#61 Raising an error in case a collection/map attribute can't be propagated due to differently parameterized attributes in source and target

processor/src/main/java/org/mapstruct/ap/processor/MapperCreationProcessor.java

@@ -30,9 +30,13 @@ import java.util.Set;
 import javax.annotation.processing.Messager;
 import javax.lang.model.element.ExecutableElement;
 import javax.lang.model.element.TypeElement;
+import javax.lang.model.type.DeclaredType;
+import javax.lang.model.type.ExecutableType;
 import javax.lang.model.type.TypeKind;
 import javax.lang.model.type.TypeMirror;
+import javax.lang.model.util.ElementFilter;
 import javax.lang.model.util.Elements;
+import javax.lang.model.util.Types;
 import javax.tools.Diagnostic.Kind;
 
 import org.mapstruct.ap.MapperPrism;
@@ -71,6 +75,7 @@ public class MapperCreationProcessor implements ModelElementProcessor<List<Metho
     private static final String IMPLEMENTATION_SUFFIX = "Impl";
 
     private Elements elementUtils;
+    private Types typeUtils;
     private Messager messager;
     private Options options;
 
@@ -82,6 +87,7 @@ public class MapperCreationProcessor implements ModelElementProcessor<List<Metho
     @Override
     public Mapper process(ProcessorContext context, TypeElement mapperTypeElement, List<Method> sourceModel) {
         this.elementUtils = context.getElementUtils();
+        this.typeUtils = context.getTypeUtils();
         this.messager = context.getMessager();
         this.options = context.getOptions();
 
@@ -554,18 +560,42 @@ public class MapperCreationProcessor implements ModelElementProcessor<List<Metho
     }
 
     /**
-     * Reports an error if source and target type of the property are different
+     * Reports an error if source the property can't be mapped from source to target. A mapping if possible if one of
-     * and neither a mapping method nor a conversion exists nor the property is
+     * the following conditions is true:
-     * of a collection type with default implementation
+     * <ul>
+     * <li>the source type is assignable to the target type</li>
+     * <li>a mapping method exists</li>
+     * <li>a built-in conversion exists</li>
+     * <li>the property is of a collection or map type and the constructor of the target type (either itself or its
+     * implementation type) accepts the source type.</li>
+     * </ul>
      *
      * @param method The mapping method owning the property mapping.
      * @param property The property mapping to check.
      */
     private void reportErrorIfPropertyCanNotBeMapped(Method method, PropertyMapping property) {
+        boolean collectionOrMapTargetTypeHasCompatibleConstructor = false;
+
+        if ( property.getTargetType().isCollectionType() || property.getTargetType().isMapType() ) {
+            if ( property.getTargetType().getImplementationType() != null ) {
+                collectionOrMapTargetTypeHasCompatibleConstructor = hasCompatibleConstructor(
+                    property.getSourceType(),
+                    property.getTargetType().getImplementationType()
+                );
+            }
+            else {
+                collectionOrMapTargetTypeHasCompatibleConstructor = hasCompatibleConstructor(
+                    property.getSourceType(),
+                    property.getTargetType()
+                );
+            }
+        }
+
         if ( property.getSourceType().isAssignableTo( property.getTargetType() ) ||
             property.getMappingMethod() != null ||
             property.getConversion() != null ||
-            property.getTargetType().getImplementationType() != null ) {
+            ( ( property.getTargetType().isCollectionType() || property.getTargetType().isMapType() ) &&
+                collectionOrMapTargetTypeHasCompatibleConstructor ) ) {
             return;
         }
 
@@ -581,4 +611,39 @@ public class MapperCreationProcessor implements ModelElementProcessor<List<Metho
             method.getExecutable()
         );
     }
+
+    /**
+     * Whether the given target type has a single-argument constructor which accepts the given source type.
+     *
+     * @param sourceType the source type
+     * @param targetType the target type
+     * @return {@code true} if the target type has a constructor accepting the given source type, {@code false}
+     *         otherwise.
+     */
+    private boolean hasCompatibleConstructor(Type sourceType, Type targetType) {
+        List<ExecutableElement> targetTypeConstructors = ElementFilter.constructorsIn(
+            targetType.getTypeElement()
+                .getEnclosedElements()
+        );
+
+        for ( ExecutableElement constructor : targetTypeConstructors ) {
+            if ( constructor.getParameters().size() != 1 ) {
+                continue;
+            }
+
+            //get the constructor resolved against the type arguments of specific target type
+            ExecutableType typedConstructor = (ExecutableType) typeUtils.asMemberOf(
+                (DeclaredType) targetType.getTypeMirror(), constructor
+            );
+
+            if ( typeUtils.isAssignable(
+                sourceType.getTypeMirror(),
+                typedConstructor.getParameterTypes().iterator().next()
+            ) ) {
+                return true;
+            }
+        }
+
+        return false;
+    }
 }

