Fixed 'IDEA-127301: NPE in decompiler' - a couple of issues with lambda processing

src/de/fernflower/main/ClassWriter.java

@@ -112,7 +112,7 @@ public class ClassWriter {
 
 	}
 	
-	public void classLambdaToJava(ClassNode node, BufferedWriter writer, int indent) throws IOException {
+	public void classLambdaToJava(ClassNode node, BufferedWriter writer, Exprent method_object, int indent) throws IOException {
 
 		// get the class node with the content method
 		ClassNode node_content = node;
@@ -136,7 +136,12 @@ public class ClassWriter {
 
 		if(node.lambda_information.is_method_reference) {
 
+			if(!node.lambda_information.is_content_method_static && method_object != null) { // reference to a virtual method
+				writer.write(method_object.toJava(indent));
+			} else { // reference to a static method 
 				writer.write(ExprProcessor.getCastTypeName(new VarType(node.lambda_information.content_class_name, false)));
+			}
+			
     		writer.write("::");
     		writer.write(node.lambda_information.content_method_name);
     
@@ -156,7 +161,7 @@ public class ClassWriter {
     			StringBuilder buff = new StringBuilder("(");
     
     			boolean firstpar = true;
-    			int index = 1;
+    			int index = node.lambda_information.is_content_method_static ? 0 : 1;;
     			
     			int start_index = md_content.params.length - md_lambda.params.length;
     			
@@ -604,7 +609,7 @@ public class ClassWriter {
 			bufstrwriter.write("(");
 	
 			boolean firstpar = true;
-			int index = 1;
+			int index = node_lambda.lambda_information.is_content_method_static ? 0 : 1;;
 			
 			int start_index = md_content.params.length - md_lambda.params.length;
 			

src/de/fernflower/main/ClassesProcessor.java

@@ -379,8 +379,8 @@ public class ClassesProcessor {
 		
 		public LambdaInformation lambda_information;
 		
-		public ClassNode(String content_class_name, String content_method_name, String content_method_descriptor, String lambda_class_name, String lambda_method_name, 
+		public ClassNode(String content_class_name, String content_method_name, String content_method_descriptor, int content_method_invokation_type,
-												String lambda_method_descriptor, StructClass classStruct) { // lambda class constructor
+										String lambda_class_name, String lambda_method_name, String lambda_method_descriptor, StructClass classStruct) { // lambda class constructor
 			this.type = CLASS_LAMBDA;
 			this.classStruct = classStruct; // 'parent' class containing the static function 
 			
@@ -393,19 +393,22 @@ public class ClassesProcessor {
 			lambda_information.content_class_name = content_class_name;
 			lambda_information.content_method_name = content_method_name;
 			lambda_information.content_method_descriptor = content_method_descriptor;
+			lambda_information.content_method_invokation_type = content_method_invokation_type; 
+			
 			lambda_information.content_method_key = InterpreterUtil.makeUniqueKey(lambda_information.content_method_name, lambda_information.content_method_descriptor);
 
 			anonimousClassType = new VarType(lambda_class_name, true);
 			
-			if(content_class_name != classStruct.qualifiedName) { // method reference. FIXME: class name alone doesn't cover it. Synthetic flag seems to be the only 'reliable' difference.
+			boolean is_method_reference = (content_class_name != classStruct.qualifiedName);
-				lambda_information.is_method_reference = true;
+			StructMethod mt = null;
-				lambda_information.is_content_method_static = true; // FIXME: consider argument flag
-			} else {
-				StructMethod mt = classStruct.getMethod(content_method_name, content_method_descriptor);
 			
-				lambda_information.is_method_reference = false;
+			if(!is_method_reference) { // content method in the same class, check synthetic flag
-				lambda_information.is_content_method_static = ((mt.getAccessFlags() & CodeConstants.ACC_STATIC) != 0);
+				mt = classStruct.getMethod(content_method_name, content_method_descriptor);
+				is_method_reference = !((mt.getAccessFlags() & CodeConstants.ACC_SYNTHETIC) != 0 || mt.getAttributes().containsKey("Synthetic")); // if not synthetic -> method reference
 			}
+			
+			lambda_information.is_method_reference = is_method_reference;
+			lambda_information.is_content_method_static = (lambda_information.content_method_invokation_type == CodeConstants.CONSTANT_MethodHandle_REF_invokeStatic); // FIXME: redundant?
 		}
 		
