A small suggestion:
As described in Firebird Pascal API User guide (section 2.5), on top of IB.pas, there are two definitions:
{$DEFINE USEFIREBIRD3API}
{$DEFINE USELEGACYFIREBIRDAPI}
which say that the ibintf package will be compiled with support for both legacy api and new api.
Now we can change this by commenting out one of these if we do not intend to use it.
Although commenting out a line is quite simple, I just prefer not to change the original sources. So I'd suggest you change these lines to:
{$IF NOT DEFINED(USEFIREBIRD3API) AND NOT DEFINED(USELEGACYFIREBIRDAPI)}
// only if none of this is already defined, define both:
{$DEFINE USEFIREBIRD3API}
{$DEFINE USELEGACYFIREBIRDAPI}
{$ENDIF}
This way, I will be able put -dUSEFIREBIRD3API in my
project's compiler options and my project will be compiled with fbintf library supporting new api only. If none of these options is added to the project options, both will be included.
In my opinion this is cleaner way than changing the sources.