fix: Fix NullPointerException when allowing duplicate classes

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

@@ -75,7 +75,8 @@ static TypeBinding searchTypeBinding(String qualifiedName, CompilationUnitDeclar
 		for (CompilationUnitDeclaration unitToProcess : unitsToProcess) {
 			if (unitToProcess.types != null) {
 				for (TypeDeclaration type : unitToProcess.types) {
-					if (qualifiedName.equals(CharOperation.toString(type.binding.compoundName))) {
+					if (type.binding != null
+							&& qualifiedName.equals(CharOperation.toString(type.binding.compoundName))) {
 						return type.binding;
 					}
 					if (type.memberTypes != null) {

src/test/java/spoon/test/model/TypeTest.java

@@ -10,6 +10,7 @@
 import org.junit.Test;
 import spoon.Launcher;
 import spoon.compiler.ModelBuildingException;
+import spoon.reflect.CtModel;
 import spoon.reflect.declaration.CtClass;
 import spoon.reflect.declaration.CtMethod;
 import spoon.reflect.declaration.CtType;
@@ -19,8 +20,11 @@
 import spoon.reflect.reference.CtTypeReference;
 import spoon.reflect.visitor.filter.AllTypeMembersFunction;
 
+import java.util.Arrays;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
+import java.util.stream.Collectors;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
@@ -140,7 +144,7 @@ public void testGetDeclaredOrIheritedFieldByReflection() throws Exception {
 
 		assertEquals("buf", type.getDeclaredOrInheritedField("buf").getSimpleName());
 		assertEquals("count", type.getDeclaredOrInheritedField("count").getSimpleName());
-		
+
 	}
 
 	@Test
@@ -176,7 +180,29 @@ public void testMultiClassEnable() {
 		spoon.buildModel();
 		assertNotNull(spoon.getFactory().Class().get("A"));
 	}
-
+
+	@Test
+	public void testMultiClassEnableWithStaticFieldAccessToNestedType() {
+		// test that ignoring duplicate classes works out when there in class A is a static field
+		// access C.someField to a nested type B.C, and A has imported B.C.
+		// This forces Spoon to search for the type C with JDTTreeBuilder.searchTypeBinding.
+		// See https://github.com/INRIA/spoon/issues/3707 for details.
+
+		Launcher launcher = new Launcher();
+		launcher.getEnvironment().setIgnoreDuplicateDeclarations(true);
+
+		launcher.addInputResource("src/test/resources/duplicates-in-submodules/moduleA");
+		launcher.addInputResource("src/test/resources/duplicates-in-submodules/moduleB");
+
+		CtModel model = launcher.buildModel();
+
+		Set<String> expectedTypeNames = new HashSet<>(
+				Arrays.asList("duplicates.Duplicate", "duplicates.Main", "duplicates.WithNestedEnum"));
+		Set<String> typeNames = model.getAllTypes().stream().map(CtType::getQualifiedName).collect(Collectors.toSet());
+
+		assertEquals(expectedTypeNames, typeNames);
+	}
+
 	private void checkIsSomething(String expectedType, CtType type) {
 		_checkIsSomething(expectedType, type);
 		_checkIsSomething(expectedType, type.getReference());

src/test/resources/duplicates-in-submodules/README.md

@@ -0,0 +1 @@
+Test files to replicate https://github.com/INRIA/spoon/issues/3707

src/test/resources/duplicates-in-submodules/moduleA/duplicates/Duplicate.java

@@ -0,0 +1,3 @@
+package duplicates;
+
+public class Duplicate {}

src/test/resources/duplicates-in-submodules/moduleA/duplicates/Main.java

@@ -0,0 +1,9 @@
+package duplicates;
+
+import duplicates.WithNestedEnum.NestedEnum;
+
+public class Main {
+    public static void main(String[] args) {
+        System.out.println(NestedEnum.YES.name());
+    }
+}

src/test/resources/duplicates-in-submodules/moduleA/duplicates/WithNestedEnum.java

@@ -0,0 +1,7 @@
+package duplicates;
+
+class WithNestedEnum {
+    public enum NestedEnum {
+        YES;
+    }
+}

src/test/resources/duplicates-in-submodules/moduleB/duplicates/Duplicate.java

@@ -0,0 +1,3 @@
+package duplicates;
+
+public class Duplicate {}