Re: parentheses matching failure on valid sexp

[Sven Joachim]

Joe Wells <jbw@macs.hw.ac.uk> writes:

> To reproduce this bug:
>
> 1. Save the attached file as foobar.el.
> 2. Run “emacs -Q foobar.el”.
> 3. Delete the trailing right parenthesis on line 435.
> 4. Type a right parenthesis.
>
> The correct behavior would be to match the leading left parenthesis on
> line 1.  The actual buggy behavior is that the message “Mismatched
> parentheses” is given.
>
> This bug is sensitive to the size of the input.  If you delete much of
> the input, then the bug goes away.

This is documented behavior, see the variable blink-matching-paren-distance:

,----
| blink-matching-paren-distance is a variable defined in `simple.el'.
| Its value is 25600
| 
| 
| Documentation:
| *If non-nil, maximum distance to search backwards for matching open-paren.
| If nil, search stops at the beginning of the accessible portion of the buffer.
| 
| You can customize this variable.
`----