Missing exported lib is only a warning, so a half-built package looks like success

[battlesnake]

Hey, first off thanks for mama. It quietly does a ton of work across our repos and mostly just gets out of the way, which is exactly the point.

Ran into a head-scratcher today and I think it comes down to one small spot in package.py, so I wanted to jot it down while it's fresh.

I ended up with a dependency whose static lib never actually got built (partly our fault, a stale build dir on our side). The thing is, mama's export step noticed the lib was missing but just logged it and carried on:

# mama/package.py, export_lib()
else:
    console(f'export_lib failed to find: {path}')

So the package reported as exported/deployed just fine, everything looked green, and the build happily went on to compile our whole app. It only fell over at the very end, at the final link, with a big pile of undefined symbols. That took a good while to trace back to the one missing .a from way earlier.

What bit me is that it's non-fatal: a target that is told to export libFoo.a but can't find libFoo.a still counts as a success, and the real failure shows up minutes later and a repo away, where it's much harder to connect back to the cause.

One small idea, if you think it's worth it: treat a missing export_lib as an error right there (or mark the target as not-actually-built so it rebuilds next pass), instead of a console warning. If some targets legitimately export optional libs, maybe an opt-in required=True on export_lib would keep both behaviours.

Nothing urgent, and I fully expect there's some history here I'm not seeing. Just figured a quick heads up might save the next person the same evening I had. Thanks again, it's a genuinely handy tool.

(Seen with mama 0.12.10; the same export_lib shape is in current main too.)