From andrspv@gmail.com

% perl6 -v
This is perl6 version 2015.05-197-g28a7697 built on MoarVM version
2015.05-79-g458940f

sub x() returns Array of Int { my @​x of Int = 1,2,3 };
sub x ( --> Array[Int]) { #`(Sub|42347328) ... }
x().WHAT.say
Type check failed for return value; expected 'Array[Int]' but got 'Array[Int]'
  in any return_error at src/vm/moar/Perl6/Ops.nqp​:639
  in sub x at <unknown file>​:1
  in block <unit> at <unknown file>​:1

Redeclaration of routine in REPL causes the following

sub x() returns Array of Int { return my @​x of Int = 1,2,3 }; x().WHAT.say
Type check failed for return value; expected 'Array[Int]' but got 'Array[Int]'
  in any return_error at src/vm/moar/Perl6/Ops.nqp​:639
  in sub x at <unknown file>​:1
  in block <unit> at <unknown file>​:1

sub x() returns Array of Int { return my @​x of Int = 1,2,3 }; x().WHAT.say
Type check failed for return value; expected 'Array[Int][Int]' but got
'Array[Int][Int]'
  in any return_error at src/vm/moar/Perl6/Ops.nqp​:639
  in sub x at <unknown file>​:1
  in block <unit> at <unknown file>​:1

sub x() returns Array of Int { return my @​x of Int = 1,2,3 }; x().WHAT.say
Type check failed for return value; expected 'Array[Int][Int][Int]'
but got 'Array[Int][Int][Int]'
  in any return_error at src/vm/moar/Perl6/Ops.nqp​:639
  in sub x at <unknown file>​:1
  in block <unit> at <unknown file>​:1

sub x() returns Array of Int { return my @​x of Int = 1,2,3 }; x().WHAT.say
Type check failed for return value; expected
'Array[Int][Int][Int][Int]' but got 'Array[Int][Int][Int][Int]'
  in any return_error at src/vm/moar/Perl6/Ops.nqp​:639
  in sub x at <unknown file>​:1
  in block <unit> at <unknown file>​:1

sub x() returns Array of Int { return my @​x of Int = 1,2,3 }; x().WHAT.say
Type check failed for return value; expected
'Array[Int][Int][Int][Int][Int]' but got
'Array[Int][Int][Int][Int][Int]'
  in any return_error at src/vm/moar/Perl6/Ops.nqp​:639
  in sub x at <unknown file>​:1
  in block <unit> at <unknown file>​:1

From @usev6

There is another recent bug report about the problem shown here​: https://rt-archive.perl.org/perl6/Ticket/Display.html?id=126136

IMHO, that other report describes the symptoms very clear and provides a good base for working on a fix.

@usev6 - Status changed from 'new' to 'open'

From @coke

On Mon Jun 15 01​:43​:52 2015, andrspv@​gmail.com wrote​:

% perl6 -v
This is perl6 version 2015.05-197-g28a7697 built on MoarVM version
2015.05-79-g458940f

sub x() returns Array of Int { my @​x of Int = 1,2,3 };
sub x ( --> Array[Int]) { #`(Sub|42347328) ... }
x().WHAT.say
Type check failed for return value; expected 'Array[Int]' but got
'Array[Int]'
in any return_error at src/vm/moar/Perl6/Ops.nqp​:639
in sub x at <unknown file>​:1
in block <unit> at <unknown file>​:1

Redeclaration of routine in REPL causes the following

sub x() returns Array of Int { return my @​x of Int = 1,2,3 };
x().WHAT.say
Type check failed for return value; expected 'Array[Int]' but got
'Array[Int]'
in any return_error at src/vm/moar/Perl6/Ops.nqp​:639
in sub x at <unknown file>​:1
in block <unit> at <unknown file>​:1

sub x() returns Array of Int { return my @​x of Int = 1,2,3 };
x().WHAT.say
Type check failed for return value; expected 'Array[Int][Int]' but got
'Array[Int][Int]'
in any return_error at src/vm/moar/Perl6/Ops.nqp​:639
in sub x at <unknown file>​:1
in block <unit> at <unknown file>​:1

sub x() returns Array of Int { return my @​x of Int = 1,2,3 };
x().WHAT.say
Type check failed for return value; expected 'Array[Int][Int][Int]'
but got 'Array[Int][Int][Int]'
in any return_error at src/vm/moar/Perl6/Ops.nqp​:639
in sub x at <unknown file>​:1
in block <unit> at <unknown file>​:1

sub x() returns Array of Int { return my @​x of Int = 1,2,3 };
x().WHAT.say
Type check failed for return value; expected
'Array[Int][Int][Int][Int]' but got 'Array[Int][Int][Int][Int]'
in any return_error at src/vm/moar/Perl6/Ops.nqp​:639
in sub x at <unknown file>​:1
in block <unit> at <unknown file>​:1

sub x() returns Array of Int { return my @​x of Int = 1,2,3 };
x().WHAT.say
Type check failed for return value; expected
'Array[Int][Int][Int][Int][Int]' but got
'Array[Int][Int][Int][Int][Int]'
in any return_error at src/vm/moar/Perl6/Ops.nqp​:639
in sub x at <unknown file>​:1
in block <unit> at <unknown file>​:1

This is fine with 2016.07.1 - Closable with tests.
--
Will "Coke" Coleda

From @zoffixznet

Tests added in Raku/roast@457d3d8b92

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