inconceivable (cargo): `inconceivable!` is a macro which closely parallels `std::unreachable`, or `std::panic`. The primary difference is that when this crate is configured with the `ub_inconceivable` option it will emit the `core::hint::unreachable_unchecked` to hint for the compiler to understand a condition should never occur.  Generally compiler(s) (the LLVM) assume UB won't happen. This macro offers the "best of both worlds", it provides a solid way of asserting/testing behavior in local builds, but also a way of stripping branches out of final release builds.  Please Note: This crate is created purely to inject undefined behavior into stable, safe rust. Systematic usage is unwise, and not recommended. 
Keywords: panic|unreachable|inconceivable|ub