Subject: bug#23097: 24.5; ispell.el: lines with both CASECHARS and NOT-CASECHARS get sent to the spell checker

From: Nikolay Kudryavtsev <[email-masked]>
Date: Wed, 14 Oct 2020 22:20:08 +0300

The whole ispell-dictionary-alist structure implies that matching would 
be done word by word. And looking into the dictionary setup is the first 
thing ispell.el user would do. Apart from NOT-CASECHARS it also has this 
element:

> OTHERCHARS is a regexp of characters in the NOT-CASECHARS set but 
> which can be
> used to construct words in some special way.  If OTHERCHARS characters 
> follow
> and precede characters from CASECHARS, they are parsed as part of a word,
> otherwise they become word-breaks...
Basically presence of both NOT-CASECHARS and OTHERCHARS implies that 
ispell.el does strict word by word matching. If we're just sending any 
line that contains a CASECHARS match, we don't really need either of 
them, since we can just match by CASECHARS alone and then send the line.

Oh, and there's another thing. Ispell.el actually does word by word 
search, but only on resume. Try my recipe again, just make the last line 
of spellchecked buffer to look like "doh kat". Then suspend the 
spellcheck after the first line and resume it with C-u M-$. You'd see 
that it skips the last line "doh" fine in this scenario. But then it 
suffers from the word mix problem described by Eli: spellchecking
dohkat" and "katdoh" results in kat alone being sent.

Thinking a bit more about this word mix problem, seems like it's not as 
simple to fix it as I thought in my previous letter, since we need some 
list of legitimate word separators for each language.

-- 
Best Regards,
Nikolay Kudryavtsev