[Development] QProperty and library coding guide

[Lars Knoll]

> On 17 Jul 2020, at 17:50, Thiago Macieira <thiago.macieira at intel.com> wrote:
> 
> On Friday, 17 July 2020 02:05:48 PDT Lars Knoll wrote:
>> Some older embedded toolchains don’t have the flag neither.
> 
> Then give them an option to opt out, at Qt configure time. That's a flag on 
> the same level as using -mfloat-abi=softfp instead of -mfloat-abi=hard or 
> using -stdlib=libc++ for Clang: completely ABI incompatible. But embedded 
> devices that build everything for the image in question can afford to make ABI 
> choices per version.

A configure option is perfectly fine for me :)
> 
> The same configure (ahem, cmake!) flag can be used to turn it on when it isn't 
> on by default. Such as when a new version of a compiler supports in 2021 or 
> later. Read: MSVC.
> 
> You may want to add this fact to archdetect.cpp (QSysInfo::buildAbi()). We can 
> also fix this automatically by having a variable that depends on the size of 
> QObject.
> 
> I'll just post this and let you ponder the consequences of this choice for 
> Linux:
> https://godbolt.org/z/nhex5x

Yes, that’s why we need to encode that into a static_assert(). But the support it coming to all compilers and Linux desktops will support the feature both with gcc and clang. I’m pretty sure ICC will follow soon.

Lars