Prevent lazy types to be accidentally computed in debug

core/descriptor.loader.java/src/org/jetbrains/jet/lang/resolve/java/lazy/types/LazyType.kt

@@ -47,4 +47,14 @@ abstract class LazyType(storageManager: StorageManager) : AbstractJetType() {
     override fun isError()= getConstructor().getDeclarationDescriptor().inn({ d -> ErrorUtils.isError(d)}, false)
 
     override fun getAnnotations(): List<AnnotationDescriptor> = listOf()
+
+    override fun toString(): String? {
+        if (!_typeConstructor.isComputed()) {
+            return "Type constructor is not computed"
+        }
+        if (!_arguments.isComputed()) {
+            return "" + getConstructor() + "<arguments are not computed>"
+        }
+        return super<AbstractJetType>.toString()
+    }
 }

core/descriptors/src/org/jetbrains/jet/lang/types/AbstractJetType.java

@@ -41,7 +41,7 @@ public abstract class AbstractJetType implements JetType {
     }
 
     @Override
-    public final String toString() {
+    public String toString() {
         List<TypeProjection> arguments = getArguments();
         return getConstructor() + (arguments.isEmpty() ? "" : "<" + argumentsToString(arguments) + ">") + (isNullable() ? "?" : "");
     }