Cmake不尊重-D CMAKE_CXX_COMPILER = g ++ [英] Cmake doesn't honour -D CMAKE_CXX_COMPILER=g++

问题描述

我试图强制cmake用g ++来构建我的cpp代码，因为默认情况下它使用clang。所以我使用： cmake -D CMAKE_CXX_COMPILER = g ++ ../ src / CMakeLists.txt 之后，cmake检查gcc和g ++（成功），但仍然 make VERBOSE = 1 产生

I'm trying to force cmake to build my cpp code with g++, as by default it uses clang instead. So I use: cmake -D CMAKE_CXX_COMPILER=g++ ../src/CMakeLists.txt after which cmake checks for gcc and g++ (with success), but nonetheless make VERBOSE=1 yields

/usr/bin/c++     -o CMakeFiles/trial_cpp.dir/trial.cpp.o -c "/Users/Kuba/Code/Sketchpad/Trial     project/src/trial.cpp"
Linking CXX executable trial_cpp
/opt/etlocal/bin/cmake -E cmake_link_script CMakeFiles/trial_cpp.dir/link.txt --verbose=1
/usr/bin/c++    -Wl,-search_paths_first -Wl,-headerpad_max_install_names   CMakeFiles/trial_cpp.dir/trial.cpp.o  -o trial_cpp 

因为它调用/ usr / bin / c ++ not / usr / bin / g ++我同意它仍然使用铛。任何想法是什么问题？我知道我有g ++，它在/ usr / bin /。
我运行的Mac OS X 10.8.2

As it calls /usr/bin/c++ not /usr/bin/g++ I concur it still uses clang. Any idea what's the problem? I know I have g++ and it's in /usr/bin/. I'm running Mac OS X 10.8.2

推荐答案

CMAKE_CXX_COMPILER只能设置第一次cmake运行在给定的构建目录中。在后续运行中将被忽略。为了更改CMAKE_CXX_COMPILER，您首先需要删除构建目录的内容，然后再次使用该选项运行cmake。

CMAKE_CXX_COMPILER can only be set the first time cmake is run in a given build directory. On subsequent runs it is ignored. In order to change CMAKE_CXX_COMPILER you first need to delete the contents of the build directory and then run cmake again with that option.

源：http://www.cmake.org/Wiki/CMake_Useful_Variables

我相信只有推理在第一次运行时使用该变量是因为以后更改它可能会使已经创建的所有内容（包括配置检查）无效，因此cmake将不得不从头开始。

I believe the reasoning for only using that variable on the first run is because changing it later would potentially invalidate everything already built including the configuration checks so cmake would have to start from scratch anyway.

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