Re: [PATCH 1/3] Fix mismatched struct vs class tags.

Pedro Alves
2016-11-24T17:02:11Z

On 11/23/2016 11:00 PM, John Baldwin wrote:
> On Wednesday, November 23, 2016 03:58:11 PM Simon Marchi wrote:
>> On 2016-11-23 15:06, John Baldwin wrote:
>>> The 'collection_list' and 'number_or_range_parser' types were converted
>>> from structs to classes, but some code still used 'struct'. Fix all
>>> references to use 'class' which fixes -Wmismatched-tags warnings issued
>>> by clang.
>>
>> Whjen using the type in a parameter or variable declaration, should we
>> simply drop the keyword?
>>
>> For example:
>>
>> - struct collection_list *collect;
>> + collection_list *collect;
>>
>> That's the approach I took in my upcoming C++ patches, so I hope it's ok
>> :). I have also dropped the "enum" keyword when possible.
>
> Hmm. I don't see anything about this in the GCC C++ language conventions,
> so I will have to defer to others as far as what is the desired style here?
> (And we should document whatever style is chosen)

I wouldn't say it's a matter of style to drop the "struct" or now.
It's just that we'll have legacy code using the explicit "struct"
style due to C heritage. Dropping it is fine. You can't drop it
in forward declarations, though.

I think I'd prefer a patch to add "-Wno-mismatched-tags" to the warning set.
This warning is useless for us. Forward declaring with "struct"
and defining with "class" is perfectly valid. That's useful as "struct"
vs "class" is just an implementation detail. IIRC, that clang
warning only exists because struct/class somehow makes a
difference with Microsoft's compilers (maybe it mangles
those differently, not sure), even though that's non conforming. But,
we don't support building with that.

Thanks,
Pedro Alves