[perl #68074] where-clauses in parametric role signatures produce internal error

[jn...@jnthn.net via RT]

On Fri Jul 31 03:19:31 2009, ml...@physik.uni-wuerzburg.de wrote:
> 12:16 <@moritz_> rakudo: role A[Int $x where { $x % 2 == 0 }] { method s {
>                  'even' } }; role A[Int $x where{ $x % 2 == 1 }] {
> method s {
>                  'odd' } }; class X does A[5]; say X.new.s
> 12:16 < p6eval> rakudo a53a1c: OUTPUT«Potential internal error:
bindability
>                 check may have done more than just binding.␤Potential
> internal
>                 error: bindability check may have done more than just
>                 binding.␤Ambiguous dispatch to multi '_block50'. Ambiguous
>                 candidates had signatures:␤:(Int $x where all({ ...
> }))␤:(Int
> 12:16 < p6eval> ..$x whe…
> 
> So the where-clauses didn't have the effect of disambiguating the
> dispatch, as they should.
> 
Some tricky hacking later:

role A[Int $x where { $x % 2 == 0 }] { method s { 'even' } }
role A[Int $x where { $x % 2 == 1 }] { method s { 'odd' } }
class X does A[5] { }
say X.new.s;
class Y does A[6] { }
say Y.new.s;

Outputs:

odd
even

\o/

Tests turned on, resolving ticket.

Thanks,

Jonathan