Compile-time checking for exhaustive switch statements and expressions

Abstract

Techniques for compiling switch blocks are disclosed. One or more embodiments analyze and rewrite a set of pattern labels in a switch block in a compile-time process for determining whether the switch block is exhaustive. At compile-time, a system populates a set with case labels from a switch block. The system applies a set of rules to iteratively re-write pattern labels in the set and checks whether the re-written set, and hence the original switch block, is exhaustive. If the compiler determines that (a) the set does not appear to be exhaustive, and (b) the set includes patterns labels, then the compiler determines whether the set may be rewritten before further analysis. The compiler iteratively re-writes and re-analyzes the case label set for exhaustivity until the case label set is determined to be exhaustive or cannot be rewritten further.