fix DescriptionRenderer failure if FunctionDescriptor.getReturnType returns null

compiler/frontend/src/org/jetbrains/jet/lang/descriptors/CallableDescriptor.java

@@ -1,6 +1,7 @@
 package org.jetbrains.jet.lang.descriptors;
 
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.lang.resolve.scopes.receivers.ReceiverDescriptor;
 import org.jetbrains.jet.lang.types.JetType;
 import org.jetbrains.jet.lang.types.TypeSubstitutor;
@@ -24,6 +25,9 @@ public interface CallableDescriptor extends DeclarationDescriptor {
     @NotNull
     JetType getReturnType();
 
+    @Nullable
+    JetType getReturnTypeSafe();
+
     @NotNull
     @Override
     CallableDescriptor getOriginal();

compiler/frontend/src/org/jetbrains/jet/lang/descriptors/FunctionDescriptorImpl.java

@@ -125,6 +125,12 @@ public class FunctionDescriptorImpl extends DeclarationDescriptorImpl implements
         return unsubstitutedReturnType;
     }
 
+    @Override
+    @Nullable
+    public JetType getReturnTypeSafe() {
+        return unsubstitutedReturnType;
+    }
+
     @NotNull
     @Override
     public FunctionDescriptor getOriginal() {

compiler/frontend/src/org/jetbrains/jet/lang/descriptors/PropertyDescriptor.java

@@ -118,6 +118,11 @@ public class PropertyDescriptor extends VariableDescriptorImpl implements Callab
         return getOutType();
     }
 
+    @Override
+    @Nullable
+    public JetType getReturnTypeSafe() {
+        return getOutType();
+    }
 
     public boolean isVar() {
         return isVar;

compiler/frontend/src/org/jetbrains/jet/lang/descriptors/PropertyGetterDescriptor.java

@@ -45,6 +45,12 @@ public class PropertyGetterDescriptor extends PropertyAccessorDescriptor {
         return returnType;
     }
 
+    @Override
+    @Nullable
+    public JetType getReturnTypeSafe() {
+        return returnType;
+    }
+
     @Override
     public <R, D> R accept(DeclarationDescriptorVisitor<R, D> visitor, D data) {
         return visitor.visitPropertyGetterDescriptor(this, data);

compiler/frontend/src/org/jetbrains/jet/lang/descriptors/PropertySetterDescriptor.java

@@ -53,6 +53,11 @@ public class PropertySetterDescriptor extends PropertyAccessorDescriptor {
         return JetStandardClasses.getUnitType();
     }
 
+    @Override
+    public JetType getReturnTypeSafe() {
+        return getReturnType();
+    }
+
     @Override
     public <R, D> R accept(DeclarationDescriptorVisitor<R, D> visitor, D data) {
         return visitor.visitPropertySetterDescriptor(this, data);

compiler/frontend/src/org/jetbrains/jet/lang/descriptors/VariableDescriptorImpl.java

@@ -89,4 +89,10 @@ public abstract class VariableDescriptorImpl extends DeclarationDescriptorImpl i
     public JetType getReturnType() {
         return getOutType();
     }
+
+    @Override
+    @Nullable
+    public JetType getReturnTypeSafe() {
+        return getOutType();
+    }
 }

compiler/frontend/src/org/jetbrains/jet/resolve/DescriptorRenderer.java

@@ -73,7 +73,11 @@ public class DescriptorRenderer implements Renderer {
     }
 
     public String renderType(JetType type) {
-        return escape(type.toString());
+        if (type == null) {
+            return escape("<?>");
+        } else {
+            return escape(type.toString());
+        }
     }
 
     protected String escape(String s) {
@@ -222,8 +226,7 @@ public class DescriptorRenderer implements Renderer {
 
             renderName(descriptor, builder);
             renderValueParameters(descriptor, builder);
-            // TODO: getReturnType may be uninitialized and throw IllegalStateException // stepan.koltsov@ 2011-11-21
-            builder.append(" : ").append(escape(renderType(descriptor.getReturnType())));
+            builder.append(" : ").append(escape(renderType(descriptor.getReturnTypeSafe())));
             return super.visitFunctionDescriptor(descriptor, builder);
         }