[Development] QProperty and library coding guide

[Thiago Macieira]

On Thursday, 16 July 2020 13:16:41 PDT Giuseppe D'Angelo via Development 
wrote:
> Il 16/07/20 12:43, Volker Hilsheimer ha scritto:
> > For pre-C++20 (where it’s possible to have zero-size structs), and for
> > compilers that don’t respect the [[no_unqiue_address]] attribute, all
> > these struct-instances are put into a union. In that case, a class using
> > QProperty will be larger (by the same amount no matter the number of
> > properties) than the same class in Qt 5. With C+++ 20 and compilers that
> > do respect [[no_unique_address]], the size and layout of these classes
> > will be the same.
> I'm not fully understanding this last part -- does changing compiler
> break ABI, because the implementation of properties change (from an
> union to [[no_unique_address]] members)?

Yes.

Already sent a -2 to the commit that added this support, because it can't 
work. The commit will need to be reverted.

-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel System Software Products