Re: integer overflow

[Chong Yidong]

Glenn Morris <address@hidden> writes:

> I don't really understand it. In a 32-bit Emacs:
>
> (1+ 536870911) -536870912
> (+ 2 536870911) -536870911
> (1+ 536870912)  536870913.0
> (1+ 4294967295) overflow
> (1+ 4294967295.0) 4294967296.0
>
> Can you summarize how it's supposed to work?

The change affects the Lisp reader: reading "536870912" or any larger
number now gives you a float Lisp object, instead of an integer Lisp
object (since there is no way to represent 536870912 or larger as
integers).  536870911 and below are still read as integers.

The change does not prevent the possibility of overflowing integers, as
your example shows.