#842 Address of a void ptr doesn't change

[Hubert Sack]

I read the RFE 905167 and wrote a short senseless
program, it results in detecting a bug:
sdcc -v
SDCC : mcs51/ds390/pic16/TININative/xa51/ds400 2.4.7
#897

int *intptr;
void *voidptr;

char main (void)
{
int x[2] = {0,4711};
char res;

voidptr = x;
intptr = x;

/*
< voidptr++; // No warning, but o.k. since sizeof(void)
== 0
*/
voidptr += sizeof(int); // but here it's *NOT*
incremented, too
intptr++;

res = (*(int *)voidptr == *intptr); // should be true

return(res);
}

[Hubert Sack]

All files (test.c, test.asm, ...) as an windows zip archive

[Maarten Brock]

Logged In: YES
user_id=888171

This is no bug. If you agree voidptr++ doesn't increment is
ok, than you should know that voidptr+=sizeof(int) doesn't
increment either. Sizeof(int) only returns a number, just like
++ means +=1. In this case 1 is the number. This number
must be multiplied by the size of the object the pointer points
to. In this case 0.

If you want to use sizeof() to increment the pointer to the
next object, it must be added to a char* casted version:

voidptr = (char*)voidptr + sizeof(int);

Hope this clarifies things