[cfe-dev] clang++: '-Wswitch-enum' turned on by default

[Douglas Gregor]

On Sep 16, 2010, at 9:12 AM, Chris Lattner wrote:

> 
> On Sep 16, 2010, at 6:42 AM, Douglas Gregor wrote:
> 
>> 
>> On Sep 16, 2010, at 3:30 AM, Alexandre Colucci wrote:
>> 
>>> Hey,
>>> 
>>> I noticed that clang++ seems to always use the option '-Wswitch-enum'. Shouldn't it be turned off by default?
>> 
>> No, it's an excellent warning to have on by default.
>> 
>>> Or is there a way to turn it off?
>> 
>> -Wno-switch-enum
> 
> I think that a more serious issue with the warning is that it can produce a *ton* of noise.  In a simple example:
> 
> enum x { a, b, c, d, e, f, g };
> 
> void foo(enum x a) {
>   switch (a) {
>   case b:
>   case c: break;
>   }
> }
> 
> we produce:
> 
> t.c:4:11: warning: enumeration value 'a' not handled in switch [-Wswitch-enum]
>   switch (a) {
>           ^
> t.c:4:11: warning: enumeration value 'd' not handled in switch [-Wswitch-enum]
> t.c:4:11: warning: enumeration value 'e' not handled in switch [-Wswitch-enum]
> t.c:4:11: warning: enumeration value 'f' not handled in switch [-Wswitch-enum]
> t.c:4:11: warning: enumeration value 'g' not handled in switch [-Wswitch-enum]
> 5 warnings generated.
> 
> In this case, I think it would be better to emit one warning say:
> 
> t.c:4:11: warning: 5 enumeration values not handled in switch: 'a', 'd', 'e' ... [-Wswitch-enum]
> 
> or something like that.  What do you think?

I think that's an excellent idea.

	- Doug

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