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