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Re: [glibc] <sys/stat.h>: Use Linux UAPI header for statx if available and useful
On 12/06/2019 17:03, Florian Weimer wrote:
> * Szabolcs Nagy:
>
>> On 12/06/2019 16:54, Florian Weimer wrote:
>>> Linux: Fix __glibc_has_include use for <sys/stat.h> and statx
>>>
>>> The identifier linux is used as a predefined macro, so the actually used
>>> path is 1/stat.h or 1/stat64.h. Using the quote-based version triggers
>>> a file lookup for /usr/include/bits/linux/stat.h (or whatever directory
>>> is used to store bits/statx.h), but since bits/ is pretty much reserved
>>> by glibc, this appears to be acceptable.
>>>
>>> This is related to GCC PR 80005: incorrect macro expansion of the
>>> argument of __has_include.
>>>
>>> Suggested by Zack Weinberg.
>>>
>>> 2019-06-12 Florian Weimer <fweimer@redhat.com>
>>>
>>> * sysdeps/unix/sysv/linux/bits/statx.h: Use string literal in
>>> argument to __glibc_has_include to inhibit macro expansion.
>>>
>>> diff --git a/sysdeps/unix/sysv/linux/bits/statx.h b/sysdeps/unix/sysv/linux/bits/statx.h
>>> index d36f44efc6..3599f85a47 100644
>>> --- a/sysdeps/unix/sysv/linux/bits/statx.h
>>> +++ b/sysdeps/unix/sysv/linux/bits/statx.h
>>> @@ -23,8 +23,8 @@
>>> #endif
>>>
>>> /* Use the Linux kernel header if available. */
>>> -#if __glibc_has_include (<linux/stat.h>)
>>> -# include <linux/stat.h>
>>> +#if __glibc_has_include ("linux/stat.h")
>>> +# include "linux/stat.h"
>>
>> i would add a comment here with the gcc bug number as a
>> reminder in case anybody wonders about ""
>
> What about this?
>
> /* Use "" to work around incorrect macro expansion of the __has_include
> argument (GCC PR 80005). */
looks good.
>
> This will be correctly only with the other patch eliminating the
> function-like macro (just posted on a new thread).
>
> Thanks,
> Florian
>