Comment 1 for bug 1819584

That's weird : There has been no platform update @Appveyor.

But the msys2 package repo has been updated, e.g.:

 mingw-w64-x86_64-gcc-8.3.0-1 -> mingw-w64-x86_64-gcc-8.3.0-2

A new dependency for winpthreads:

  mingw-w64-x86_64-winstorecompat-git-7.0.0.5324.fde585a1-1

This all points into the same directions I have on my own machine with the GCC8.x-MSYS2-Environment (still using GCC 7.x and an older Boost because of this.).

Investigating...