# New Ticket Created by "Carl Mäsak"
# Please include the string: [perl #114134]
# in the subject line of all future correspondence about this issue.
# <URL: https://rt.perl.org:443/rt3/Ticket/Display.html?id=114134 >
<masak> I've golfed the segfault from a few days ago.
<masak> it might be the strangest I've ever seen. but it's very
consistent. lots of components, though.
<masak> r: use Test; class A {}; (-> &c, $m { A.new()(); CATCH {
default { ok 1, $m } } })(A, "")
<p6eval> rakudo 74e183: OUTPUT«(signal SEGV)»
* masak submits rakudobug
<[Coke]> masak++
<masak> feel free to submit shorter versions to the channel if you
find any. I will add them to the RT ticket.
<gfldex> Segmentation fault (core dumped) # under cygwin
<moritz> r: class A {}; (-> &c, $m { A.new()(); CATCH { default { say
$m } } } )(Mu.new, '')
22:06 <+p6eval> rakudo 74e183: OUTPUT«Null PMC access in
find_method('gist') [...]
<masak> that looks like a clue of some sort.
<masak> note that A is sent in as &c, and that was the original issue:
a non-Callable was invoked.
<moritz> masak: but shouldn't it fail to bind in the first place?
<moritz> I mean, A to &c
<masak> yes.
masak> and maybe it does, I dunno.
<moritz> r: sub f(&c) { }; f(class { })
<p6eval> rakudo 74e183: OUTPUT«Nominal type check failed for parameter
'&c'; expected Callable but got <anon> instead [...]
<masak> but the A.new()(); these is necessary.
<masak> which indicates the first line gets run.
<masak> r: use Test; class A {}; (-> &c, $m { CATCH { default { ok 1,
$m } } })(A, "")
<p6eval> rakudo 74e183: OUTPUT«(signal SEGV)»
<masak> I stand corrected. :)
<masak> that explains a lot. the CATCH catches binding errors.
<masak> and then the $m never gets bound, because the binder wasn't done!
<moritz> erm, what?
<masak> I couldn't have trolled Rakudo better if I had wanted to! :D
<moritz> a CATCH block catches... no way
<masak> yes way.
<masak> that's what happens.
<masak> it's so obvious now.
<moritz> I... hope that it's not supposed to catch those.
<masak> no, I don't think it is.
<moritz> ah, and that's why I got the null PMC access
<masak> but I can see why that falls out. I think binding is lexically
done inside of the callee.
<moritz> r: sub f(&x) { CATCH { default { say "OH NOES" } } }; f 3
<p6eval> rakudo 74e183: OUTPUT«===SORRY!===CHECK FAILED:Calling 'f'
will never work with argument types (int) (line 1) Expected:
:(&x)»
<jnthn> Huh, I thought exception handlers weren't set up until after
the binding...
<moritz> r: sub f(&x) { CATCH { default { say "OH NOES" } } }; f Mu.new
<p6eval> rakudo 74e183: OUTPUT«OH NOES»
<moritz> that's a short version :-)
<moritz> masak++
<masak> now without the segv :)
<moritz> aye
<moritz> jnthn: looking at the generate code, it seems it 1) does a
capture_lex 2) sets up the exception handler 3) calls
perl6_take_dipatcher 4) declares $_, $/, $! and call_sig and 5) calls
bind_signature
<jnthn> hah
<moritz> new $P1043, 'ExceptionHandler'
<moritz> set_label $P1043, control_1042
<moritz> $P1043."handle_types_except"(.CONTROL_ALL)
<moritz> I guess the binder does not generate a CONTROL exception
<jnthn> I...don't think they should be control exceptions.
<jnthn> Failing to bind is a real exception.
* moritz thinks so too
<jnthn> It's that the handler shouldn't be set up at that point.
