#1821 nullpointer due to @BeanMapping via inheritance (#1822) (#1932)

(cherry picked from commit ade4f4d7e2ab87b2e0f113221d3fc9a6729f78cc)

processor/src/main/java/org/mapstruct/ap/internal/model/source/BeanMapping.java

@@ -44,7 +44,7 @@ public class BeanMapping {
      */
     public static BeanMapping forInheritance( BeanMapping map ) {
         return new BeanMapping(
-            map.selectionParameters,
+            SelectionParameters.forInheritance( map.selectionParameters ),
             map.nullValueMappingStrategy,
             map.nullValuePropertyMappingStrategy,
             map.nullValueCheckStrategy,

processor/src/main/java/org/mapstruct/ap/internal/model/source/SelectionParameters.java

@@ -26,6 +26,23 @@ public class SelectionParameters {
     private final Types typeUtils;
     private final SourceRHS sourceRHS;
 
+    /**
+     * Returns new selection parameters
+     *
+     * ResultType is not inherited.
+     *
+     * @param selectionParameters
+     * @return
+     */
+    public static SelectionParameters forInheritance(SelectionParameters selectionParameters) {
+        return new SelectionParameters(
+            selectionParameters.qualifiers,
+            selectionParameters.qualifyingNames,
+            null,
+            selectionParameters.typeUtils
+        );
+    }
+
     public SelectionParameters(List<TypeMirror> qualifiers, List<String> qualifyingNames, TypeMirror resultType,
         Types typeUtils) {
         this( qualifiers, qualifyingNames, resultType, typeUtils, null );

processor/src/test/java/org/mapstruct/ap/test/bugs/_1821/Issue1821Mapper.java

@@ -0,0 +1,32 @@
+/*
+ * 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._1821;
+
+import org.mapstruct.BeanMapping;
+import org.mapstruct.InheritConfiguration;
+import org.mapstruct.Mapper;
+import org.mapstruct.factory.Mappers;
+
+@Mapper
+public interface Issue1821Mapper {
+
+    Issue1821Mapper INSTANCE = Mappers.getMapper( Issue1821Mapper.class );
+
+    @BeanMapping( resultType = Target.class )
+    Target map(Source source);
+
+    @InheritConfiguration( name = "map" )
+    ExtendedTarget mapExtended(Source source);
+
+    class Target {
+    }
+
+    class ExtendedTarget extends Target {
+    }
+
+    class Source {
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/bugs/_1821/Issue1821Test.java

@@ -0,0 +1,24 @@
+/*
+ * 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._1821;
+
+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;
+
+@IssueKey("1797")
+@RunWith( AnnotationProcessorTestRunner.class)
+@WithClasses( Issue1821Mapper.class )
+public class Issue1821Test {
+
+    @Test
+    public void shouldNotGiveNullPtr() {
+        Issue1821Mapper.INSTANCE.map( new Issue1821Mapper.Source() );
+    }
+
+}