ISO Pascal reference manual

PROGRAM fail(output);
FUNCTION two:integer; FORWARD;
PROCEDURE show; BEGIN
writeln(two);
END;
FUNCTION two:integer; {not permitted}
BEGIN
two := 22222;
END;
BEGIN
show;
END.
*ERROR 68 -- the type of result returned by does not
match a previous FORWARD declaration
This message is issued when the type of a function is different from a
previous specification of that function. The error is an additional indication
of trouble as it is only ever generated under the circumstances when error
70 will also be issued.
PROGRAM fail(output);
FUNCTION two:integer; FORWARD;
PROCEDURE show; BEGIN
writeln(two);
END;
FUNCTION two:real; [not permitted}
[and the wrong type}
BEGIN
two := 22.222;
END;
BEGIN
show;
END.
68 Pascal Issue I