Fix build issue

[Urgau]

Fix build issue on Archlinux with gcc 8.2.0

[Urgau]

Can this pull request be merged ?

[mutability]

What's the error this fixes?

[Urgau]

I don't remember the exact message but it was a message like this: you cannot not move callsign to mm->callsign with the size of mm->callsign.

I just retry this on my new machine with gcc 8.2.0 and I don't get this error any more.

[mutability]

Ok. If you see it again, reopen this & let me know the exact error. Both callsign and mm->callsign are declared as char[9] so I can't see an obvious reason for this.

[Urgau]

Here is the error:

In file included from /usr/include/string.h:494,
from dump1090.h:66,
from comm_b.c:21:
Dans la fonction « memcpy »,
mis en ligne depuis « decodeBDS20.part.2 » à comm_b.c:228:9,
mis en ligne depuis « decodeBDS20 » à comm_b.c:194:12:
/usr/include/bits/string_fortified.h:34:10: error: « __builtin_memcpy » forme le décalage [10, 16] qui est hors des limites [0, 9] de l'objet « callsign » avec le type « char[9] » [-Werror=array-bounds]
return __builtin___memcpy_chk (__dest, __src, __len, __bos0 (__dest));
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
comm_b.c: Dans la fonction « decodeBDS20 »:
comm_b.c:195:10: note: « callsign » déclaré ici
char callsign[9];
^~~~~~~~
cc1 : tous les avertissements sont traités comme des erreurs

Sorry for the french

[mutability]

This has got to be a compiler bug, none of the arrays involved have a size of 16 bytes. Not much I can do about compiler bugs, sorry :( Maybe you can report it upstream?

[mutability]

FWIW I cannot reproduce this with
gcc version 8.2.0 (Ubuntu 8.2.0-1ubuntu2~18.04)
even with -D_FORTIFY_SOURCE=2 -fstack-protector-strong set.
(Also tried all the different values of -Wstringop-overflow with no luck)

[Urgau]

To be precise I now use "gcc (GCC) 8.2.1 20181127" on Archlinux in a armv7 device.