'auto' is only available to use when the type of a variable can be automatically deduced from its initializer, meaning the declaration would be redundant. It has nothing to do with type conversions.
edit: now I see what you mean in the context of adding assertions to make type conversions safer, and how there could be some parallels with auto for that
It's implicit declaration, which seems worse in some ways than implicit conversions. After a conversion you know what type you have even if not the type you started with.
edit: now I see what you mean in the context of adding assertions to make type conversions safer, and how there could be some parallels with auto for that