fix: several improvements for generics and type inference

- support 'extends' for generic type variables
- insert cast instructions to help type inference (#956)
- correct move instructions insertion (to resolve types in PHI)

Signed-off-by: Skylot <skylot@gmail.com>

jadx-core/src/main/java/jadx/core/clsp/ConvertToClsSet.java → jadx-cli/src/main/java/jadx/cli/clst/ConvertToClsSet.java

@@ -1,4 +1,4 @@
-package jadx.core.clsp;
+package jadx.cli.clst;
 
 import java.io.IOException;
 import java.nio.file.Path;
@@ -16,6 +16,7 @@
 import jadx.api.plugins.JadxPluginManager;
 import jadx.api.plugins.input.JadxInputPlugin;
 import jadx.api.plugins.input.data.ILoadResult;
+import jadx.core.clsp.ClsSet;
 import jadx.core.dex.nodes.RootNode;
 
 /**
@@ -50,6 +51,7 @@ public static void main(String[] args) throws IOException {
 		ClsSet set = new ClsSet(root);
 		set.loadFrom(root);
 		set.save(output);
+
 		LOG.info("Output: {}, file size: {}B", output, output.toFile().length());
 		LOG.info("done");
 	}

jadx-core/src/main/java/jadx/core/Consts.java

@@ -10,6 +10,7 @@ public class Consts {
 	public static final String CLASS_STRING = "java.lang.String";
 	public static final String CLASS_CLASS = "java.lang.Class";
 	public static final String CLASS_THROWABLE = "java.lang.Throwable";
+	public static final String CLASS_EXCEPTION = "java.lang.Exception";
 	public static final String CLASS_ENUM = "java.lang.Enum";
 
 	public static final String CLASS_STRING_BUILDER = "java.lang.StringBuilder";

jadx-core/src/main/java/jadx/core/clsp/ClsSet.java

@@ -32,15 +32,13 @@
 import jadx.core.dex.info.MethodInfo;
 import jadx.core.dex.instructions.args.ArgType;
 import jadx.core.dex.nodes.ClassNode;
-import jadx.core.dex.nodes.GenericTypeParameter;
 import jadx.core.dex.nodes.MethodNode;
 import jadx.core.dex.nodes.RootNode;
 import jadx.core.utils.exceptions.DecodeException;
 import jadx.core.utils.exceptions.JadxRuntimeException;
 import jadx.core.utils.files.FileUtils;
 import jadx.core.utils.files.ZipSecurity;
 
-import static jadx.core.utils.Utils.isEmpty;
 import static jadx.core.utils.Utils.notEmpty;
 
 /**
@@ -139,7 +137,7 @@ private void processMethodDetails(MethodNode mth, List<ClspMethod> methods) {
 		ArgType genericRetType = mth.getReturnType();
 		boolean varArgs = accessFlags.isVarArgs();
 		List<ArgType> throwList = mth.getThrows();
-		List<GenericTypeParameter> typeParameters = mth.getTypeParameters();
+		List<ArgType> typeParameters = mth.getTypeParameters();
 		// add only methods with additional info
 		if (varArgs
 				|| notEmpty(throwList)
@@ -186,7 +184,7 @@ private static ClspClass getCls(String fullName, Map<String, ClspClass> names) {
 		return cls;
 	}
 
-	void save(Path path) throws IOException {
+	public void save(Path path) throws IOException {
 		FileUtils.makeDirsForFile(path);
 		String outputName = path.getFileName().toString();
 		if (outputName.endsWith(CLST_EXTENSION)) {
@@ -225,7 +223,7 @@ void save(Path path) throws IOException {
 		}
 	}
 
-	public void save(OutputStream output) throws IOException {
+	private void save(OutputStream output) throws IOException {
 		DataOutputStream out = new DataOutputStream(output);
 		out.writeBytes(JADX_CLS_SET_HEADER);
 		out.writeByte(VERSION);
@@ -239,7 +237,7 @@ public void save(OutputStream output) throws IOException {
 		}
 		for (ClspClass cls : classes) {
 			writeArgTypesArray(out, cls.getParents(), names);
-			writeGenericTypeParameters(out, cls.getTypeParameters(), names);
+			writeArgTypesList(out, cls.getTypeParameters(), names);
 			List<ClspMethod> methods = cls.getSortedMethodsList();
 			out.writeShort(methods.size());
 			for (ClspMethod method : methods) {
@@ -250,20 +248,6 @@ public void save(OutputStream output) throws IOException {
 		LOG.info("Classes: {}, methods: {}, file size: {}B", classes.length, methodsCount, out.size());
 	}
 
