Fix method references to private instance methods being invoked with invokespecial instead of invokevirtual

Really fixes #17

Author: luontola

retrolambda/src/main/java/net/orfjackal/retrolambda/LambdaClassBackporter.java

@@ -23,6 +23,7 @@ private static class LambdaClassVisitor extends ClassVisitor {
         private final int targetVersion;
         private String lambdaClass;
         private Type constructor;
+        private Handle implMethod;
         private LambdaFactoryMethod factoryMethod;
 
         public LambdaClassVisitor(ClassWriter cw, int targetVersion) {
@@ -34,6 +35,7 @@ public LambdaClassVisitor(ClassWriter cw, int targetVersion) {
         public void visit(int version, int access, String name, String signature, String superName, String[] interfaces) {
             lambdaClass = name;
             LambdaReifier.setLambdaClass(lambdaClass);
+            implMethod = LambdaReifier.getLambdaImplMethod();
             factoryMethod = LambdaReifier.getLambdaFactoryMethod();
 
             if (version > targetVersion) {
@@ -52,7 +54,7 @@ public MethodVisitor visitMethod(int access, String name, String desc, String si
             }
             MethodVisitor mv = super.visitMethod(access, name, desc, signature, exceptions);
             mv = new MagicLambdaRemovingMethodVisitor(mv);
-            mv = new PrivateMethodInvocationFixingMethodVisitor(mv, factoryMethod.getInvoker());
+            mv = new PrivateMethodInvocationFixingMethodVisitor(mv, implMethod);
             return mv;
         }
 
@@ -135,18 +137,24 @@ public void visitMethodInsn(int opcode, String owner, String name, String desc)
 
     private static class PrivateMethodInvocationFixingMethodVisitor extends MethodVisitor {
 
-        private final String invoker;
+        private final Handle implMethod;
 
-        public PrivateMethodInvocationFixingMethodVisitor(MethodVisitor mv, Class<?> invoker) {
+        public PrivateMethodInvocationFixingMethodVisitor(MethodVisitor mv, Handle implMethod) {
             super(ASM4, mv);
-            this.invoker = Type.getInternalName(invoker);
+            this.implMethod = implMethod;
         }
 
         @Override
         public void visitMethodInsn(int opcode, String owner, String name, String desc) {
+            // Java 8's lambda classes get away with calling private virtual methods
+            // by using invokespecial because the JVM relaxes the bytecode validation
+            // of the lambda classes it generates. We must however use invokevirtual
+            // for them (which is possible because we also make them non-private).
             if (opcode == INVOKESPECIAL
-                    && owner.equals(invoker)
-                    && LambdaNaming.LAMBDA_IMPL_METHOD.matcher(name).matches()) {
+                    && !name.equals("<init>")
+                    && owner.equals(implMethod.getOwner())
+                    && name.equals(implMethod.getName())
+                    && desc.equals(implMethod.getDesc())) {
                 opcode = INVOKEVIRTUAL;
             }
             super.visitMethodInsn(opcode, owner, name, desc);

retrolambda/src/main/java/net/orfjackal/retrolambda/LambdaFactoryMethod.java

@@ -10,12 +10,10 @@ public class LambdaFactoryMethod {
 
     private final String owner;
     private final String desc;
-    private final Class<?> invoker;
 
-    public LambdaFactoryMethod(String lambdaClass, Type invokedType, Class<?> invoker) {
+    public LambdaFactoryMethod(String lambdaClass, Type invokedType) {
         owner = lambdaClass;
         desc = invokedType.getDescriptor();
-        this.invoker = invoker;
     }
 
     public String getOwner() {
@@ -29,8 +27,4 @@ public String getName() {
     public String getDesc() {
         return desc;
     }
-
-    public Class<?> getInvoker() {
-        return invoker;
-    }
 }

retrolambda/src/main/java/net/orfjackal/retrolambda/LambdaNaming.java

@@ -15,10 +15,4 @@ public class LambdaNaming {
      * Java 8 produces at runtime classes named {@code EnclosingClass$$Lambda$1}
      */
     public static final Pattern LAMBDA_CLASS = Pattern.compile("^.+\\$\\$Lambda\\$\\d+$");
-
-    /**
-     * Oracle JDK 8 compiler names the methods {@code lambda$methodName$0} but the
-     * Eclipse JDT compiler names them {@code lambda$0} (similar to older JDK 8 EA builds).
-     */
-    public static final Pattern LAMBDA_IMPL_METHOD = Pattern.compile("^lambda(\\$.*)?\\$\\d+$");
 }

