Michael Tuexen writes:

> Hi Marius,
>
> I tried to compile it on Mac OS X, but the following comes up: [...]
>
> srfi-13.c: In function `scm_string_trim_right':
> srfi-13.c:771: warning: passing arg 3 of `scm_i_get_substring_spec'
> from incompatible pointer type

I've attached a patch that replaces the remaining occurrences of int in 
srfi-13.c with size_t. In addition to these replacements, the function 
string_reverse_x() makes sure that the variable cend is only 
decremented if it's value is greater than zero.

One thing that I noted is that the variable cfrom in scm_xsubstring() 
and the variable csfrom in scm_string_xcopy_x() are of type size_t but 
that they are checked for negative values:

int t = ((cfrom < 0) ? -cfrom : cfrom) % (cend - cstart);
if (cfrom < 0)
....

I've tested this patch on Mac OS X and OpenBSD.

BTW, do you prefer included or attached patches?