processor/src/test/java/org/mapstruct/ap/test/collection/erroneous/AnotherTarget.java

@@ -0,0 +1,34 @@
+/**
+ *  Copyright 2012-2013 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.collection.erroneous;
+
+import java.util.Map;
+
+public class AnotherTarget {
+
+    private Map<String, String> barMap;
+
+    public Map<String, String> getBarMap() {
+        return barMap;
+    }
+
+    public void setBarMap(Map<String, String> barMap) {
+        this.barMap = barMap;
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/collection/erroneous/ErroneousCollectionMapper.java

@@ -0,0 +1,27 @@
+/**
+ *  Copyright 2012-2013 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.collection.erroneous;
+
+import org.mapstruct.Mapper;
+
+@Mapper
+public interface ErroneousCollectionMapper {
+
+    Target sourceToTarget(Source source);
+}

processor/src/test/java/org/mapstruct/ap/test/collection/erroneous/ErroneousCollectionMappingTest.java

@@ -0,0 +1,86 @@
+/**
+ *  Copyright 2012-2013 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.collection.erroneous;
+
+import javax.tools.Diagnostic.Kind;
+
+import org.mapstruct.ap.testutil.IssueKey;
+import org.mapstruct.ap.testutil.MapperTestBase;
+import org.mapstruct.ap.testutil.WithClasses;
+import org.mapstruct.ap.testutil.compilation.annotation.CompilationResult;
+import org.mapstruct.ap.testutil.compilation.annotation.Diagnostic;
+import org.mapstruct.ap.testutil.compilation.annotation.ExpectedCompilationOutcome;
+import org.testng.annotations.Test;
+
+/**
+ * Test for illegal mappings between collection types, iterable and non-iterable types etc.
+ *
+ * @author Gunnar Morling
+ */
+public class ErroneousCollectionMappingTest extends MapperTestBase {
+
+    @Test
+    @IssueKey("6")
+    @WithClasses({ ErroneousCollectionToNonCollectionMapper.class })
+    @ExpectedCompilationOutcome(
+        value = CompilationResult.FAILED,
+        diagnostics = {
+            @Diagnostic(type = ErroneousCollectionToNonCollectionMapper.class,
+                kind = Kind.ERROR,
+                line = 28,
+                messageRegExp = "Can't generate mapping method from iterable type to non-iterable type"),
+            @Diagnostic(type = ErroneousCollectionToNonCollectionMapper.class,
+                kind = Kind.ERROR,
+                line = 30,
+                messageRegExp = "Can't generate mapping method from non-iterable type to iterable type")
+        }
+    )
+    public void shouldFailToGenerateImplementationBetweenCollectionAndNonCollection() {
+    }
+
+    @Test
+    @WithClasses({ ErroneousCollectionMapper.class, Source.class, Target.class })
+    @ExpectedCompilationOutcome(
+        value = CompilationResult.FAILED,
+        diagnostics = {
+            @Diagnostic(type = ErroneousCollectionMapper.class,
+                kind = Kind.ERROR,
+                line = 26,
+                messageRegExp = "Can't map property \"java\\.util\\.Set<java\\.lang\\.String> fooSet\" to" +
+                        " \"java\\.util\\.Set<java\\.lang\\.Long> fooSet\""),
+        }
+    )
+    public void shouldFailToGenerateImplementationDueToDifferentlyParameterizedCollections() {
+    }
+
+    @Test
+    @WithClasses({ ErroneousMapMapper.class, Source.class, AnotherTarget.class })
+    @ExpectedCompilationOutcome(
+        value = CompilationResult.FAILED,
+        diagnostics = {
+            @Diagnostic(type = ErroneousMapMapper.class,
+                kind = Kind.ERROR,
+                line = 26,
+                messageRegExp = "Can't map property \"java\\.util\\.Map<java\\.lang\\.String,java\\.lang\\.Long>" +
+                        " barMap\" to \"java.util.Map<java\\.lang\\.String,java\\.lang\\.String> barMap\"")
+        }
+    )
+    public void shouldFailToGenerateImplementationDueToDifferentlyParameterizedMaps() {
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/collection/erroneous/ErroneousCollectionToNonCollectionMapper.java

