#1566, #1253 Add support for initializing the AccessorNamingStrategy with Elements and Types and use Types for determining fluent setters

* This allows using generic builders

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

@@ -114,7 +114,10 @@ public class MappingProcessor extends AbstractProcessor {
         super.init( processingEnv );
 
         options = createOptions();
-        annotationProcessorContext = new AnnotationProcessorContext( processingEnv.getElementUtils() );
+        annotationProcessorContext = new AnnotationProcessorContext(
+            processingEnv.getElementUtils(),
+            processingEnv.getTypeUtils()
+        );
     }
 
     private Options createOptions() {

processor/src/main/java/org/mapstruct/ap/internal/util/AnnotationProcessorContext.java

@@ -12,6 +12,7 @@ import java.util.ServiceLoader;
 
 import javax.lang.model.element.TypeElement;
 import javax.lang.model.util.Elements;
+import javax.lang.model.util.Types;
 
 import org.mapstruct.ap.spi.AccessorNamingStrategy;
 import org.mapstruct.ap.spi.AstModifyingAnnotationProcessor;
@@ -20,13 +21,14 @@ import org.mapstruct.ap.spi.DefaultAccessorNamingStrategy;
 import org.mapstruct.ap.spi.DefaultBuilderProvider;
 import org.mapstruct.ap.spi.ImmutablesAccessorNamingStrategy;
 import org.mapstruct.ap.spi.ImmutablesBuilderProvider;
+import org.mapstruct.ap.spi.MapStructProcessingEnvironment;
 
 /**
  * Keeps contextual data in the scope of the entire annotation processor ("application scope").
  *
  * @author Gunnar Morling
  */
-public class AnnotationProcessorContext {
+public class AnnotationProcessorContext implements MapStructProcessingEnvironment {
 
     private List<AstModifyingAnnotationProcessor> astModifyingAnnotationProcessors;
 
@@ -36,11 +38,13 @@ public class AnnotationProcessorContext {
 
     private AccessorNamingUtils accessorNaming;
     private Elements elementUtils;
+    private Types typeUtils;
 
-    public AnnotationProcessorContext(Elements elementUtils) {
+    public AnnotationProcessorContext(Elements elementUtils, Types typeUtils) {
         astModifyingAnnotationProcessors = java.util.Collections.unmodifiableList(
                 findAstModifyingAnnotationProcessors() );
         this.elementUtils = elementUtils;
+        this.typeUtils = typeUtils;
     }
 
     /**
@@ -67,6 +71,7 @@ public class AnnotationProcessorContext {
             defaultBuilderProvider = new ImmutablesBuilderProvider();
         }
         this.accessorNamingStrategy = Services.get( AccessorNamingStrategy.class, defaultAccessorNamingStrategy );
+        this.accessorNamingStrategy.init( this );
         this.builderProvider = Services.get( BuilderProvider.class, defaultBuilderProvider );
         this.accessorNaming = new AccessorNamingUtils( this.accessorNamingStrategy );
         this.initialized = true;
@@ -86,6 +91,16 @@ public class AnnotationProcessorContext {
         return processors;
     }
 
+    @Override
+    public Elements getElementUtils() {
+        return elementUtils;
+    }
+
+    @Override
+    public Types getTypeUtils() {
+        return typeUtils;
+    }
+
     public List<AstModifyingAnnotationProcessor> getAstModifyingAnnotationProcessors() {
         return astModifyingAnnotationProcessors;
     }

processor/src/main/java/org/mapstruct/ap/spi/AccessorNamingStrategy.java

@@ -15,6 +15,15 @@ import javax.lang.model.element.ExecutableElement;
  */
 public interface AccessorNamingStrategy {
 
+    /**
+     * Initializes the accessor naming strategy with the MapStruct processing environment.
+     *
+     * @param processingEnvironment environment for facilities
+     */
+    default void init(MapStructProcessingEnvironment processingEnvironment) {
+
+    }
+
     /**
      * Returns the type of the given method.
      *

processor/src/main/java/org/mapstruct/ap/spi/DefaultAccessorNamingStrategy.java

@@ -12,8 +12,10 @@ import javax.lang.model.element.TypeElement;
 import javax.lang.model.type.DeclaredType;
 import javax.lang.model.type.TypeKind;
 import javax.lang.model.type.TypeMirror;
+import javax.lang.model.util.Elements;
 import javax.lang.model.util.SimpleElementVisitor6;
 import javax.lang.model.util.SimpleTypeVisitor6;
+import javax.lang.model.util.Types;
 
 import org.mapstruct.ap.spi.util.IntrospectorUtils;
 
@@ -26,6 +28,15 @@ public class DefaultAccessorNamingStrategy implements AccessorNamingStrategy {
 
     private static final Pattern JAVA_JAVAX_PACKAGE = Pattern.compile( "^javax?\\..*" );
 
