#1904 Create compilation error if a mapper could not be created due to a TypeHierarchyErroneousException

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

@@ -27,6 +27,7 @@ import javax.lang.model.SourceVersion;
 import javax.lang.model.element.Element;
 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.util.ElementKindVisitor6;
 import javax.tools.Diagnostic.Kind;
@@ -115,7 +116,7 @@ public class MappingProcessor extends AbstractProcessor {
      * generated by other processors), this mapper will not be generated; That's fine, the compiler will raise an error
      * due to the inconsistent Java types used as source or target anyways.
      */
-    private Set<TypeElement> deferredMappers = new HashSet<>();
+    private Set<DeferredMapper> deferredMappers = new HashSet<>();
 
     @Override
     public synchronized void init(ProcessingEnvironment processingEnv) {
@@ -163,6 +164,40 @@ public class MappingProcessor extends AbstractProcessor {
             Set<TypeElement> mappers = getMappers( annotations, roundEnvironment );
             processMapperElements( mappers, roundContext );
         }
+        else if ( !deferredMappers.isEmpty() ) {
+            // If the processing is over and there are deferred mappers it means something wrong occurred and
+            // MapStruct didn't generate implementations for those
+            for ( DeferredMapper deferredMapper : deferredMappers ) {
+
+                TypeElement deferredMapperElement = deferredMapper.deferredMapperElement;
+                Element erroneousElement = deferredMapper.erroneousElement;
+                String erroneousElementName;
+
+                if ( erroneousElement instanceof QualifiedNameable ) {
+                    erroneousElementName = ( (QualifiedNameable) erroneousElement ).getQualifiedName().toString();
+                }
+                else {
+                    erroneousElementName = erroneousElement.getSimpleName().toString();
+                }
+
+                // When running on Java 8 we need to fetch the deferredMapperElement again.
+                // Otherwise the reporting will not work properly
+                deferredMapperElement = annotationProcessorContext.getElementUtils()
+                    .getTypeElement( deferredMapperElement.getQualifiedName() );
+
+                processingEnv.getMessager()
+                    .printMessage(
+                        Kind.ERROR,
+                        "No implementation was created for " + deferredMapperElement.getSimpleName() +
+                            " due to having a problem in the erroneous element " + erroneousElementName + "." +
+                            " Hint: this often means that some other annotation processor was supposed to" +
+                            " process the erroneous element. You can also enable MapStruct verbose mode by setting" +
+                            " -Amapstruct.verbose=true as a compilation argument.",
+                        deferredMapperElement
+                    );
+            }
+
+        }
 
         return ANNOTATIONS_CLAIMED_EXCLUSIVELY;
     }
@@ -174,7 +209,8 @@ public class MappingProcessor extends AbstractProcessor {
     private Set<TypeElement> getAndResetDeferredMappers() {
         Set<TypeElement> deferred = new HashSet<>( deferredMappers.size() );
 
-        for (TypeElement element : deferredMappers ) {
+        for ( DeferredMapper deferredMapper : deferredMappers ) {
+            TypeElement element = deferredMapper.deferredMapperElement;
             deferred.add( processingEnv.getElementUtils().getTypeElement( element.getQualifiedName() ) );
         }
 
@@ -229,12 +265,15 @@ public class MappingProcessor extends AbstractProcessor {
                 processMapperTypeElement( context, mapperElement );
             }
             catch ( TypeHierarchyErroneousException thie ) {
+                Element erroneousElement = roundContext.getAnnotationProcessorContext()
+                    .getTypeUtils()
+                    .asElement( thie.getType() );
                 if ( options.isVerbose() ) {
                     processingEnv.getMessager().printMessage(
                         Kind.NOTE, "MapStruct: referred types not available (yet), deferring mapper: "
                             + mapperElement );
                 }
-                deferredMappers.add( mapperElement );
+                deferredMappers.add( new DeferredMapper( mapperElement, erroneousElement ) );
             }
             catch ( Throwable t ) {
                 handleUncaughtError( mapperElement, t );
@@ -347,4 +386,15 @@ public class MappingProcessor extends AbstractProcessor {
             return Integer.compare( o1.getPriority(), o2.getPriority() );
         }
     }
+
+    private static class DeferredMapper {
+
+        private final TypeElement deferredMapperElement;
+        private final Element erroneousElement;
+
+        private DeferredMapper(TypeElement deferredMapperElement, Element erroneousElement) {
+            this.deferredMapperElement = deferredMapperElement;
+            this.erroneousElement = erroneousElement;
+        }
+    }
 }

processor/src/test/java/org/mapstruct/ap/test/bugs/_1904/AstModifyingAnnotationProcessorSaysNo.java

