Fix regression for Kotlin companion objects

src/main/java/io/vertx/codegen/ClassModel.java

@@ -313,6 +313,11 @@ protected void checkConstantType(VariableElement elem, TypeInfo type, TypeMirror
     if (isLegalNonCallableReturnType(type, allowAnyJavaType)) {
       return;
     }
+    // Workaround for Kotlin companion objects.
+    // https://github.com/vert-x3/vertx-lang-kotlin/issues/93
+    if (type.getName().equalsIgnoreCase(modelElt.getQualifiedName().toString() + "." + type.getSimpleName())) {
+      return;
+    }
     throw new GenException(elem, "type " + type + " is not legal for use for a constant type in code generation");
   }
 

src/test/java/io/vertx/test/codegen/ClassTest.java

@@ -2490,6 +2490,15 @@ public void testImplPackage() throws Exception {
   }
 
   @Test
+  public void testInterfaceWithKotlinCompanionObject() throws Exception {
+    ClassModel model = new GeneratorHelper().generateClass(InterfaceWithCompanionObject.class);
+  }
+
+  @Test(expected = GenException.class)
+  public void testInterfaceUnrelatedCompanionObject() throws Exception {
+    ClassModel model = new GeneratorHelper().generateClass(InterfaceWithUnrelatedCompanionClass.class);
+  }
+
   public void testJsonMapper() throws Exception {
     ClassModel model = new GeneratorHelper().generateClass(WithMyPojo.class);
     assertFalse(model.getAnnotations().isEmpty());

src/test/java/io/vertx/test/codegen/testapi/Companion.java

@@ -0,0 +1,13 @@
+package io.vertx.test.codegen.testapi;
+
+public final class Companion {
+  static final Companion $$INSTANCE;
+
+  public final void create() {
+  }
+
+  static {
+    Companion var0 = new Companion();
+    $$INSTANCE = var0;
+  }
+}

src/test/java/io/vertx/test/codegen/testapi/InterfaceWithCompanionObject.java

@@ -0,0 +1,26 @@
+package io.vertx.test.codegen.testapi;
+
+import io.vertx.codegen.annotations.GenIgnore;
+import io.vertx.codegen.annotations.VertxGen;
+
+/**
+ * @author Richard Gomez
+ */
+@VertxGen
+public interface InterfaceWithCompanionObject {
+
+  InterfaceWithCompanionObject.Companion Companion = InterfaceWithCompanionObject.Companion.$$INSTANCE;
+
+  @GenIgnore
+  public static final class Companion {
+    static final InterfaceWithCompanionObject.Companion $$INSTANCE;
+
+    public final void create() {
+    }
+
+    static {
+      InterfaceWithCompanionObject.Companion var0 = new InterfaceWithCompanionObject.Companion();
+      $$INSTANCE = var0;
+    }
+  }
+}

src/test/java/io/vertx/test/codegen/testapi/InterfaceWithUnrelatedCompanionClass.java

@@ -0,0 +1,13 @@
+package io.vertx.test.codegen.testapi;
+
+import io.vertx.codegen.annotations.GenIgnore;
+import io.vertx.codegen.annotations.VertxGen;
+
+/**
+ * @author Richard Gomez
+ */
+@VertxGen
+public interface InterfaceWithUnrelatedCompanionClass {
+  Companion CompanionField = Companion.$$INSTANCE;
+}
+