const struct test x = {0};
will compile giving only some misleading warnings, no
errors.
I compile using
sdcc -mpic14 -p16c745 -c --std-c99
sdcc --version
gives
SDCC :
mcs51/gbz80/z80/avr/ds390/pic16/pic14/TININative/xa51/ds400/hc08
2.5.6 #1246 (Apr 12 2006) (UNIX)
This should now be fixed for all but pic14 targets.