告诉CMake使用C ++编译器的C文件来自CMake？ [英] Tell CMake to use C++ compiler for C files coming from CMake?

问题描述

这类似于强制CMake使用C ++编译器将C文件与Visual Studio ，但它不完全相同。它不一样，因为它的CMake文件导致失败;我在几乎所有的现代平台上工作，从BSD和OS X到Solaris和Unix。

我试图避免CMake执行无用的检查：

 项目（cryptopp，CXX）
  

b $ b

下面是当我尝试生成makefile时会发生什么：

  $ cmake。 
  - 检查系统是否是大端
  - 搜索16位整数
  - 检查无符号short的大小
 CMake错误在/usr/share/cmake-2.8/ Modules / CheckTypeSize.cmake：82（try_compile）：
文件的未知扩展名.c
 
 /home/jeffrey/cryptopp/CMakeFiles/CheckTypeSize/CMAKE_SIZEOF_UNSIGNED_SHORT.c 
 
 try_compile（）仅适用于已启用的语言。目前这些是：
 
 CXX 
 
请参阅project（）命令以启用其他语言。 
调用堆栈（最近调用）：
 /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）
  

我们没有任何C文件在我们的项目，所以我们应该是安全的项目（cryptopp，CXX）（如果我正在阅读 cmake - -help-command project ）。

引用的问题涉及项目文件，而不是CMake文件。

如何告诉CMake为所有文件使用C ++编译器，包括它自己的CMake文件？

---

我在Ubuntu 12 LTS上，它提供：

  $ cmake --version 
 2.8.7 
  

解决方案

$ c> .c 作为 CXX 编译器的有效文件扩展名。即使这是非常先进的CMake东西，你可能需要 - 如果你必须支持旧版本的CMake - 无论如何制定规则覆盖脚本。

所以我已经成功测试了以下内容：

CryptoppMakeRulesOverwrite.cmake / p>

 列表（APPEND CMAKE_CXX_SOURCE_FILE_EXTENSIONS c）
  

CMakeLists.txt

  cmake_minimum_required（VERSION 2.8.7 FATAL_ERROR） 
 
 set（CMAKE_USER_MAKE_RULES_OVERRIDECryptoppMakeRulesOverwrite.cmake）
 
项目（cryptopp，CXX）
 
 include（CheckTypeSize）
 CHECK_TYPE_SIZE unsigned shortCMAKE_SIZEOF_UNSIGNED_SHORT）
  

由于@Tsyvarev已注释 check_type_size（） 支持 LANGUAGE 参数，但不幸的是没有CMake版本2.8.7。但此旧版本已支持 CMAKE_USER_MAKE_RULES_OVERRIDE 。

所以我仍然想知道，如果不是最好的解决方案是去一个较新的版本的CMake（强迫一些旧的CMake版本的用户升级）。或撰写您自己的 try_compile（） 的片段。

参考 b $ b

如何在CMake项目中将全局文件扩展名（* .pde）添加到GCC，该对象被视为C ++代码< a>

更改CMAKE_CXX_FLAGS_DEBUG的默认值和CMake 中的朋友

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.

I tried to avoid useless checks being performed by CMake:

project(cryptopp, CXX)

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)

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).

The cited question talks about project files, but not CMake files.

How do I tell CMake to use C++ compiler for all files, including its own CMake files?

---

I'm on Ubuntu 12 LTS, and it provides:

$ cmake --version
cmake version 2.8.7

解决方案

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.

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)

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.

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.

References

• How to add in a CMake project a global file extension (*.pde) to GCC which is treated like C++ code
• Change default value of CMAKE_CXX_FLAGS_DEBUG and friends in CMake

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