@@ -23,7 +23,7 @@ import java.util.Set;
 import org.mapstruct.Mapper;
 
 @Mapper
-public interface ErronuousMapper {
+public interface ErroneousCollectionToNonCollectionMapper {
 
     Integer stringSetToInteger(Set<String> strings);
 

processor/src/test/java/org/mapstruct/ap/test/collection/erroneous/ErroneousMapMapper.java

@@ -0,0 +1,27 @@
+/**
+ *  Copyright 2012-2013 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.collection.erroneous;
+
+import org.mapstruct.Mapper;
+
+@Mapper
+public interface ErroneousMapMapper {
+
+    AnotherTarget sourceToTarget(Source source);
+}

processor/src/test/java/org/mapstruct/ap/test/collection/erroneous/ErronuousCollectionMappingTest.java

@@ -1,56 +0,0 @@
-/**
- *  Copyright 2012-2013 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.collection.erroneous;
-
-import javax.tools.Diagnostic.Kind;
-
-import org.mapstruct.ap.testutil.IssueKey;
-import org.mapstruct.ap.testutil.MapperTestBase;
-import org.mapstruct.ap.testutil.WithClasses;
-import org.mapstruct.ap.testutil.compilation.annotation.CompilationResult;
-import org.mapstruct.ap.testutil.compilation.annotation.Diagnostic;
-import org.mapstruct.ap.testutil.compilation.annotation.ExpectedCompilationOutcome;
-import org.testng.annotations.Test;
-
-/**
- * Test for illegal mappings between iterable and non-iterable types.
- *
- * @author Gunnar Morling
- */
-@WithClasses({ ErronuousMapper.class })
-public class ErronuousCollectionMappingTest extends MapperTestBase {
-
-    @Test
-    @IssueKey("6")
-    @ExpectedCompilationOutcome(
-        value = CompilationResult.FAILED,
-        diagnostics = {
-            @Diagnostic(type = ErronuousMapper.class,
-                kind = Kind.ERROR,
-                line = 28,
-                messageRegExp = "Can't generate mapping method from iterable type to non-iterable type\\."),
-            @Diagnostic(type = ErronuousMapper.class,
-                kind = Kind.ERROR,
-                line = 30,
-                messageRegExp = "Can't generate mapping method from non-iterable type to iterable type\\.")
-        }
-    )
-    public void shouldFailToGenerateMappingFromListToString() {
-    }
-}

processor/src/test/java/org/mapstruct/ap/test/collection/erroneous/Source.java

@@ -0,0 +1,45 @@
+/**
+ *  Copyright 2012-2013 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.collection.erroneous;
+
+import java.util.Map;
+import java.util.Set;
+
+public class Source {
+
+    private Set<String> fooSet;
+
+    private Map<String, Long> barMap;
+
+    public Set<String> getFooSet() {
+        return fooSet;
+    }
+
+    public void setFooSet(Set<String> fooSet) {
+        this.fooSet = fooSet;
+    }
+
+    public Map<String, Long> getBarMap() {
+        return barMap;
+    }
+
+    public void setBarMap(Map<String, Long> barMap) {
+        this.barMap = barMap;
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/collection/erroneous/Target.java

@@ -0,0 +1,34 @@
+/**
+ *  Copyright 2012-2013 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.collection.erroneous;
+
+import java.util.Set;
+
+public class Target {
+
+    private Set<Long> fooSet;
+
+    public Set<Long> getFooSet() {
+        return fooSet;
+    }
+
+    public void setFooSet(Set<Long> fooSet) {
+        this.fooSet = fooSet;
+    }
+}