFile):
    # 相关属性与设置
    # 版本号可能随机
    generators = "CMakeDeps", "CMakeToolchain"
    requires = "boost/1.80.0", "openssl/3.3.5", "myotherlib/1.0@myremote/testing"
    
    def layout(self):
        cmake_layout(self)

    def generate(self):
        toolchain = CMakeToolchain(self)
        toolchain.generate()
        deps = CMakeDeps(self)
        deps.generate()

    def build(self):
        cmake = CMake(self)
        cmake.configure()
        cmake.build()

已尝试的CMake install配置 #

install(
  TARGETS iface
  EXPORT ifaceTargets
  FILE_SET ifaceHeaders
  DESTINATION include)

install(
  EXPORT ifaceTargets
  FILE ifaceTargets.cmake
  NAMESPACE myproject::
  DESTINATION lib/cmake/iface)

install(
  TARGETS myLib
  EXPORT myLibTargets
  FILE_SET myLibHeaders
  DESTINATION myLib_include
  ARCHIVE_DESTINATION lib)

install(
  EXPORT myLibTargets
  FILE myLibTargets.cmake
  NAMESPACE myproject::
  DESTINATION lib/cmake/mylib)

已尝试的Conan package_info配置 #

def package(self):
    cmake = CMake(self)
    cmake.install()

def package_info(self):
    self.cpp_info.components["myLib"].libs = ["myLib"]
    self.cpp_info.components["myLib"].set_property("cmake_target_name", "myproject::myLib")
    self.cpp_info.components["myLib"].includedirs = ["myLib_include"]
    self.cpp_info.components["myLib"].requires = []

    self.cpp_info.components["iface"].set_property("cmake_target_name", "myproject::iface")
    self.cpp_info.components["iface"].includedirs = ["include"]
    self.cpp_info.components["iface"].requires = ["boost::boost", "openssl::openssl", "myotherlib::myotherlib"]    

完全可以在单个项目内实现这种依赖隔离，核心是确保CMake导出的Target和Conan的组件配置完全解耦，避免意外的依赖传递。以下是关键调整点：

1. CMake层面：阻断myLib与iface的间接依赖 #

检查myLib的配置，确保：

• myLib的公开头文件（如threeLib.h）没有包含iface下的头文件
• 没有误写target_link_libraries(myLib PUBLIC iface)这类代码，确保myLib的PUBLIC/INTERFACE属性完全不涉及iface

当前myLib仅PRIVATE依赖Boost的配置是正确的，这部分依赖不会传递给链接myLib的其他项目。

2. 修复CMake导出配置的语法错误 #

你提供的install(EXPORT myLibTargets)代码曾漏写DESTINATION关键字，会导致导出文件路径错误，其他项目无法正确识别myproject::myLib的独立配置，修正后如下：

install(
  EXPORT myLibTargets
  FILE myLibTargets.cmake
  NAMESPACE myproject::
  DESTINATION lib/cmake/mylib)

3. Conan层面：清空全局依赖，明确组件边界 #

Conan的全局cpp_info会被所有组件继承，需要先清空全局配置，再分别定义组件的依赖：

def package_info(self):
    # 清空全局cpp_info，避免组件继承不必要的依赖
    self.cpp_info.clear()

    # 配置myLib组件，明确无依赖
    mylib_comp = self.cpp_info.components["myLib"]
    mylib_comp.libs = ["myLib"]
    mylib_comp.set_property("cmake_target_name", "myproject::myLib")
    mylib_comp.includedirs = ["myLib_include"]
    mylib_comp.requires = []

    # 配置iface组件，绑定Boost等依赖
    iface_comp = self.cpp_info.components["iface"]
    iface_comp.set_property("cmake_target_name", "myproject::iface")
    iface_comp.includedirs = ["include"]
    iface_comp.requires = ["boost::boost", "openssl::openssl", "myotherlib::myotherlib"]

4. 验证依赖传递逻辑 #

其他项目使用时，需明确指定依赖的组件：

• 仅需myLib：在conanfile.py中声明依赖后，CMake中用find_package(myProject REQUIRED COMPONENTS myLib)，再链接myproject::myLib，此时不会引入Boost等依赖
• 需要iface：指定COMPONENTS iface，此时才会自动引入对应的依赖链

额外验证技巧 #

用cmake --graphviz=dep.dot ..生成项目依赖图，直观检查myproject::myLib的依赖链是否仅包含自身，无额外依赖。

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