#2056: Handle null TypeMirror in uses and import gracefully

Due to a bug in javac (JDK-8229535) for an annotation with Class values, instead of returning a TypeMirror with TypeKind#ERROR the compiler returns the string "<error>". Eclipse doesn't have this problem currently.

integrationtest/src/test/java/org/mapstruct/itest/tests/MavenIntegrationTest.java

@@ -135,4 +135,25 @@ public class MavenIntegrationTest {
 
     }
 
+    /**
+     * Tests usage of MapStruct with another processor that generates the uses type of a mapper.
+     */
+    @ProcessorTest(baseDir = "usesTypeGenerationTest", processorTypes = {
+        ProcessorTest.ProcessorType.JAVAC
+    })
+    void usesTypeGenerationTest() {
+    }
+
+    /**
+     * Tests usage of MapStruct with another processor that generates the uses type of a mapper.
+     */
+    @ProcessorTest(baseDir = "usesTypeGenerationTest", processorTypes = {
+        ProcessorTest.ProcessorType.ECLIPSE_JDT
+    })
+    @EnabledForJreRange(min = JRE.JAVA_11)
+    // For some reason the second run with eclipse does not load the ModelElementProcessor(s) on java 8,
+    // therefore we run this only on Java 11
+    void usesTypeGenerationTestEclipse() {
+    }
+
 }

integrationtest/src/test/resources/usesTypeGenerationTest/generator/pom.xml

@@ -0,0 +1,43 @@
+<!--
+
+    Copyright MapStruct Authors.
+
+    Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+
+-->
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>org.mapstruct.itest</groupId>
+        <artifactId>itest-usestypegeneration-aggregator</artifactId>
+        <version>1.0.0</version>
+        <relativePath>../pom.xml</relativePath>
+    </parent>
+
+    <artifactId>itest-usestypegeneration-generator</artifactId>
+    <packaging>jar</packaging>
+
+    <dependencies>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <compilerArgs>
+                        <compilerArg>-proc:none</compilerArg>
+                    </compilerArgs>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+</project>

integrationtest/src/test/resources/usesTypeGenerationTest/generator/src/main/java/org/mapstruct/itest/usestypegeneration/UsesTypeGenerationProcessor.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.itest.usestypegeneration;
+
+import java.io.IOException;
+import java.io.Writer;
+import java.util.Set;
+
+import javax.annotation.processing.AbstractProcessor;
+import javax.annotation.processing.RoundEnvironment;
+import javax.annotation.processing.SupportedAnnotationTypes;
+import javax.lang.model.element.TypeElement;
+import javax.tools.JavaFileObject;
+
+/**
+ * Generate conversion uses.
+ *
+ * @author Filip Hrisafov
+ *
+ */
+@SupportedAnnotationTypes("*")
+public class UsesTypeGenerationProcessor extends AbstractProcessor {
+
+    private boolean hasRun = false;
+
+    @Override
+    public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
+        if ( !hasRun ) {
+            try {
+                    JavaFileObject dto = processingEnv.getFiler().createSourceFile( "org.mapstruct.itest.usestypegeneration.usage.StringUtils" );
+                    Writer writer = dto.openWriter();
+
+                    writer.append( "package org.mapstruct.itest.usestypegeneration.usage;" );
+                    writer.append( "\n" );
+                    writer.append( "public class StringUtils {" );
+                    writer.append( "\n" );
+                    writer.append( "    public static String upperCase(String string) {" );
+                    writer.append( "\n" );
+                    writer.append( "              return string == null ? null : string.toUpperCase();" );
+                    writer.append( "\n" );
+                    writer.append( "    }" );
+                    writer.append( "\n" );
+                    writer.append( "}" );
+
+                    writer.flush();
+                    writer.close();
+            }
+            catch (IOException e) {
+                    throw new RuntimeException( e );
+            }
+
+            hasRun = true;
+        }
+
+        return false;
+    }
+}

integrationtest/src/test/resources/usesTypeGenerationTest/generator/src/main/resources/META-INF/services/javax.annotation.processing.Processor

