add a few comments to bisect-runner.pl docs

./perl -Ilib t/op/sort.t won't do what you want, because tests that
don't use Test::More don't set an error code on their own, you need to
run it under the harness
clean up compilation warnings
pp.c: Restore uninit warning to study

Also, prevent a crash when SvCUR is used on a non-PV.
regen_perly.pl: support latest bison-2.5.1

bison-2.5.1 adds less superfluous semicolons at the end of action blocks,
but works fine.
perly.*: update regen_perly checksum
fix 4f8dbb2d
more in depth tests for 8e4ecf2
propagate context into overloads [perl #47119]

amagic_call now does its best to propagate the operator's context into
the overload callback. It's not always possible - for instance,
dereferencing and stringify/boolify/numify always have to return a
value, even if it's not used, due to the way the overload callback works
in those cases - but the majority of cases should now work. In
particular, overloading <> to handle list context properly is now
possible.

For backcompat reasons (amagic_call and friends are technically public
api functions), list context will not be propagated unless specifically
requested via the AMGf_want_list flag. If this is passed, and the
operator is called in list context, amagic_call returns an AV* holding
all of the returned values instead of an SV*. Void context always
results in amagic_call returning &PL_sv_undef.
perldiag: Add missing regexp delims
diagnostics.t: Restore test name removed by f0e510f
Don’t let formats outlive their outer subs

This began crashing in 5.11.3:

sub foo {
  sub bar {
    my ($a,$b,$c,$d,$e,$f,$g,$h,$i,$j,$k,$l,$m,$n,$o,$p,$q,$r,$s,$x);
    format =
@||||||
$x
.
  }
}
undef *bar;
write;

(On some systems, you need more alphabet soup to make it crash.)

This commit (just the perly.y part shown) caused it to crash:

commit 421f30ed1e95009450bdc7905bf3433ee806ea4f
Author: Zefram <zefram@fysh.org>
Date:   Tue Dec 15 11:48:31 2009 +0100

    [perl #22977] Bug in format/write

diff --git a/perly.y b/perly.y
index 18e5875..a61a6b3 100644
--- a/perly.y
+++ b/perly.y
@@ -511,7 +511,9 @@ peg	:	PEG
 	;

 format	:	FORMAT startformsub formname block
-			{ SvREFCNT_inc_simple_void(PL_compcv);
+			{
+			  CV *fmtcv = PL_compcv;
+			  SvREFCNT_inc_simple_void(PL_compcv);
 #ifdef MAD
 			  $$ = newFORM($2, $3, $4);
 			  prepend_madprops($1->tk_mad, $$, 'F');
@@ -521,6 +523,10 @@ format	:	FORMAT startformsub formname block
 			  newFORM($2, $3, $4);
 			  $$ = (OP*)NULL;
 #endif
+			  if (CvOUTSIDE(fmtcv) && !CvUNIQUE(CvOUTSIDE(fmtcv))) {
+			    SvREFCNT_inc_simple_void(fmtcv);
+			    pad_add_anon((SV*)fmtcv, OP_NULL);
+			  }
 			}
 	;

Unfortunately, adding the format to the pad like that (to allow
pad_fixup_inner_anons to fix up formats as well as subs) is proble-
matic.  It causes the format’s CvOUTSIDE to be weak.  Since the for-
mat does not hold a reference count on its outer sub, that sub can be
freed before the format.  When that happens, regular subs are fixed
up by having CvOUTSIDE change to point to the grandparent.  If you
do that for formats, you run into a problem: Formats can be cloned
even when the outer sub is not running.  Formats are cloned whenever
invoked *by name* via write.  If CvOUTSIDE points to a different sub,
then closing over the scalars in specific pad offsets in that sub can
result in reading past the end of the pad.  If you don’t read past the
end of the pad, you are still making variables close over unrelated variables, so the inner $x could close over an outer @y, etc.  Subrou-
tines don’t have that problem, as they can only be cloned when they
have an outer sub.  (Even though the outer sub’s prototype, if it is a
closure, might have been freed, the outer sub itself is still running
and referenced by the context stack.)

This commit changes the direction of the weak reference between an
outer sub’s pad and an inner format, fixing the crash.

To do so, it has to store, not the format itself, but a weak RV point-
ing to the format, in the outer sub’s pad.
perldelta updates for 6728836, d60d201, 82f9620, 7878705
fix storing objects with reftype REF [perl #113880]
Formats in closures called outside closures → crash

If a format closing over lexical variables is defined inside a clo-
sure, it must only be called directly inside that closure, not from
any other eval, sub, or format.

Calling it from anywhere else started causing a crash in 5.10.0,
because the format would try to close over variables in the currently-
running sub, using padoffsets intended for a completely unrelated pad.

This commit stops it from crashing by checking whether the currently-
running sub is a clone of the format’s outer sub (a closure proto-
type).  If it is not, the outer closure prototype is used, resulting
in ‘Variable is not available’ warnings.

This makes things work as well as they did in 5.8.  Ideally, we should
search the call stack for the topmost clone of the format’s outer sub;
but I’m saving that for another commit.
"use overload fallback => 0" should enable overloading [perl #113010]

This makes

  package Foo;
  use overload fallback => 0;

and

  package Bar;
  use overload '+' => \&add, fallback => 0;

behave identically when an operator other than '+' is used.
perldelta for 27c6f44
fix 386a548 for fallback => undef

The default case for non-overloaded classes is fallback => 1, so saying
fallback => 1 on its own shouldn't enable overloading, but saying
fallback => undef on its own should (even though undef is the default
for overloaded classes).
Add CVf_SLABBED flag

This will indicate that a CV has a reference count on, and ownership
of, a slab used for allocating ops.
dump.c: Dump CVf_SLABBED
Flag ops that are on the savestack

This is to allow future commits to free dangling ops after errors.

If an op is on the savestack, then it is going to be freed by scope.c,
and op_free must not be called on it by anyone else.

So we flag such ops new.