Panicking from C is not UB in newer rust versions and will reliably
trigger an abort (without unwinding). In older rust versions, it is
technically UB but empirically it seems to "just work" (and what should
it realistically do except crashing, which is what we intent).
Since there's potentially no unwinding, we can't test this behavior
using [should_panic]. This PR will instead check the libtest output
explicitly in our CI tests.
Fixes#228.
It's super dangerous to use Cargo features for this, since they can be set
accidentally (or maliciously by any crate in a user's entire dep tree). Instead
we can just require users set `RUSTFLAGS` appropriately, which we can easily
do in our fuzzing scripts.
Devrandom
Tim Ruffing
Andrew Poelstra
Elichai Turkel