[perl #19135] string eval turns off readonlyness on lexicals

On Sun Sep 26 12:46:49 2010, sprout wrote:
> On Sun Sep 19 12:10:11 2010, sprout wrote:
> > The readonliness is turned off explicitly in pad_free under ithreads.
> >    See also bug #19022, which resulted from the same change. There is
> >    some discussion there, too, but nobody seemed to know exactly why
> >    the readonliness needed to be turned off.
> > 
> > Change 4761/2aa1bed, from January of 2000, added that SvREADONLY_off.
> >    It is supposed to make sure that pad entries that were constants
> >    will not be constants the next time they are used.
> > 
> > My question is: When the addresses of those scalars are reused, won’t
> >    the scalars be wiped clean? (In case it’s not obvious, I have very
> >    little idea how pads actually work.)
> > 
> > I tried simply deleting that SvREADONLY_off, and all tests pass (see
> >    the first attached patch).
> > 
> > Then I thought that maybe I should check that the SV is freed, and
> >    only then do SvREADONLY_off, to preserve the original intent of
> >    change 4761/2aa1bed. That worked too.
> > 
> > So, here are two patches. Take your pick.
> 
> Has anyone in the know had a chance to review these yet?

Well...? :-)

Here is a better test case, with no Internals:: stuff:

$ perl5.13.5 -wle 'for my $k(!0) { eval "\$k"; eval { $k = 7 }; print
"a"=~/a/ }'
7

• [perl #19135] string eval turns off readonlyness on lexicals by Father Chrysostomos via RT
• Re: [perl #19135] string eval turns off readonlyness on lexicals by Dave Mitchell
• [perl #19135] string eval turns off readonlyness on lexicals by Father Chrysostomos via RT