[PATCH] Fix few build warnings with LLVM toolchain

[Martin Sebor]

On 5/28/19 10:31 AM, Martin Sebor wrote:
> On 5/28/19 4:24 AM, Martin Liška wrote:
>> On 5/28/19 11:31 AM, David CARLIER wrote:
>>> Hi,
>>>
>>> Here a tiny patch to fix few build warnings.
>>>
>>> Kind regards.
>>>
>>
>> Hi.
>>
>> Well, I see a lot of these struct/class discrepancies when building 
>> GCC with LLVM.
>> Question is whether it worth changing?
> 
> I think it's nice for these to be spelled consistently and no benefit
> to mixing and matching them.  If it cleans up common warnings I see
> no reason not to make the change.
> 
> FWIW, it's also a common convention to use struct for PODs and class
> for types with user-defined ctors, and even if GCC doesn't subscribe
> to it, make a change in support of it is an improvement independent
> of the Visual C++ warning.  (As might be adding such a warning to
> GCC to help enforce the convention on projects that do follow it.)

Jeff reminded me in a code review the other day that GCC does
have a guideline for defining POD structs with the keyword
"struct" and classes with ctors/dtors using "class":

   https://gcc.gnu.org/codingconventions.html#Struct_Use

I quickly prototyped a warning to see how closely GCC follows
this convention.  The result shows that out of just under 800
structs and classes defined in GCC sources some 200 use
the keyword 'struct' despite having a ctor or dtor, or about
25%.  So as is the case with most other conventions, without
a tool to help remind us they exist they are unlikely to be
followed with enough consistency to be worth putting in place
to begin with.

Martin