bug#70816: 29.2; Flymake fails in latex-mode when the buffer is narrowed

[Eli Zaretskii <eliz@gnu.org>]

> Cc: 70816@debbugs.gnu.org
> From: Arash Esbati <arash@gnu.org>
> Date: Tue, 07 May 2024 17:19:03 +0200
> 
> Vangelis Evangelou <evangelou@gmail.com> writes:
> 
> > With the buffer having the contents shown below,
> > 1. Enable flymake-mode.
> > 2. Narrow from the top of the buffer down to the indicated comment.
> > 3. Execute flymake-start.
> 
> The reproducer for me was to save a file like this (note the first blank
> lines):
> 
> --8<---------------cut here---------------start------------->8---
> 
> 
> 
> \documentclass{article}
> \begin{document}
> 0
> a
> b
> cf
> % <----- End narrow
> d
> e
> f
> g
> h
> i
> j{
> \end{document}
> --8<---------------cut here---------------end--------------->8---
> 
> Then:
> 
>   • emacs -Q
>   • M-x toggle-debug-on-error RET
>   • Visit the file, M-x flymake-mode RET
>   • Mark '\document... End narrow' and hit 'C-x n n'
>   • Put point after c and hit f

Spencer, can you please look into this?

> 
> This is what the debugger says (linebreaks added manually):
> 
> --8<---------------cut here---------------start------------->8---
> Debugger entered--Lisp error: (wrong-type-argument integer-or-marker-p nil)
>   make-overlay(nil nil)
>   flymake--highlight-line(#s(flymake--diag :locus #<buffer
>   flymake-test.tex> :beg nil :end nil :type :warning :text "No match
> found for `{'." :backend tex-chktex :data nil :overlay-properties nil
> :overlay nil :orig-beg nil :orig-end nil))
>   flymake--publish-diagnostics((#s(flymake--diag :locus #<buffer
> flymake-test.tex> :beg nil :end nil :type :warning :text "No match
> found for `{'." :backend tex-chktex :data nil :overlay-properties nil
> :overlay nil :orig-beg nil :orig-end nil) #s(flymake--diag :locus
> #<buffer flymake-test.tex> :beg 54 :end 73 :type :warning :text
> "Number of `{' doesn't match the number of `}'!" :backend tex-chktex
> :data nil :overlay-properties nil :overlay nil :orig-beg 54 :orig-end
> 73)) :backend tex-chktex :state #s(flymake--state :running
> backend-token1 :reported-p nil :disabled nil :diags (#s(flymake--diag
> :locus #<buffer flymake-test.tex> :beg nil :end nil :type :warning
> :text "No match found for `{'." :backend tex-chktex :data nil
> :overlay-properties nil :overlay nil :orig-beg nil :orig-end nil))
> :foreign-diags #<hash-table eql 0/0 0x43d74c56 ...>) :region nil)
>   flymake--handle-report(tex-chktex backend-token1 (#s(flymake--diag
> :locus #<buffer flymake-test.tex> :beg nil :end nil :type :warning
> :text "No match found for `{'." :backend tex-chktex :data nil
> :overlay-properties nil :overlay nil :orig-beg nil :orig-end nil)
> #s(flymake--diag :locus #<buffer flymake-test.tex> :beg 54 :end 73
> :type :warning :text "Number of `{' doesn't match the number of `}'!"
> :backend tex-chktex :data nil :overlay-properties nil :overlay nil
> :orig-beg 54 :orig-end 73)))
>   apply(flymake--handle-report tex-chktex backend-token1
> (#s(flymake--diag :locus #<buffer flymake-test.tex> :beg nil :end nil
> :type :warning :text "No match found for `{'." :backend tex-chktex
> :data nil :overlay-properties nil :overlay nil :orig-beg nil :orig-end
> nil) #s(flymake--diag :locus #<buffer flymake-test.tex> :beg 54 :end
> 73 :type :warning :text "Number of `{' doesn't match the number of
> `}'!" :backend tex-chktex :data nil :overlay-properties nil :overlay
> nil :orig-beg 54 :orig-end 73)))
>   #f(compiled-function (&rest args) #<bytecode
> -0x16dfa1c308597683>)((#s(flymake--diag :locus #<buffer
> flymake-test.tex> :beg nil :end nil :type :warning :text "No match
> found for `{'." :backend tex-chktex :data nil :overlay-properties nil
> :overlay nil :orig-beg nil :orig-end nil) #s(flymake--diag :locus
> #<buffer flymake-test.tex> :beg 54 :end 73 :type :warning :text
> "Number of `{' doesn't match the number of `}'!" :backend tex-chktex
> :data nil :overlay-properties nil :overlay nil :orig-beg 54 :orig-end
> 73)))
>   #f(compiled-function (process event) #<bytecode
> -0x13a3e83da652160>)(#<process tex-chktex> "finished\n")
> --8<---------------cut here---------------end--------------->8---
> 
> Best, Arash
> 
> 
> 
>