[GitHub] [incubator-brpc] hthao commented on issue #1693: compile failed with error "error: macro "__has_attribute" requires an identifier"

[GitBox <gi...@apache.org>]

hthao commented on issue #1693:
URL: https://github.com/apache/incubator-brpc/issues/1693#issuecomment-1040044934


   > 谢谢反馈，该问题是因为在编译时指定了选项 -D__const__= 导致的，brpc在编译时需要添加这个宏来避免gcc对errno宏做优化从而[导致未定义行为](https://github.com/apache/incubator-brpc/blob/master/docs/cn/thread_local.md#gcc4%E4%B8%8B%E7%9A%84errno%E9%97%AE%E9%A2%98)
   > 
   > 你的系统文件（/usr/include/x86_64-linux-gnu/sys/cdefs.h） 在 #if 中测试了 `__glibc_has_attribute (__const__)`，这个宏展开之后是` __has_attribute (__const__)`, 由于brpc在编译时将 **const** 定义成了空，所以报错了。比较快的解决方案是直接删掉后边的 `__glibc_has_attribute (__const__)`
   > 
   > ps：提issue的时候可以预览一下，编译错误里的`__const__`变成了加粗的 **const** 了
   
   谢谢快速反馈，修改系统文件貌似不现实，需要再研究一下解决方案，多谢。


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