Re: ex-nextstate on commented line

On Thu, Apr 16, 2015 at 11:09 AM, Paul Johnson <paul@pjcj.net> wrote:
> I have tracked down the cause of some Devel::Cover failures with
> bleadperl:
>
> $ perl5.20.2 -MO=Concise -e '#x'
> -e syntax OK
> $ perl5.21.6 -MO=Concise -e '#x'
> -e syntax OK
> $ perl5.21.7 -MO=Concise -e '#x'
> 3  <@> leave[1 ref] vKP/REFC ->(end)
> 1     <0> enter ->2
> 2     <0> stub v ->3
> -     <;> ex-nextstate(main 1 -e:1) v:{ ->3
> -e syntax OK
> $ perl5.21.11 -MO=Concise -e '#x'
> 3  <@> leave[1 ref] vKP/REFC ->(end)
> 1     <0> enter ->2
> 2     <0> stub v ->3
> -     <;> ex-nextstate(main 1 -e:1) v:{ ->3
> -e syntax OK
>
> Thoughts?

Bisect says it came in here:

  34b54951568575920f2307bea918f5549bd5a82f is the first bad commit
  commit 34b54951568575920f2307bea918f5549bd5a82f
  Author: Father Chrysostomos <sprout@cpan.org>
  Date:   Thu Nov 20 09:23:35 2014 -0800

    [perl #77452] Deparse { ...; BEGIN{} } correctly

    8635e3c2 (5.21.6) changed the COP sequence numbers for nested blocks,
    such that most BEGIN blocks (incl. ‘use’ statements) and sub declara-
    tions end up in the right place.  However, it had the side effect of
    causing declarations at the end of the enclosing scope to fall out of
    it and appear below.

    This commit fixes that by adding an extra nulled COP to the end of the
    enclosing scope if that scope ends with a sub, so the final declara-
    tion gets deparsed before it.

    The frequency of sub declarations at the end of the enclosing scope is
    sufficiently low (I’m guessing a bit here) that this slight increase
    in run-time memory usage is probably acceptable.

    I had to change B::Deparse to deparse nulled COPs the same way it does
    live COPs, which means we get more extraneous semicolons than before.
    I hope to fix that in a forthcoming commit.  I also ran into a B bug,
    in that null ops are not presented to Perl code with the right op
    class (see the blessing in the patch).  I plan to fix that in a separ-
    ate commit, too.

-- Matthew Horsfall (alh)

• ex-nextstate on commented line by Paul Johnson
• Re: ex-nextstate on commented line by wolfsage
• Re: ex-nextstate on commented line by Paul Johnson
• Re: ex-nextstate on commented line by Dave Mitchell
• Re: ex-nextstate on commented line by Paul Johnson