bug#39137: 26.3; ispell-really-hunspell sometimes fails in init

bug#39137: 26.3; ispell-really-hunspell sometimes fails in init

[Bob Rogers]

   Spell checking can die with "(wrong-type-argument stringp nil)" when
ispell-really-hunspell is true.  To reproduce (if it reproduces at all
on your system), just do "emacs -Q" with Hunspell installed and M-$ on
any of the words in the startup screen.

   On some of the systems I use, it fails reliably when initializing; on
others, it works reliably.  All systems are running the openSUSE Leap
15.1 release of GNU/Linux, fully updated, with the identical locally-
built RPM version of Emacs 26.3 (with no local patches) and the distro
Hunspell 1.6.2.  The key seems to be whether ispell-dictionary-alist is
initialized before ispell-start-process is called; just a warning to
anyone who fails to reproduce this.  But since it fails in "emacs -Q" on
systems with apparently identical software, I am at a complete loss to
figure this out.

When it fails, the backtrace looks like this:

	Debugger entered--Lisp error: (wrong-type-argument stringp nil)
	  string-match("," nil 0)
	  split-string(nil "," t)
	  ispell-parse-hunspell-affix-file(nil)
	  ispell-hunspell-fill-dictionary-entry(nil)
	  ispell-start-process()
	  ispell-init-process()
	  ispell-buffer-local-words()
	  ispell-accept-buffer-local-defs()
	  ispell-word(nil nil nil t)
	  funcall-interactively(ispell-word nil nil nil t)
	  call-interactively(ispell-word nil nil)
	  command-execute(ispell-word)

The problem seems to be related to this code in the start of
ispell-start-process:

  ;; Parse hunspell affix file if using hunspell and entry is uninitialized.
  (if ispell-really-hunspell
      (or (cadr (assoc ispell-current-dictionary ispell-dictionary-alist))
	  (ispell-hunspell-fill-dictionary-entry ispell-current-dictionary)))

It appears that "nil" is valid for ispell-current-dictionary and means
"default", but ispell-hunspell-fill-dictionary-entry expects only a
string.  On that basis, I would claim that there is a bug that has
perhaps been hidden by being on a rare execution path.  But if
ispell-dictionary-alist is already initialized with a "nil" entry, then
ispell-hunspell-fill-dictionary-entry never gets called, leading to the
"reproducible irreproducibility" of this bug.  And if
ispell-dictionary-alist should *always* be initialized and contain the
current entry, then this is dead code.

   I don't know where or how ispell-current-dictionary is getting set up
on some systems but not on others, nor how it ought to be set up, so I
am unable to take this any further.


					-- Bob Rogers
					   Modular Genetics Inc.
					   http://www.modulargenetics.com/

------------------------------------------------------------------------
In GNU Emacs 26.3 (build 1, x86_64-suse-linux-gnu, GTK+ Version 3.22.30)
 of 2019-11-21 built on yuggoth
Windowing system distributor 'The X.Org Foundation', version 11.0.12003000
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bug#39137: 26.3; ispell-really-hunspell sometimes fails in init

[Eli Zaretskii]

> From: Bob Rogers <rogers@modulargenetics.com>
> Date: Tue, 14 Jan 2020 16:25:07 -0500
> 
>    Spell checking can die with "(wrong-type-argument stringp nil)" when
> ispell-really-hunspell is true.  To reproduce (if it reproduces at all
> on your system), just do "emacs -Q" with Hunspell installed and M-$ on
> any of the words in the startup screen.

Granted, this doesn't reproduce on my system.  And I have difficulty
understanding how could it reproduce on _any_ system, especially in
"emacs -Q".

>    On some of the systems I use, it fails reliably when initializing; on
> others, it works reliably.  All systems are running the openSUSE Leap
> 15.1 release of GNU/Linux, fully updated, with the identical locally-
> built RPM version of Emacs 26.3 (with no local patches) and the distro
> Hunspell 1.6.2.  The key seems to be whether ispell-dictionary-alist is
> initialized before ispell-start-process is called

Can you step through the ispell.el's initialization code, and explain
how come ispell-dictionary-alist ends up being uninitialized by the
time ispell-start-process is called for spell-checking?  This
shouldn't happen.

>   ;; Parse hunspell affix file if using hunspell and entry is uninitialized.
>   (if ispell-really-hunspell
>       (or (cadr (assoc ispell-current-dictionary ispell-dictionary-alist))
> 	  (ispell-hunspell-fill-dictionary-entry ispell-current-dictionary)))
> 
> It appears that "nil" is valid for ispell-current-dictionary and means
> "default", but ispell-hunspell-fill-dictionary-entry expects only a
> string.  On that basis, I would claim that there is a bug that has
> perhaps been hidden by being on a rare execution path.  But if
> ispell-dictionary-alist is already initialized with a "nil" entry, then
> ispell-hunspell-fill-dictionary-entry never gets called, leading to the
> "reproducible irreproducibility" of this bug.  And if
> ispell-dictionary-alist should *always* be initialized and contain the
> current entry, then this is dead code.

It isn't dead code, it just assumes that either
ispell-current-dictionary is nil and there's a nil entry in
ispell-dictionary-alist, or it is a string that specifies a new
dictionary, which is then used to update ispell-dictionary-alist.

We need to establish how come the first assumption is false on those
affected systems.

Thanks.

bug#39137: 26.3; ispell-really-hunspell sometimes fails in init

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

> Can you step through the ispell.el's initialization code, and explain
> how come ispell-dictionary-alist ends up being uninitialized by the
> time ispell-start-process is called for spell-checking?  This
> shouldn't happen.

More information was requested, but no response was given within a
year, so I'm closing this bug report.  If the problem still exists,
please respond to this email and we'll reopen the bug report.

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

bug#39137: 26.3; ispell-really-hunspell sometimes fails in init

[Bob Rogers]

   From: Lars Ingebrigtsen <larsi@gnus.org>
   Date: Fri, 29 Jan 2021 08:27:00 +0100

   Eli Zaretskii <eliz@gnu.org> writes:

   > Can you step through the ispell.el's initialization code, and explain
   > how come ispell-dictionary-alist ends up being uninitialized by the
   > time ispell-start-process is called for spell-checking?  This
   > shouldn't happen.

   More information was requested, but no response was given within a
   year, so I'm closing this bug report.  If the problem still exists,
   please respond to this email and we'll reopen the bug report.

My apologies for being so lazy, but I finally got around to checking
this out.  I went to reproduce the problem and found that the current
Emacs 27.2-rc2 on the affected system now produces the following error
message:

	ispell-find-hunspell-dictionaries: Can t find Hunspell dictionary with a .aff affix file

So it was a Hunspell configuration issue (further investigation found
the missing RPM), and not an Emacs problem.  And I'm glad to see that
the Hunspell initialization now reports this intelligibly.

					-- Bob

bug#39137: 26.3; ispell-really-hunspell sometimes fails in init

[Lars Ingebrigtsen]

Bob Rogers <rogers@modulargenetics.com> writes:

> 	ispell-find-hunspell-dictionaries: Can t find Hunspell dictionary with a .aff affix file
>
> So it was a Hunspell configuration issue (further investigation found
> the missing RPM), and not an Emacs problem.  And I'm glad to see that
> the Hunspell initialization now reports this intelligibly.

Thanks for checking.

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