From 4f76208c62971e7eca45dab831a379dd342214a4 Mon Sep 17 00:00:00 2001
From: Filip Hrisafov <filip.hrisafov@gmail.com>
Date: Sat, 7 Mar 2020 18:16:38 +0100
Subject: [PATCH] #2021 Generate compilable code when Decorator is nested
 within the Mapper

We need to treat the import of the decoratorType specially when it is nested.
Calling addIfImportRequired is not the most correct approach since it would
lead to checking if the type is to be imported and that would be false
since the Decorator is a nested class within the Mapper.
However, when generating the Decorator this is not needed, because the Decorator is a top level class itself

In a nutshell creating the Decorator should have its own ProcessorContext, but it doesn't
---
 .../ap/internal/model/Decorator.java          | 17 ++++++++++-
 .../ap/test/bugs/_2021/Issue2021Mapper.java   | 22 +++++++++++++++
 .../ap/test/bugs/_2021/Issue2021Test.java     | 28 +++++++++++++++++++
 3 files changed, 66 insertions(+), 1 deletion(-)
 create mode 100644 processor/src/test/java/org/mapstruct/ap/test/bugs/_2021/Issue2021Mapper.java
 create mode 100644 processor/src/test/java/org/mapstruct/ap/test/bugs/_2021/Issue2021Test.java

diff --git a/processor/src/main/java/org/mapstruct/ap/internal/model/Decorator.java b/processor/src/main/java/org/mapstruct/ap/internal/model/Decorator.java
index ab37cb77d..e61a25a47 100644
--- a/processor/src/main/java/org/mapstruct/ap/internal/model/Decorator.java
+++ b/processor/src/main/java/org/mapstruct/ap/internal/model/Decorator.java
@@ -125,7 +125,22 @@ public class Decorator extends GeneratedType {
     @Override
     public SortedSet<Type> getImportTypes() {
         SortedSet<Type> importTypes = super.getImportTypes();
-        addIfImportRequired( importTypes, decoratorType );
+        // DecoratorType needs special handling in case it is nested
+        // calling addIfImportRequired is not the most correct approach since it would
+        // lead to checking if the type is to be imported and that would be false
+        // since the Decorator is a nested class within the Mapper.
+        // However, when generating the Decorator this is not needed,
+        // because the Decorator is a top level class itself
+        // In a nutshell creating the Decorator should have its own ProcessorContext, but it doesn't
+        if ( decoratorType.getPackageName().equalsIgnoreCase( getPackageName() ) ) {
+            if ( decoratorType.getTypeElement() != null &&
+                decoratorType.getTypeElement().getNestingKind().isNested() ) {
+                importTypes.add( decoratorType );
+            }
+        }
+        else {
+            importTypes.add( decoratorType );
+        }
         return importTypes;
     }
 
diff --git a/processor/src/test/java/org/mapstruct/ap/test/bugs/_2021/Issue2021Mapper.java b/processor/src/test/java/org/mapstruct/ap/test/bugs/_2021/Issue2021Mapper.java
new file mode 100644
index 000000000..4627f2232
--- /dev/null
+++ b/processor/src/test/java/org/mapstruct/ap/test/bugs/_2021/Issue2021Mapper.java
@@ -0,0 +1,22 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.bugs._2021;
+
+import org.mapstruct.DecoratedWith;
+import org.mapstruct.Mapper;
+
+/**
+ * @author Filip Hrisafov
+ */
+@Mapper
+@DecoratedWith(Issue2021Mapper.Decorator.class)
+public interface Issue2021Mapper {
+
+    abstract class Decorator implements Issue2021Mapper {
+
+    }
+
+}
diff --git a/processor/src/test/java/org/mapstruct/ap/test/bugs/_2021/Issue2021Test.java b/processor/src/test/java/org/mapstruct/ap/test/bugs/_2021/Issue2021Test.java
new file mode 100644
index 000000000..f111799d5
--- /dev/null
+++ b/processor/src/test/java/org/mapstruct/ap/test/bugs/_2021/Issue2021Test.java
@@ -0,0 +1,28 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.bugs._2021;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mapstruct.ap.testutil.IssueKey;
+import org.mapstruct.ap.testutil.WithClasses;
+import org.mapstruct.ap.testutil.runner.AnnotationProcessorTestRunner;
+
+/**
+ * @author Filip Hrisafov
+ */
+@IssueKey("2021")
+@RunWith(AnnotationProcessorTestRunner.class)
+@WithClasses({
+    Issue2021Mapper.class
+})
+public class Issue2021Test {
+
+    @Test
+    public void shouldCompile() {
+
+    }
+}