 		public ClassNode(int type, StructClass classStruct) {
@@ -425,6 +428,9 @@ public class ClassesProcessor {
 		}
 
 		public class LambdaInformation {
+			
+			
+			
 			public String class_name;
 			public String method_name;
 			public String method_descriptor;
@@ -432,6 +438,7 @@ public class ClassesProcessor {
 			public String content_class_name;
 			public String content_method_name;
 			public String content_method_descriptor;
+			public int content_method_invokation_type; // values from CONSTANT_MethodHandle_REF_*
 			
 			public String content_method_key;
 			

src/de/fernflower/main/rels/LambdaProcessor.java

@@ -98,7 +98,8 @@ public class LambdaProcessor {
 							
 							LinkConstant content_method_handle = (LinkConstant)bootstrap_arguments.get(1);
 
-							ClassNode node_lambda = clprocessor.new ClassNode(content_method_handle.classname, content_method_handle.elementname, content_method_handle.descriptor, 
+							ClassNode node_lambda = clprocessor.new ClassNode(content_method_handle.classname, content_method_handle.elementname, 
+									                                          content_method_handle.descriptor, content_method_handle.index1,
 									                                          lambda_class_name, lambda_method_name, lambda_method_descriptor, cl);
 							node_lambda.simpleName = cl.qualifiedName + "##Lambda_" + invoke_dynamic.index1 + "_" + invoke_dynamic.index2;
 							node_lambda.enclosingMethod = InterpreterUtil.makeUniqueKey(mt.getName(), mt.getDescriptor());

src/de/fernflower/main/rels/MethodProcessorThread.java

@@ -175,7 +175,7 @@ public class MethodProcessorThread implements Runnable {
 		ClearStructHelper.clearStatements(root);
 		
 		ExprProcessor proc = new ExprProcessor();
-		proc.processStatement(root, cl.getPool());
+		proc.processStatement(root, cl);
 
 //		DotExporter.toDotFile(graph, new File("c:\\Temp\\fern3.dot"), true);
 //		System.out.println(graph.toString());

src/de/fernflower/main/rels/NestedClassProcessor.java

@@ -56,8 +56,8 @@ public class NestedClassProcessor {
 	
 	public void processClass(ClassNode root, ClassNode node) {
 
-		// hide lambda content methods
+		// hide synthetic lambda content methods
-		if(node.type == ClassNode.CLASS_LAMBDA) {
+		if(node.type == ClassNode.CLASS_LAMBDA && !node.lambda_information.is_method_reference) {
 			ClassNode node_content = DecompilerContext.getClassprocessor().getMapRootClasses().get(node.classStruct.qualifiedName);
 			if(node_content != null && node_content.wrapper != null) {
 				node_content.wrapper.getHideMembers().add(node.lambda_information.content_method_key);

src/de/fernflower/modules/decompiler/ExprProcessor.java

@@ -14,22 +14,48 @@
 
 package de.fernflower.modules.decompiler;
 
