E.12. abuild --help rules toolchain:mingw

** Help for users of the "mingw" compiler **

Abuild's mingw support is incomplete.  At present, it is implemented
using Cygwin's gcc or g++ with the -mno-cygwin option.

There are a few known problems.  Since abuild itself is a Windows
application but make and gcc are both provided by Cygwin, absolute
paths are not portable between the two systems.  This means that
abuild's mingw support will almost surely not work if there are any
absolute paths in your build or if there are any build items that span
drive letters.  However, for simple builds, it will probably work fine
and generate executables that don't depend on Cygwin at runtime.

Because of the incomplete nature of mingw support, you must set the
environment variable MINGW=1 in order for abuild to make the mingw
compiler available as a platform choice.