Subject: bug#53343: 29.0.50; assertion failure in diff--iterate-hunks

From: Lars Ingebrigtsen <[email-masked]>
Date: Fri, 21 Jan 2022 12:07:49 +0100

Stephen Berman <[email-masked]> writes:

> On the other hand, I get the assertion failure with the above recipe in
> emacs-28 and emacs-27, and it seems unlikely that such a bug in
> diff-mode would have gone unnoticed till now, so maybe the diff is
> malformed.  (Though if so, why does the failure not happen when visiting
> the file containing the diff?)

I tried

(setq debug-on-error t)

put the diff in a file, and got a backtrace when loading it.

Debugger entered--Lisp error: (error "Unknown diff hunk type")
  signal(error ("Unknown diff hunk type"))
  error("Unknown diff hunk type")
  diff-hunk-text("" nil nil)
  diff-syntax-fontify-hunk(506 506 t)
etc

So I've now made that function less assertative, and that fixes this
issue.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no