[Bug modula2/109908] New: Delete from m2iso Strings is broken

["gaius at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109908

            Bug ID: 109908
           Summary: Delete from m2iso Strings is broken
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: modula2
          Assignee: gaius at gcc dot gnu.org
          Reporter: gaius at gcc dot gnu.org
  Target Milestone: ---

Created attachment 55117
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=55117&action=edit
test code for m2iso Strings.Delete

As reported on the gm2 mailing list the m2iso Strings.Delete is broken for
example the following test code fails:

$ gm2 --version
gm2 (GCC) 14.0.0 20230511 (experimental)
Copyright (C) 2023 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ gm2 -g -fiso testdelete.mod
$ ./a.out

after Delete string one = '1'
error: string one should be empty after delete
error: string one have length 0 after delete
after Delete string two = '221'
error: string two should be '2' after delete
error: string two have length 1 after delete
after Delete string three = '233221'
error: string three should be '23' after delete
error: string three should have length 2 after delete
after Delete string four = ''
after Delete string large = '01234567890123456789'
after Delete string large = '01234567890123456789'
after Delete string three = '133221'
error: string three should be '13' after delete
error: string three should have length 2 after delete
after Delete string four = '13'