Question

can somebody please explain what does it mean :
passing arg 1 of 'free' discards qualifiers from pointer target type

Answer 1

I believe “discards qualifies” pertains to const or volatile. So you’re probably passing a const pointer as a non-const argument.

You code probably resembles the following:

#include <stdlib.h>
int main() {
    const double *x ;
    x = (double *) malloc(4 * sizeof(double)) ;
    free(x) ;
    return 0 ;
}

I borrowed this example from a similar question asked on an online forum.

The problem is that since you’ve said the data you’re point to is const, you can’t change it. You can’t initialize it, you can’t modify it, you can’t free it. So don’t use a const pointer as your only pointer to the result of a malloc.