传递编译器选项cmake

Question

我知道如何使用cmake命令传递编译器选项

set(CMAKE_CXX_FLAGS "-Wall -Wno-dev -Wl,-rpath=/home/abcd/libs/")

是否还有任何方法可以从命令行传递选项,这将覆盖CMakeList.txt选项,类似于 -

cmake -Wl,-rpath=/home/abcd/newlibs/ path/to/CMakeLists.txt

要么

cmake -D CMAKE_CXX_FLAGS="-Wno-dev -Wl,-rpath=/home/abcd/libs/" path/to/CMakeLists.txt

我的主要问题是我想知道如何追加标志以及如何从命令行覆盖现有的编译器标志.

Answer 1

是的,您可以附加编译器和链接器选项.但是你需要在CMake中区分两件事:第一次调用生成构建环境,以及在更改CMakeList.txt文件或依赖项后重新生成构建环境的所有连续调用.

以下是一些可能性(不包括更复杂的工具链变体):

附加编译器标志

1. 缓存CMAKE_CXX_FLAGS变量的初始内容是CMAKE_CXX_FLAGS_INIT在OS /工具链检测期间由CMake自身设置的组合以及CXXFLAGS环境变量中设置的任何组合.所以你最初可以打电话:

   cmake -E env CXXFLAGS="-Wall" cmake ..
   

2. 之后CMake会期望用户CMAKE_CXX_FLAGS直接修改缓存变量以附加内容,例如使用像ccmakeCMake 一样的编辑器.

3. 您可以轻松地介绍自己的构建类型ALL_WARNINGS.构建类型特定部分附加:

    cmake -DCMAKE_CXX_FLAGS_ALL_WARNINGS:STRING="-Wall" -DCMAKE_BUILD_TYPE=ALL_WARNINGS ..
   

附加链接器标志

链接器选项或多或少等同于编译器选项.只是CMake的变量名取决于目标类型(EXE,SHARED或MODULE).

1. 的CMAKE_EXE_LINKER_FLAGS_INIT,CMAKE_SHARED_LINKER_FLAGS_INIT或CMAKE_MODULE_LINKER_FLAGS_INIT不与环境现状变量结合LDFLAGS到CMAKE_EXE_LINKER_FLAGS,CMAKE_SHARED_LINKER_FLAGS和CMAKE_MODULE_LINKER_FLAGS.

   所以你可以打电话:

   cmake -E env LDFLAGS="-rpath=/home/abcd/libs/" cmake ..
   

2. 往上看.

3. 附加构建类型特定部分:

   cmake -DCMAKE_SHARED_LINKER_FLAGS_MY_RPATH:STRING="-rpath=/home/abcd/libs/" -DCMAKE_BUILD_TYPE=MY_RPATH ..
   

备择方案

请注意,CMake确实提供了特殊的变量来以独立于平台的方式设置编译器/链接器标志.因此,您无需了解特定的编译器/链接器选项.

这里有些例子:

• CMAKE_CXX_STANDARD
• CMAKE_POSITION_INDEPENDENT_CODE
• CMAKE_BUILD_RPATH
• CMAKE_INSTALL_RPATH_USE_LINK_PATH

遗憾的是编译器的警告级别没有(尚未)

参考

• 在CMake中更改CMAKE_CXX_FLAGS_DEBUG和朋友的默认值
• 如何在CMake中设置警告级别？

Answer 2

我的回答旨在证明一件事：

命令行选项像CMAKE_C_FLAGS并且CMAKE_CXX_FLAGS总是附加并且从不覆盖。

它来了。

准备文件夹下的文件 hello_world

你好ç

#include <stdio.h>


int main(int argc, char* argv[]) {
    printf("Hello World!\n");
#ifdef DEFINED_IN_CMAKELISTS
    printf("You are here because you defined DEFINED_IN_CMAKELISTS in CMakeLists and it is not overwritten.\n");
#else
    printf("You are here because CLI CMAKE_C_FLAGS overwrote DEFINED_IN_CMAKELISTS, or you have NOT defined DEFINED_IN_CMAKELISTS.\n");
#endif 
#ifdef DEFINED_IN_CLI
    printf("You are here because you defined DEFINED_IN_CLI when running cmake -DCMAKE_C_FLAGS.\n");
#else
    printf("You are here because you have NOT defined DEFINED_IN_CLI when running cmake -DCMAKE_C_FLAGS.\n");
#endif // #ifdef DEFINED_IN_CLI
    return 0;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.4.1 FATAL_ERROR)
project(Hello)

set(HELLO_SRCS Hello.c)

add_executable(Hello ${HELLO_SRCS})

set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DDEFINED_IN_CMAKELISTS")

生成 CMake 文件

cmake_minimum_required(VERSION 3.4.1 FATAL_ERROR)
project(Hello)

set(HELLO_SRCS Hello.c)

add_executable(Hello ${HELLO_SRCS})

set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DDEFINED_IN_CMAKELISTS")

制作并运行

$ mkdir _build && cd _build && cmake ..
-- The C compiler identification is AppleClang 11.0.3.11030032
-- The CXX compiler identification is AppleClang 11.0.3.11030032
-- Check for working C compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/cc
-- Check for working C compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++
-- Check for working CXX compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /Users/me/Desktop/_dev/playground/cmake/hello_world/_build

$ make
Scanning dependencies of target Hello
[ 50%] Building C object CMakeFiles/Hello.dir/Hello.c.o
[100%] Linking C executable Hello
[100%] Built target Hello

从命令行定义新的编译器选项

$ ./Hello
Hello World!
You are here because you defined DEFINED_IN_CMAKELISTS in CMakeLists and it is not overwritten.
You are here because you have NOT defined DEFINED_IN_CLI when running cmake -DCMAKE_C_FLAGS.

制作并运行

$ cmake -DCMAKE_C_FLAGS="-DDEFINED_IN_CLI" ..
-- Configuring done
-- Generating done
-- Build files have been written to: /Users/me/Desktop/_dev/playground/cmake/hello_world/_build

$ make
[ 50%] Building C object CMakeFiles/Hello.dir/Hello.c.o
[100%] Linking C executable Hello
[100%] Built target Hello

结论

从上面的测试中，您可以看到即使没有使用类似的硬附加

-DCMAKE_C_FLAGS="${CMAKE_C_FLAGS} -DDEFINED_IN_CLI"

，CMake 仍然将 CLI 选项附加到CMakeLists.txt.

Answer 3

cmake -D CMAKE_CXX_FLAGS="-Wno-dev -Wl,-rpath=/home/abcd/libs/" path/to/CMakeLists.txt

这应该可以工作，问题是，如果您find_package()还更改了的某些软件包CMAKE_CXX_FLAGS，那么它不仅会部分工作。

Answer 4

也许这会起作用 -

cmake -DCMAKE_CXX_FLAGS="$(CMAKE_CXX_FLAGS) -DYOUR_CUSTOM_DEFINE=1" <rest of original cmake cmdline>

就像上面提到的托马兹。-m