CMake命令行定义不会导致工具链文件 [英] CMake Command Line Definitions Not Perpetuating To Toolchain File

问题描述

我有一个cmake交叉编译器工具链文件，缩写为：

I have a cmake cross compiler toolchain file, abridged as:

set(CMAKE_SYSTEM_NAME Linux)
if( DEFINED TC_PATH )
    message( STATUS " TC_PATH IS defined. ${TC_PATH}" )
else()
    message( FATAL_ERROR " TC_PATH not defined." )
endif()

set(CMAKE_C_COMPILER ${TC_PATH}/usr/bin/i586-linux/i586-linux-gcc )
set(CMAKE_CXX_COMPILER ${TC_PATH}/usr/bin/i586-linux/i586-linux-g++ )
set(CMAKE_LINKER ${TC_PATH}/usr/bin/i586-linux/i586-linux-ld )

我调用cmake，设置TC_PATH以及工具链文件：

I call cmake, setting the TC_PATH as well as the toolchain file:

~/CMakeTest/output $ cmake -DTC_PATH:PATH=/opt/toolchain -DCMAKE_TOOLCHAIN_FILE=../toolchain.cmake ../

看来cmake是多次调用工具链文件。在前两次，TC_PATH检查成功，但后来，识别编译器后，它会抛出一个错误：

It appears cmake is invoking the toolchain file multiple times. On the first two time, the TC_PATH check succeeds, but later, after identifying the compilers, it throws an error:

--  TC_PATH IS defined. /opt/toolchain
--  TC_PATH IS defined. /opt/toolchain
-- The C compiler identification is GNU 4.9.1
-- The CXX compiler identification is GNU 4.9.1
-- Check for working C compiler: /opt/toolchain/usr/bin/i586-linux/i586-linux-gcc
CMake Error at /home/gnac/CMakeTest/toolchain.cmake:4 (message):
   TC_PATH not defined.
Call Stack (most recent call first):
  /home/gnac/CMakeTest/output/CMakeFiles/3.0.2/CMakeSystem.cmake:6 (include)
  CMakeLists.txt:2 (project)

因此，在shell中设置永久环境变量之外，我如何设置TC_PATH

So, outside of setting a permanent environment variable in the shell, how I can set the TC_PATH variable via the command line so that it will be remain in context while executing the cmake generate command?

推荐答案

您的工具链需要通过命令行来保存在上下文中自给自足。失败的步骤是 try_compile（） 这不是你的缓存变量。

Your toolchain needs to be self-sufficient. The step that fails is a try_compile() which is not getting your cached variables.

您的工具链档案看起来不像是交叉编译（没有 CMAKE_SYSTEM_NAME ），因此您可以执行以下操作之一（除了设置 CC 和 CXX 环境变数）：

Your toolchain file does not look like you're cross-compiling (it does not have a CMAKE_SYSTEM_NAME) so you can do one of the following (besides setting the CC and CXX environment variables as you have mentioned):

1. 足以给出 C 和/或 CXX 编译器的完整路径取决于您启用的语言），CMake将自动检测您的GNU工具链的其余部分。

1. It's sufficient to give the full path to your C and/or CXX compiler (depending on which languages you enabled), CMake will detect the rest of your GNU toolchain automatically

cmake -DCMAKE_C_COMPILER:PATH=/opt/toolchain/usr/bin/i586-linux/i586-linux-gcc 
      -DCMAKE_CXX_COMPILER:PATH=/opt/toolchain/usr/bin/i586-linux/i586-linux-g++ ...

将以下内容添加到您的工具链以跳过编译器测试（因为不是所有选项都可以传递给它，因为你选择的编译器/链接器不会产生有效的可执行文件）

Add the following to your toolchain to skip the compiler tests (because not all options may be passed to it or because your compiler/linker of choice will not produce a valid executable)

set(CMAKE_C_COMPILER_WORKS 1 CACHE INTERNAL "")
set(CMAKE_CXX_COMPILER_WORKS 1 CACHE INTERNAL "")

或者只需使用 CMakeForceCompiler 宏，但使用的是Discouraged。如果可能，请避免使用此模块。

Or just use the CMakeForceCompiler macros, but the use is "Discouraged. Avoid using this module if possible."

使用 configure_file（）文件（只需确保在 project（）调用之前执行此操作）

Use configure_file() to put the path into your toolchain file (just make sure to do it before the project() call)

$ c> find_program（）如果你的工具链的可能路径已知从外面设置它（见例如此处）

Prefer find_program() if the possible paths of your toolchain are known over setting it from the outside (see e.g. here)

参考

• CMake常见问题：如何使用不同的编译器？


• 如何为cmake指定新的gcc路径


• CMake Cross Compiling


• cmake：指定编译器的问题（2）


• cmake使用特定链接器交叉编译不会传递参数到armlink
• 
  
• CMake：订单是解析的文件（缓存，工具链，...）？

• CMake FAQ: How do I use a different compiler?
• how to specify new gcc path for cmake
• CMake Cross Compiling
• cmake: problems specifying the compiler (2)
• cmake cross-compile with specific linker doesn't pass arguments to armlink
• CMake: In which Order are Files parsed (Cache, Toolchain, …)?

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