From @lizmat

[15​:31​:47] <lizmat> m​: sub a(Int(Cool​:D) $a) { say $a }; a Cool # feels this should fail
[15​:31​:48] <+camelia> rakudo-moar d29715​: OUTPUT«use of uninitialized value of type Cool in numeric context in sub a at /tmp/L77KWsiM9N​:1␤␤0␤»
[15​:32​:03] <lizmat> or complain about the :D in the coercer
[15​:32​:16] <lizmat> std​: sub a(Int(Cool​:D) $a) { say $a }; a Cool
[15​:32​:18] <+camelia> std f9b7f55​: OUTPUT«ok 00​:01 141m␤»
[15​:33​:06] <lizmat> m​: sub a(Cool​:D $a as Int) { say $a }; a Cool # should fail like this
[15​:33​:06] <+camelia> rakudo-moar d29715​: OUTPUT«Parameter '$a' requires an instance, but a type object was passed␤ in sub a at /tmp/D5UepJwrRP​:1␤ in block <unit> at /tmp/D5UepJwrRP​:1␤␤»
[15​:33​:30] <timotimo> sounds reasonable to me, maybe someone could rakudobug it
[15​:33​:50] <lizmat> I will
[15​:34​:12] <jnthn> lizmat​: Yeah...which in turn really wants definedness types to become first class too...

From @skids

On Mon, 09 Feb 2015 06​:35​:57 -0800, elizabeth wrote​:

[15​:31​:47] <lizmat> m​: sub a(Int(Cool​:D) $a) { say $a }; a Cool
# feels this should fail
[15​:31​:48] <+camelia> rakudo-moar d29715​: OUTPUT«use of
uninitialized value of type Cool in numeric context in sub a at
/tmp/L77KWsiM9N​:1␤␤0␤»
[15​:32​:03] <lizmat> or complain about the :D in the coercer
[15​:32​:16] <lizmat> std​: sub a(Int(Cool​:D) $a) { say $a }; a Cool
[15​:32​:18] <+camelia> std f9b7f55​: OUTPUT«ok 00​:01 141m␤»
[15​:33​:06] <lizmat> m​: sub a(Cool​:D $a as Int) { say $a }; a Cool
# should fail like this
[15​:33​:06] <+camelia> rakudo-moar d29715​: OUTPUT«Parameter '$a'
requires an instance, but a type object was passed␤ in sub a at
/tmp/D5UepJwrRP​:1␤ in block <unit> at /tmp/D5UepJwrRP​:1␤␤»
[15​:33​:30] <timotimo> sounds reasonable to me, maybe someone could
rakudobug it
[15​:33​:50] <lizmat> I will
[15​:34​:12] <jnthn> lizmat​: Yeah...which in turn really wants
definedness types to become first class too...

Some cases of this work now, and the rest are covered by RT#​126433.
Tests were rearranged to reflect this in roast commit 574035ff4,
so resolving this ticket and leaving RT#​126433 for the outstanding issues.

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

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