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Am Mit, 2004-11-17 um 20.58 schrieb fz...@austin.rr.com:
> > Hello Frank.
> >
> > I am not a fan of this patch.
> > I think it will work but I think it is a hack.
> >
> > It seems that only a few backends have problems with this.
>
> A few backend are creating the name of the manufacturer from the scsi inquiry.
> A lot of backends are creating their mode list from the device.
> This patch will allow us to get rid of about 150 (IMO legitimate) warnings.
> The current code is not clean.
>
>
> > Why not fix it in a proper way:
>
> The non hack solution is to have two headers: one for the symbols exported
> and one for internal use. Same as what is done with the linux kernel
> structure s.
>
> >
> > create the strings as non const and then set the
> > sane_device structur to point to these strings?!
>
> This will not work. That why there is so much warnings.
IMO thats not ture.
It is allowed to do this:
char *hello;
const char *hello_const;
hello="ABC";
hello_const = hello;
and this produces a warning:
*hello_const = 'A';
what is correct becaus we use a pointer to a const char to change the
char so it is not const any more.
It is not a const pointer to a char, it is a pointer to a const char.
And it is allowed to make a pointer of type pointer to const char point
to a (non const) char.
I attach a little test c-code for this. Compile with
gcc consttest.c -o consttest -Wall
(gcc version 3.2.2 20030222)
Oliver
>
> >
> > But when I am the only one who is against this patch
> > then I will be quiet and it will be ok for me. It is nothing
> > that will steal my sleep :)
> >
>
> Your input is appreciated. Thanks.
>
> Frank.
>
>
>
>
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#include "stdio.h"
#include "stdlib.h"
int main()
{
const char *hello_const;
char *hello;
printf("defining hello=\"Hello\"\n");
printf("defining hello_const = hello\n");
hello = "Hello";
hello_const = hello;
printf("hello = %s\n", hello);
printf("hello_const = %s\n", hello_const);
printf("\n");
printf("defining hello = (char *) malloc(10)\n");
printf("defining *hello = \'A\'\n");
printf("defining *(hello+1) = \'B\'\n");
printf("defining hello_const = hello\n");
hello= (char *) malloc(10);
hello_const = hello;
*hello='A';
*(hello+1)='B';
hello[2]=0;
printf("hello = %s\n", hello);
printf("hello_const = %s\n", hello_const);
printf("\n");
printf("unallowed defining *hello_const = \'X\'\n");
*hello_const='X';
printf("hello = %s\n", hello);
printf("hello_const = %s\n", hello_const);
return 0;
}
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