Re: Clean up compiler warnings

[Andrew Cagney <ac131313 at cygnus dot com>]

"J.T. Conklin" wrote:
> 
> >>>>> "Andrew" == Andrew Cagney <ac131313@cygnus.com> writes:
> Andrew> When switching on an enum (as in this case) I've typically
> Andrew> found it better to explicitly list all cases rather than use a
> Andrew> default.  That way, when a new element is added to the enum,
> Andrew> the -Wswitch warning is available as a tool to the programmer
> Andrew> to identify where code needs to be altered.  As an aside, that
> Andrew> is why a switch on an enum rather than an if/elsif chain often
> Andrew> proves more resilient to long term maintenance.
> 
> What happens when an enum gets assigned a value that's not in the set
> of elements?  If there isn't a default case, we won't catch the error.
> 
> For example:
> 
>         enum foo {
>                 RED,
>                 GREEN,
>                 BLUE
>         } foo;
> 
>         ...
> 
>         foo = 10;               /* bogus assignment */
> 
>         ...
> 
>         switch (foo) {
>         case RED:
>                 ...; break;
>         case GREEN:
>                 ...; break;
>         case BLUE:
>                 ...; break;
>         }
> 
> Without a default case, program flow will continue after the switch
> statement.  With one, your -Wswitch trick won't work.  I'm not sure
> which is worse.

This is true. As with anything we can only go so far in attempt to
defend against bad code :-(

	Andrew