@@ -0,0 +1,4 @@
+# Copyright MapStruct Authors.
+#
+# Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+org.mapstruct.itest.usestypegeneration.UsesTypeGenerationProcessor

integrationtest/src/test/resources/usesTypeGenerationTest/pom.xml

@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+
+    Copyright MapStruct Authors.
+
+    Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+
+-->
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>org.mapstruct</groupId>
+        <artifactId>mapstruct-it-parent</artifactId>
+        <version>1.0.0</version>
+        <relativePath>../pom.xml</relativePath>
+    </parent>
+
+    <groupId>org.mapstruct.itest</groupId>
+    <artifactId>itest-usestypegeneration-aggregator</artifactId>
+    <packaging>pom</packaging>
+
+    <modules>
+        <module>generator</module>
+        <module>usage</module>
+    </modules>
+</project>

integrationtest/src/test/resources/usesTypeGenerationTest/usage/pom.xml

@@ -0,0 +1,52 @@
+<!--
+
+    Copyright MapStruct Authors.
+
+    Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+
+-->
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>org.mapstruct.itest</groupId>
+        <artifactId>itest-usestypegeneration-aggregator</artifactId>
+        <version>1.0.0</version>
+        <relativePath>../pom.xml</relativePath>
+    </parent>
+    
+    <artifactId>itest-usestypegeneration-usage</artifactId>
+    <packaging>jar</packaging>
+
+    <dependencies>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.12</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.mapstruct.itest</groupId>
+            <artifactId>itest-usestypegeneration-generator</artifactId>
+            <version>1.0.0</version>
+            <scope>provided</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <compilerArgs>
+                        <compilerArg>-XprintProcessorInfo</compilerArg>
+                        <compilerArg>-XprintRounds</compilerArg>
+                    </compilerArgs>
+                    <testCompilerArgument>-proc:none</testCompilerArgument>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+</project>

integrationtest/src/test/resources/usesTypeGenerationTest/usage/src/main/java/org/mapstruct/itest/usestypegeneration/usage/Order.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.itest.usestypegeneration.usage;
+
+/**
+ * @author Filip Hrisafov
+ */
+public class Order {
+
+    private String item;
+
+    public String getItem() {
+        return item;
+    }
+
+    public void setItem(String item) {
+        this.item = item;
+    }
+}

integrationtest/src/test/resources/usesTypeGenerationTest/usage/src/main/java/org/mapstruct/itest/usestypegeneration/usage/OrderDto.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.itest.usestypegeneration.usage;
+
+/**
+ * @author Filip Hrisafov
+ */
+public class OrderDto {
+
+    private String item;
+
+    public String getItem() {
+        return item;
+    }
+
+    public void setItem(String item) {
+        this.item = item;
+    }
+}

integrationtest/src/test/resources/usesTypeGenerationTest/usage/src/main/java/org/mapstruct/itest/usestypegeneration/usage/OrderMapper.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.itest.usestypegeneration.usage;
+
+import org.mapstruct.Mapper;
+import org.mapstruct.factory.Mappers;
+
+/**
+ * @author Filip Hrisafov
+ */
+@Mapper(uses = StringUtils.class)
+public interface OrderMapper {
+
+    OrderMapper INSTANCE = Mappers.getMapper( OrderMapper.class );
+
+    OrderDto orderToDto(Order order);
+}

integrationtest/src/test/resources/usesTypeGenerationTest/usage/src/test/java/org/mapstruct/itest/usestypegeneration/usage/GeneratedUsesTypeTest.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.itest.usestypegeneration.usage;
+
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Integration test for using MapStruct with another annotation processor that generates the other mappers for uses
+ *
+ * @author Filip Hrisafov
+ */
+public class GeneratedUsesTypeTest {
+
+    @Test
+    public void considersPropertiesOnGeneratedSourceAndTargetTypes() {
+        Order order = new Order();
+        order.setItem( "my item" );
+
+        OrderDto dto = OrderMapper.INSTANCE.orderToDto( order );
+        assertThat( dto.getItem() ).isEqualTo( "MY ITEM" );
+    }
+}

