https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81939
--- Comment #2 from Vittorio Zecca <zeccav at gmail dot com> --- Did you get MALLOC checks? *** Error in `./a.out': free(): invalid pointer: 0x0000000000c0b560 *** *** Error in `./a.out': free(): invalid pointer: 0x0000000000c0b6a0 *** *** Error in `./a.out': free(): invalid pointer: 0x0000000000c0c9f0 *** I have MALLOC_CHECK_=1