5.5.1.1 Static semantics

Let-coercion between the following pairs of source declared types or literals and destination declared types is invalid:

Source Declared Type or Literal	Destination Declared Type
Any type	Any fixed-size array
Any numeric type or Boolean or Date	Resizable Byte()
Any type except a non-Byte resizable or fixed-size array or Variant	Any non-Byte resizable array
Any type except a UDT or Variant	Any UDT
Any type except Variant	Any class or Object
Any class which has no accessible default Property Get or function, or which has an accessible default Property Get or function for which it is statically invalid to Let-coerce its declared type to the destination declared type	Any type
Any non-Byte resizable or fixed-size array	Resizable array of different element type than source type or any non-array type except Variant
Any UDT	Different UDT than source type or any non-UDT type except Variant
UDT not imported from external reference or array of UDTs not imported from external reference or array of fixed-length strings	Variant
Nothing	Any type except a class or Object or Variant

 

It is also invalid to implicitly Let-coerce from the LongLong declared type to any declared type other than LongLong or Variant. Such coercions are only valid when done explicitly by use of a CType explicit coercion function.