From @skids

"is default(Mu)" works fine on a variable, but runs into syntax issues on attributes...
weirdly... only for Mu.

$ perl6 -e 'my $a is default(Mu);'
$ perl6 -e 'class A { has $.a is default(Mu); }'
===SORRY!=== Error while compiling -e
Can't use unknown trait 'is default' in an attribute declaration.
at -e​:1
  expecting any of​:
  rw
  readonly
  box_target
  leading_docs
  trailing_docs
$ perl6 -e 'class A { has $.a is default(Nil); }'
$

I will be adding fudged tests to S02-names/is_default.t for this.

From @zoffixznet

On Wed, 13 Sep 2017 18​:27​:37 -0700, bri@​abrij.org wrote​:

"is default(Mu)" works fine on a variable, but runs into syntax issues
on attributes...
weirdly... only for Mu.

$ perl6 -e 'my $a is default(Mu);'
$ perl6 -e 'class A { has $.a is default(Mu); }'
===SORRY!=== Error while compiling -e
Can't use unknown trait 'is default' in an attribute declaration.
at -e​:1
expecting any of​:
rw
readonly
box_target
leading_docs
trailing_docs
$ perl6 -e 'class A { has $.a is default(Nil); }'
$

I will be adding fudged tests to S02-names/is_default.t for this.

Thank you for the report. This is now fixed.

Fix​: rakudo/rakudo@54507ac94e
Tests (unfudged and expanded)​: Raku/roast@c537352009

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

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