fix: Fix method resolution for inner interfaces (#4008)

src/main/java/spoon/support/visitor/ClassTypingContext.java

@@ -364,6 +364,10 @@ private CtTypeReference<?> getEnclosingType(CtTypeReference<?> typeRef) {
 			if (declType == null) {
 				return null;
 			}
+			if (type.isInterface()) {
+				// Case: we have a declaring type and the inner type is an interface. So the nested interface is implicitly static.
+				return null;
+			}
 			if (declType.isInterface()) {
 				//nested types of interfaces are static
 				return null;

src/test/java/spoon/test/ctType/CtTypeTest.java

@@ -37,7 +37,6 @@
 import spoon.reflect.visitor.filter.TypeFilter;
 import spoon.test.ctType.testclasses.X;
 
-import java.nio.file.Paths;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
@@ -46,6 +45,9 @@
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 
+import static org.hamcrest.CoreMatchers.anyOf;
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.MatcherAssert.assertThat;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertSame;
@@ -267,4 +269,19 @@ public void testTypeDeclarationToReferenceRoundTripInNamedModule() {
 
 		assertSame(reFetchedTypeDecl, typeDecl);
 	}
+	@Test
+	public void testGetAllExecutablesOnTypeImplementingNestedInterface() {
+		// contract: implicit static nested interfaces are correct handled in getAllExecutables.
+		Launcher launcher = new Launcher();
+		launcher.addInputResource("src/test/resources/extendsStaticInnerType");
+		CtModel model = launcher.buildModel();
+		CtType<?> type = model.getAllTypes().stream().filter(v -> v.getSimpleName().contains("BarBaz")).findAny().get();
+		int expectedNumExecutablesInJDK8 = 13;
+		int expectedNumExecutablesPostJDK8 = 14;
+		int numExecutables = type.getAllExecutables().size();
+		assertThat(numExecutables, anyOf(
+				equalTo(expectedNumExecutablesInJDK8),
+				equalTo(expectedNumExecutablesPostJDK8))
+		);	
+	}
 }

src/test/resources/extendsStaticInnerType/BarBaz.java

@@ -0,0 +1,10 @@
+package extendsStaticInnerType;
+
+public class BarBaz implements FooBar.Crashy {
+
+  @Override
+  public String foo() {
+    return "bar!";
+  }
+
+}

src/test/resources/extendsStaticInnerType/FooBar.java

@@ -0,0 +1,9 @@
+package extendsStaticInnerType;
+
+public class FooBar {
+
+  public interface Crashy {
+
+    String foo();
+  }
+}