Re: Stack overflow in regexp matcher

[Stefan Monnier]

> what this might mean?

Although, strictly speaking, regular expressions can be matched using
a finite-state machine, Emacs's regexp-matcher uses a backtracking matcher
and if the backtracking stack is too large you get a stack overflow.

In your case "nnfolder.*?sent" might work better.


        Stefan


PS: As for why not use a finite-state machine... well one of the reasons
    is that it's extra work, another is that Emacs's regexps aren't pure
    regular expressions (most obviously because of backrefs).
    Supposedly the latest glibc regexp code uses an FSM, and hopefully
    someone will hack on it at some point to make it useable for Emacs.
    In the mean time, you'll have to be careful with regexps to try and
    avoid excessive stack use.