Cygwin be gone
..well, almost.
If you look at bug 294122, you will notice that support for MSYS has been added to Mozilla's build system.
The relevant build notes are here:
Building with MSYS, Attachment 184389
"Just running "make clean" on Cygwin takes almost 6 minutes, vs only 1 minute with MSYS."
MSYS is a Minimal UNIX-like SYStem from MingW. Together with msysDTK (developer toolkit), it can replace cygwin as the base Windows build environment.
The big advantage of MSYS is speed. If you have ever built Mozilla on Windows, you will have noticed the abhorrent performance of Cygwin's make. make forks (or spawns as it is called in Win32) itself many hundred times during the course of a build which takes ages to complete. In comparison, MSYS is much more light-weight, zooming through the Makefile hierarchy like there is no tomorrow.
MSYS and msysDTK are fairly complete for this task. /bin/sh, CVS, make, vim - all the basics are there.
As the bug report notes, an iconv check has been recently added to Mozilla's configure. So, unless you install iconv separately, you currently still need cygwin. Perhaps iconv could be added to the msysDTK or be made available otherwise to address this.
