[Development] Requiring minimum GCC 7/MinGW (was: Dropping MinGW support in Qt 6 (Was: HEADS-UP: QStringLiteral))

[Thiago Macieira]

On Friday, 23 August 2019 00:12:50 PDT Roland Winklmeier wrote:
> Just for your awareness: There is an old bug related to thread_local in
> MinGW which afaik was never fixed. It compiles correctly, but every
> executable crashes during shutdown. Not sure if this relevant in this case,
> just mentioning it:
> https://github.com/msys2/MINGW-packages/issues/2519

The description of the bug says "winpthreads", which means it's not MinGW, 
it's Cygwin/MSYS2.

libgcc on pure MinGW doesn't use winpthreads, it uses Win32.

Anyway, let's apply Q_THREAD_LOCAL. If that causes GCC-built MinGW 
applications to crash on exit, then we stop using GCC and switch to Clang.

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