+    protected Elements elementUtils;
+    protected Types typeUtils;
+
+    @Override
+    public void init(MapStructProcessingEnvironment processingEnvironment) {
+        this.elementUtils = processingEnvironment.getElementUtils();
+        this.typeUtils = processingEnvironment.getTypeUtils();
+    }
+
     @Override
     public MethodType getMethodType(ExecutableElement method) {
         if ( isGetterMethod( method ) ) {
@@ -90,8 +101,7 @@ public class DefaultAccessorNamingStrategy implements AccessorNamingStrategy {
         return method.getParameters().size() == 1 &&
             !JAVA_JAVAX_PACKAGE.matcher( method.getEnclosingElement().asType().toString() ).matches() &&
             !isAdderWithUpperCase4thCharacter( method ) &&
-            //TODO The Types need to be compared with Types#isSameType(TypeMirror, TypeMirror)
-            method.getReturnType().toString().equals( method.getEnclosingElement().asType().toString() );
+            typeUtils.isAssignable( method.getReturnType(), method.getEnclosingElement().asType() );
     }
 
     /**

processor/src/main/java/org/mapstruct/ap/spi/MapStructProcessingEnvironment.java

@@ -0,0 +1,37 @@
+/*
+ * 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.spi;
+
+import javax.lang.model.util.Elements;
+import javax.lang.model.util.Types;
+
+/**
+ * MapStruct will provide the implementations of its SPIs with on object implementing this interface so they can use
+ * facilities provided by it. It is a subset of {@link javax.annotation.processing.ProcessingEnvironment
+ * ProcessingEnvironment}.
+ *
+ * @author Filip Hrisafov
+ * @see javax.annotation.processing.ProcessingEnvironment
+ */
+public interface MapStructProcessingEnvironment {
+
+    /**
+     * Returns an implementation of some utility methods for
+     * operating on elements
+     *
+     * @return element utilities
+     */
+    Elements getElementUtils();
+
+    /**
+     * Returns an implementation of some utility methods for
+     * operating on types.
+     *
+     * @return type utilities
+     */
+    Types getTypeUtils();
+
+}

processor/src/test/java/org/mapstruct/ap/test/bugs/_1566/AbstractBuilder.java

@@ -0,0 +1,19 @@
+/*
+ * 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._1566;
+
+/**
+ * @author Filip Hrisafov
+ */
+public abstract class AbstractBuilder<T extends AbstractBuilder<T>> {
+    String id;
+
+    @SuppressWarnings("unchecked")
+    public T id(final String id) {
+        this.id = id;
+        return (T) this;
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/bugs/_1566/Issue1566Mapper.java

@@ -0,0 +1,20 @@
+/*
+ * 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._1566;
+
+import org.mapstruct.Mapper;
+import org.mapstruct.factory.Mappers;
+
+/**
+ * @author Filip Hrisafov
+ */
+@Mapper
+public interface Issue1566Mapper {
+
+    Issue1566Mapper INSTANCE = Mappers.getMapper( Issue1566Mapper.class );
+
+    Target map(Source source);
+}

processor/src/test/java/org/mapstruct/ap/test/bugs/_1566/Issue1566Test.java

@@ -0,0 +1,41 @@
+/*
+ * 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._1566;
+
+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;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Filip Hrisafov
+ */
+@WithClasses({
+    AbstractBuilder.class,
+    Issue1566Mapper.class,
+    Source.class,
+    Target.class
+})
+@IssueKey("1566")
+@RunWith(AnnotationProcessorTestRunner.class)
+public class Issue1566Test {
+
+    @Test
+    public void genericMapperIsCorrectlyUsed() {
+        Source source = new Source();
+        source.setId( "id-123" );
+        source.setName( "Source" );
+
+        Target target = Issue1566Mapper.INSTANCE.map( source );
+
+        assertThat( target ).isNotNull();
+        assertThat( target.getId() ).isEqualTo( "id-123" );
+        assertThat( target.getName() ).isEqualTo( "Source" );
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/bugs/_1566/Source.java

@@ -0,0 +1,31 @@
+/*
+ * 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._1566;
+
+/**
+ * @author Filip Hrisafov
+ */
+public class Source {
+
+    private String id;
+    private String name;
+
+    public String getId() {
+        return id;
+    }
+
+    public void setId(String id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/bugs/_1566/Target.java

@@ -0,0 +1,45 @@
+/*
+ * 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._1566;
+
+/**
+ * @author Filip Hrisafov
+ */
+public class Target {
+
+    private final String id;
+    private final String name;
+
+    private Target(String id, String name) {
+        this.id = id;
+        this.name = name;
+    }
+
+    public String getId() {
+        return id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    public static class Builder extends AbstractBuilder<Builder> {
+        private String name;
+
+        public Builder name(String name) {
+            this.name = name;
+            return this;
+        }
+
+        public Target build() {
+            return new Target( id, name );
+        }
+    }
+}