UAST: findAttributeValue returns default value when no declared value found

plugins/uast-kotlin/src/org/jetbrains/uast/kotlin/declarations/KotlinUAnnotation.kt

@@ -42,7 +42,7 @@ class KotlinUAnnotation(
     }
 
     override fun findAttributeValue(name: String?): UExpression? =
-            findDeclaredAttributeValue(name)
+            findDeclaredAttributeValue(name) ?: findAttributeDefaultValue(name ?: "value")
 
     override fun findDeclaredAttributeValue(name: String?): UExpression? {
         return attributeValues.find {
@@ -52,5 +52,15 @@ class KotlinUAnnotation(
         }?.expression
     }
 
+    private fun findAttributeDefaultValue(name: String): UExpression? {
+        val parameter = resolvedAnnotation
+                                ?.annotationClass
+                                ?.unsubstitutedPrimaryConstructor
+                                ?.valueParameters
+                                ?.find { it.name.asString() == name } ?: return null
+
+        val defaultValue = (parameter.source.getPsi() as? KtParameter)?.defaultValue ?: return null
+        return getLanguagePlugin().convertWithParent(defaultValue)
+    }
 }
 

plugins/uast-kotlin/tests/KotlinUastApiTest.kt

@@ -104,4 +104,12 @@ class KotlinUastApiTest : AbstractKotlinUastTest() {
             assertEquals("String", elvisExpression.getExpressionType()!!.presentableText)
         }
     }
+
+    @Test fun testFindAttributeDefaultValue() {
+        doTest("AnnotationParameters") { _, file ->
+            val witDefaultValue = file.findElementByText<UAnnotation>("@WithDefaultValue")
+            assertEquals(42, witDefaultValue.findAttributeValue("value")!!.evaluate())
+            assertEquals(42, witDefaultValue.findAttributeValue(null)!!.evaluate())
+        }
+    }
 }