[PATCH 06/13] manual: Allow getsubopt example to compile with GCC 15.

[Sam James]

Collin Funk <collin.funk1@gmail.com> writes:

> GCC 15 turned -Wincompatible-pointer-types into a compiler error instead
> of a warning by default. This patch prevents the following error:

We made those changes in GCC 14. What did change in 15 is that you see
this "more often" because we changed the default -std= to gnu23. But
that doesn't apply here.

>
>     $ gcc manual/examples/subopt.c
>     manual/examples/subopt.c: In function ‘main’:
>     manual/examples/subopt.c:64:40: error: passing argument 2 of ‘getsubopt’ from incompatible pointer type [-Wincompatible-pointer-types]
>        64 |           switch (getsubopt (&subopts, mount_opts, &value))
>           |                                        ^~~~~~~~~~
>           |                                        |
>           |                                        const char **
>     In file included from manual/examples/subopt.c:19:
>     /usr/include/stdlib.h:1100:47: note: expected ‘char * const* restrict’ but argument is of type ‘const char **’
>      1100 |                       char *const *__restrict __tokens,
>           |                       ~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~
> ---
>  manual/examples/subopt.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/manual/examples/subopt.c b/manual/examples/subopt.c
> index e7a073099a..63b5271483 100644
> --- a/manual/examples/subopt.c
> +++ b/manual/examples/subopt.c
> @@ -61,7 +61,7 @@ main (int argc, char **argv)
>        case 'o':
>          subopts = optarg;
>          while (*subopts != '\0')
> -          switch (getsubopt (&subopts, mount_opts, &value))
> +          switch (getsubopt (&subopts, (char * const *) mount_opts, &value))
>              {
>              case RO_OPTION:
>                read_only = 1;