#1835: Error in the utf8 egg's substring=?

[Chicken Trac]

#1835: Error in the utf8 egg's substring=?
------------------------+---------------------------------
 Reporter:  siiky       |                 Owner:  siiky
     Type:  defect      |                Status:  assigned
 Priority:  major       |             Milestone:  someday
Component:  extensions  |               Version:  5.4.0
 Keywords:  utf8        |  Estimated difficulty:
------------------------+---------------------------------
 First found it using tab-completion in {{{csi}}}:

 {{{
 Error: (substring=?) out of range
 3
 0
 3

         Call history:

         utf8-srfi-13.scm:374: proc
         utf8-srfi-13.scm:374: proc
         utf8-srfi-13.scm:374: proc
         utf8-srfi-13.scm:374: proc
         utf8-srfi-13.scm:374: proc
         utf8-srfi-13.scm:374: proc
         utf8-srfi-13.scm:374: proc
         utf8-srfi-13.scm:374: proc
         utf8-srfi-13.scm:374: proc
         utf8-srfi-13.scm:374: proc
         utf8-srfi-13.scm:374: proc
         utf8-srfi-13.scm:374: proc
         utf8-srfi-13.scm:374: proc
         utf8-srfi-13.scm:374: proc
         utf8-srfi-13.scm:374: proc
         utf8-srfi-13.scm:374: proc              <--
 }}}

 This is seen in the egg's tests as well: http://salmonella-linux-x86.call-
 cc.org/master/clang/linux/x86/2024/04/11/salmonella-report/test/utf8.html
 ({{{chicken-install}}}'s exit code is 0, I'm not seeing why -- there's a
 {{{test-begin}}} at the top and a {{{test-end}}} at the bottom -- though
 this is another problem):

 {{{
 (string-prefix? "元麻布" "麻布十番" 1) ........................ [ERROR]

 Error: (substring=?) out of range
 6
 0
 6
 (string-prefix? "元麻布" "麻" 1 2) ............................... [ERROR]

 Error: (substring=?) out of range
 3
 0
 3
 }}}

 It's almost certain these errors are related to the recent changes made to
 {{{substring=?}}} and friends: https://code.call-cc.org/cgi-
 bin/gitweb.cgi?p=chicken-
 core.git;a=commit;h=0e97b648407d750f1e476e3c193e136126558346

-- 
Ticket URL: <https://bugs.call-cc.org/ticket/1835>
CHICKEN Scheme <https://www.call-cc.org/>
CHICKEN Scheme is a compiler for the Scheme programming language.