-	private static void writeGenericTypeParameters(DataOutputStream out,
-			List<GenericTypeParameter> typeParameters,
-			Map<String, ClspClass> names) throws IOException {
-		if (isEmpty(typeParameters)) {
-			out.writeByte(0);
-		} else {
-			writeUnsignedByte(out, typeParameters.size());
-			for (GenericTypeParameter typeParameter : typeParameters) {
-				writeArgType(out, typeParameter.getTypeVariable(), names);
-				writeArgTypesList(out, typeParameter.getExtendsList(), names);
-			}
-		}
-	}
-
 	private static void writeMethod(DataOutputStream out, ClspMethod method, Map<String, ClspClass> names) throws IOException {
 		MethodInfo methodInfo = method.getMethodInfo();
 		writeString(out, methodInfo.getName());
@@ -272,7 +256,7 @@ private static void writeMethod(DataOutputStream out, ClspMethod method, Map<Str
 
 		writeArgTypesList(out, method.containsGenericArgs() ? method.getArgTypes() : Collections.emptyList(), names);
 		writeArgType(out, method.getReturnType(), names);
-		writeGenericTypeParameters(out, method.getTypeParameters(), names);
+		writeArgTypesList(out, method.getTypeParameters(), names);
 		out.writeBoolean(method.isVarArg());
 		writeArgTypesList(out, method.getThrows(), names);
 	}
@@ -323,11 +307,11 @@ private static void writeArgType(DataOutputStream out, ArgType argType, Map<Stri
 		} else if (argType.isGeneric()) {
 			out.writeByte(TypeEnum.GENERIC.ordinal());
 			out.writeInt(getCls(argType, names).getId());
-			ArgType[] types = argType.getGenericTypes();
-			writeArgTypesArray(out, types, names);
+			writeArgTypesList(out, argType.getGenericTypes(), names);
 		} else if (argType.isGenericType()) {
 			out.writeByte(TypeEnum.GENERIC_TYPE_VARIABLE.ordinal());
 			writeString(out, argType.getObject());
+			writeArgTypesList(out, argType.getExtendTypes(), names);
 		} else if (argType.isObject()) {
 			out.writeByte(TypeEnum.OBJECT.ordinal());
 			out.writeInt(getCls(argType, names).getId());
@@ -380,26 +364,12 @@ private void load(InputStream input) throws IOException, DecodeException {
 				ClspClass nClass = classes[i];
 				ClassInfo clsInfo = ClassInfo.fromType(root, nClass.getClsType());
 				nClass.setParents(readArgTypesArray(in));
-				nClass.setTypeParameters(readGenericTypeParameters(in));
+				nClass.setTypeParameters(readArgTypesList(in));
 				nClass.setMethods(readClsMethods(in, clsInfo));
 			}
 		}
 	}
 
-	private List<GenericTypeParameter> readGenericTypeParameters(DataInputStream in) throws IOException {
-		int count = readUnsignedByte(in);
-		if (count == 0) {
-			return Collections.emptyList();
-		}
-		List<GenericTypeParameter> list = new ArrayList<>(count);
-		for (int i = 0; i < count; i++) {
-			ArgType typeVariable = readArgType(in);
-			List<ArgType> extendsList = readArgTypesList(in);
-			list.add(new GenericTypeParameter(typeVariable, extendsList));
-		}
-		return list;
-	}
-
 	private List<ClspMethod> readClsMethods(DataInputStream in, ClassInfo clsInfo) throws IOException {
 		int mCount = in.readShort();
 		List<ClspMethod> methods = new ArrayList<>(mCount);
@@ -421,7 +391,7 @@ private ClspMethod readMethod(DataInputStream in, ClassInfo clsInfo) throws IOEx
 		if (Objects.equals(genericRetType, retType)) {
 			genericRetType = retType;
 		}
-		List<GenericTypeParameter> typeParameters = readGenericTypeParameters(in);
+		List<ArgType> typeParameters = readArgTypesList(in);
 		boolean varArgs = in.readBoolean();
 		List<ArgType> throwList = readArgTypesList(in);
 		MethodInfo methodInfo = MethodInfo.fromDetails(root, clsInfo, name, argTypes, retType);
@@ -482,20 +452,12 @@ private ArgType readArgType(DataInputStream in) throws IOException {
 
