TypeInfo problem

[Lloyd Dupont]

Let's say I have 2 value only accessible through function pointers taking a 
variant parameter.
(they will throw on incorrect value, but I'd rather avoid that).
I also know the TypeInfo of both variables.
How could I know that a given TypeInfo is a valid value for another 
TypeInfo.

In other words I'd like to write a method like
bool isAcceptable(TypeInfo srcValueType, TypeInfo dstType) {  /* ?? */ }