Quasar M4 is an attempt to provide a drop-in replacement for the GNU implementation of the M4 macro language. Quasar M4 was forked from FreeBSD 9.1, but will not attempt to follow changes in the BSD code, as it is focused more on providing a drop-in replacement for GNU M4 for Linux users. Quasar M4 provides several more GNU compatibility features than BSD M4, and all GNU compatibility features are on by default and can not be turned off. Although Quasar M4 is a much smaller and simpler program than GNU M4, implementing nearly the same feature set in about 1/20 the code size, I implemented Quasar M4 because GNU M4 is nearly impossible to compile in unusual minimalist Linux environments. Quasar M4 is available under the same BSD license as the BSD M4 from which it is derived.
January 30, 2015. Fixed a bug in which undiversion was not working correctly in some environments. Removed the -g flag, which enabled certain GNU compatibility features, and had those features enabled by default instead. Improved the build system and documentation.
April 5, 2013. Initial release after porting from BSD M4. Rewrote the build system, ported to Linux, and implemented the -P, -F, and -R flags.
You can contact me by email at william (at) haddonthethird (dot) net.