How are function pointers type unsafe

Question

First of all type-safe means that anything that a compiler can catch straight away if done incorrectly.

Now, I heard function pointers are not type safe however when

Answer 1

Function pointers are strongly discouraged in nesC (a dialect of C used in TinyOs), for the reason that they hinder optimisation. Here static code analysis (or rather the lack of its applicability) is a bigger concern than type-safety, but I'm not sure whether these issues could be confused.

Another issue might be the use of function pointers as event handlers. When using a general event scheduler, you may want to abstract from the proper type, which would mean that you could have the idea to store function pointers as void* just for the sake of modularity. This would be a prominent example of type-unsafe usage of function pointers instead of type-safe dynamic binding usage.