From @zhuomingliang

JimmyZ> rakudo​: my class bar { method Str() { '11'; }; }; multi sub foo(bar $x as Int is copy) { say ++$x }; augment class bar { method Int() { '10' }}; foo(bar.new());

p6eval> rakudo 1eef08​: OUTPUT«Can't augment class bar without 'use MONKEY_TYPING'â�¤current instr.​: 'perl6;Perl6;Grammar;add_name' pc 42888 (src/gen/perl6-grammar.pir​:353)â�¤Â»

JimmyZ> rakudo​: my class bar { method Str() { '11'; }; }; multi sub foo(bar $x as Int is copy) { say ++$x }; my augment class bar { method Int() { '10' }}; foo(bar.new());
p6eval> rakudo 1eef08​: OUTPUT«Malformed my at line 11, near "augment cl"â�¤current instr.​: 'perl6;HLL;Grammar;panic' pc 501 (ext/nqp-rx/src/stage0/HLL-s0.pir​:327)â�¤Â»

JimmyZ> rakudo​: my class bar { method Str() { '11'; }; }; multi sub
foo(bar $x as Int is copy) { say ++$x }; augment my class bar { method
Int() { '10' }}; foo(bar.new());
p6eval> rakudo 1eef08​: OUTPUT«Malformed augment at line 11, near "my class b"â�¤current instr.​: 'perl6;HLL;Grammar;panic' pc 501
(ext/nqp-rx/src/stage0/HLL-s0.pir​:327)â�¤Â»

In order to discourage casual misuse of these declarators, they are not
allowed on global classes unless you put a special declaration at the
top​:
  use MONKEY_TYPING;
this is from​: http://perlcabal.org/syn/S12.html#line_2022

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��亮

From @coke

On Wed May 05 00​:22​:54 2010, jimmy wrote​:

JimmyZ> rakudo​: my class bar { method Str() { '11'; }; }; multi sub
foo(bar $x as Int is copy) { say ++$x }; augment class bar { method
Int() { '10' }}; foo(bar.new());

p6eval> rakudo 1eef08​: OUTPUT«Can't augment class bar without 'use
MONKEY_TYPING'â�¤current instr.​: 'perl6;Perl6;Grammar;add_name' pc 42888
(src/gen/perl6-grammar.pir​:353)â�¤Â»

JimmyZ> rakudo​: my class bar { method Str() { '11'; }; }; multi sub
foo(bar $x as Int is copy) { say ++$x }; my augment class bar { method
Int() { '10' }}; foo(bar.new());
p6eval> rakudo 1eef08​: OUTPUT«Malformed my at line 11, near "augment
cl"â�¤current instr.​: 'perl6;HLL;Grammar;panic' pc 501 (ext/nqp-
rx/src/stage0/HLL-s0.pir​:327)â�¤Â»

JimmyZ> rakudo​: my class bar { method Str() { '11'; }; }; multi sub
foo(bar $x as Int is copy) { say ++$x }; augment my class bar { method
Int() { '10' }}; foo(bar.new());
p6eval> rakudo 1eef08​: OUTPUT«Malformed augment at line 11, near "my
class b"â�¤current instr.​: 'perl6;HLL;Grammar;panic' pc 501
(ext/nqp-rx/src/stage0/HLL-s0.pir​:327)â�¤Â»

In order to discourage casual misuse of these declarators, they are
not
allowed on global classes unless you put a special declaration at the
top​:
use MONKEY_TYPING;
this is from​: http://perlcabal.org/syn/S12.html#line_2022

�此�你身��康�天天快�
��亮

This appears to do something closer to the right thing now​:

If you remove the "my" from the augment​:

19​:18 <[Coke]> rakudo​: use MONKEY_TYPING;my class bar { method Str() { '11'; };
  }; multi sub foo(bar $x as Int is copy) { say ++$x }; augment
  class bar { method Int() { '10' }}; foo(bar.new());
19​:18 <p6eval> rakudo ebd4d8​: OUTPUT«Type check failed in assignment to '$x';
  expected 'bar' but got 'Str'â�¤ in sub prefix​:<++> at
  src/gen/CORE.setting​:1050â�¤ in sub foo at /tmp/xUD1IINzZM​:1â�¤ in
  block <anon> at /tmp/xUD1IINzZM​:1â�¤ in <anon> at
  /tmp/xUD1IINzZM​:1â�¤â�¤Â»

It allows the augment and then complains about the '10' you passed to ++

This matches with a straight sub that does the same thing​:

19​:21 <[Coke]> rakudo​: sub foo (Int $x as Str) { say $x.WHAT}; foo(3)
19​:21 <p6eval> rakudo ebd4d8​: OUTPUT«Str()â�¤Â»
19​:23 <[Coke]> rakudo​: sub foo (Int $x as Str) { say $x.WHAT}; foo('3')
19​:23 <p6eval> rakudo ebd4d8​: OUTPUT«Nominal type check failed for parameter
  '$x'; expected Int but got Str insteadâ�¤ in sub foo at
  /tmp/9Ad8a8pUd8​:1â�¤ in block <anon> at /tmp/9Ad8a8pUd8​:1â�¤ in
  <anon> at /tmp/9Ad8a8pUd8​:1â�¤â�¤Â»

So I think this is closable modulo tests.

--
Will "Coke" Coleda

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

From @moritz

Now tested in S12-class/augment-supersede.t.

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