Exhaustiveness checking in TypeScript

Unreachable code path optimization hint for Swift

A Rust macro xkcd_unreachable!() inspired by https://xkcd.com/2200/

Files you can't open

unreachable compiler hint for C

Compile time asserts and other utilities for code validation

A syntax extension that denotes unreachable code and prints descriptive errors when the code is reached

Exception types for marking unreachable/unimplemented code