From: "Emilio Cobos Álvarez" <emilio@crisal.io>
To: Florian Weimer <fweimer@redhat.com>, libc-alpha@sourceware.org
Cc: "Emilio Cobos Álvarez" <emilio@crisal.io>
Subject: [PATCH v2] libc: Don't use a custom wrapper macro around __has_include.
Date: Thu, 21 Nov 2019 14:21:01 +0100 [thread overview]
Message-ID: <20191121132101.84999-1-emilio@crisal.io> (raw)
In-Reply-To: <875zjdo045.fsf@oldenburg2.str.redhat.com>
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 [1] for a reduced test-case since I initially thought this was a clang bug,
and [2] for more context.
Apparently doing this is invalid C++ per [cpp.cond], which mentions [3]:
> The #ifdef and #ifndef directives, and the defined conditional inclusion
> operator, shall treat __has_include and __has_cpp_attribute as if they
> were the names of defined macros. The identifiers __has_include and
> __has_cpp_attribute shall not appear in any context not mentioned in this
> subclause.
[1]: https://bugs.llvm.org/show_bug.cgi?id=43982
[2]: https://bugs.llvm.org/show_bug.cgi?id=37990
[3]: http://eel.is/c++draft/cpp.cond#7.sentence-2
---
misc/sys/cdefs.h | 8 --------
sysdeps/unix/sysv/linux/bits/statx.h | 12 +++++++-----
2 files changed, 7 insertions(+), 13 deletions(-)
diff --git a/misc/sys/cdefs.h b/misc/sys/cdefs.h
index abcb0d5e3c..467dbd9547 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 ff3f2e8973..2015c8262e 100644
--- a/sysdeps/unix/sysv/linux/bits/statx.h
+++ b/sysdeps/unix/sysv/linux/bits/statx.h
@@ -26,11 +26,13 @@
/* 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
+#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
--
2.24.0
next prev parent reply other threads:[~2019-11-21 13:23 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-12 18:31 [PATCH] libc: Don't use a custom wrapper macro around __has_include Emilio Cobos Álvarez
2019-11-21 13:00 ` Florian Weimer
2019-11-21 13:21 ` Emilio Cobos Álvarez [this message]
2019-11-21 13:28 ` Emilio Cobos Álvarez
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