[fpc-devel] Bug 4004

Hans-Peter Diettrich DrDiettrich at compuserve.de
Tue Jun 7 02:07:13 CEST 2005

Gerhard Scholz wrote:
> The check for overflow is obviously implemented different in 2.0.0 and 2.1.1

I'm not sure, at least

> .L9:
>      movw %dx,-12(%ebp)
> .Ll3:

suggests that the target is not an integer, but instead is a (possibly
unsigned) word type. Please check again!

> A solution would be to replace that line by:
>     d := integer(Ord(a))-Ord(b)
> It seems that the compiler now sees a "ord(c)" to be a BYTE, and BYTE - BYTE
> shall give a BYTE, and -1 is not in the range allowed for a BYTE.

Differences always should be interpreted as signed values, the error
message IMO comes from the final assignment.

> The line " i := Ord('0')-Ord('1') " in the main program is not interesting,
> since it contains a constant expression and is converted to " i := -1 " by
> the compiler.

Now you assume that the difference can exceed the range of Ord(char),
when computed at compile time? Or is it only the different type of the
target variable?


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