Potential pointer corruption.
If code assumes that pointers and integers are the same size (in an arithmetic context), there will be problems.
Pointer arithmetic is often a source of problems when migrating code. The ISO C standard dictates that incrementing a pointer adds the size of the data type to which it points to the pointer value. For example, if the variable p is a pointer to long, the operation (p+1) increments the value of p by 4 bytes (in 32-bit mode) or by 8 bytes (in 64-bit mode). Therefore, casts between long* and int* are problematic because of the size differences between pointer objects (32 bits versus 64 bits).
