Formalise which versions of TeX Live/engines/Lua are supported about l3build

[josephwright]

I'm minded to say 'TeX Live 2016 versions onward': OK?

[josephwright]

I think with the move to a stand-alone script it will make sense to say that we only support the latest releases once TL'18 is out (and so the script is generally available). What I'll do is document that and get it to CTAN shortly.

[wspr]

Fine with me. It never occurs to me that people might run new code on old distributions...

[FrankMittelbach]

I just did by mistake on this machine ... it had some full set of latex files in my private |~/texmf| and as a result all my formats were 2015 even though it was a 2017 TL :-) gave me a strange error message this morning which made me realize that something is weird

[FrankMittelbach]

I'm minded to say 'TeX Live 2016 versions onward': OK?

yes

[josephwright]

LuaTeX is likely to give failures between different releases: I'll probably note that in the docs.

[cereda]

@josephwright Perhaps a compatibility matrix might help.

[FrankMittelbach]

@cereda keeping that maintained is more trouble than it is worth and a stale matrix helps nobody, so I don't think so in that case.

[cereda]

@FrankMittelbach ack. 😉

[josephwright]

Note that the biggest single issue is that LuaTeX normalisation depends on the release. So you have to update .tlg files every TeX Live release. That doesn't mean that l3build fails with TeX Live 2016: it's only the 'un-normlisable' bits that have altered.

[josephwright]

I think we are now in a position where it's 'any recent release' - I'd expect TL'20 and TL'21 to work at least.