Final fix: convert Undeclared variables encoded as simple associatins…

… to real variable objects.

Current bootstrap process use simple associations to represent vars in Undeclared registry. 
It breaks introduced logic here which explicitly return existing variable from Undeclared registry:
    - compiler parts expect kind of variable and not a simple association.
The bootstrap will be updated at some point. But now this case needs to be supported: 
  - declaring undefined var should update registered variable when it's type is not undeclared var

src/Kernel/UndeclaredVariable.class.st

@@ -16,8 +16,16 @@ UndeclaredVariable class >> registeredWithName: aString [
 	| varName |
 	varName := aString asSymbol.
 
-	Undeclared add: (self named: varName).
-	^OCUndeclaredVariable new name: varName
+	Undeclared associationAt: varName ifPresent: [ :found | 
+		found class == Association ifTrue: [ 
+			"Found undeclared var can be an association during current bootstrap process.
+			So here we should convert it to real variable object otherwise the build will be broken"
+			found becomeForward: (self named: varName)].
+		^found	].
+
+	^(self named: varName)
+		register;
+		yourself
 ]
 
 { #category : #OCVARIABLE }

src/OpalCompiler-Tests/OCCompiledMethodIntegrityTest.class.st

@@ -128,3 +128,25 @@ OCCompiledMethodIntegrityTest >> testUndeclaredVariableWhenItIsAlreadyRegistered
 	self assert: undeclaredBinding identicalTo: var.
 	undeclaredBinding unregister
 ]
+
+{ #category : #test }
+OCCompiledMethodIntegrityTest >> testUndeclaredVariableWhenItIsAlreadyRegisteredAsAssociation [
+	"Test describes current state of bootstrap where undeclared vars are encoded using associations.
+	It breaks introduced logic which explicitly return existing variable from Undeclared registry. 
+	Compiler parts expect kind of variable and not a simple association.
+	The bootstrap will be updated at some point. But now this case needs to be supported: 
+		- declaring undefined var should update registered variable when its type is not undeclared var"
+	| newCompiledMethod undeclaredBinding |
+	Undeclared add: #undeclaredTestVar -> nil.
+	newCompiledMethod := OpalCompiler new
+		source:
+			'methodWithUndeclaredVar
+											^ undeclaredTestVar';
+		class: OCMockCompilationClass;
+		compile.
+
+	undeclaredBinding := newCompiledMethod literals detect: [ :each | each name = #undeclaredTestVar ].
+	self assert: undeclaredBinding class equals: UndeclaredVariable.
+	self assert: undeclaredBinding identicalTo: (Undeclared associationAt: #undeclaredTestVar).
+	undeclaredBinding unregister
+]