bug#50861: Bug in kexport:html

[Hugo Thunnissen]

Hi there,

I am using hyperbole version 7.1.3.
On GNU Emacs 27.2 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.25)

When exporting a kotl-mode file using `kexport:html' I encountered a
problem with the regex that is used to replace klinks with a HTML anchor
tag. The problem seemed to stem from the use of the \\0 back
reference. 

Relevant part of the backtrace:

    Debugger entered--Lisp error: (error "Invalid use of ‘\\’ in replacement 
text")
    replace-match("<A HREF=\"#k\\1\">\\0</A>" nil nil "&lt;@ 5a&gt;" nil)


I was able to fix the problem with the following code:
    
    (eval-after-load 'kotl-mode
      (let ((klink-replacement
             (cons (format "&lt;\\s-*@\\s-*\\(%s\\)[^=&>]*&gt;"
                               kexport:kcell-partial-reference-regexp)
                   "<A HREF=\"#k\\1\">\\1</A>")))
        (setf (alist-get (car klink-replacement) kexport:html-replacement-alist 
nil nil 'string=)
              (cdr klink-replacement))))
    
which essentially just replaces the \0 reference in the replacement
text with a \1 reference. I can't find documentation of a \0
back-reference in the elisp regexp manual, as the \N references are
1-based according to it
(https://www.gnu.org/software/emacs/manual/html_node/elisp/Regexp-Backslash.html).
 Is
there something I'm missing?

If there is something I can do to help or give you more information, let
me know.

-Hugo