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From: Florian Weimer <fweimer@redhat.com>
To: Szabolcs Nagy <Szabolcs.Nagy@arm.com>
Cc: Zack Weinberg <zackw@panix.com>, nd <nd@arm.com>,
	GNU C Library <libc-alpha@sourceware.org>
Subject: Re: [glibc] <sys/stat.h>: Use Linux UAPI header for statx if
	available and useful
References: <20190612110504.66041.qmail@sourceware.org>
	<87ftoe7utd.fsf@oldenburg2.str.redhat.com>
	<CAKCAbMj2G7_1bAuE+5X0qvNGMTMN9QenzOpgJmkwC4LK_mrGzA@mail.gmail.com>
	<87y3266czw.fsf@oldenburg2.str.redhat.com>
	<c35c19da-b775-3435-d38e-702f30bc6ac3@arm.com>
Date: Wed, 12 Jun 2019 17:54:20 +0200
In-Reply-To: <c35c19da-b775-3435-d38e-702f30bc6ac3@arm.com> (Szabolcs Nagy's
	message of "Wed, 12 Jun 2019 15:31:39 +0000")
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* Szabolcs Nagy:

> ouch, use the ""
>
> (clang __has_include seems not to expand)

Yes, that's what I saw as well in my testing.  Below is a lightly tested
patch.

Thanks,
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.

2019-06-12  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"
 # ifdef STATX_TYPE
 #  define __statx_timestamp_defined 1
 #  define __statx_defined 1