Я запутался. А какой MinGW нынче самый правильный: https://mingw-w64.org/ или www.mingw.org/ или https://nuwen.net/mingw.html ?
вот что по этому поводу в qt:
MinGW distributions and versions
There are actually different MinGW toolchains and packages available:
MinGW.org is the original project. The latest version gcc 4.7.2. It only compiles for 32 bit binaries.
MinGW-w64 [mingw-w64.sourceforge.net] is a fork with the original aim to also support generation of 64 bit binaries. By now it also supports a much larger part of the Win32 API. The MinGW-w64 project does host several different binary packages, done by different people.
There are binary installers targetting MinGW for both Qt 4 and Qt 5. Up to Qt 4.8.6, Qt 4 ones are built with a MinGW.org toolchain using gcc 4.4. Newer Qt 4.8 binary packages ship with a mingw-w64 based toolchain. For Qt 5, a newer MinGW-w64 toolchain is actually required.