The best answer really is "Your mileage may vary." MSYS make is nominally based on GNU make, but using the MinGW platform interface instead of directly accessing the Windows platform underneath. Electric Make supports GNU make emulation of course, so that part should be no problem; but you may run into trouble with some MinGW-specific platform quirks. Unfortunately we don't have an exhaustive list of MinGW platform differences compared to Windows, so we can't really tell you where you might see problems. I would guess that it would be around the way file paths are specified, or with support for filesystem constructs beyond the most rudimentary files/directories (eg, symlinks, which are not really directly supported on Windows, and therefore must be emulated by the platform interface in some fashion). In addition, there is always the possibility that MSYS has modified some aspect of GNU make behavior.
Do note that in ElectricAccelerator 6.2.0 we added very, very limited support for the MinGW platform, via the
--emake-platform=mingw command-line option. Enabling that will cause emake to use MinGW-specific behaviors where we have implemented them. Be warned however, this support is extremely limited in 6.2.0, and the presence of that option is not a commitment to provide support for other MinGW behaviors. If it works for you, great! If not, we'll consider enhancement requests on a case-by-case basis.
--emake-platform is orthogonal to
--emake-emulation: one controls the platform interface, the other the make emulation mode. You may need to specify both depending on exactly what version of GNU make your version of MSYS make is based upon.