1. A method of providing compiler option consistency checking for an incremental compilation process, the method comprising: receiving a candidate code unit at a compiler, the candidate code unit associated with a current consistency rule, the current consistency rule comprising current compiler options and corresponding current compiler option values; accessing a saved precompiled code unit associated with the candidate code unit, the saved precompiled code unit associated with a saved consistency rule, the saved consistency rule comprising saved compiler options and corresponding saved compiler option values; determining, at the compiler, prior to compiling or precompiling the candidate code unit, that the saved precompiled code unit can be reused for the candidate code unit, the determining comprising comparing the current consistency rule to the saved consistency rule; compiling the candidate code unit and saving the candidate code unit with current compiler options and consistency rule based on determining that the current consistency rule is not a subset of the saved consistency rule; and reusing the saved precompiled code unit as part of an incremental compilation process performed by the compiler based on determining that the current consistency rule is a subset of the saved consistency rule, and that the current consistency rule has no additional options to process.