This commits fixes the flat encoding and decoding (and consequently,
the zigzag) for large integers in the following ways:
- It removes support for encoding and decoding i128 values.
- It optionally (feature = "num-bigint") introduces encoding and
decoding of large sized integers through the num-bigint::BigInt
type.
Without the feature enabled, it is still possible to encode and decode
isize values; but the use of i128 is now prohibited (as it would
overflow on boundaries) in favor of arbitrarily sized integers.
The commit also introduces a missing property roundtrip for encoding
and decoding large integers, which was missing and thus, failed to
identify the overflow problem.
See related issue: https://github.com/aiken-lang/aiken/issues/796
7cb1ffe100