From @thundergnat

Post GLR, implicitly returning nothing from a subroutine now returns an
empty container. Becomes a problem when assigning to an array as it now
ends up containing an element even if none was returned.

  perl6 -e' sub h () { return }; my @​p = h(); say @​p, so @​p '
  [(Any)]True

  perl6 -e' sub h () { }; my @​p = h(); say @​p, so @​p '
  [(Any)]True

Now if you want to return nothing, you need to do it explicitly.

  perl6 -e' sub h () { return () }; my @​p = h(); say @​p, so @​p '
  []False

  perl6 -e' sub h () { () }; my @​p = h(); say @​p, so @​p '
  []False

Could be argued that it isn't a bug, but it is surprising to me and is
different from pre GLR behaviour.

From @thundergnat

Added tests to roast. Raku/roast@4841832#diff-900f81c3d5336ef22ff70a27fed79b1d

From @TimToady

In C culture, a bare return means "This is a procedure, not a function, and I'm not expecting to return anything", and so I think the absence of a meaningful value is properly conveyed by Nil in Perl 6. If the intent of a return is to allow interpolation of Slip or (), then that choice should be made explicit. Nil is a better default because it doesn't accidentally disappear in an unintended list context. In this sense, Nil can be considered the most basic failure value, designed to trip things up downstream if abused.

Roast changes​: Raku/roast@cecbb2a9a7

The RT System itself - Status changed from 'new' to 'open'

@TimToady - Status changed from 'open' to 'rejected'