[ModularForms] Upgrade to version 0.2.1

[martinra]

In the meantime, FLINT has incorporated Arb, which is therefore no longer a separate dependency.

The skipped v0.2 was an internal build that contained an error.

[fingolfin]

Tests are failing

[martinra]

I hope to get to this on the weekend; But if I may, one question: I was urged to widen compatibility to get this into Yggdrasil, but we never develop or build for anything but Linux. Is it correct to narrow compatibility to what is actually supported?

[fingolfin]

If something really doesn't work on a platform and requires major work to support, then it is OK to drop it, but it is still strongly recommended to at least document why something was disabled ("disable platform X because Y fails"), so that someone who does need it there in the future has a better idea of what's going on.

In this particular case it seems your handcrafted build system assumes a linker supporting the -r flag with a certain meaning?

Anyway, in the end, do what you need to do.

[martinra]

Just to keep this updated: I decided to port the building system to CMake (or Mason, still not quite decided). I'll just need time to do this, since it's years ago that I touched CMake.

[fingolfin]

That sounds great @martinra, but just to clarify my perhaps somewhat cryptic earlier comment (sorry): if you need this now, you don't have to rewrite your build system just to make me happy: i.e. we can merge this if yo disable the apple platforms, just please add a comment why ("build system uses -r as linker flag in a way that is not supported by macOS linker" or so).

But of course if you really are OK with improving that build system, that'd be even nicer :-)