Delphi XE - RawByteString vs AnsiString

Question

I had a similar question to this here: Delphi XE - should I use String or AnsiString? . After deciding that it is right to use ANSI strings in a (large) library of mine, I have

Answer 1

RawByteString is still an "AnsiString." It is best described as a "universal receiver" which means it will take on whatever the source-string's codepage is at the point of assignment without forcing a codepage conversion. RawByteString was intended to be used only as a function parameter so that you will, as you've discovered, not incur a conversion between AnsiStrings with differing code-page affinities when calling utility functions which take AnsiStrings.

However, in the case above, you're assigning what is essentially an AnsiString to a UnicodeString which will incur a conversion. It must do a conversion because the RawByteString has a payload of 8bit-based characters, whereas a string (UnicodeString) has a payload of 16bit-based characters.