Earlier quoted context omitted.
MSYS2 is a fork of Cygwin. The goal is to make it easier to compile software targeting Windows. Some notable changes are: - It has its own package repository, using PKGBUILDs on github. It can also be updated from within its own shell. Cygwin doesn't do this, for very important reasons, involving autorebase hell which MSYS2 is certainly still subject to. - In their fork of cygwin1.dll, they removed support for symlin…
One more important note about compiling software with MSYS2 is that the msys2 version of cygwin1.dll (i forget how it's renamed) obviously inherits the same license as cygwin1.dll. Cygwin1.dll is not LGPL. It is GPL . So any program you release compiled with MSYS2 inherits GPL virality, unless you pay Red Hat for a commercial Cygwin license.
The 'msys2' software repository (as opposed to the 'mingw32' and 'mingw64' ones) contains things that link to msys-2.0.dll which is GPL, and yes it includes compilers and linkers that in turn generate new PECOFF objects that in turn link to msys-2.0.dll. This repository exists mostly as build scaffolding (Autotools, bash) to support building native Windows software (as exists in the other two repositories) and that is the real goal of MSYS2. If you want POSIX-y GPLed software on Windows, use Cygwin.
You are right to caution people on the naive usage of our msys2/gcc package, but you've made it sound like something much worse than it is.