bug#63837: 29.0.91; delete-forward-char error with composed text

bug#63837: 29.0.91; delete-forward-char error with composed text

[Thiago Melo]

* How to reproduce:

0. Start emacs with `emacs -Q'
1. Create some text composition, e.g. eval: `(insert (compose-chars ?+))'
2. Move cursor to before composed character
3. `M-x delete-forward-char' or press <delete> key

* Backtrace:

Debugger entered--Lisp error: (wrong-type-argument sequencep t)
  lgstring-glyph-boundary(t 1 2)
  delete-forward-char(1 nil)
  funcall-interactively(delete-forward-char 1 nil)
  call-interactively(delete-forward-char nil nil)
  command-execute(delete-forward-char)

bug#63837: 29.0.91; delete-forward-char error with composed text

[Robert Pluim]

>>>>> On Fri, 2 Jun 2023 10:42:29 +0000, Thiago Melo <tmdmelo@gmail.com> said:

    Thiago> * How to reproduce:
    Thiago> 0. Start emacs with `emacs -Q'
    Thiago> 1. Create some text composition, e.g. eval: `(insert (compose-chars ?+))'
    Thiago> 2. Move cursor to before composed character
    Thiago> 3. `M-x delete-forward-char' or press <delete> key

    Thiago> * Backtrace:

    Thiago> Debugger entered--Lisp error: (wrong-type-argument sequencep t)
    Thiago>   lgstring-glyph-boundary(t 1 2)
    Thiago>   delete-forward-char(1 nil)
    Thiago>   funcall-interactively(delete-forward-char 1 nil)
    Thiago>   call-interactively(delete-forward-char nil nil)
    Thiago>   command-execute(delete-forward-char)

How about this (for master, since your example is somewhat contrived :-))

diff --git a/lisp/simple.el b/lisp/simple.el
index 3f88fcb8d03..efe6895fabc 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -1527,9 +1527,11 @@ delete-forward-char
                           ;; character.
                           ((<= to pos)
                            (1+ pos))
-                          (t
+                          ((vectorp (nth 2 cmp))
                            (lgstring-glyph-boundary (nth 2 cmp)
-                                                    from (1+ pos)))))
+                                                    from (1+ pos)))
+                          (t
+                           (1+ pos))))
                      (1+ pos)))
              (setq n (1- n)))
            (delete-char (- pos start) killflag)))


Robert
-- 

bug#63837: 29.0.91; delete-forward-char error with composed text

[Eli Zaretskii]

> From: Thiago Melo <tmdmelo@gmail.com>
> Date: Fri, 2 Jun 2023 10:42:29 +0000
> 
> * How to reproduce:
> 
> 0. Start emacs with `emacs -Q'
> 1. Create some text composition, e.g. eval: `(insert (compose-chars ?+))'
> 2. Move cursor to before composed character
> 3. `M-x delete-forward-char' or press <delete> key
> 
> * Backtrace:
> 
> Debugger entered--Lisp error: (wrong-type-argument sequencep t)
>   lgstring-glyph-boundary(t 1 2)
>   delete-forward-char(1 nil)
>   funcall-interactively(delete-forward-char 1 nil)
>   call-interactively(delete-forward-char nil nil)
>   command-execute(delete-forward-char)

Thanks, should be now fixed on the emacs-29 branch.

bug#63837: 29.0.91; delete-forward-char error with composed text

[Eli Zaretskii]

> Cc: 63837@debbugs.gnu.org
> From: Robert Pluim <rpluim@gmail.com>
> Date: Fri, 02 Jun 2023 14:05:17 +0200
> 
> How about this (for master, since your example is somewhat contrived :-))

The example might be contrived, but the recognition of static
compositions is completely incorrect: find-composition returns a
3-element list for those, not a two-element list.

I fixed that on emacs-29.

bug#63837: 29.0.91; delete-forward-char error with composed text

[Thiago Melo]

On Fri, Jun 2, 2023 at 12:05 PM Robert Pluim <rpluim@gmail.com> wrote:
> How about this [...]
>
> diff --git a/lisp/simple.el b/lisp/simple.el
> [...]

Thank you, Robert.  I've tested your patch and it works in my simple
situation.  But I cannot tell if it works with other cases.  Consider
Bug#56237, for example.

> [...] since your example is somewhat contrived :-)

I actually found it with the package `org-superstar-mode', while
trying to delete the headline star characters it creates.

bug#63837: 29.0.91; delete-forward-char error with composed text

[Thiago Melo]

On Fri, Jun 2, 2023 at 12:48 PM Eli Zaretskii <eliz@gnu.org> wrote:
> I fixed that on emacs-29.

Thanks, Eli.  It also works for me.

I also saw the related Bug#56237.  From what I could test, it seems
your fix doesn't cause a regression in their use case.  Right? (eg,
when deleting the text "ரு போ").

bug#63837: 29.0.91; delete-forward-char error with composed text

[Eli Zaretskii]

> From: Thiago Melo <tmdmelo@gmail.com>
> Date: Fri, 2 Jun 2023 13:42:19 +0000
> Cc: Robert Pluim <rpluim@gmail.com>, 63837@debbugs.gnu.org
> 
> On Fri, Jun 2, 2023 at 12:48 PM Eli Zaretskii <eliz@gnu.org> wrote:
> > I fixed that on emacs-29.
> 
> Thanks, Eli.  It also works for me.

Thanks, closing the bug.

> I also saw the related Bug#56237.  From what I could test, it seems
> your fix doesn't cause a regression in their use case.  Right? (eg,
> when deleting the text "ரு போ").

The current fix didn't touch that case, it only touched the case of
static compositions, not automatic compositions.