如何删除 CMake 中的特定系统包含目录

有没有办法告诉 CMake 排除某些系统包含路径？

例如，我定义了 string.h 两次，一次在 /usr/include/c++/v1 (libc++) 中，一次在 /usr/include/ 中，当我编译时出现以下错误：

error: functions that differ only in their return type cannot be overloaded

because char *strchr (const char *__s, int __c)每个文件中都可以找到函数。

我只想使用 libc++ 中的一个。

I tried set(CMAKE_IGNORE_PATH "/usr/include")但是当我在详细模式下使用 clang 进行编译时，我仍然看到搜索路径中使用了“/usr/include”。

Edit:

使用以下 CMakeLists.txt

project(my_lib)
set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -v")
set(SOURCES my_lib.cpp)
add_library(my_lib STATIC ${SOURCES})
set(CMAKE_DEBUG_TARGET_PROPERTIES INCLUDE_DIRECTORIES)

我有这个输出：

[ 50%] Building CXX object CMakeFiles/my_lib.dir/my_lib.cpp.o
clang version 4.0.1-6 (tags/RELEASE_401/final)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/7.2.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.2.0
Selected GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/7.2.0
Candidate multilib: .;@m64
Selected multilib: .;@m64
 "/usr/lib/llvm-4.0/bin/clang" -cc1 -triple x86_64-pc-linux-gnu -emit-obj -mrelax-all -disable-free -disable-llvm-verifier -discard-value-names -main-file-name my_lib.cpp -mrelocation-model static -mthread-model posix -mdisable-fp-elim -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -v -dwarf-column-info -debugger-tuning=gdb -coverage-notes-file /media/sf_wncd-app/wasm/cmake/build_linux/CMakeFiles/my_lib.dir/my_lib.cpp.gcno -resource-dir /usr/lib/llvm-4.0/bin/../lib/clang/4.0.1 -internal-isystem /usr/bin/../lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/c++/7.2.0 -internal-isystem /usr/bin/../lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/x86_64-linux-gnu/c++/7.2.0 -internal-isystem /usr/bin/../lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/x86_64-linux-gnu/c++/7.2.0 -internal-isystem /usr/bin/../lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/c++/7.2.0/backward -internal-isystem /usr/include/clang/4.0.1/include/ -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-4.0/bin/../lib/clang/4.0.1/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fdeprecated-macro -fdebug-compilation-dir /media/sf_wncd-app/wasm/cmake/build_linux -ferror-limit 19 -fmessage-length 228 -fobjc-runtime=gcc -fcxx-exceptions -fexceptions -fdiagnostics-show-option -fcolor-diagnostics -o CMakeFiles/my_lib.dir/my_lib.cpp.o -x c++ /media/sf_wncd-app/wasm/cmake/my_lib.cpp
clang -cc1 version 4.0.1 based upon LLVM 4.0.1 default target x86_64-pc-linux-gnu
ignoring nonexistent directory "/include"
ignoring duplicate directory "/usr/bin/../lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/x86_64-linux-gnu/c++/7.2.0"
ignoring duplicate directory "/usr/include/clang/4.0.1/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/bin/../lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/c++/7.2.0
 /usr/bin/../lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/x86_64-linux-gnu/c++/7.2.0
 /usr/bin/../lib/gcc/x86_64-linux-gnu/7.2.0/../../../../include/c++/7.2.0/backward
 /usr/include/clang/4.0.1/include
 /usr/local/include
 /usr/include/x86_64-linux-gnu
 /usr/include
End of search list.
[100%] Linking CXX static library libmy_lib.a
[100%] Built target my_lib

当我使用时：

project(my_lib)
set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -v")
set(SOURCES my_lib.cpp)
set(CMAKE_IGNORE_PATH "/usr/include")
add_library(my_lib STATIC ${SOURCES})
set(CMAKE_DEBUG_TARGET_PROPERTIES INCLUDE_DIRECTORIES)

我得到了完全相同的输出。/usr/include仍然在那里。我猜 CMAKE_IGNORE_PATH 不适用于系统路径？

如果我采取clang 使用了错误的系统包含目录 https://stackoverflow.com/questions/27319561/clang-is-using-the-wrong-system-include-directory，那么 CMake 的答案是使用CMAKE_<LANG>_COMPILER_EXTERNAL_TOOLCHAIN https://cmake.org/cmake/help/latest/variable/CMAKE_LANG_COMPILER_EXTERNAL_TOOLCHAIN.html指定自定义 GCC 工具链。

参考

• Clang Developers - 实现与 CMake 的便捷交叉编译 http://clang-developers.42468.n3.nabble.com/Towards-convenient-cross-compiling-with-CMake-td4036182.html