 			case GENERIC:
 				ArgType clsType = classes[in.readInt()].getClsType();
-				int typeLength = readUnsignedByte(in);
-				ArgType[] generics;
-				if (typeLength == 0) {
-					generics = null;
-				} else {
-					generics = new ArgType[typeLength];
-					for (int i = 0; i < typeLength; i++) {
-						generics[i] = readArgType(in);
-					}
-				}
-				return ArgType.generic(clsType, generics);
+				return ArgType.generic(clsType, readArgTypesList(in));
 
 			case GENERIC_TYPE_VARIABLE:
-				return ArgType.genericType(readString(in));
+				String typeVar = readString(in);
+				List<ArgType> extendTypes = readArgTypesList(in);
+				return ArgType.genericType(typeVar, extendTypes);
 
 			case OBJECT:
 				return classes[in.readInt()].getClsType();

jadx-core/src/main/java/jadx/core/clsp/ClspClass.java

@@ -8,7 +8,6 @@
 import java.util.Objects;
 
 import jadx.core.dex.instructions.args.ArgType;
-import jadx.core.dex.nodes.GenericTypeParameter;
 
 /**
  * Class node in classpath graph
@@ -19,7 +18,7 @@ public class ClspClass {
 	private final int id;
 	private ArgType[] parents;
 	private Map<String, ClspMethod> methodsMap = Collections.emptyMap();
-	private List<GenericTypeParameter> typeParameters = Collections.emptyList();
+	private List<ArgType> typeParameters = Collections.emptyList();
 
 	public ClspClass(ArgType clsType, int id) {
 		this.clsType = clsType;
@@ -69,11 +68,11 @@ public void setMethods(List<ClspMethod> methods) {
 		setMethodsMap(map);
 	}
 
-	public List<GenericTypeParameter> getTypeParameters() {
+	public List<ArgType> getTypeParameters() {
 		return typeParameters;
 	}
 
-	public void setTypeParameters(List<GenericTypeParameter> typeParameters) {
+	public void setTypeParameters(List<ArgType> typeParameters) {
 		this.typeParameters = typeParameters;
 	}
 

jadx-core/src/main/java/jadx/core/clsp/ClspMethod.java

@@ -7,7 +7,6 @@
 
 import jadx.core.dex.info.MethodInfo;
 import jadx.core.dex.instructions.args.ArgType;
-import jadx.core.dex.nodes.GenericTypeParameter;
 import jadx.core.dex.nodes.IMethodDetails;
 import jadx.core.utils.Utils;
 
@@ -19,13 +18,13 @@ public class ClspMethod implements IMethodDetails, Comparable<ClspMethod> {
 	private final MethodInfo methodInfo;
 	private final List<ArgType> argTypes;
 	private final ArgType returnType;
-	private final List<GenericTypeParameter> typeParameters;
+	private final List<ArgType> typeParameters;
 	private final List<ArgType> throwList;
 	private final boolean varArg;
 
 	public ClspMethod(MethodInfo methodInfo,
 			List<ArgType> argTypes, ArgType returnType,
-			List<GenericTypeParameter> typeParameters,
+			List<ArgType> typeParameters,
 			boolean varArgs, List<ArgType> throwList) {
 		this.methodInfo = methodInfo;
 		this.argTypes = argTypes;
@@ -59,7 +58,7 @@ public int getArgsCount() {
 	}
 
 	@Override
-	public List<GenericTypeParameter> getTypeParameters() {
+	public List<ArgType> getTypeParameters() {
 		return typeParameters;
 	}
 

jadx-core/src/main/java/jadx/core/clsp/SimpleMethodDetails.java

@@ -5,7 +5,6 @@
 
 import jadx.core.dex.info.MethodInfo;
 import jadx.core.dex.instructions.args.ArgType;
-import jadx.core.dex.nodes.GenericTypeParameter;
 import jadx.core.dex.nodes.IMethodDetails;
 
 public class SimpleMethodDetails implements IMethodDetails {
@@ -32,7 +31,7 @@ public List<ArgType> getArgTypes() {
 	}
 
 	@Override
-	public List<GenericTypeParameter> getTypeParameters() {
+	public List<ArgType> getTypeParameters() {
 		return Collections.emptyList();
 	}
 

jadx-core/src/main/java/jadx/core/codegen/ClassGen.java

@@ -36,7 +36,6 @@
 import jadx.core.dex.instructions.mods.ConstructorInsn;
 import jadx.core.dex.nodes.ClassNode;
 import jadx.core.dex.nodes.FieldNode;
-import jadx.core.dex.nodes.GenericTypeParameter;
 import jadx.core.dex.nodes.InsnNode;
 import jadx.core.dex.nodes.MethodNode;
 import jadx.core.dex.nodes.RootNode;
@@ -189,23 +188,22 @@ public void addClassDeclaration(CodeWriter clsCode) {
 		}
 	}
 
