We've been wrongly representing large ints as BigInt, causing them to
behave differently in the VM through builtins like 'serialise_data'.
Indeed, we expect anything that fits in 8 bytes to be encoded as Major
Type 0 or 1. But we were switching to encoding as Major type 6
(tagged, PosBigInt, NegBigInt) for much smaller values! Anything
outside of the range [-2^32, 2^32-1] would be treated as big int
(positive or negative).
Why? Because we checked whether a value i would fit in an i64, and if
it didn't we treated it as big int. But the reality is more subtle...
Fortunately, Rust has i128 and the minicbor library implements TryFrom
which enforces that the value fits in a range of [-2^64, 2^64 - 1], so
we're back on track easily.
to pass 2 of the conformance tests, we need to make sure
that we aren't typechecking builtin arguments as arguments
are applied. This switches push to by removing the call to check_type
and then reworking all the associated unwrap methods on Value
so that they return the same errors that were being returned before.
KtorZ