-import java.util.*;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
 
 import de.fernflower.code.CodeConstants;
 import de.fernflower.code.Instruction;
 import de.fernflower.code.InstructionSequence;
 import de.fernflower.code.cfg.BasicBlock;
 import de.fernflower.main.DecompilerContext;
-import de.fernflower.modules.decompiler.exps.*;
+import de.fernflower.modules.decompiler.exps.ArrayExprent;
+import de.fernflower.modules.decompiler.exps.AssignmentExprent;
+import de.fernflower.modules.decompiler.exps.ConstExprent;
+import de.fernflower.modules.decompiler.exps.ExitExprent;
+import de.fernflower.modules.decompiler.exps.Exprent;
+import de.fernflower.modules.decompiler.exps.FieldExprent;
+import de.fernflower.modules.decompiler.exps.FunctionExprent;
+import de.fernflower.modules.decompiler.exps.IfExprent;
+import de.fernflower.modules.decompiler.exps.InvocationExprent;
+import de.fernflower.modules.decompiler.exps.MonitorExprent;
+import de.fernflower.modules.decompiler.exps.NewExprent;
+import de.fernflower.modules.decompiler.exps.SwitchExprent;
+import de.fernflower.modules.decompiler.exps.VarExprent;
 import de.fernflower.modules.decompiler.sforms.DirectGraph;
 import de.fernflower.modules.decompiler.sforms.DirectNode;
 import de.fernflower.modules.decompiler.sforms.FlattenStatementsHelper;
 import de.fernflower.modules.decompiler.sforms.FlattenStatementsHelper.FinallyPathWrapper;
-import de.fernflower.modules.decompiler.stats.*;
+import de.fernflower.modules.decompiler.stats.BasicBlockStatement;
+import de.fernflower.modules.decompiler.stats.CatchAllStatement;
+import de.fernflower.modules.decompiler.stats.CatchStatement;
+import de.fernflower.modules.decompiler.stats.RootStatement;
+import de.fernflower.modules.decompiler.stats.Statement;
 import de.fernflower.modules.decompiler.vars.VarProcessor;
 import de.fernflower.struct.StructClass;
+import de.fernflower.struct.attr.StructBootstrapMethodsAttribute;
+import de.fernflower.struct.attr.StructGeneralAttribute;
 import de.fernflower.struct.consts.ConstantPool;
+import de.fernflower.struct.consts.LinkConstant;
+import de.fernflower.struct.consts.PooledConstant;
 import de.fernflower.struct.consts.PrimitiveConstant;
 import de.fernflower.struct.gen.MethodDescriptor;
 import de.fernflower.struct.gen.VarType;
@@ -124,7 +150,7 @@ public class ExprProcessor implements CodeConstants {
 
 	private VarProcessor varProcessor = (VarProcessor) DecompilerContext.getProperty(DecompilerContext.CURRENT_VAR_PROCESSOR);
 
-	public void processStatement(RootStatement root, ConstantPool pool) {
+	public void processStatement(RootStatement root, StructClass cl) {
 
 		FlattenStatementsHelper flatthelper = new FlattenStatementsHelper();
 		DirectGraph dgraph = flatthelper.buildDirectGraph(root);
@@ -179,7 +205,7 @@ public class ExprProcessor implements CodeConstants {
 
 			BasicBlockStatement block = node.block;
 			if (block != null) {
-				processBlock(block, data, pool);
+				processBlock(block, data, cl);
 				block.setExprents(data.getLstExprents());
 			}
 
@@ -291,7 +317,10 @@ public class ExprProcessor implements CodeConstants {
 		}
 	}
 
-	public void processBlock(BasicBlockStatement stat, PrimitiveExprsList data, ConstantPool pool) {
+	public void processBlock(BasicBlockStatement stat, PrimitiveExprsList data, StructClass cl) {
+
+		ConstantPool pool = cl.getPool();
+		StructBootstrapMethodsAttribute bootstrap = (StructBootstrapMethodsAttribute)cl.getAttributes().getWithKey(StructGeneralAttribute.ATTRIBUTE_BOOTSTRAP_METHODS);
 		
 		BasicBlock block = stat.getBlock();
 
@@ -516,7 +545,18 @@ public class ExprProcessor implements CodeConstants {
 			case opc_invokeinterface:
 			case opc_invokedynamic:
 				if(instr.opcode != opc_invokedynamic || instr.bytecode_version >= CodeConstants.BYTECODE_JAVA_7) {
-					InvocationExprent exprinv = new InvocationExprent(instr.opcode, pool.getLinkConstant(instr.getOperand(0)), stack);
+					
+					LinkConstant invoke_constant = pool.getLinkConstant(instr.getOperand(0));
+					int dynamic_invokation_type = -1;
+					
+					if(instr.opcode == opc_invokedynamic && bootstrap != null) {
+						List<PooledConstant> bootstrap_arguments = bootstrap.getMethodArguments(invoke_constant.index1);
+						LinkConstant content_method_handle = (LinkConstant)bootstrap_arguments.get(1);
+						
+						dynamic_invokation_type = content_method_handle.index1;
+					}
+					
+					InvocationExprent exprinv = new InvocationExprent(instr.opcode, invoke_constant, stack, dynamic_invokation_type);
 					if (exprinv.getDescriptor().ret.type == CodeConstants.TYPE_VOID) {
 						exprlist.add(exprinv);
 					} else {

src/de/fernflower/modules/decompiler/FinallyProcessor.java

@@ -206,7 +206,7 @@ public class FinallyProcessor {
 		}
 		
 		ExprProcessor proc = new ExprProcessor();
-		proc.processStatement(root, mt.getClassStruct().getPool());
+		proc.processStatement(root, mt.getClassStruct());
 