-	public boolean addGenericTypeParameters(CodeWriter code, List<GenericTypeParameter> generics, boolean classDeclaration) {
+	public boolean addGenericTypeParameters(CodeWriter code, List<ArgType> generics, boolean classDeclaration) {
 		if (generics == null || generics.isEmpty()) {
 			return false;
 		}
 		code.add('<');
 		int i = 0;
-		for (GenericTypeParameter genericInfo : generics) {
+		for (ArgType genericInfo : generics) {
 			if (i != 0) {
 				code.add(", ");
 			}
-			ArgType type = genericInfo.getTypeVariable();
-			if (type.isGenericType()) {
-				code.add(type.getObject());
+			if (genericInfo.isGenericType()) {
+				code.add(genericInfo.getObject());
 			} else {
-				useClass(code, type);
+				useClass(code, genericInfo);
 			}
-			List<ArgType> list = genericInfo.getExtendsList();
+			List<ArgType> list = genericInfo.getExtendTypes();
 			if (list != null && !list.isEmpty()) {
 				code.add(" extends ");
 				for (Iterator<ArgType> it = list.iterator(); it.hasNext();) {
@@ -517,15 +515,15 @@ public void useClass(CodeWriter code, ArgType type) {
 		}
 
 		useClass(code, ClassInfo.fromType(cls.root(), type));
-		ArgType[] generics = type.getGenericTypes();
+		List<ArgType> generics = type.getGenericTypes();
 		if (generics != null) {
 			code.add('<');
-			int len = generics.length;
+			int len = generics.size();
 			for (int i = 0; i < len; i++) {
 				if (i != 0) {
 					code.add(", ");
 				}
-				ArgType gt = generics[i];
+				ArgType gt = generics.get(i);
 				ArgType wt = gt.getWildcardType();
 				if (wt != null) {
 					ArgType.WildcardBound bound = gt.getWildcardBound();

jadx-core/src/main/java/jadx/core/codegen/MethodGen.java

@@ -185,7 +185,7 @@ private void addMethodArguments(CodeWriter code, List<RegisterArg> args) {
 			CodeVar var;
 			if (ssaVar == null) {
 				// null for abstract or interface methods
-				var = CodeVar.fromMthArg(mthArg);
+				var = CodeVar.fromMthArg(mthArg, classGen.isFallbackMode());
 			} else {
 				var = ssaVar.getCodeVar();
 			}

jadx-core/src/main/java/jadx/core/codegen/NameGen.java

@@ -72,11 +72,13 @@ private void addNamesUsedInClass() {
 	}
 
 	public String assignArg(CodeVar var) {
-		String name = makeArgName(var);
 		if (fallback) {
-			return name;
+			return getFallbackName(var);
 		}
-		name = getUniqueVarName(name);
+		if (var.isThis()) {
+			return RegisterArg.THIS_ARG_NAME;
+		}
+		String name = getUniqueVarName(makeArgName(var));
 		var.setName(name);
 		return name;
 	}
@@ -118,24 +120,17 @@ private String getUniqueVarName(String name) {
 	}
 
 	private String makeArgName(CodeVar var) {
-		if (fallback) {
-			return getFallbackName(var);
-		}
-		if (var.isThis()) {
-			return RegisterArg.THIS_ARG_NAME;
-		}
 		String name = var.getName();
-		String varName = name != null ? name : guessName(var);
-		if (NameMapper.isReserved(varName)) {
-			varName = varName + 'R';
+		if (name == null) {
+			name = guessName(var);
 		}
-		if (!NameMapper.isValidAndPrintable(varName)) {
-			varName = getFallbackName(var);
+		if (!NameMapper.isValidAndPrintable(name)) {
+			name = getFallbackName(var);
 		}
 		if (Consts.DEBUG) {
-			varName += '_' + getFallbackName(var);
+			name += '_' + getFallbackName(var);
 		}
-		return varName;
+		return name;
 	}
 
 	private String getFallbackName(CodeVar var) {

jadx-core/src/main/java/jadx/core/dex/attributes/AFlag.java

@@ -67,6 +67,7 @@ public enum AFlag {
 	 */
 	EXPLICIT_PRIMITIVE_TYPE,
 	EXPLICIT_CAST,
+	SOFT_CAST, // synthetic cast to help type inference
 
 	INCONSISTENT_CODE, // warning about incorrect decompilation
 }