Fail during compile if required methods are missing (#18924)

A ComponentConnector must override either getWidget or createWidget for
the framework to know the type of the component's widget. Similarly
either getRenderer och createRenderer must be overridden for
AbstractRendererConnector.

Prior to this patch, the compilation succeeded when critical methods
were missing - the user just got various hard-to-debug issues when the
broken connector was used.

Change-Id: I6ec07e2f1c1b15047802e64208485b1d999c0aee

1 files changed, 10 insertions, 0 deletions

diff --git a/client-compiler/src/com/vaadin/server/widgetsetutils/metadata/WidgetInitVisitor.java b/client-compiler/src/com/vaadin/server/widgetsetutils/metadata/WidgetInitVisitor.java
index a77b523d14..9a9cac18ba 100644
--- a/client-compiler/src/com/vaadin/server/widgetsetutils/metadata/WidgetInitVisitor.java
+++ b/client-compiler/src/com/vaadin/server/widgetsetutils/metadata/WidgetInitVisitor.java
@@ -42,6 +42,16 @@ public class WidgetInitVisitor extends TypeVisitor {
             // Needs GWT constructor if createWidget is not overridden
             if (createWidgetClass.getQualifiedSourceName().equals(
                     AbstractComponentConnector.class.getCanonicalName())) {
+                if (getWidget
+                        .getEnclosingType()
+                        .getQualifiedSourceName()
+                        .equals(AbstractComponentConnector.class
+                                .getCanonicalName())) {
+                    logger.log(Type.ERROR, type.getQualifiedSourceName()
+                            + " must override either createWidget or getWidget");
+                    throw new UnableToCompleteException();
+                }
+
                 bundle.setNeedsGwtConstructor(widgetType);
 
                 // Also needs widget type to find the right GWT constructor