 		SSAConstructorSparseEx ssa = new SSAConstructorSparseEx();
 		ssa.splitVariables(root, mt);

src/de/fernflower/modules/decompiler/SimplifyExprentsHelper.java

@@ -721,6 +721,9 @@ public class SimplifyExprentsHelper {
 					
 					NewExprent newexp = new NewExprent(new VarType(lambda_class_name, true), null, 0);
 					newexp.setConstructor(in); 
+					// note: we don't set the instance to null with in.setInstance(null) like it is done for a common constructor invokation
+					// lambda can also be a reference to a virtual method (e.g. String x; ...(x::toString);)
+					// in this case instance will hold the corresponding object
 					
 					return newexp;
 				}

src/de/fernflower/modules/decompiler/exps/InvocationExprent.java

@@ -76,7 +76,7 @@ public class InvocationExprent extends Exprent {
 	
 	public InvocationExprent() {}
 			
-	public InvocationExprent(int opcode, LinkConstant cn, ListStack<Exprent> stack) {
+	public InvocationExprent(int opcode, LinkConstant cn, ListStack<Exprent> stack, int dynamic_invokation_type) {
 		
 		name = cn.elementname;
 		classname = cn.classname;
@@ -99,6 +99,7 @@ public class InvocationExprent extends Exprent {
 			
 			classname = "java/lang/Class"; // dummy class name
 			invoke_dynamic_classsuffix = "##Lambda_" + cn.index1 + "_" + cn.index2;
+			
 		}
 		
 		if("<init>".equals(name)) {
@@ -114,7 +115,13 @@ public class InvocationExprent extends Exprent {
 			lstParameters.add(0, stack.pop());
 		}
 		
-		if(opcode == CodeConstants.opc_invokestatic || opcode == CodeConstants.opc_invokedynamic) {
+		if(opcode == CodeConstants.opc_invokedynamic) {
+			if(dynamic_invokation_type == CodeConstants.CONSTANT_MethodHandle_REF_invokeStatic) {
+				isStatic = true;
+			} else {
+				instance = lstParameters.get(0); // FIXME: remove the first parameter completely from the list. It's the object type for a virtual lambda method.   
+			}
+		} else if(opcode == CodeConstants.opc_invokestatic) {
 			isStatic = true;
 		} else {
 			instance = stack.pop(); 

src/de/fernflower/modules/decompiler/exps/NewExprent.java

@@ -133,6 +133,12 @@ public class NewExprent extends Exprent {
 		List<Exprent> lst = new ArrayList<Exprent>();
 		if(newtype.arraydim == 0) {
 			if(constructor != null) {
+				Exprent constructor_instance = constructor.getInstance();
+				
+				if(constructor_instance != null) { // should be true only for a lambda expression with a virtual content method  
+					lst.add(constructor_instance);
+				}
+				
 				lst.addAll(constructor.getLstParameters());
 			}
 		} else {
@@ -193,7 +199,8 @@ public class NewExprent extends Exprent {
 				boolean firstpar = true;
 				int start = 0, end = invsuper.getLstParameters().size();
 				if (enumconst) {
-          start += 2; end -= 1;
+					start += 2;
+					end -= 1;
 				}
 				for(int i = start; i < end; i++) {
 					if (sigFields == null || sigFields.get(i) == null) {
@@ -254,7 +261,7 @@ public class NewExprent extends Exprent {
 			ClassWriter clwriter = new ClassWriter();
 			try {
 				if (lambda) {
-					clwriter.classLambdaToJava(child, bufstrwriter, indent);
+					clwriter.classLambdaToJava(child, bufstrwriter, (constructor == null ? null : constructor.getInstance()), indent);
 				} else {
 					clwriter.classToJava(child, bufstrwriter, indent);
 				}
@@ -264,7 +271,8 @@ public class NewExprent extends Exprent {
 			}
 
 			if (lambda && !DecompilerContext.getOption(IFernflowerPreferences.LAMBDA_TO_ANONYMOUS_CLASS)) {
-				buf.setLength(0); // remove the usual 'new <class>()', it will be replaced with lambda style '() ->'  
+				buf.setLength(0); // remove the usual 'new <class>()', it will
+								  // be replaced with lambda style '() ->'
 			}
 
 			buf.append(strwriter.toString());