Emacs core dump in a file with whitespace character %09

[MatthewZMD]

I have this minor mode enabled globally for all of my prog-modes. Recently I notice Emacs suddenly core dump when I am navigating a file. After some research, it occurs when a line containing the whitespace character " " with Unicode entity %09. If I open a file containing this character with highlight-indent-guides mode disabled, Emacs won't core dump. As I M-x highlight-indent-guides-mode manually, Emacs immediately core dump.

However, I cannot reproduce this bug in a completely new file that does not contain this character initially. Does anyone have a clue?

Emacs Version: GNU Emacs 28.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.13, cairo version 1.17.3) of 2020-01-18 config

[DarthFennec]

Strange. Any particular major mode or situation this happens in, or is it everywhere? What if a file has tab characters later in a line, and none in indentation? It doesn't make much sense to me that opening a file with tabs causes the crash, yet adding tabs to a new file does not, since it uses the same code to highlight both situations, but this might end up being an important clue. I haven't tried Emacs 28 yet, so it might introduce some incompatibility that could be causing this.

If you start with a clean config, with only this mode loaded, does it still happen? That would tell us whether the problem is caused by some other part of your configuration.

[MatthewZMD]

Strange. Any particular major mode or situation this happens in, or is it everywhere?

I encountered it in c-mode.

What if a file has tab characters later in a line, and none in indentation? It doesn't make much sense to me that opening a file with tabs causes the crash, yet adding tabs to a new file does not, since it uses the same code to highlight both situations, but this might end up being an important clue.

It doesn't make sense to me as well.

I haven't tried Emacs 28 yet, so it might introduce some incompatibility that could be causing this.

If you start with a clean config, with only this mode loaded, does it still happen? That would tell us whether the problem is caused by some other part of your configuration.

I'll keep in mind and test when I have the time.

-- Mingde (Matthew) Zeng