Regular crash in modifying regex

[Richard Kimberly Heck]

On 1/14/21 3:45 AM, Kornel Benko wrote:
> Am Thu, 14 Jan 2021 07:53:16 +0100
> schrieb Jürgen Spitzmüller <spitz at lyx.org>:
>
>> Am Donnerstag, dem 14.01.2021 um 00:58 +0100 schrieb Kornel Benko:
>>> How to reproduce
>>>
>>> 1.) Open lyx file e.g. Additional.lyx
>>> 2.) select AdvFind
>>> 3.) select regexp-mode
>>> 4.) insert any text not in this file
>>> 5.) select search for section
>>> 6.) change to not ignore format
>>> 7.) start search
>>> 8.) cancel the search (with escape)
>>> 9.) clean the regex content and try to insert anything ==> crash
>>>
>>> BTW, lyx2.3 does not crash.  
>> Does not crash for me. Can you produce a backtrace?
>>
>> Jürgen
>>
> Yes, attached. Last commit was fcea6c47.

That is even weirder. You're getting an assertion, on the ground that a
TOC is being requested that does not yet exist, and the type is
"tableofcontents", which is supposed always to exist. But maybe that
makes sense if it is the TOC for the F&R Buffer itself that is being
queried: Probably it does not have a TOC at all.

You might try reverting the problematic commit and see if that helps
(i.e., if master minus that commit asserts). That would at least give us
another data point.

Oh, I see it! The TocBackend::toc method has two versions: A const one
and a non-const one. Because of the const patch, the const one is being
called, I think. It asserts when the requested TOC does not exist,
whereas the other one just creates it and moves along. Though now I'm
puzzled why I don't get a crash. But that makes me think that this has
just revealed some other bug.

Riki