retrolambda/src/main/java/net/orfjackal/retrolambda/LambdaReifier.java

@@ -19,13 +19,13 @@ public class LambdaReifier {
     // is spying on the LambdaMetafactory's dynamically generated bytecode.
     // We expect only one class being processed at a time, so it should
     // be an error if these collections contain more than one element.
-    private static final BlockingDeque<Class<?>> currentInvoker = new LinkedBlockingDeque<>(1);
+    private static final BlockingDeque<Handle> currentLambdaImplMethod = new LinkedBlockingDeque<>(1);
     private static final BlockingDeque<Type> currentInvokedType = new LinkedBlockingDeque<>(1);
     private static final BlockingDeque<String> currentLambdaClass = new LinkedBlockingDeque<>(1);
 
-    public static LambdaFactoryMethod reifyLambdaClass(Class<?> invoker, String invokedName, Type invokedType, Handle bsm, Object[] bsmArgs) {
+    public static LambdaFactoryMethod reifyLambdaClass(Handle lambdaImplMethod, Class<?> invoker, String invokedName, Type invokedType, Handle bsm, Object[] bsmArgs) {
         try {
-            setInvoker(invoker);
+            setLambdaImplMethod(lambdaImplMethod);
             setInvokedType(invokedType);
 
             // Causes the lambda class to be loaded. Retrolambda's Java agent
@@ -42,8 +42,8 @@ public static LambdaFactoryMethod reifyLambdaClass(Class<?> invoker, String invo
         }
     }
 
-    public static void setInvoker(Class<?> invoker) {
-        currentInvoker.push(invoker);
+    private static void setLambdaImplMethod(Handle lambdaImplMethod) {
+        currentLambdaImplMethod.push(lambdaImplMethod);
     }
 
     private static void setInvokedType(Type invokedType) {
@@ -54,15 +54,18 @@ public static void setLambdaClass(String lambdaClass) {
         currentLambdaClass.push(lambdaClass);
     }
 
+    public static Handle getLambdaImplMethod() {
+        return currentLambdaImplMethod.getFirst();
+    }
+
     public static LambdaFactoryMethod getLambdaFactoryMethod() {
         String lambdaClass = currentLambdaClass.getFirst();
         Type invokedType = currentInvokedType.getFirst();
-        Class<?> invoker = currentInvoker.getFirst();
-        return new LambdaFactoryMethod(lambdaClass, invokedType, invoker);
+        return new LambdaFactoryMethod(lambdaClass, invokedType);
     }
 
     private static void resetGlobals() {
-        currentInvoker.clear();
+        currentLambdaImplMethod.clear();
         currentInvokedType.clear();
         currentLambdaClass.clear();
     }

retrolambda/src/main/java/net/orfjackal/retrolambda/LambdaUsageBackporter.java

@@ -118,7 +118,6 @@ public InvokeDynamicInsnConvertingMethodVisitor(int api, MethodVisitor mv, Strin
         @Override
         public void visitInvokeDynamicInsn(String name, String desc, Handle bsm, Object... bsmArgs) {
             if (bsm.getOwner().equals(LambdaNaming.LAMBDA_METAFACTORY)) {
-                lambdaImplMethods.add((Handle) bsmArgs[1]);
                 backportLambda(name, Type.getType(desc), bsm, bsmArgs);
             } else {
                 super.visitInvokeDynamicInsn(name, desc, bsm, bsmArgs);
@@ -127,7 +126,9 @@ public void visitInvokeDynamicInsn(String name, String desc, Handle bsm, Object.
 
         private void backportLambda(String invokedName, Type invokedType, Handle bsm, Object[] bsmArgs) {
             Class<?> invoker = loadClass(myClassName);
-            LambdaFactoryMethod factory = LambdaReifier.reifyLambdaClass(invoker, invokedName, invokedType, bsm, bsmArgs);
+            Handle lambdaImplMethod = (Handle) bsmArgs[1];
+            lambdaImplMethods.add(lambdaImplMethod);
+            LambdaFactoryMethod factory = LambdaReifier.reifyLambdaClass(lambdaImplMethod, invoker, invokedName, invokedType, bsm, bsmArgs);
             super.visitMethodInsn(INVOKESTATIC, factory.getOwner(), factory.getName(), factory.getDesc());
         }