#312 rename TypeUtilsJDK8Fix to SpecificCompilerWorkarounds and encapsulate all access to Types#erasure(..) by that class, preventing ClassCastExceptions in Eclipse JDT in case we try to determine the erasure of "void"

processor/src/main/java/org/mapstruct/ap/model/common/Type.java

@@ -24,6 +24,7 @@ import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+
 import javax.lang.model.element.AnnotationMirror;
 import javax.lang.model.element.Element;
 import javax.lang.model.element.ElementKind;
@@ -40,7 +41,7 @@ import javax.lang.model.util.Types;
 import org.mapstruct.ap.util.Executables;
 import org.mapstruct.ap.util.Filters;
 import org.mapstruct.ap.util.Nouns;
-import org.mapstruct.ap.util.TypeUtilsJDK6Fix;
+import org.mapstruct.ap.util.SpecificCompilerWorkarounds;
 
 /**
  * Represents (a reference to) the type of a bean property, parameter etc. Types are managed per generated source file.
@@ -239,7 +240,7 @@ public class Type extends ModelElement implements Comparable<Type> {
         return new Type(
             typeUtils,
             elementUtils,
-            typeUtils.erasure( typeMirror ),
+            SpecificCompilerWorkarounds.erasure( typeUtils, typeMirror ),
             typeElement,
             typeParameters,
             implementationType,
@@ -429,8 +430,9 @@ public class Type extends ModelElement implements Comparable<Type> {
 
     private boolean isSubType(TypeMirror candidate, Class<?> clazz) {
         String className = clazz.getCanonicalName();
-        TypeMirror classType = typeUtils.erasure( elementUtils.getTypeElement( className ).asType() );
-        return TypeUtilsJDK6Fix.isSubType( typeUtils, candidate, classType );
+        TypeMirror classType =
+            SpecificCompilerWorkarounds.erasure( typeUtils, elementUtils.getTypeElement( className ).asType() );
+        return SpecificCompilerWorkarounds.isSubType( typeUtils, candidate, classType );
     }
 
     /**

processor/src/main/java/org/mapstruct/ap/model/common/TypeFactory.java

@@ -51,7 +51,9 @@ import javax.lang.model.util.Types;
 import org.mapstruct.ap.prism.MappingTargetPrism;
 import org.mapstruct.ap.prism.TargetTypePrism;
 import org.mapstruct.ap.util.AnnotationProcessingException;
-import org.mapstruct.ap.util.TypeUtilsJDK6Fix;
+import org.mapstruct.ap.util.SpecificCompilerWorkarounds;
+
+import static org.mapstruct.ap.util.SpecificCompilerWorkarounds.erasure;
 
 /**
  * Factory creating {@link Type} instances.
@@ -74,12 +76,10 @@ public class TypeFactory {
         this.elementUtils = elementUtils;
         this.typeUtils = typeUtils;
 
-        iterableType = typeUtils.erasure( elementUtils.getTypeElement( Iterable.class.getCanonicalName() ).asType() );
-        collectionType = typeUtils.erasure(
-            elementUtils.getTypeElement( Collection.class.getCanonicalName() )
-                .asType()
-        );
-        mapType = typeUtils.erasure( elementUtils.getTypeElement( Map.class.getCanonicalName() ).asType() );
+        iterableType = erasure( typeUtils, elementUtils.getTypeElement( Iterable.class.getCanonicalName() ).asType() );
+        collectionType =
+            erasure( typeUtils, elementUtils.getTypeElement( Collection.class.getCanonicalName() ).asType() );
+        mapType = erasure( typeUtils, elementUtils.getTypeElement( Map.class.getCanonicalName() ).asType() );
 
         implementationTypes.put( Iterable.class.getName(), getType( ArrayList.class ) );
         implementationTypes.put( Collection.class.getName(), getType( ArrayList.class ) );
@@ -123,10 +123,9 @@ public class TypeFactory {
 
         Type implementationType = getImplementationType( mirror );
 
-        boolean isVoid = mirror.getKind() == TypeKind.VOID;
-        boolean isIterableType = !isVoid && TypeUtilsJDK6Fix.isSubType( typeUtils, mirror, iterableType );
-        boolean isCollectionType = !isVoid && TypeUtilsJDK6Fix.isSubType( typeUtils, mirror, collectionType );
-        boolean isMapType = !isVoid && TypeUtilsJDK6Fix.isSubType( typeUtils, mirror, mapType );
+        boolean isIterableType = SpecificCompilerWorkarounds.isSubType( typeUtils, mirror, iterableType );
+        boolean isCollectionType = SpecificCompilerWorkarounds.isSubType( typeUtils, mirror, collectionType );
+        boolean isMapType = SpecificCompilerWorkarounds.isSubType( typeUtils, mirror, mapType );
 
         boolean isEnumType;
         boolean isInterface;

processor/src/main/java/org/mapstruct/ap/model/source/MethodMatcher.java

@@ -36,7 +36,7 @@ import javax.lang.model.util.SimpleTypeVisitor6;
 import javax.lang.model.util.Types;
 
 import org.mapstruct.ap.model.common.Type;
-import org.mapstruct.ap.util.TypeUtilsJDK6Fix;
+import org.mapstruct.ap.util.SpecificCompilerWorkarounds;
 
