From @masak

<moritz_> rakudo​: sub swap($a is rw, $b is rw) { ($a, $b) = ($b, $a)
}; swap(3, 4) # should that die?
<p6eval> rakudo c4857a​: ( no output )
<moritz_> I'm quite sure it should :/
<masak> aye, me too.
* moritz_ predicts masak's next line
* masak does the thing that fulfills that prediction
<masak> rakudo​: sub foo($a is rw) { $a = 5 }; foo(42)
<p6eval> rakudo c4857a​: OUTPUT«Cannot assign to readonly value
<masak> rakudo​: (1, 2) = 3, 4
<p6eval> rakudo c4857a​: ( no output )
<masak> ok, so it's the list assignment that doesn't pick up on non-rw values.

From @markjreed

Huh? Those are explicitly read-write. Why is it dying at all?

On Sat, May 1, 2010 at 9​:17 AM, Carl Mäsak <perl6-bugs-followup@​perl.org>wrote​:

# New Ticket Created by "Carl Mäsak"
# Please include the string​: [perl #​74820]
# in the subject line of all future correspondence about this issue.
# <URL​: http://rt.perl.org/rt3/Ticket/Display.html?id=74820 >

<moritz_> rakudo​: sub swap($a is rw, $b is rw) { ($a, $b) = ($b, $a)
}; swap(3, 4) # should that die?
<p6eval> rakudo c4857a​: ( no output )
<moritz_> I'm quite sure it should :/
<masak> aye, me too.
* moritz_ predicts masak's next line
* masak does the thing that fulfills that prediction
<masak> rakudo​: sub foo($a is rw) { $a = 5 }; foo(42)
<p6eval> rakudo c4857a​: OUTPUT«Cannot assign to readonly value
<masak> rakudo​: (1, 2) = 3, 4
<p6eval> rakudo c4857a​: ( no output )
<masak> ok, so it's the list assignment that doesn't pick up on non-rw
values.

--
Mark J. Reed <markjreed@​gmail.com>

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

From @masak

Carl (>>), Mark (>)​:

<moritz_> rakudo​: sub swap($a is rw, $b is rw) { ($a, $b) = ($b, $a)
}; swap(3, 4) # should that die?

Huh? Those are explicitly read-write. Why is it dying at all?

We're passing in 3 and 4, which are constants. The parameters $a and $b are indeed marked as
rw, but they're bound directly to immutable values, so Rakudo should die at runtime because
you can't change 3 and 4.

From @moritz

Am 03.05.2010 12​:30, schrieb Mark J. Reed​:

Huh? Those are explicitly read-write. Why is it dying at all?

Yes. I think masak++ picked up the wrong lines from p6eval​:

<@​moritz_> rakudo​: sub swap($a, $b) { ($a, $b) = ($b, $a) }; swap my $z
= 2, my $y = 5;
<+p6eval> rakudo c4857a​: ( no output )

*this* should die.

On Sat, May 1, 2010 at 9​:17 AM, Carl Mäsak<perl6-bugs-followup@​perl.org>wrote​:

# New Ticket Created by "Carl Mäsak"
# Please include the string​: [perl #​74820]
# in the subject line of all future correspondence about this issue.
#<URL​: http://rt.perl.org/rt3/Ticket/Display.html?id=74820>

<moritz_> rakudo​: sub swap($a is rw, $b is rw) { ($a, $b) = ($b, $a)
}; swap(3, 4) # should that die?
<p6eval> rakudo c4857a​: ( no output )
<moritz_> I'm quite sure it should :/
<masak> aye, me too.
* moritz_ predicts masak's next line
* masak does the thing that fulfills that prediction
<masak> rakudo​: sub foo($a is rw) { $a = 5 }; foo(42)
<p6eval> rakudo c4857a​: OUTPUT«Cannot assign to readonly value
<masak> rakudo​: (1, 2) = 3, 4
<p6eval> rakudo c4857a​: ( no output )
<masak> ok, so it's the list assignment that doesn't pick up on non-rw
values.

From @coke

On Mon May 03 04​:20​:44 2010, moritz wrote​:

Am 03.05.2010 12​:30, schrieb Mark J. Reed​:

Huh? Those are explicitly read-write. Why is it dying at all?

Yes. I think masak++ picked up the wrong lines from p6eval​:

<@​moritz_> rakudo​: sub swap($a, $b) { ($a, $b) = ($b, $a) }; swap my
$z
= 2, my $y = 5;
<+p6eval> rakudo c4857a​: ( no output )

*this* should die.

On Sat, May 1, 2010 at 9​:17 AM, Carl M�sak<perl6-bugs-
followup@​perl.org>wrote​:

# New Ticket Created by "Carl M�sak"
# Please include the string​: [perl #​74820]
# in the subject line of all future correspondence about this
issue.
#<URL​: http://rt.perl.org/rt3/Ticket/Display.html?id=74820>

<moritz_> rakudo​: sub swap($a is rw, $b is rw) { ($a, $b) = ($b,
$a)
}; swap(3, 4) # should that die?
<p6eval> rakudo c4857a​: ( no output )
<moritz_> I'm quite sure it should :/
<masak> aye, me too.
* moritz_ predicts masak's next line
* masak does the thing that fulfills that prediction
<masak> rakudo​: sub foo($a is rw) { $a = 5 }; foo(42)
<p6eval> rakudo c4857a​: OUTPUT�Cannot assign to readonly value
<masak> rakudo​: (1, 2) = 3, 4
<p6eval> rakudo c4857a​: ( no output )
<masak> ok, so it's the list assignment that doesn't pick up on
non-rw
values.

And now it does​:

$ ./perl6 foo -e 'sub swap($a, $b) { ($a, $b) = ($b, $a) }; swap my $z = 2, my $y = 5;'
Cannot assign to a readonly variable or a value
  in method STORE at src/gen/CORE.setting​:3369
  in sub swap at foo​:1
  in sub swap at foo​:1
  in <anon> at foo​:1
  in <anon> at foo​:1

tests needed.

--
Will "Coke" Coleda

From @moritz

Now tested in t/spec/S06-traits/is-rw.t.

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