Re: [PATCH 2/5] Fix some "enum value 'SYM_...' not handled in switch" warnings

[Josh Triplett <josh@joshtriplett.org>]

On Tue, Jul 21, 2009 at 10:15:49PM +0100, Ramsay Jones wrote:
> Josh Triplett wrote:
> > On Sat, Jul 18, 2009 at 09:41:46PM +0100, Ramsay Jones wrote:
> >> These warnings were issued by gcc v3.4.4, but not by gcc v4.1.2.
> >> So I guess gcc probably found these warnings to be too noisy ...
> > [...]
> >> --- a/parse.c
> >> +++ b/parse.c
> >> @@ -2616,6 +2616,8 @@ struct token *external_declaration(struct token *token, struct symbol_list **lis
> >>  			case SYM_ENUM:
> >>  			case SYM_RESTRICT:
> >>  				base_type->ident = ident;
> >> +			default:
> >> +				break;
> >>  			}
> > 
> > I don't think you want to add defaults like this just to avoid warnings.
> > Warnings like that can help when adding a new item to an enum, to find
> > the places where you need to extend the code to hand the new item.  And
> > since current GCC doesn't even issue the warning by default, it seems
> > even more unnecessary to add that default case.
> > 
> 
> OK...
> 
> So, if I understand your argument, in order to make the best use of these
> warnings, then the correct change would look like the diff given below,
> and (for more up-to-date gcc) add -Wswitch-enum to CFLAGS (at least
> occasionally).
[...]
> diff --git a/parse.c b/parse.c
> index e5ad867..afe39c3 100644
> --- a/parse.c
> +++ b/parse.c
> @@ -2616,6 +2616,23 @@ struct token *external_declaration(struct token *token, struct symbol_list **lis
>  			case SYM_ENUM:
>  			case SYM_RESTRICT:
>  				base_type->ident = ident;
> +				break;
> +			case SYM_UNINITIALIZED:
> +			case SYM_PREPROCESSOR:
> +			case SYM_BASETYPE:
> +			case SYM_NODE:
> +			case SYM_PTR:
> +			case SYM_FN:
> +			case SYM_ARRAY:
> +			case SYM_TYPEDEF:
> +			case SYM_TYPEOF:
> +			case SYM_MEMBER:
> +			case SYM_BITFIELD:
> +			case SYM_LABEL:
> +			case SYM_FOULED:
> +			case SYM_KEYWORD:
> +			case SYM_BAD:
> +				break;

This represents exactly why more recent GCC defaults this warning to
off. ;)

No, I don't think writing the code this way helps.  I think it makes
more sense to leave the warning off and not bother placating older
versions of GCC.

- Josh Triplett