I don't know how complete this is, but it certainly detects some of the
most obvious cases which are most likely to be bugs.
While I'm at it, this is as good a time as any to add a general way of
reporting warnings, similar to the way of reporting errors.
Still a couple of things to resolve in coverage and totality checking
before we can switch on %default, so don't expect quite the right
behaviour just yet. More progress though!
Also working on this has caught a few totality errors in the Idris 2
code base that Idris 1 missed... so these are fixed on the way.
The hack (optimisation?) to normalise integer literals when below some
threshold is fine on the RHS, but on the LHS causes problems since we
need them in normal form for pattern matching. Fixes#112
This improves coverage checking, because it can now see that things like
(Z = S x) and (x = S x) are empty. Previously, it only checked that all
possible constructors had a disjoint index. Now, it looks for matches
and checks for disjointness in the matches, which catches a lot more
things especially with equality.
This is added to functions which are guaranteed to be productive. The
check is currently very conservative - just added when every clause is
constructor headed (or headed by an AllGuarded function), and there are
no other function applications.
If we never evaluate under Delay at all, we won't inline interface
methods, which means productive things defined in an interface can never
be today. So, make sure to set the tcinline flag before quoting the
Delayed closure.
As in Idris 1 - if an interface declares a method as total or covering,
then all implementations have to satisfy that.
Temporarily turn off %default directive again, at least until totality
checking works as it should (this is probably better than removing it
from various places because I'll forget to put them back)
