Each of the various packages, which are distributed by MinGW.OSDN, is governed by its own individual copyright and licensing terms. In summary, the applicable terms for the web‑site content, and for the most commonly deployed packages, are as follows:—
Not to be confused with Microsoft’s “Windows Subsystem for Linux”, (MinGW.OSDN’s adoption of the “WSL” acronym preceded Microsoft’s by several years), the “MinGW.OSDN Windows System Libraries” comprise:—
Prior to version 4.0, these constituents of MinGW.OSDN WSL were released independently, with no synchronization of their version numbers. There is a commonly held misconception, that both of these constituent packages were released into the public domain, and thus, were exempt from licensing and copyright considerations. However, while it is true that all direct contributors to MinGW agreed to waive copyright, it is not, and never has been true that the entire code base is exempt from copyright; in fact, substantial portions of the code base have been acquired from third parties, who retain copyright, and have granted permission to redistribute under licences such as BSD, or MIT/X11, so while parts of the code base may be public domain, the work as a whole must be considered to be licensed under a hybrid collection of BSD, MIT/X11, and a few other compatible (generally very permissive) licences.
From version 4.0 onwards, the two constituents of the “MinGW.OSDN Windows System Libraries” have been published as an integrated package set; (version 4.x blurred the distinction between the two constituents; version 5.x reinstated it, but the two constituents are always released concurrently, with strictly synchronized version numbers). Additionally, from the release of version 4.0, and on account of the inadmissibility of the very concept of public domain, in certain legal jurisdictions, the entire “MinGW.OSDN Windows System Libraries” suite has been published under the terms of the MIT/X11 Licence, (except in the case of those elements of the code base to which some alternative explicit licence was already applicable; such elements retain their original licensing terms).
The code profiling extensions, which are included within the “MinGW.OSDN Windows System Libraries” distribution, are licensed under the terms of the GNU General Public Licence (GPL), Version‑2. If you use these profiling extensions within your code, then your application becomes subject to the terms of the GPL‑v2.
Other than the “MinGW.OSDN Windows System Libraries”, the principal packages which comprise the MinGW distribution, including the “GNU Compiler Collection (GCC)”, the “GNU Binary Utilities (binutils)”, the “GNU Debugger (GDB)”, and “GNU Make”, are derived from upstream GNU packages; as such, they are distributed under the terms of the GNU General Public Licence; (in the case of more recent releases, this will normally be GPL‑v3; earlier releases may often still be under GPL‑v2).