Add support for dereferencing optional references

runtime/interpreter/interpreter_expression.go

@@ -697,16 +697,33 @@
 		)
 
 	case ast.OperationMul:
-		referenceValue, ok := value.(ReferenceValue)
-		if !ok {
-			panic(errors.NewUnreachableError())
+
+		if _, ok := value.(NilValue); ok {
+			return Nil
 		}
+
 		locationRange := LocationRange{
 			Location:    interpreter.Location,
 			HasPosition: expression,
 		}
+		var isOptional bool
+
+		if someValue, ok := value.(*SomeValue); ok {
+			isOptional = true
+			value = someValue.InnerValue(interpreter, locationRange)
+		}
 
-		return DereferenceValue(interpreter, locationRange, referenceValue)
+		referenceValue, ok := value.(ReferenceValue)
+		if !ok {
+			panic(errors.NewUnreachableError())
+		}
+
+		dereferencedValue := DereferenceValue(interpreter, locationRange, referenceValue)
+		if isOptional {
+			return NewSomeValueNonCopying(interpreter, dereferencedValue)
+		} else {
+			return dereferencedValue
+		}
 
 	case ast.OperationMove:
 		interpreter.invalidateResource(value)

runtime/interpreter/value.go

@@ -19432,8 +19432,8 @@ type SomeValue struct {
 	isDestroyed bool
 }
 
-func NewSomeValueNonCopying(interpreter *Interpreter, value Value) *SomeValue {
-	common.UseMemory(interpreter, common.OptionalValueMemoryUsage)
+func NewSomeValueNonCopying(memoryGauge common.MemoryGauge, value Value) *SomeValue {
+	common.UseMemory(memoryGauge, common.OptionalValueMemoryUsage)
 
 	return NewUnmeteredSomeValueNonCopying(value)
 }

runtime/sema/check_unary_expression.go

@@ -62,6 +62,13 @@ func (checker *Checker) VisitUnaryExpression(expression *ast.UnaryExpression) Ty
 		return checkExpectedType(valueType, SignedNumberType)
 
 	case ast.OperationMul:
+
+		var isOptional bool
+		if optionalType, ok := valueType.(*OptionalType); ok {
+			isOptional = true
+			valueType = optionalType.Type
+		}
+
 		referenceType, ok := valueType.(*ReferenceType)
 		if !ok {
 			if !valueType.IsInvalidType() {
@@ -97,7 +104,13 @@ func (checker *Checker) VisitUnaryExpression(expression *ast.UnaryExpression) Ty
 			)
 		}
 
-		return innerType
+		if isOptional {
+			return &OptionalType{
+				Type: innerType,
+			}
+		} else {
+			return innerType
+		}
 
 	case ast.OperationMove:
 		if !valueType.IsInvalidType() &&