Re: aliasing between const and non-const objects

[Michael Matz <matz at suse dot de>]

Hi,

On Tue, 29 Jul 2003, Richard Earnshaw wrote:

> > You'll get a warning for the latter assignment, though.  Nevethess you are
> > right.  I should have provided a more complete example:
>
> I hope not.  Otherwise you would get a warning every time you passed a
> non-const char pointer to strcpy as a source argument.

That the other way around.  There you add the const qualifier, but
removing it (implicitely or explicitely) gives a warning:

const char *cp;
char *ncp;
void g(char *p);
void f()
{
  char *lncp = cp;
  ncp = cp;
  g(cp);
}

ctonc.c: In function `f':
ctonc.c:6: warning: initialization discards qualifiers from pointer target type
ctonc.c:7: warning: assignment discards qualifiers from pointer target type
ctonc.c:8: warning: passing arg 1 of `g' discards qualifiers from pointer target type

> The code is not much dissimilar to
>
>  char a[5] = "abc";
>  char b[5];
>
>  strcpy (b, a);

this is a char* --> const char* conversion which is okay.


Ciao,
Michael.