#434 construct resultType based on @BeanMaping#resultType when no factory method selected

processor/src/main/java/org/mapstruct/ap/model/BeanMappingMethod.java

@@ -35,10 +35,12 @@ import org.mapstruct.ap.model.PropertyMapping.JavaExpressionMappingBuilder;
 import org.mapstruct.ap.model.PropertyMapping.PropertyMappingBuilder;
 import org.mapstruct.ap.model.common.Parameter;
 import org.mapstruct.ap.model.common.Type;
+import org.mapstruct.ap.model.source.BeanMapping;
 import org.mapstruct.ap.model.source.Mapping;
 import org.mapstruct.ap.model.source.SourceMethod;
 import org.mapstruct.ap.model.source.SourceReference;
 import org.mapstruct.ap.option.ReportingPolicy;
+import org.mapstruct.ap.prism.BeanMappingPrism;
 import org.mapstruct.ap.prism.CollectionMappingStrategyPrism;
 import org.mapstruct.ap.prism.NullValueMappingPrism;
 import org.mapstruct.ap.util.Executables;
@@ -59,6 +61,7 @@ public class BeanMappingMethod extends MappingMethod {
     private final List<PropertyMapping> constantMappings;
     private final MethodReference factoryMethod;
     private final boolean mapNullToDefault;
+    private final Type resultType;
 
     public static class Builder {
 
@@ -106,7 +109,26 @@ public class BeanMappingMethod extends MappingMethod {
                 MapperConfig.getInstanceOn( ctx.getMapperTypeElement() ).isMapToDefault( prism );
 
             MethodReference factoryMethod = ctx.getMappingResolver().getFactoryMethod( method, method.getResultType() );
-            return new BeanMappingMethod( method, propertyMappings, factoryMethod, mapNullToDefault );
+
+            // if there's no factory method, try the resultType in the @BeanMapping
+            Type resultType = null;
+            if ( factoryMethod == null ) {
+                BeanMappingPrism beanMappingPrism = BeanMappingPrism.getInstanceOn( method.getExecutable() );
+                BeanMapping beanMapping
+                    = BeanMapping.fromPrism( beanMappingPrism, method.getExecutable(), ctx.getMessager() );
+                if ( beanMapping != null && beanMapping.getResultType() != null ) {
+                    resultType = ctx.getTypeFactory().getType( beanMapping.getResultType() );
+                    if ( !resultType.isAssignableTo( method.getResultType() ) ) {
+                        ctx.getMessager().printMessage(
+                            Diagnostic.Kind.ERROR,
+                            String.format( "%s not assignable to: %s.", resultType, method.getResultType() ),
+                            method.getExecutable(),
+                            beanMappingPrism.mirror );
+                    }
+                }
+            }
+
+            return new BeanMappingMethod( method, propertyMappings, factoryMethod, mapNullToDefault, resultType );
         }
 
         /**
@@ -429,7 +451,8 @@ public class BeanMappingMethod extends MappingMethod {
     private BeanMappingMethod(SourceMethod method,
                               List<PropertyMapping> propertyMappings,
                               MethodReference factoryMethod,
-                              boolean mapNullToDefault) {
+                              boolean mapNullToDefault,
+                              Type resultType ) {
         super( method );
         this.propertyMappings = propertyMappings;
 
@@ -449,6 +472,7 @@ public class BeanMappingMethod extends MappingMethod {
         }
         this.factoryMethod = factoryMethod;
         this.mapNullToDefault = mapNullToDefault;
+        this.resultType = resultType;
     }
 
     public List<PropertyMapping> getPropertyMappings() {
@@ -467,6 +491,16 @@ public class BeanMappingMethod extends MappingMethod {
         return mapNullToDefault;
     }
 
+    @Override
+    public Type getResultType() {
+        if ( resultType == null ) {
+            return super.getResultType();
+        }
+        else {
+            return resultType;
+        }
+    }
+
     @Override
     public Set<Type> getImportTypes() {
         Set<Type> types = super.getImportTypes();

processor/src/test/java/org/mapstruct/ap/test/selection/resulttype/Apple.java

@@ -24,6 +24,11 @@ package org.mapstruct.ap.test.selection.resulttype;
  */
 public class Apple extends Fruit {
 
+
+    public Apple() {
+        super( "constructed-by-constructor" );
+    }
+
     public Apple(String type) {
         super( type );
     }

processor/src/test/java/org/mapstruct/ap/test/selection/resulttype/ErroneousFruitMapper2.java

