[pushed] Don't use a custom wrapper macro around __has_include (bug 25189).

Message ID 20191121170010.048172816F@gnutoolchain-gerrit.osci.io
State New
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  • [pushed] Don't use a custom wrapper macro around __has_include (bug 25189).
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Commit Message

Simon Marchi (Code Review) Nov. 21, 2019, 5 p.m.
Sourceware to Gerrit sync has submitted this change.

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

Don't use a custom wrapper macro around __has_include (bug 25189).

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

Change-Id: Id4b8ee19176a9e4624b533087ba870c418f27e60
---
M misc/sys/cdefs.h
M sysdeps/unix/sysv/linux/bits/statx.h
2 files changed, 7 insertions(+), 13 deletions(-)

Approvals:
  Florian Weimer: Looks good to me, approved



-- 
Gerrit-Project: glibc
Gerrit-Branch: master
Gerrit-Change-Id: Id4b8ee19176a9e4624b533087ba870c418f27e60
Gerrit-Change-Number: 697
Gerrit-PatchSet: 5
Gerrit-Owner: Florian Weimer <fweimer@redhat.com>
Gerrit-Reviewer: Emilio Cobos Álvarez <emilio@crisal.io>
Gerrit-Reviewer: Florian Weimer <fw@deneb.enyo.de>
Gerrit-Reviewer: Florian Weimer <fweimer@redhat.com>
Gerrit-MessageType: merged

Patch

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..2015c82 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