Smartmatch doesn't produce correct result on a run-time created class stored in a Scalar container

[vrurg]

The Problem

When a class is created with Metamodel::ClassHOW.new_type at run-time and stored in a scalar then smartmatching of an object created of this class with the containing scalar gives False.

Expected Behavior

Object must smartmatch its class.

Steps to Reproduce

This code:

my $a = Metamodel::ClassHOW.new_type(name => "A");
$a.^compose;
say $a.new.WHAT ~~ $a

prints False.

Environment

• Operating system: macOS 10.14, Linux
• Compiler version (perl6 -v): This is Rakudo version 2018.12 built on MoarVM version 2018.12
  Also tested against Perl6/MoarVM 2017.10

[lizmat]

This appears to be related to the fact that you're putting the class definition into a scalar container by assigning to $a. If you bind to $a, it appears to work, for me at least.

my $a := Metamodel::ClassHOW.new_type(name => "A");
$a.^compose;
say $a.new.WHAT ~~ $a;    # True

[vrurg]

Yes, it does. And this is the advise I gave on IRC and how I fixed similar issue in my own code. But the point is that this works:

my $a = class A { };
say $a.new ~~ $a;

And I see no reason why creation from the metamodel class must not work either. Here is another interesting variation of the code:

my $b = my $a := Metamodel::ClassHOW.new_type(name => "A"); 
$a.^compose; # Use of $b here changes the result
my $o = $a.new;
say $o ~~ $a; 
say $o ~~ $b

Depending on whether compose is called on $a or $b the resulting smartmatch gives either both True for $a, or both False for $b.

[lizmat]

Fixed with ab8052d .

[vrurg]

Tested with rakudobrew, on moar-blead:

This is Rakudo version 2018.12-200-gd6b1bd2ae built on MoarVM version 2018.12-27-g9ce36b6a2

The reported buggy behavior is not reproducible on neither variant of the code I tried. Looks like it's fixed.

[Altai-man]

Tests proposed at Raku/roast#540