[review] libc: Don't use a custom wrapper macro around __has_include.

["Florian Weimer (Code Review)" <gerrit at gnutoolchain-gerrit dot osci dot io>]

Change URL: https://gnutoolchain-gerrit.osci.io/r/c/glibc/+/697
......................................................................

libc: Don't use a custom wrapper macro around __has_include.

This causes issues when using clang with -frewrite-includes to e.g., submit the
translation unit to a distributed compiler.

In my case, I was building Firefox using sccache.

See https://bugs.llvm.org/show_bug.cgi?id=43982 for a reduced test-case since I
initially thought this was a clang bug.

Apparently doing this is invalid C++ per:

 * http://eel.is/c++draft/cpp.cond#7.sentence-2

(See https://bugs.llvm.org/show_bug.cgi?id=37990)

Signed-off-by: Emilio Cobos Álvarez <emilio@crisal.io>
Change-Id: Id4b8ee19176a9e4624b533087ba870c418f27e60
---
M misc/sys/cdefs.h
M sysdeps/unix/sysv/linux/bits/statx.h
2 files changed, 8 insertions(+), 14 deletions(-)



diff --git a/misc/sys/cdefs.h b/misc/sys/cdefs.h
index abcb0d5..467dbd9 100644
--- a/misc/sys/cdefs.h
+++ b/misc/sys/cdefs.h
@@ -412,14 +412,6 @@
 # define __glibc_has_attribute(attr)	0
 #endif
 
-#ifdef __has_include
-/* Do not use a function-like macro, so that __has_include can inhibit
-   macro expansion.  */
-# define __glibc_has_include __has_include
-#else
-# define __glibc_has_include(header)	0
-#endif
-
 #if (!defined _Noreturn \
      && (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) < 201112 \
      &&  !__GNUC_PREREQ (4,7))
diff --git a/sysdeps/unix/sysv/linux/bits/statx.h b/sysdeps/unix/sysv/linux/bits/statx.h
index ff3f2e8..14d5992 100644
--- a/sysdeps/unix/sysv/linux/bits/statx.h
+++ b/sysdeps/unix/sysv/linux/bits/statx.h
@@ -26,12 +26,14 @@
 
 /* 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
-# endif
+#ifdef __has_include
+#  if __has_include("linux/stat.h")
+#   include "linux/stat.h"
+#   ifdef STATX_TYPE
+#    define __statx_timestamp_defined 1
+#    define __statx_defined 1
+#   endif
+#  endif
 #endif
 
 #include <bits/statx-generic.h>

-- 
Gerrit-Project: glibc
Gerrit-Branch: master
Gerrit-Change-Id: Id4b8ee19176a9e4624b533087ba870c418f27e60
Gerrit-Change-Number: 697
Gerrit-PatchSet: 1
Gerrit-Owner: Florian Weimer <fweimer@redhat.com>
Gerrit-MessageType: newchange