Another problem, also reported on the macpascal mailing list and reproduced by the following program:
[G5:gcc/p/test] adriaan% cat avo12.pas program avo12;
type Str255 = record sLength: Byte; sChars: packed array[1..255] of char; end;
function StringToStr255 ( const s: String ) = Result : Str255; begin Result.sLength := Min( Length( s ), 255 ); if Result.sLength > 0 then begin Result.sChars[1..Result.sLength] := s[1..Result.sLength]; end; end;
procedure DrawString1( const s: Str255); external name 'DrawString'; procedure DrawString2( protected var s: Str255); external name 'DrawString';
begin DrawString1( StringToStr255( 'Hello')); {OK} DrawString2( StringToStr255( 'Hello')) {Error: reference expected, value given} end.
[G5:gcc/p/test] adriaan% gpc avo12.pas avo12.pas: In main program: avo12.pas:19: error: reference expected, value given
In gpc-20030830, this was no problem, but now it is no longer allowed, which is quite inconvenient. In the GPC interfaces for Mac OS X, we use the external declaration form with a "protected var" because (according to the gc docs) the "const" declaration form doesn't guarantuee that the parameter is passed by reference, which is an ABI requirement.
Regards,
Adriaan van Os