如何忽略CMakeLists.txt中单个CMake命令的错误？ [英] How can I ignore errors on an individual CMake command in my CMakeLists.txt?

问题描述

我有一个项目，其中 CMakeLists.txt 尝试读取可能存在或可能不存在的文件。丢失文件不是问题，脚本可以处理任何一种情况。如果我们可以检测到已知的Linux发行版，则可以使用它来稍微调整编译环境：

  file（读/ etc / redhat-发行RHREL）
 if（RHREL匹配 Red Hat Enterprise Linux Server版本6 *）
＃调整RHEL6 
 elseif（RHREL匹配 Red Hat Enterprise Linux Server版本7 *）
＃调整RHEL7 
 else（）
＃读取失败，或者我们没有匹配已知的RHEL版本
＃后退到合理的默认值
 endif（）
  

问题在于，当 file（READ ...）失败，似乎正在使用 SEND_ERROR 参数输出一条消息。这意味着我的配置按照我的预期继续进入了所有的 else（），但是在配置结束时 CMake 拒绝生成 Makefile 。

如何运行 file（READ）以这样的方式我可以在本地处理错误并防止它们使整个配置失败？

解决方案

将我的评论变成答案

在这种特殊情况下，您还可以检查 CMAKE_HOST_SYSTEM 。

更普遍的答案是，您必须将代码移至外部CMake脚本中，并使用所有功能强大的 execute_process（） 命令：

FileDumpRedHatRelease .cmake

  file（读取/ etc / redhat-release RHREL）
 execute_process（COMMAND $ {CMAKE_COMMAND} -E echo $ {RHREL}）
 
 ＃或如果您不介意以STATUS消息
＃开头的破折号（因为正常的CMake消息发送到stderr）
 #message（STATUS $ {RHREL}）
  

CMakeLists.txt

  execute_process（
 COMMAND $ {CMAKE_COMMAND} -P $ {CMAKE_CURRENT_LIST_DIR} /FileDumpRedHatRelease.cmake 
 OUTPUT_VARIABLE RHREL 
 ERROR_QUIET 
）
  

参考文献

即使这些参考文献都在讨论可能失败的 add_custom_command（）命令，您也可以看到 execute_process（）和外部CMake脚本，例如：



• CMake：忽略返回代码ADD_CUSTOM_COMMAND（hhc.exe）


• 0013146：ADD_CUSTOM_COMMAND没有输出/结果变量

I have a project where the CMakeLists.txt attempts to read a file which may or may not be present. It is not a problem for the file to be missing and the script handles either case. This is used to tweak the compilation environment slightly if we can detect a known Linux distribution:

file (READ /etc/redhat-release RHREL)
if (RHREL MATCHES "Red Hat Enterprise Linux Server release 6*")
   # tweak for RHEL6
elseif (RHREL MATCHES "Red Hat Enterprise Linux Server release 7*")
   # tweak for RHEL7
else()
   # either read failed, or we didn't match a known RHEL release
   # fallback to reasonable defaults
endif()

The problem is that when file(READ...) fails it seems to be outputting a message using the SEND_ERROR parameter. This means that my configuration continues into the catch-all else() as I expect, but at the end of configuration CMake refuses to generate a Makefile.

How can I run file(READ) in such a way that I can cope with errors locally and prevent them from failing the entire configuration?

解决方案

Turning my comment into an answer

In this special case, you could also check CMAKE_HOST_SYSTEM.

The more general answer is you have to move your code into an external CMake script and call it with the all mighty execute_process() command:

FileDumpRedHatRelease.cmake

file(READ /etc/redhat-release RHREL)
execute_process(COMMAND ${CMAKE_COMMAND} -E echo "${RHREL}")

# or if you don't mind the '-- ' leading dashes with STATUS messages
# (because normal CMake messages go to stderr)
#message(STATUS "${RHREL}")

CMakeLists.txt

execute_process( 
    COMMAND ${CMAKE_COMMAND} -P "${CMAKE_CURRENT_LIST_DIR}/FileDumpRedHatRelease.cmake"
    OUTPUT_VARIABLE RHREL
    ERROR_QUIET
)

References

Even those references are all discussing an add_custom_command() command that could fail, you can see the usage of execute_process() and external CMake scripts in such cases:

• catch return value in CMake add_custom_command?
• CMake: Ignoring return codes on ADD_CUSTOM_COMMAND (hhc.exe)
• 0013146: ADD_CUSTOM_COMMAND has no OUTPUT / RESULT Variable

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