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Re: [glibc] <sys/stat.h>: Use Linux UAPI header for statx if available and useful
* Szabolcs Nagy:
> 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.
Thanks. Updated patch below. I plan to push this soon.
Florian
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.
2019-06-14 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..206878723f 100644
--- a/sysdeps/unix/sysv/linux/bits/statx.h
+++ b/sysdeps/unix/sysv/linux/bits/statx.h
@@ -23,8 +23,11 @@
#endif
/* Use the Linux kernel header if available. */
-#if __glibc_has_include (<linux/stat.h>)
-# include <linux/stat.h>
+
+/* Use "" to work around incorrect macro expansion of the
+ __has_include argument (GCC PR 80005). */
+#if __glibc_has_include ("linux/stat.h")
+# include "linux/stat.h"
# ifdef STATX_TYPE
# define __statx_timestamp_defined 1
# define __statx_defined 1