From a9ffac8596b094da8563aa5dd5d81c946670afe5 Mon Sep 17 00:00:00 2001 From: A. Wilcox Date: Sat, 23 Jun 2018 17:57:48 -0500 Subject: Don't use __extension__ in C++ code A few important notes: * __extension__ is a GNU C "alternate" keyword, not a C++ keyword.[1] * __extension__ is designed to work on "expressions"; it does work on #include_next in C mode, but it has no effect in C++ mode; the warning will still appear, if enabled, even with __extension__ preceding #include_next. This is because #include_next is not considered an expression in C++, so the compiler attaches __extension__ to the first expression of the header. All of this leads us to a build failure while building at least all Mozilla software. Moz has an alternate -isystem dir searched before /usr/include that overrides some headers, including . The first statement in each of these headers is a #pragma, and since __extension__ is looking for an expression, and #pragma is a "null" expression, we end up with the following error: dist/system_wrappers/features.h:1:9: error: '#pragma' is not allowed here Since __extension__ has no effect on #include_next in C++ mode anyway, and since it can cause breakage, this commit omits __extension__ in C++ mode. [1]: https://gcc.gnu.org/onlinedocs/gcc-6.4.0/gcc/Alternate-Keywords.html --- include/stdio.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/stdio.h') diff --git a/include/stdio.h b/include/stdio.h index b67f9ce..a965184 100644 --- a/include/stdio.h +++ b/include/stdio.h @@ -16,7 +16,9 @@ #ifndef _FORTIFY_STDIO_H #define _FORTIFY_STDIO_H +#ifndef __cplusplus __extension__ +#endif #include_next #if defined(_FORTIFY_SOURCE) && _FORTIFY_SOURCE > 0 && defined(__OPTIMIZE__) && __OPTIMIZE__ > 0 -- cgit v1.3