[Development] QtCS: Notes from Modern C++ session

[Marc Mutz]

On Sunday 14 June 2015 12:06:21 Knoll Lars wrote:
[ regarding = default, = delete ]
> The main place where we use this feature is anyway with Q_DISABLE_COPY. So
> for now, I don't think it's a huge problem if we can't use those.

That's = delete, yes, and you can always make those into linker errors by 
leaving the function undefined (and sometimes, for member functions, into a 
compiler error by marking them private). Q_DECL_EQ_DELETE then just lifts 
those errors to an earlier stage, with a better error message. No 
functionality is lost.

= default, however, has no workaround. We can't even use Q_DECL_EQ_DELETE, 
because it qualitatively changes the nature of the special member function 
it's applied to: in one case, it's user-provided, in the other, compiler-
synthesized. That can turn non-trivial types into trivial ones, and as I 
recently learned from Thiago, that may change the way an object of the type is 
passed by-value to functions.

So, we might as well remove Q_DECL_EQ_DEFAULT, I think.

Thanks,
Marc

-- 
Marc Mutz <marc.mutz at kdab.com> | Senior Software Engineer
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