[Interest] qt 5.15.0 msvc 2019

[maitai]

Hi all,

I am a bit confused with qt 5.15.0 on Windows.

The downloader proposes either MSVC2015 or MSVC2019, why not MSVC2017, 
mystery.

I chose 2019, and installed relevant MSVC/Visual basic suites.

All good, build ok, etc. Installer installs MSVC 2019 if missing, etc.

Then users start to complain about crashes (only on Windows 7), I said 
OK, let's go back to msvc2017/qt 5.14.2 for them.

And then finally digging more into it, I can see that using this version 
without changing a line in our code is much slower than qt 5.14.2 (= 10 
times slower in some specific cases)

Then I looked at options->qtVersions etc and qt 5.15.0(msvc 2019) wants 
msvc 2017 in fact (msvc version 15, if I try 16 this is not accepted).

What is the deal here?

Thanks as usual
Philippe.