条件CXX_FLAGS使用cmake基于编译器？ [英] Conditional CXX_FLAGS using cmake based on compiler?

问题描述

我刚刚开始在一些个人和学校的项目中使用CMake，我已经被一个小问题所困扰。

I've just started using CMake for some personal and school projects, and I've been stumped by a minor issue.

我想试试获得在多个编译器（在这种情况下为g ++，cl和bcc32）下的C ++程序编译。我有不同的命令行开关为每个编译器，我正在尝试做的是基本上做一个gnu / ms / borland目录，并在那里创建CMake的东西（通过输入目录并做一个 cmake - DCMAKE_CXX_COMPILER = g ++
..在gnu目录中）。

Let's say I'm trying to get a C++ program compiling under multiple compilers (g++, cl, and bcc32 in this case). I have different command line switches for each compiler, and what I was attempting to do was to basically make a gnu/ms/borland directory and create CMake stuff in there (by entering the directories and doing a cmake -DCMAKE_CXX_COMPILER=g++ .. in the gnu, directory, for instance).

在顶层的CMakeLists.txt目录，我尝试按照以下行做一些事情：

In the CMakeLists.txt on the top level directory, I tried doing something along the lines of:

if(CMAKE_CXX_COMPILER STREQUAL g++)

  set(CMAKE_CXX_FLAGS "-Wextra -Wall -ansi -pedantic")

等都与elsifs为其他编译器，但是这似乎不能正确工作 - 它完全删除 CXXFLAGS 。如果我使文件完全无条件（即，只是假设g ++和使用g ++标志。）行。工作。

And so on with elsifs for the other compilers, but this doesn't seem to work correctly -- it drops the CXXFLAGS entirely. The line works if I make the file completely unconditional (ie, just assume g++ and use g++ flags.).

我在这里做错了，如何处理这种问题？

What am I doing wrong here, or is there a better way to handle this sort of a problem?

推荐答案

有一堆预定义的CMake变量，取决于您使用的编译器：

There are a bunch of pre-defined CMake variables depending on the compiler you're using:

if (MSVC)
  set ( CMAKE_CXX_FLAGS "/GLOBAL_FLAGS_GO_HERE")
  set ( CMAKE_CXX_FLAGS_DEBUG "/DEBUG_FLAGSS_GO_HERE")
  set ( CMAKE_CXX_FLAGS_RELEASE  "/RELEASE_FLAGS_GO_HERE" )
endif ()

if (BORLAND)
  set ( CMAKE_CXX_FLAGS "/GLOBAL_FLAGS_GO_HERE")
  set ( CMAKE_CXX_FLAGS_DEBUG "/DEBUG_FLAGS_GO_HERE")
  set ( CMAKE_CXX_FLAGS_RELEASE  "/RELEASE_FLAGS_GO_HERE" )
endif ()

if (CMAKE_COMPILER_IS_GNUCXX)
  set ( CMAKE_CXX_FLAGS "/GLOBAL_FLAGS_GO_HERE")
  set ( CMAKE_CXX_FLAGS_DEBUG "/DEBUG_FLAGS_GO_HERE")
  set ( CMAKE_CXX_FLAGS_RELEASE  "/RELEASE_FLAGS_GO_HERE" )
endif ()

如果你希望你的编译器选项覆盖在生成的CMakeCache坚持：

If you want your compiler options to override and persist in the generated CMakeCache:

if (CMAKE_COMPILER_IS_GNUCXX)

  set ( CMAKE_CXX_FLAGS "/GLOBAL_FLAGS_GO_HERE" 
        CACHE STRING "g++ Compiler Flags for All Builds" FORCE)

  set ( CMAKE_CXX_FLAGS_DEBUG "/DEBUG_FLAGS_GO_HERE"
        CACHE STRING "g++ Compiler Flags for Debug Builds" FORCE)

  set ( CMAKE_CXX_FLAGS_RELEASE  "/RELEASE_FLAGS_GO_HERE"
        CACHE STRING "g++ Compiler Flags for Release Builds" FORCE)

endif ()

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