> On 11 Apr 2017, at 14:44, Eigil Skjæveland (via RT) > <perl6-bugs-follo...@perl.org> wrote: > > # New Ticket Created by Eigil Skjæveland > # Please include the string: [perl #131134] > # in the subject line of all future correspondence about this issue. > # <URL: https://rt.perl.org/Ticket/Display.html?id=131134 > > > >> my Int @a = 1, 2; >> my int @b = 1, 2; >> say so @a[-1 ^ 0]; > True >> say so @b[-1 ^ 0]; > False >> say @a[-1 ^ 0]; > Index out of range. Is: -1, should be in 0..^Inf > in block <unit> at <unknown file> line 1 > >> say @b[-1 ^ 0]; > one(2, 1) > > It seems the native int array treats negative indices in a junction as > relative to the end of the array.
Any expression resulting in a negative value at runtime, exposes this behaviour: $ 6 'my int @a = ^10; my $a = 0; dd @a[$a-1]’ 9 At the moment, this happens because the AT-POS candidate directly uses nqp::atposref_i for performance reasons. Exactly for that reason, I don’t think we should fix this at the Perl 6 level, because we would lose a *lot* of performance if we did. So, *if* we consider this to be a bug (and personally, I think it is), the index checking should happen at the VM level, rather than at the Perl 6 level.