@@ -0,0 +1,23 @@
+/*
+ * 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._1904;
+
+import javax.lang.model.type.TypeMirror;
+
+import org.mapstruct.ap.spi.AstModifyingAnnotationProcessor;
+
+/**
+ * @author Filip Hrisafov
+ */
+public class AstModifyingAnnotationProcessorSaysNo implements AstModifyingAnnotationProcessor {
+    @Override
+    public boolean isTypeComplete(TypeMirror type) {
+        if ( type.toString().contains( "CarManualDto" ) ) {
+            return false;
+        }
+        return true;
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/bugs/_1904/Issue1904Mapper.java

@@ -0,0 +1,49 @@
+/*
+ * 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._1904;
+
+import org.mapstruct.Mapper;
+
+/**
+ * @author Filip Hrisafov
+ */
+@Mapper
+public interface Issue1904Mapper {
+
+    CarManualDto translateManual(CarManual manual);
+
+    /**
+     * @author Filip Hrisafov
+     */
+    class CarManual {
+
+        private String content;
+
+        public String getContent() {
+            return content;
+        }
+
+        public void setContent(String content) {
+            this.content = content;
+        }
+    }
+
+    /**
+     * @author Filip Hrisafov
+     */
+    class CarManualDto {
+
+        private String content;
+
+        public String getContent() {
+            return content;
+        }
+
+        public void setContent(String content) {
+            this.content = content;
+        }
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/bugs/_1904/Issue1904Test.java

@@ -0,0 +1,48 @@
+/*
+ * 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._1904;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mapstruct.ap.spi.AstModifyingAnnotationProcessor;
+import org.mapstruct.ap.testutil.IssueKey;
+import org.mapstruct.ap.testutil.WithClasses;
+import org.mapstruct.ap.testutil.WithServiceImplementation;
+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.mapstruct.ap.testutil.runner.AnnotationProcessorTestRunner;
+
+/**
+ * @author Filip Hrisafov
+ */
+@IssueKey("1904")
+@RunWith(AnnotationProcessorTestRunner.class)
+@WithClasses({
+    Issue1904Mapper.class,
+})
+@WithServiceImplementation(
+    provides = AstModifyingAnnotationProcessor.class,
+    value = AstModifyingAnnotationProcessorSaysNo.class
+)
+public class Issue1904Test {
+
+    @Test
+    @ExpectedCompilationOutcome(value = CompilationResult.FAILED, diagnostics = {
+        @Diagnostic(
+            type = Issue1904Mapper.class,
+            kind = javax.tools.Diagnostic.Kind.ERROR,
+            line = 14,
+            messageRegExp = ".*No implementation was created for Issue1904Mapper due to having a problem in the " +
+                "erroneous element .*\\.CarManualDto. Hint: this often means that some other annotation processor " +
+                "was supposed to process the erroneous element. You can also enable MapStruct verbose mode by " +
+                "setting -Amapstruct.verbose=true as a compilation argument."
+        )
+    })
+    public void shouldHaveCompilationErrorIfMapperCouldNotBeCreated() {
+
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/verbose/VerboseTest.java

@@ -16,6 +16,9 @@ import org.mapstruct.ap.spi.ImmutablesBuilderProvider;
 import org.mapstruct.ap.testutil.IssueKey;
 import org.mapstruct.ap.testutil.WithClasses;
 import org.mapstruct.ap.testutil.WithServiceImplementation;
+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.mapstruct.ap.testutil.compilation.annotation.ExpectedNote;
 import org.mapstruct.ap.testutil.compilation.annotation.ProcessorOption;
 import org.mapstruct.ap.testutil.runner.AnnotationProcessorTestRunner;
@@ -57,6 +60,15 @@ public class VerboseTest {
     @ProcessorOption(name = "mapstruct.verbose", value = "true")
     @WithClasses(CreateBeanMapping.class)
     @ExpectedNote("^MapStruct: referred types not available \\(yet\\), deferring mapper:.*CreateBeanMapping.*$")
+    @ExpectedCompilationOutcome(value = CompilationResult.FAILED, diagnostics = {
+        @Diagnostic(
+            type = CreateBeanMapping.class,
+            kind = javax.tools.Diagnostic.Kind.ERROR,
+            line = 12,
+            messageRegExp = ".*No implementation was created for CreateBeanMapping due to having a problem in the " +
+                "erroneous element .*"
+        )
+    })
     public void testDeferred() {
     }