Hah, thank you! That's what I get with fiddling with large integers I suppose... Setting to a reasonably lower number seems to have resolved the issue!

On Tue, Jun 8, 2021 at 2:00 PM Roman Perepelitsa <roman.perepelitsa@gmail.com> wrote:
On Tue, Jun 8, 2021 at 10:42 PM Jonathan Ching <jon48c@gmail.com> wrote:
>
> It doesn't seem like the issue is resolved by 5.8. Could it be something else?

I can reproduce this:

    % docker run -e TERM -it --rm zshusers/zsh:5.8 zsh
    7a7002248c6a# print 'HISTFILE=~/hist'              >>~/.zshrc
    7a7002248c6a# print 'HISTSIZE=9223372036854775807' >>~/.zshrc
    7a7002248c6a# print 'SAVEHIST=9223372036854775807' >>~/.zshrc
    7a7002248c6a# print 'setopt incappendhistory'      >>~/.zshrc
    7a7002248c6a# exec zsh
    7a7002248c6a# echo 1
    1
    7a7002248c6a# echo 2
    2
    7a7002248c6a# cat ~/hist
    echo 1
    echo 2
    cat ~/hist
    7a7002248c6a# echo "
    dquote>
    7a7002248c6a# cat ~/hist
    echo 1
    cat ~/hist

Replacing 9223372036854775807with mere 1000000000000000000 avoids the issue.

From my experience with zsh source code, it doesn't bother with
handling integer overflow, so I'm not sure how serious this bug is.

Roman.