[Development] Raising the minimum to C++20

Thiago Macieira thiago.macieira at intel.com
Wed May 3 18:03:14 CEST 2023

On Tuesday, 2 May 2023 23:16:19 PDT Marc Mutz via Development wrote:
> [1] I also heard the idea to make C++20 mandatory for building Qt, but
> user projects could continue to use C++17. That would require _forward_
> binary compatibility between stdlib implementations. Given that a C++20
> stdlib must needs contain more symbols (C++20-only features), it's
> almost guaranteed that forward BC isn't maintained by stdlibs.

I don't see that as a conclusion.

The library is the library. Whether you've compiled as C++14, 17, 20 or 23 
before linking to it is immaterial. What matters is the symbols it provides 
and the Standard Libraries must, by necessity, offer all the symbols that any 
compilation of their headers would require.

Upping our build requirements would allow us to offer symbols in our libraries 
that could only be accessed by code compiled under C++20. Right now, we can't 
do that and we must provide certain workarounds.

Thiago Macieira - thiago.macieira (AT) intel.com
  Cloud Software Architect - Intel DCAI Cloud Engineering
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