Invasion analysis to identify open types

The automated identification of open types of a multi-function input program. The automated identification of open types is performed without annotations in the input program, but rather by identifying a set of invading types of the program, with each of the invading types being an open type. The identification of invading types may be performed iteratively until the set of invading types no longer grows. The set of open types may be used for any purpose such as perhaps the de-virtualization of an input program during compilation.