From @lizmat

[14​:56​:02] <lizmat> m​: sub a(--> Int​:D) { Int }; a # jnthn, is this supposed to die or not ?
[14​:56​:03] <+camelia> rakudo-moar dafcfe​: ( no output )
[14​:56​:48] <lizmat> jnthn​: perhaps a compile time NYI for --> Foo​:D ?
[15​:00​:14] <jnthn> lizmat​: Either we should fix it or disallow it
[15​:00​:48] <lizmat> jnthn​: will ticket it, ok?
[15​:00​:59] <jnthn> +1

From @FROGGS

Seems to work now that we have DefiniteHOW​:

m​: sub a() returns Int​:U { 42 }; say &a.returns; a
rakudo-moar 8f4e90​: OUTPUT«(Int​:U)␤Type check failed for return value; expected Int​:U but got Int␤ in sub a at /tmp/LRo5pcMZof​:1␤ in block <unit> at /tmp/LRo5pcMZof​:1␤␤»

m​: sub a() returns Int​:D { Int }; say &a.returns; a
rakudo-moar 8f4e90​: OUTPUT«(Int​:D)␤Type check failed for return value; expected Int​:D but got Int␤ in sub a at /tmp/SnKt55D7zj​:1␤ in block <unit> at /tmp/SnKt55D7zj​:1␤␤»

Tagging it testneeded.

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

From @FROGGS

Marked existing tests as related to this ticket​:
Raku/roast@5bd83c5b01

Closing ticket.

@FROGGS - Status changed from 'open' to 'resolved'