@@ -0,0 +1,39 @@
+/**
+ *  Copyright 2012-2015 Gunnar Morling (http://www.gunnarmorling.de/)
+ *  and/or other contributors as indicated by the @authors tag. See the
+ *  copyright.txt file in the distribution for a full listing of all
+ *  contributors.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.mapstruct.ap.test.selection.resulttype;
+
+import org.mapstruct.BeanMapping;
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+import org.mapstruct.factory.Mappers;
+
+/**
+ *
+ * @author Sjaak Derksen
+ */
+@Mapper
+public interface ErroneousFruitMapper2 {
+
+    ErroneousFruitMapper2 INSTANCE = Mappers.getMapper( ErroneousFruitMapper2.class );
+
+    @BeanMapping(resultType = Banana.class)
+    @Mapping(target = "type", ignore = true)
+    Apple map(AppleDto source);
+
+}

processor/src/test/java/org/mapstruct/ap/test/selection/resulttype/InheritanceSelectionTest.java

@@ -65,16 +65,42 @@ public class InheritanceSelectionTest {
     }
 
     @Test
-    @WithClasses( { ConflictingFruitFactory.class, TargetTypeSelectingFruitMapper.class, Banana.class } )
-    public void testForkedInheritanceHierarchyButDefinedTargetType() {
+    @WithClasses( { ConflictingFruitFactory.class, ResultTypeSelectingFruitMapper.class, Banana.class } )
+    public void testResultTypeBasedFactoryMethodSelection() {
 
         FruitDto fruitDto = new FruitDto( null );
-        Fruit fruit = TargetTypeSelectingFruitMapper.INSTANCE.map( fruitDto );
+        Fruit fruit = ResultTypeSelectingFruitMapper.INSTANCE.map( fruitDto );
         assertThat( fruit ).isNotNull();
         assertThat( fruit.getType() ).isEqualTo( "apple" );
 
     }
 
+    @Test
+    @IssueKey("434")
+    @WithClasses( { ResultTypeConstructingFruitMapper.class } )
+    public void testResultTypeBasedConstructionOfResult() {
+
+        FruitDto fruitDto = new FruitDto( null );
+        Fruit fruit = ResultTypeConstructingFruitMapper.INSTANCE.map( fruitDto );
+        assertThat( fruit ).isNotNull();
+        assertThat( fruit.getType() ).isEqualTo( "constructed-by-constructor" );
+    }
+
+    @Test
+    @ExpectedCompilationOutcome(
+        value = CompilationResult.FAILED,
+        diagnostics = {
+            @Diagnostic(type = ErroneousFruitMapper2.class,
+                kind = Kind.ERROR,
+                line = 35,
+                messageRegExp = ".*\\.Banana not assignable to: .*\\.Apple.")
+        }
+    )
+    @IssueKey("434")
+    @WithClasses( { ErroneousFruitMapper2.class, Banana.class } )
+    public void testResultTypeBasedConstructionOfResultNonAssignable() {
+    }
+
     @Test
     @IssueKey("433")
     @WithClasses( {

processor/src/test/java/org/mapstruct/ap/test/selection/resulttype/ResultTypeConstructingFruitMapper.java

@@ -0,0 +1,39 @@
+/**
+ *  Copyright 2012-2015 Gunnar Morling (http://www.gunnarmorling.de/)
+ *  and/or other contributors as indicated by the @authors tag. See the
+ *  copyright.txt file in the distribution for a full listing of all
+ *  contributors.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.mapstruct.ap.test.selection.resulttype;
+
+import org.mapstruct.BeanMapping;
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+import org.mapstruct.factory.Mappers;
+
+/**
+ *
+ * @author Sjaak Derksen
+ */
+@Mapper
+public interface ResultTypeConstructingFruitMapper {
+
+    ResultTypeConstructingFruitMapper INSTANCE = Mappers.getMapper( ResultTypeConstructingFruitMapper.class );
+
+    @BeanMapping(resultType = Apple.class)
+    @Mapping(target = "type", ignore = true)
+    Fruit map(FruitDto source);
+
+}

processor/src/test/java/org/mapstruct/ap/test/selection/resulttype/ResultTypeSelectingFruitMapper.java

@@ -28,10 +28,9 @@ import org.mapstruct.factory.Mappers;
  * @author Sjaak Derksen
  */
 @Mapper(uses = ConflictingFruitFactory.class)
+public interface ResultTypeSelectingFruitMapper {
 
-public interface TargetTypeSelectingFruitMapper {
-
-    TargetTypeSelectingFruitMapper INSTANCE = Mappers.getMapper( TargetTypeSelectingFruitMapper.class );
+    ResultTypeSelectingFruitMapper INSTANCE = Mappers.getMapper( ResultTypeSelectingFruitMapper.class );
 
     @BeanMapping(resultType = Apple.class)
     @Mapping(target = "type", ignore = true)