Musings on GAPROOT

[fingolfin]

I wonder if setup-gap could export a global GAPROOT environment variable, so that all the other actions could reference it?

I never was comfortable with hardcoding a GAPROOT location everywhere; then again, it's not that bad as we control the environment.

But on the longterm, I guess we could instead let setup-gap install gap (or rather some shell script with that name which invokes the real GAP?) into a directory in the PATH. For the remaining cases that need it, well, one can figure it out from GAP code via Filename(DirectoriesLibrary(""),"sysinfo.gap"); (and then remove "/sysinfo.gap" from the end).

Finally, I think that future GAP versions should have a --get-gaproot or --sysinfopath or --get-primary-gaproot command line option so that one can query this more easily for scripts.

Originally posted by @fingolfin in gap-actions/process-coverage#7 (comment)

[fingolfin]

An alternative (not mutually exclusive) of course is to turn GAPROOT into an input for those actions that need it. Which is essentially just build-pkg, it seems -- run-pkg-tests only needs it to invoke gap (but that'd be covered by having that in PATH); and similar for process-coverage, which also uses GAPROOT inside some GAP code, which however could also figure it out on its own as sketched above.