@Phil, then the VM does not support it. I believe the latest VM from files.pharo.org should support it, but not the stable one.

@Denis Sure move it to MirrorPrimitive and update the WriteBarrier tests.

On Wed, Jan 25, 2017 at 3:09 PM, Denis Kudriashov <dionisiydk@gmail.com> wrote:

2017-01-25 13:59 GMT+01:00 Cl��ment Bera <bera.clement@gmail.com>:

It also raise another question: does these primitives support mirror approach? (when it can be called with receiver as first argument?)

Yes I made sure the mirror approach works. Even better, there are tests ensuring that it works. You can see in the class WriteBarrierTest that objects can become read-only through an instance of TTMirror, look for example into the users of TTMirror>>#setIsReadOnlyObjectOf: object to: boolean.

I think we need move it to��MirrorPrimitives which was introduced in Pharo 6.