Incomplete type hierarchy when using method reference

[trancexpress]

See: https://bugs.eclipse.org/bugs/show_bug.cgi?id=560545

To reproduce, compute the type hierarchy of TestInterface in the following snippet:

public class TestClass {

	interface TestInterface {
		void testMethod();
	}

	public TestInterface ti1 = TestClass.this::testMethod;
	public TestInterface ti2 = () -> testMethod();
	public TestInterface ti3 = new TestInterface() {
		public void testMethod() {
			TestClass.this.testMethod();
		}
	};

	public void testMethod() {
		System.out.println("TestClass.testMethod()");
	}

	public static void main(String[] args) {
		TestClass t = new TestClass();
		t.ti1.testMethod();
		t.ti2.testMethod();
		t.ti3.testMethod();
	}
}

Observe that no implementer is found for the method reference. Only for the lambda and the anonymous type.

[trancexpress]

Example stack trace when a subtype is found (the lambda):

"Worker-5: Computing type hierarchy of 'TestInterface - test.TestClass'..." #122 prio=5 os_prio=0 cpu=676.35ms elapsed=1091.81s tid=0x00007f0e3c001670 nid=0xe759 at breakpoint [0x00007f0ef1798000]
   java.lang.Thread.State: RUNNABLE
        at org.eclipse.jdt.internal.core.hierarchy.TypeHierarchy.addSubtype(TypeHierarchy.java:238)
        at org.eclipse.jdt.internal.core.hierarchy.TypeHierarchy.cacheSuperInterfaces(TypeHierarchy.java:297)
        at org.eclipse.jdt.internal.core.hierarchy.HierarchyBuilder.connect(HierarchyBuilder.java:193)
        at org.eclipse.jdt.internal.core.hierarchy.HierarchyResolver.reportHierarchy(HierarchyResolver.java:613)
        at org.eclipse.jdt.internal.core.hierarchy.HierarchyResolver.resolve(HierarchyResolver.java:900)
        at org.eclipse.jdt.internal.core.hierarchy.IndexBasedHierarchyBuilder.buildForProject(IndexBasedHierarchyBuilder.java:265)
        at org.eclipse.jdt.internal.core.hierarchy.IndexBasedHierarchyBuilder.buildFromPotentialSubtypes(IndexBasedHierarchyBuilder.java:376)
        at org.eclipse.jdt.internal.core.hierarchy.IndexBasedHierarchyBuilder.build(IndexBasedHierarchyBuilder.java:166)
        at org.eclipse.jdt.internal.core.hierarchy.TypeHierarchy.compute(TypeHierarchy.java:323)
        at org.eclipse.jdt.internal.core.hierarchy.TypeHierarchy.refresh(TypeHierarchy.java:1319)
        - locked <0x0000000615f71400> (a org.eclipse.jdt.internal.core.hierarchy.TypeHierarchy)
        at org.eclipse.jdt.internal.ui.typehierarchy.TypeHierarchyLifeCycle.doHierarchyRefresh(TypeHierarchyLifeCycle.java:331)
        at org.eclipse.jdt.internal.ui.typehierarchy.TypeHierarchyLifeCycle.doHierarchyRefreshBackground(TypeHierarchyLifeCycle.java:272)
        at org.eclipse.jdt.internal.ui.typehierarchy.TypeHierarchyLifeCycle$1.run(TypeHierarchyLifeCycle.java:225)
        at org.eclipse.core.internal.jobs.Worker.run(Worker.java:63)

HierarchyResolver.typeBindings is being iterated over in HierarchyResolver.reportHierarchy(), it doesn't contain anything about the method reference.

The lambda is stored here:

"Worker-14: Computing type hierarchy of 'TestInterface - test.TestClass'..." #333 prio=5 os_prio=0 cpu=191.82ms elapsed=1131.52s tid=0x00007f50e4001670 nid=0xb4ab at breakpoint [0x00007f51c85fe000]
   java.lang.Thread.State: RUNNABLE
        at org.eclipse.jdt.internal.core.hierarchy.HierarchyResolver.remember(HierarchyResolver.java:435)
        at org.eclipse.jdt.internal.core.hierarchy.HierarchyResolver.remember(HierarchyResolver.java:442)
        at org.eclipse.jdt.internal.core.hierarchy.HierarchyResolver.rememberAllTypes(HierarchyResolver.java:535)
        at org.eclipse.jdt.internal.core.hierarchy.HierarchyResolver.resolve(HierarchyResolver.java:874)
        at org.eclipse.jdt.internal.core.hierarchy.IndexBasedHierarchyBuilder.buildForProject(IndexBasedHierarchyBuilder.java:265)
        at org.eclipse.jdt.internal.core.hierarchy.IndexBasedHierarchyBuilder.buildFromPotentialSubtypes(IndexBasedHierarchyBuilder.java:376)
        at org.eclipse.jdt.internal.core.hierarchy.IndexBasedHierarchyBuilder.build(IndexBasedHierarchyBuilder.java:166)
        at org.eclipse.jdt.internal.core.hierarchy.TypeHierarchy.compute(TypeHierarchy.java:323)
        at org.eclipse.jdt.internal.core.hierarchy.TypeHierarchy.refresh(TypeHierarchy.java:1319)
        - locked <0x000000062bc21430> (a org.eclipse.jdt.internal.core.hierarchy.TypeHierarchy)
        at org.eclipse.jdt.internal.ui.typehierarchy.TypeHierarchyLifeCycle.doHierarchyRefresh(TypeHierarchyLifeCycle.java:331)
        at org.eclipse.jdt.internal.ui.typehierarchy.TypeHierarchyLifeCycle.doHierarchyRefreshBackground(TypeHierarchyLifeCycle.java:272)
        at org.eclipse.jdt.internal.ui.typehierarchy.TypeHierarchyLifeCycle$1.run(TypeHierarchyLifeCycle.java:225)
        at org.eclipse.core.internal.jobs.Worker.run(Worker.java:63)

Maybe extra code is needed around the fix for https://bugs.eclipse.org/bugs/show_bug.cgi?id=400905, in HierarchyResolver.rememberAllTypes()... And in particular something like this will have to be added for method references that are assigned to a local variable (or a field): org.eclipse.jdt.internal.compiler.ast.LambdaExpression.getTypeBinding().LambdaTypeBinding

There is a bunch of other code around this LambdaTypeBinding, see e.g. HandleFactory.createLambdaTypeElement()

[trancexpress]

Would be good if we also take care of or make progress towards this bug: https://bugs.eclipse.org/bugs/show_bug.cgi?id=539602