parent/pom.xml

@@ -21,7 +21,7 @@
 
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-        <org.mapstruct.gem.version>1.0.0.Alpha1</org.mapstruct.gem.version>
+        <org.mapstruct.gem.version>1.0.0.Alpha2</org.mapstruct.gem.version>
         <!-- We can't go to 3.0.0-M2 as it has a regression. See https://issues.apache.org/jira/browse/MENFORCER-306 -->
         <org.apache.maven.plugins.enforcer.version>3.0.0-M1</org.apache.maven.plugins.enforcer.version>
         <org.apache.maven.plugins.surefire.version>3.0.0-M3</org.apache.maven.plugins.surefire.version>

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

@@ -29,6 +29,7 @@ import javax.lang.model.element.ElementKind;
 import javax.lang.model.element.Name;
 import javax.lang.model.element.QualifiedNameable;
 import javax.lang.model.element.TypeElement;
+import javax.lang.model.type.TypeMirror;
 import javax.lang.model.util.ElementKindVisitor6;
 import javax.tools.Diagnostic.Kind;
 
@@ -177,7 +178,8 @@ public class MappingProcessor extends AbstractProcessor {
                     erroneousElementName = ( (QualifiedNameable) erroneousElement ).getQualifiedName().toString();
                 }
                 else {
-                    erroneousElementName = erroneousElement.getSimpleName().toString();
+                    erroneousElementName =
+                        erroneousElement != null ? erroneousElement.getSimpleName().toString() : null;
                 }
 
                 // When running on Java 8 we need to fetch the deferredMapperElement again.
@@ -265,9 +267,10 @@ public class MappingProcessor extends AbstractProcessor {
                 processMapperTypeElement( context, mapperElement );
             }
             catch ( TypeHierarchyErroneousException thie ) {
-                Element erroneousElement = roundContext.getAnnotationProcessorContext()
+                TypeMirror erroneousType = thie.getType();
+                Element erroneousElement = erroneousType != null ? roundContext.getAnnotationProcessorContext()
                     .getTypeUtils()
-                    .asElement( thie.getType() );
+                    .asElement( erroneousType ) : null;
                 if ( options.isVerbose() ) {
                     processingEnv.getMessager().printMessage(
                         Kind.NOTE, "MapStruct: referred types not available (yet), deferring mapper: "

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

@@ -8,7 +8,6 @@ package org.mapstruct.ap.internal.model.source;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
-import java.util.stream.Collectors;
 import javax.lang.model.type.DeclaredType;
 import javax.lang.model.type.TypeMirror;
 import javax.lang.model.util.Elements;
@@ -21,6 +20,7 @@ import org.mapstruct.ap.internal.gem.NullValueCheckStrategyGem;
 import org.mapstruct.ap.internal.gem.NullValueMappingStrategyGem;
 import org.mapstruct.ap.internal.gem.NullValuePropertyMappingStrategyGem;
 import org.mapstruct.ap.internal.gem.ReportingPolicyGem;
+import org.mapstruct.ap.spi.TypeHierarchyErroneousException;
 
 /**
  * Chain Of Responsibility Pattern.
@@ -110,9 +110,18 @@ public abstract class DelegatingOptions {
     }
 
     protected Set<DeclaredType> toDeclaredTypes(List<TypeMirror> in, Set<DeclaredType> next) {
-        Set result = in.stream()
+        Set<DeclaredType> result = new LinkedHashSet<>();
-            .map( DeclaredType.class::cast )
+        for ( TypeMirror typeMirror : in ) {
-            .collect( Collectors.toCollection( LinkedHashSet::new ) );
+            if ( typeMirror == null ) {
+                // When a class used in uses or imports is created by another annotation processor
+                // then javac will not return correct TypeMirror with TypeKind#ERROR, but rather a string "<error>"
+                // the gem tools would return a null TypeMirror in that case.
+                // Therefore throw TypeHierarchyErroneousException so we can postpone the generation of the mapper
+                throw new TypeHierarchyErroneousException( typeMirror );
+            }
+
+            result.add( (DeclaredType) typeMirror );
+        }
         result.addAll( next );
         return result;
     }