 /**
  * SourceMethodMatcher $8.4 of the JavaLanguage specification describes a method body as such:
@@ -222,8 +222,8 @@ public class MethodMatcher {
             }
             else {
                 // check if types are in bound
-                if ( TypeUtilsJDK6Fix.isSubType( typeUtils, t.getLowerBound(), p ) &&
-                    TypeUtilsJDK6Fix.isSubType( typeUtils, p, t.getUpperBound() ) ) {
+                if ( SpecificCompilerWorkarounds.isSubType( typeUtils, t.getLowerBound(), p ) &&
+                    SpecificCompilerWorkarounds.isSubType( typeUtils, p, t.getUpperBound() ) ) {
                     genericTypesMap.put( t, p );
                     return Boolean.TRUE;
                 }
@@ -243,7 +243,7 @@ public class MethodMatcher {
                     case DECLARED:
                         // for example method: String method(? extends String)
                         // isSubType checks range [subtype, type], e.g. isSubtype [Object, String]==true
-                        return TypeUtilsJDK6Fix.isSubType( typeUtils, p, extendsBound );
+                        return SpecificCompilerWorkarounds.isSubType( typeUtils, p, extendsBound );
 
                     case TYPEVAR:
                         // for example method: <T extends String & Serializable> T method(? extends T)
@@ -265,7 +265,7 @@ public class MethodMatcher {
                         // for example method: String method(? super String)
                         // to check super type, we can simply reverse the argument, but that would initially yield
                         // a result: <type, superType] (so type not included) so we need to check sameType also.
-                        return TypeUtilsJDK6Fix.isSubType( typeUtils, superBound, p ) ||
+                        return SpecificCompilerWorkarounds.isSubType( typeUtils, superBound, p ) ||
                             typeUtils.isSameType( p, superBound );
 
                     case TYPEVAR:
@@ -284,7 +284,7 @@ public class MethodMatcher {
                         // to check super type, we can simply reverse the argument, but that would initially yield
                         // a result: <type, superType] (so type not included) so we need to check sameType also.
                         TypeMirror superBoundAsDeclared = typeParameter.getBounds().get( 0 );
-                        return ( TypeUtilsJDK6Fix.isSubType( typeUtils, superBoundAsDeclared, p ) ||
+                        return ( SpecificCompilerWorkarounds.isSubType( typeUtils, superBoundAsDeclared, p ) ||
                             typeUtils.isSameType( p, superBoundAsDeclared ) );
                     default:
                         // does this situation occur?
@@ -325,7 +325,7 @@ public class MethodMatcher {
         if ( t != null && bounds != null ) {
             for ( TypeMirror bound : bounds ) {
                 if ( !( bound.getKind().equals( TypeKind.DECLARED ) &&
-                    TypeUtilsJDK6Fix.isSubType( typeUtils, t, bound ) ) ) {
+                    SpecificCompilerWorkarounds.isSubType( typeUtils, t, bound ) ) ) {
                     return false;
                 }
             }

processor/src/main/java/org/mapstruct/ap/util/SpecificCompilerWorkarounds.java

@@ -19,20 +19,25 @@
 
 package org.mapstruct.ap.util;
 
+import javax.lang.model.type.TypeKind;
 import javax.lang.model.type.TypeMirror;
 import javax.lang.model.util.Types;
 
 /**
- * Work-around for a bug related to sub-typing in the Eclipse JSR 269 implementation.
+ * Contains workarounds for various quirks in specific compilers.
+ *
  * @author Sjaak Derksen
+ * @author Andreas Gudian
  */
-public class TypeUtilsJDK6Fix {
+public class SpecificCompilerWorkarounds {
 
-    private TypeUtilsJDK6Fix() { }
+    private SpecificCompilerWorkarounds() { }
 
     /**
      * Tests whether one type is a subtype of another. Any type is considered to be a subtype of itself. Also see <a
      * href="http://docs.oracle.com/javase/specs/jls/se8/html/jls-4.html">JLS section 4.10, Subtyping</a>.
+     * <p />
+     * Work-around for a bug related to sub-typing in the Eclipse JSR 269 implementation.
      *
      * @param types the type utils
      * @param t1 the first type
@@ -41,6 +46,31 @@ public class TypeUtilsJDK6Fix {
      * @throws IllegalArgumentException if given an executable or package type
      */
     public static boolean isSubType(Types types, TypeMirror t1, TypeMirror t2) {
-        return types.isSubtype( types.erasure( t1 ), types.erasure( t2 ) );
+        if ( t1.getKind() == TypeKind.VOID ) {
+            return false;
+        }
+
+        return types.isSubtype( erasure( types, t1 ), erasure( types, t2 ) );
+    }
+
+    /**
+     * Returns the erasure of a type.
+     * <p/>
+     * Performs an additional test on the given type to check if it is not void. Calling
+     * {@link Types#erasure(TypeMirror)} with a void kind type will create a ClassCastException in Eclipse JDT.
+     *
+     * @param types the type utils
+     * @param t the type to be erased
+     * @return the erasure of the given type
+     * @throws IllegalArgumentException if given a package type
+     * @jls 4.6 Type Erasure
+     */
+    public static TypeMirror erasure(Types types, TypeMirror t) {
+        if ( t.getKind() == TypeKind.VOID ) {
+            return t;
+        }
+        else {
+            return types.erasure( t );
+        }
     }
 }