[Buildroot] [PATCH v2, 1/1] package/kismet: fix build with gcc >= 9
Thomas Petazzoni
thomas.petazzoni at bootlin.com
Wed Aug 26 21:35:30 UTC 2020
On Mon, 24 Aug 2020 20:21:21 +0200
Fabrice Fontaine <fontaine.fabrice at gmail.com> wrote:
> Adding -std=c++11 fix the build and can be removed as soon as kismet is
> bumped to latest version as the offending code has been removed. It
> should be noted that kismet builds fine with gcc 8 so it remains unclear
> why this build failure is raised only with gcc >= 9 (build failure
> confirmed with gcc 9 and 10)
Meh, this looks weird :/
bits/socket.h defines the field like this:
#if __glibc_c99_flexarr_available
__extension__ unsigned char __cmsg_data __flexarr; /* Ancillary data. */
#endif
and __glibc_c99_flexarr_available is defined as follows:
/* Support for flexible arrays.
Headers that should use flexible arrays only if they're "real"
(e.g. only if they won't affect sizeof()) should test
#if __glibc_c99_flexarr_available. */
#if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
# define __flexarr []
# define __glibc_c99_flexarr_available 1
#elif __GNUC_PREREQ (2,97)
/* GCC 2.97 supports C99 flexible array members as an extension,
even when in C89 mode or compiling C++ (any version). */
# define __flexarr []
# define __glibc_c99_flexarr_available 1
#elif defined __GNUC__
/* Pre-2.97 GCC did not support C99 flexible arrays but did have
an equivalent extension with slightly different notation. */
# define __flexarr [0]
# define __glibc_c99_flexarr_available 1
#else
/* Some other non-C99 compiler. Approximate with [1]. */
# define __flexarr [1]
# define __glibc_c99_flexarr_available 0
#endif
Some it's really unclear how -std=c++11 can fix the issue.
Could you have a look at which of those #if case we fall into in the
different cases (between gcc 8.x and gcc 9.x, with/without -std=c++11) ?
Thanks!
Thomas
--
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
More information about the buildroot
mailing list