bug#36650: 27.0.50; CC Mode: Support C++ attributes

[Óscar Fuentes]

Alan Mackenzie <acm@muc.de> writes:

> Yes.  I'll have a look at this.

Thanks.

>> In general, considering them part of the following token for indentation
>> purposes and fontifying with some existing or new face should be enough.
>
> I will probably end up treating attributes as syntactic whitespace.
> They have no syntactic connection with the code they are embedded in,
> any more than macros do.

I don't know how syntactic whitespace works on CC Mode, so just in case
I'll mention that this code

int foo([[maybe_unused]] int a,
        int b);
        
should not be formatted as

int foo([[maybe_unused]] int a,
                         int b);