https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63303
--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> --- (In reply to mikulas from comment #4) > ... and another related problem (try this on 32-bit system): > > #include <stdio.h> > #include <stdlib.h> > > int main(void) > { > short *a = malloc(0x50000000 * sizeof(short)); > short *b = a + 0x50000000; > printf("%ld\n", (long)(b - a)); > return 0; > } > > Here, the return value should be positive (0x50000000), but it is negative. > IMHO, according to the C standard, this is program correct and positive > result should be returned. This testcase is invalid, you really can't have an object bigger than half of the address space in C/C++, pointer difference is signed ptrdiff_t and if you have larger object, you can't subtract arbitrary char pointers in it anymore. If you need more than 2GB in a single array, just use 64-bit system.