告诉 CMake 对来自 CMake 的 C 文件使用 C++ 编译器? [英] Tell CMake to use C++ compiler for C files coming from CMake?
问题描述
这类似于强制 CMake 对带有 Visual Studio 的 C 文件使用 C++ 编译器，但并不完全相同.它不一样，因为它的 CMake 文件导致失败；我在几乎所有现代平台上工作，从 BSD 和 OS X 到 Solaris 和 Unix.
This is similar to Force CMake to use C++ compiler for C files with Visual Studio, but its not quite the same. Its not the same because a its CMake file causing the failure; and I'm working on nearly every modern platform, from BSDs and OS X through Solaris and Unix.
我试图避免 CMake 执行无用的检查:
I tried to avoid useless checks being performed by CMake:
project(cryptopp, CXX)
以下是我尝试生成 makefile 时发生的情况:
Here's what happens when I attempt to generate the makefile:
$ cmake .
-- Check if the system is big endian
-- Searching 16 bit integer
-- Check size of unsigned short
CMake Error at /usr/share/cmake-2.8/Modules/CheckTypeSize.cmake:82 (try_compile):
Unknown extension ".c" for file
/home/jeffrey/cryptopp/CMakeFiles/CheckTypeSize/CMAKE_SIZEOF_UNSIGNED_SHORT.c
try_compile() works only for enabled languages. Currently these are:
CXX
See project() command to enable other languages.
Call Stack (most recent call first):
/usr/share/cmake-2.8/Modules/CheckTypeSize.cmake:167 (__check_type_size_impl)
/usr/share/cmake-2.8/Modules/TestBigEndian.cmake:27 (CHECK_TYPE_SIZE)
CMakeLists.txt:49 (TEST_BIG_ENDIAN)
我们的项目中没有任何 C 文件，因此使用 project(cryptopp, CXX) 应该是安全的(如果我正在阅读 cmake --help-command project 正确).
We don't have any C files in our project, so we should be safe with project(cryptopp, CXX) (if I am reading cmake --help-command project correctly).
引用的问题涉及项目文件，但不涉及 CMake 文件.
The cited question talks about project files, but not CMake files.
如何告诉 CMake 对所有文件使用 C++ 编译器，包括它自己的 CMake 文件?
How do I tell CMake to use C++ compiler for all files, including its own CMake files?
我使用的是 Ubuntu 12 LTS，它提供:
I'm on Ubuntu 12 LTS, and it provides:
$ cmake --version
cmake version 2.8.7
推荐答案
有多种方法可以将 .c 添加为 CXX 编译器的有效文件扩展名.即使这是非常高级的 CMake 东西，您也可能需要 - 如果您必须支持旧版本的 CMake - 无论如何都需要制作规则覆盖脚本".
There are ways to add .c as a valid file extension for the CXX compiler. Even this being very advanced CMake stuff, you may need - if you are bound to support older versions of CMake - a "make rules overwrite script" anyway.
所以我已经成功测试了以下内容:
So I've successfully tested the following:
CryptoppMakeRulesOverwrite.cmake
list(APPEND CMAKE_CXX_SOURCE_FILE_EXTENSIONS c)
CMakeLists.txt
cmake_minimum_required(VERSION 2.8.7 FATAL_ERROR)
set(CMAKE_USER_MAKE_RULES_OVERRIDE "CryptoppMakeRulesOverwrite.cmake")
project(cryptopp CXX)
include(CheckTypeSize)
CHECK_TYPE_SIZE("unsigned short" CMAKE_SIZEOF_UNSIGNED_SHORT)
正如@Tsyvarev 所评论的check_type_size() 支持 LANGUAGE 参数，但遗憾的是 CMake 版本 2.8.7 不支持.但是这个旧版本已经支持 CMAKE_USER_MAKE_RULES_OVERRIDE.
As @Tsyvarev has commented check_type_size() supports a LANGUAGE parameter, but unfortunately not for CMake version 2.8.7. But this older version does already support CMAKE_USER_MAKE_RULES_OVERRIDE.
所以我仍然想知道是否最好的解决方案是使用较新版本的 CMake(迫使一些旧版本的 CMake 用户升级).或者编写自己的 try_compile() 片段.
So I'm still wondering if not the best solution would be to go to a newer version of CMake (forcing some users of older CMake versions to upgrade). Or writing your own try_compile() snippets.
参考资料
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