Good news.
I am currently using msys2 prebuild 3.0.5 for my work, hope msys2 will supply 3.1.5 prebuild, but using their build system(pacman, pkg build) is a bit complex to build wxwidgets library myself, anyone had done this? It needs some customized patches.
I think Msys2 thought 3.0.5 as the official release version, 3.1.x is development version.