update_syntax_cache: conflict between BOB and BO accessible region; patch
Stephen J. Turnbull writes:
Alan Mackenzie writes:
> However, when it drops off the end, update_syntax_cache wrongly sets its
> boundary positions to the ABSOLUTE BEGINNING/END of buffer. This is
> clearly wrong.
Do you have a test case that shows actual erroneous behavior fixed by
changing this? While I agree with your intuition, the syntax cache
has a ton of unintuitive code, and the specification for its behavior
is completely undocumented. Patches based on intuition make me very
nervous.
OK, I have a test case that basically follows your recipe given
elsewhere and shows the bug, and is fixed by your suggested patch. It
took a bit of fiddling to get something that works in a vanilla temp
buffer, but I understand this stuff a lot better now. :-/
I'll be committing something tomorrow, but I want to go over the whole
function first. (There was a third instance of the same "absolute
vs. accessible" bug sandwiched between the ones you proposed fixing.
Given that we've already found about 5 bugs in the syntax cache code,
there are probably more....)
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