RB - RBTrait DNU asTraitComposition *and* cannot be created easily in RBNamespace

[badetitou]

Bug description
It is not possible to use a trait made in RB in another entity in the same RB environment.
(I cannot create a RBTrait named "TMyTrait", not install in the system yet, and use it in a class "MyClass")
We got an error with asTraitComposition

This feature is used by the SmaCC project.

To Reproduce
Execute the following code

namespace := RBNamespace new.
change := namespace smaccDefineTrait: [ :builder |
	builder
		name: #TMyTrait;
		package: #HelloWorld;
		beTrait ].

(namespace classNamed: #TMyTrait). "rb-TMyTrait"

namespace defineClass: [ :builder |
	builder
		name: #MyClass;
		traits: { (namespace classNamed: #TMyTrait) };
		package: #HelloWorld ]

You'll notice the method smaccDefineTrait: which is a copy of RBNamespace>>#defineClass: but adapted to create RBTrait (because their is no method to create RBTrait too.

To avoid searching, here is the implementation of RBNamespace>>#smaccDefineTrait: for Pharo12

smaccDefineTrait: aBuilderBlock
	| change newClass newClassName |
	change := changes defineClass: aBuilderBlock.
	newClassName := change changeClassName.
	newClass := self classNamed: newClassName. 
	newClass
		ifNil: [ | newMetaclass |
			self unmarkAsRemoved: newClassName.
			newClass := self rbTraitClass named: newClassName.
			newMetaclass := self rbTraitedMetaclassClass named: newClassName.
			newClass model: self.
			newMetaclass model: self.
			newClasses
				at: newClassName
				put: (Array with: newClass with: newMetaclass) ].
	newClass superclass: nil.
	self rootClasses add: newClass.
	newClass classSide superclass: nil.
	newClass instanceVariableNames: #().
	newClass classVariableNames: #().
	newClass poolDictionaryNames: #().
	newClass packageName: change package.
	^ change

Expected behavior
I believe we should be able to deal with Trait easily in RB and the asTraitComposition should work

Version information:

• OS: ArchLinux
• Version: rolling
• Pharo Version 12

Expected development cost
I don't know, but I can help to reproduce the issue.

[Ducasse]

Pay attention RB never worked with traits.

[badetitou]

Is it something we want? ( Making RB dealing with Traits )
( I know it can require too much time and so the community has to work on it )