From @moritz

< moritz> r​: enum day <a b c d e>;say day(3) === d; "foo" but d; say
"alive"; "foo" but day(3)
<+p6eval> rakudo 2ac569​: OUTPUT«True␤alive␤Type check failed
  in assignment to '$!day'; expected 'day' but got 'Int'␤
  in block <anon> at src/gen/CORE.setting​:650␤
  in method BUILD_LEAST_DERIVED at src/gen/CORE.setting​:637␤
  in sub infix​:<but> at src/gen/CORE.setting​:10579␤
< moritz> day(3) === d is True, but '"foo" but d' and '"foo" but
day(3)' dies?
< moritz> r​: enum A <b c>; nqp​::say nqp​::iscont(b); nqp​::say
  nqp​::iscont(A(0))
<+p6eval> rakudo 2ac569​: OUTPUT«0␤0␤»

So that's not the problem either.

From @moritz

fixed by jnthn++ in 9c85a3b and tested in S12-enum/pseudo-functional.t

@moritz - Status changed from 'new' to 'resolved'