bug: Type of string concatenation is null

[Egor18]

Hi!
I found out that Spoon returns null type for 2 or more concatenations of string literals.
For example:
String s = "one" + "two" + "three";
Spoon says that the type of "two" + "three" is null, but it's actually String.
I provided the test that demonstrates that.

Moreover, I'm sure that the problem is here:

spoon/src/main/java/spoon/support/compiler/jdt/ParentExiter.java

Lines 421 to 432 in f2ecd5d

	} else if (jdtTreeBuilder.getContextBuilder().stack.peek().node instanceof StringLiteralConcatenation) {
	CtBinaryOperator<?> op = operator.getFactory().Core().createBinaryOperator();
	op.setKind(BinaryOperatorKind.PLUS);
	op.setLeftHandOperand(operator.getRightHandOperand());
	op.setRightHandOperand((CtExpression<?>) child);
	operator.setRightHandOperand(op);
	int[] lineSeparatorPositions = jdtTreeBuilder.getContextBuilder().getCompilationUnitLineSeparatorPositions();
	SourcePosition leftPosition = op.getLeftHandOperand().getPosition();
	SourcePosition rightPosition = op.getRightHandOperand().getPosition();
	op.setPosition(op.getFactory().createSourcePosition(leftPosition.getCompilationUnit(), leftPosition.getSourceStart(), rightPosition.getSourceEnd(), lineSeparatorPositions));
	return;
	}

We create a new CtBinaryOperator but do not set its type.

So I tried to fix that by adding setType call:
op.setType((CtTypeReference) operator.getFactory().Type().STRING);

This fix works and type appears, but AstParentConsistencyChecker does not like it, because setType sets parent of the reference to op, so I'm getting:

java.lang.IllegalStateException: Element: java.lang.String
Signature: spoon.support.reflect.reference.CtTypeReferenceImpl@943a4c32
Class: class spoon.support.reflect.reference.CtTypeReferenceImpl
position: (unknown file)
 is set as child of
Element: (("two" + "three") + "four")
Signature: spoon.support.reflect.code.CtBinaryOperatorImpl@1
Class: class spoon.support.reflect.code.CtBinaryOperatorImpl
position: (/home/egor/spoon/src/test/java/spoon/test/type/testclasses/Foo.java:7)
however it is visited as a child of
Element: ("two" + "three")
Signature: spoon.support.reflect.code.CtBinaryOperatorImpl@1
Class: class spoon.support.reflect.code.CtBinaryOperatorImpl
position: (/home/egor/spoon/src/test/java/spoon/test/type/testclasses/Foo.java:7)

Do you have any ideas how to set the parent properly here?
Thanks.

[monperrus]

Thanks for the fix!

Maybe the short op.setType((CtTypeReference) operator.getFactory().Type().STRING.clone()) (call to clone)

or

ref =
(CtTypeReference) operator.getFactory().Type().STRING.clone()
ref.setParent(op)
op.setType(ref)

[Egor18]

Yes, it works, but Travis is stuck. I'll try to trigger it again.

[Egor18]

I think it's ready :)

[monperrus]

Thanks a lot!