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[perl #118691] Perl crash on usage of index [-1] for array in subroutine call

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James E Keenan via RT
June 30, 2013 12:37
[perl #118691] Perl crash on usage of index [-1] for array in subroutine call
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On Sat Jun 29 10:13:54 2013, sprout wrote:
> On Sat Jun 29 08:06:12 2013, jkeenan wrote:
> > Your fourth call is not equivalent to your third call.  There's no '//'
> > operator imposing a context on $array[-1].  Perl looks at that variable
> > directly and notes that it runs afoul of the error condition described
> > above.  You're asking for $array[-1] to spring to life.  I'm sure that
> > there are others who can explain better than I can why we treat that as
> > a fatal error -- but fatal it is nonetheless.
> Whether this is a bug or no, it is certainly surprising--and fixable.

I think what is more surprising is that the poster's second and fourth
cases behave differently, i.e., that func($array[0]) has at least the
appearance of being well-behaved, whereas func($array[-1] generates a
fatal error.

> It’s just a matter of tweaking the defer logic in pp_aelem.  Then rvalue
> uses of $_[0] within the function will just work, but assignment to
> $_[0] will croak with the same error (i.e., the error will be delayed as
> long as possible).

Do we really want to do that?

via perlbug:  queue: perl5 status: open

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