On windows, it was observed that all executables were also producing a .lib and .exp file, even though no symbols should have been exported (e.g. from unit tests).
Dumping the file showed that the exported symbols were specializations of mongo::parseNumberFromStringWtihBase.
It appears that parseNumberFromStringWtihBase uses the unconditional export macro MONGO_COMPILER_API_EXPORT instead of the conditional MONGO_CLIENT_API macro, forcing the symbol to be exported and causing the generation of .lib and .exp files for all executables linking to the parse_number.obj file.
Arguably, we should remove MONGO_CLIENT_API everywhere in the kernel now that the driver has diverged. Alternatively, we should just change this instance of MONGO_COMPILER_API_EXPORT to MONGO_CLIENT_API.