[fpc-pascal] code example where AnsiString used in FCL (SqlDB) causes data loss

[Jonas Maebe]

Graeme Geldenhuys wrote on Wed, 11 May 2016:

> My test program under FPC 2.6.4 doesn't give problems. It's when that
> same program is compiled under FPC 3.0.0 that it does. All due to String
> (and thus AnsiString) changing its encoding based on the running
> environment.

In FPC 2.6.x, if you use a widestring manager (such as cwstring), the  
code page of shortstring/ansistring/pchar /also/ depends on the  
running environment, in fact in exactly the same way as in FPC 3.x.  
The main thing that is new in FPC 3.x, is that instead of the RTL  
assuming that all ansistring contents are always encoded in this code  
page, we now explicitly attach the code page information in a hidden  
field of the ansistring structure (so different ansistrings can have  
different encodings, but the default for plain ansistrings remains  
exactly the same).

> With FPC 2.6.4 compiled programs, no matter the environment
> (UTF-8 or Latin-1), my test program behaves the same.

As I asked before: did you change "String" to "Unicodestring" when  
compiling under FPC 2.6.4? As mentioned before, {$modeswitch  
unicodestrings} is a new feature in FPC 3.0 and is ignored by FPC  
2.6.4 (you will get a warning about this when compiling with FPC  
2.6.4, but not an error).


Jonas