Improve ClassCastException message

Author: gilles-duboscq

espresso/src/com.oracle.truffle.espresso/src/com/oracle/truffle/espresso/constantpool/RuntimeConstantPool.java

@@ -378,21 +378,7 @@ public ResolvedClassConstant resolveClassConstant(int classIndex, ObjectKlass ac
                                 "Access check of: " + checkedKlass.getType() + " from " + accessingKlass.getType() + " throws IllegalAccessError");
                 StringBuilder errorMessage = new StringBuilder("failed to access class ");
                 errorMessage.append(checkedKlass.getExternalName()).append(" from class ").append(accessingKlass.getExternalName());
-                if (context.getJavaVersion().modulesEnabled()) {
-                    errorMessage.append(" (");
-                    if (accessingKlass.module() == checkedKlass.module()) {
-                        errorMessage.append(checkedKlass.getExternalName());
-                        errorMessage.append(" and ");
-                        ClassRegistry.classInModuleOfLoader(context.getClassLoadingEnv(), accessingKlass, true, errorMessage, meta);
-                    } else {
-                        // checkedKlass is not an array type (getElementalType) nor a
-                        // primitive type (it would have passed the access checks)
-                        ClassRegistry.classInModuleOfLoader(context.getClassLoadingEnv(), (ObjectKlass) checkedKlass, false, errorMessage, meta);
-                        errorMessage.append("; ");
-                        ClassRegistry.classInModuleOfLoader(context.getClassLoadingEnv(), accessingKlass, false, errorMessage, meta);
-                    }
-                    errorMessage.append(")");
-                }
+                ClassRegistry.appendModuleAndLoadersDetails(context.getClassLoadingEnv(), checkedKlass, accessingKlass, errorMessage, context);
                 throw meta.throwExceptionWithMessage(meta.java_lang_IllegalAccessError, errorMessage.toString());
             }
             return new ResolvedFoundClassConstant(klass);

espresso/src/com.oracle.truffle.espresso/src/com/oracle/truffle/espresso/impl/ClassRegistry.java

@@ -629,7 +629,7 @@ private ObjectKlass createKlass(EspressoContext context, ParserKlass parserKlass
             }
             if (!Klass.checkAccess(superKlass, klass)) {
                 StringBuilder sb = new StringBuilder().append("class ").append(klass.getExternalName()).append(" cannot access its superclass ").append(superKlass.getExternalName());
-                superTypeAccessMessage(env, klass, superKlass, sb, context);
+                appendModuleAndLoadersDetails(env, klass, superKlass, sb, context);
                 throw EspressoClassLoadingException.illegalAccessError(sb.toString());
             }
             if (!superKlass.permittedSubclassCheck(klass)) {
@@ -641,7 +641,7 @@ private ObjectKlass createKlass(EspressoContext context, ParserKlass parserKlass
             if (interf != null) {
                 if (!Klass.checkAccess(interf, klass)) {
                     StringBuilder sb = new StringBuilder().append("class ").append(klass.getExternalName()).append(" cannot access its superinterface ").append(interf.getExternalName());
-                    superTypeAccessMessage(env, klass, interf, sb, context);
+                    appendModuleAndLoadersDetails(env, klass, interf, sb, context);
                     throw EspressoClassLoadingException.illegalAccessError(sb.toString());
                 }
                 if (!interf.permittedSubclassCheck(klass)) {
@@ -653,24 +653,24 @@ private ObjectKlass createKlass(EspressoContext context, ParserKlass parserKlass
         return klass;
     }
 
-    private static void superTypeAccessMessage(ClassLoadingEnv env, ObjectKlass sub, ObjectKlass sup, StringBuilder sb, EspressoContext context) {
+    public static void appendModuleAndLoadersDetails(ClassLoadingEnv env, Klass klass1, Klass klass2, StringBuilder sb, EspressoContext context) {
         if (context.getJavaVersion().modulesEnabled()) {
             sb.append(" (");
             Meta meta = context.getMeta();
-            if (sup.module() == sub.module()) {
-                sb.append(sub.getExternalName());
+            if (klass2.module() == klass1.module()) {
+                sb.append(klass1.getExternalName());
                 sb.append(" and ");
-                classInModuleOfLoader(env, sup, true, sb, meta);
+                classInModuleOfLoader(env, klass2, true, sb, meta);
             } else {
-                classInModuleOfLoader(env, sub, false, sb, meta);
+                classInModuleOfLoader(env, klass1, false, sb, meta);
                 sb.append("; ");
-                classInModuleOfLoader(env, sup, false, sb, meta);
+                classInModuleOfLoader(env, klass2, false, sb, meta);
             }
             sb.append(")");
         }
     }
 
-    public static void classInModuleOfLoader(ClassLoadingEnv env, ObjectKlass klass, boolean plural, StringBuilder sb, Meta meta) {
+    public static void classInModuleOfLoader(ClassLoadingEnv env, Klass klass, boolean plural, StringBuilder sb, Meta meta) {
         assert meta.getJavaVersion().modulesEnabled() && meta.java_lang_ClassLoader_nameAndId != null;
         sb.append(klass.getExternalName());
         if (plural) {

espresso/src/com.oracle.truffle.espresso/src/com/oracle/truffle/espresso/nodes/quick/CheckCastQuickNode.java

@@ -25,11 +25,13 @@
 import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.espresso.classfile.bytecode.Bytecodes;
+import com.oracle.truffle.espresso.impl.ClassRegistry;
 import com.oracle.truffle.espresso.impl.Klass;
 import com.oracle.truffle.espresso.meta.Meta;
 import com.oracle.truffle.espresso.nodes.BytecodeNode;
 import com.oracle.truffle.espresso.nodes.EspressoFrame;
 import com.oracle.truffle.espresso.nodes.bytecodes.InstanceOf;
+import com.oracle.truffle.espresso.runtime.EspressoContext;
 import com.oracle.truffle.espresso.runtime.staticobject.StaticObject;
 
 public final class CheckCastQuickNode extends QuickNode {
@@ -62,6 +64,11 @@ public int execute(VirtualFrame frame, boolean isContinuationResume) {
 
     @TruffleBoundary
     private String getExceptionMessage(BytecodeNode root, StaticObject receiver) {
-        return receiver.getKlass().getType() + " cannot be cast to: " + typeToCheck.getType() + " in context " + root.getMethod().toString();
+        Klass receiverKlass = receiver.getKlass();
+        StringBuilder sb = new StringBuilder();
+        sb.append("class ").append(receiverKlass.getExternalName()).append(" cannot be cast to ").append(typeToCheck.getExternalName());
+        EspressoContext context = root.getMethod().getContext();
+        ClassRegistry.appendModuleAndLoadersDetails(context.getClassLoadingEnv(), receiverKlass, typeToCheck, sb, context);
+        return sb.toString();
     }
 }