I found what appears to a subtle difference between the Delphi & Kylix3 handling of dynamic array assignment and FPC in Delphi mode. If an assignment is made along the lines:
type
TArray : array of Integer;
var
A, B : TArray;
I : Integer;
type
function F ( C : TArray ) : TArray;
begin
{ does nothing }
end
begin
SetLength(B,4);
for I := 0 to 3 do
B[I] := I;
A := Copy(B);
A := F(B); { what is the correct answer here? }
end;a question arises as to the value of A. Should it be nil or should it be a copy of B?
Delphi and Kylix assume that because the function F does not assign a value to Result (ie, does not assign a return value) that the Lvalue assigned from F remains unchanged.
FPC assigns nil to A which IMHO is correct, but not when run in "bug for bug" Delphi compatibility mode.
Obviously F not assigning Result is a programming error, but unfortunately it can be a common one in legacy code.
What do others think about this compatibility difference?
Should it be fixed or should (possibly large) legacy codebases be debugged?
Cheers, Bruce.