#1401 improvements by direct assigning constants

2025-07-12 00:00:08 +08:00 · 2018-04-01 15:15:42 +02:00 · 2018-04-01 15:15:42 +02:00 · 35f5400e00
commit 35f5400e00
parent 2fe7f6be2b
17 changed files with 850 additions and 17 deletions
--- a/documentation/src/main/asciidoc/mapstruct-reference-guide.asciidoc
+++ b/documentation/src/main/asciidoc/mapstruct-reference-guide.asciidoc
@ -1918,7 +1918,8 @@ This chapter describes several advanced options which allow to fine-tune the beh
 [[default-values-and-constants]]
 === Default values and constants

-Default values can be specified to set a predefined value to a target property if the corresponding source property is `null`. Constants can be specified to set such a predefined value in any case. Default values and constants are specified as String values and are subject to type conversion either via built-in conversions or the invocation of other mapping methods in order to match the type required by the target property.
+Default values can be specified to set a predefined value to a target property if the corresponding source property is `null`. Constants can be specified to set such a predefined value in any case. Default values and constants are specified as String values. When the target type is a primitive or a boxed type, the String value is taken literal. Bit / octal / decimal / hex patterns are allowed in such case as long as they are a valid literal.
+In all other cases, constant or default values are subject to type conversion either via built-in conversions or the invocation of other mapping methods in order to match the type required by the target property.

 A mapping with a constant must not include a reference to a source property. The following example shows some mappings using default values and constants:

--- a/processor/src/main/java/org/mapstruct/ap/internal/model/BeanMappingMethod.java
+++ b/processor/src/main/java/org/mapstruct/ap/internal/model/BeanMappingMethod.java
@ -496,13 +496,14 @@ public class BeanMappingMethod extends NormalTypeMappingMethod {
                propertyMapping = new ConstantMappingBuilder()
                    .mappingContext( ctx )
                    .sourceMethod( method )
-                    .constantExpression( "\"" + mapping.getConstant() + "\"" )
+                    .constantExpression( mapping.getConstant() )
                    .targetProperty( targetProperty )
                    .targetPropertyName( mapping.getTargetName() )
                    .formattingParameters( mapping.getFormattingParameters() )
                    .selectionParameters( mapping.getSelectionParameters() )
                    .existingVariableNames( existingVariableNames )
                    .dependsOn( mapping.getDependsOn() )
+                    .mirror( mapping.getMirror() )
                    .build();
                handledTargets.add( mapping.getTargetName() );
            }
--- a/processor/src/main/java/org/mapstruct/ap/internal/model/PropertyMapping.java
+++ b/processor/src/main/java/org/mapstruct/ap/internal/model/PropertyMapping.java
@ -23,6 +23,7 @@ import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 import java.util.Set;
+import javax.lang.model.element.AnnotationMirror;

 import javax.lang.model.element.ExecutableElement;
 import javax.lang.model.type.DeclaredType;
@ -116,6 +117,7 @@ public class PropertyMapping extends ModelElement {

        protected List<String> dependsOn;
        protected Set<String> existingVariableNames;
+        protected AnnotationMirror mirror;

        MappingBuilderBase(Class<T> selfType) {
            super( selfType );
@ -146,6 +148,11 @@ public class PropertyMapping extends ModelElement {
            return (T) this;
        }

+        T mirror(AnnotationMirror mirror) {
+            this.mirror = mirror;
+            return (T) this;
+        }
+
        private Type determineTargetType() {
            // This is a bean mapping method, so we know the result is a declared type
            DeclaredType resultType = (DeclaredType) method.getResultType().getEffectiveType().getTypeMirror();
@ -359,7 +366,7 @@ public class PropertyMapping extends ModelElement {
                &&  ( !rhs.getSourceType().isPrimitive() || rhs.getSourcePresenceCheckerReference() != null) ) {
                // cannot check on null source if source is primitive unless it has a presence checker
                PropertyMapping build = new ConstantMappingBuilder()
-                    .constantExpression( '"' + defaultValue + '"' )
+                    .constantExpression( defaultValue )
                    .formattingParameters( formattingParameters )
                    .selectionParameters( selectionParameters )
                    .dependsOn( dependsOn )
@ -749,7 +756,12 @@ public class PropertyMapping extends ModelElement {
        public PropertyMapping build() {
            // source
            String sourceErrorMessagePart = "constant '" + constantExpression + "'";
-            Type sourceType = ctx.getTypeFactory().getType( String.class );
+
+            Type sourceType = ctx.getTypeFactory().getTypeForConstant( targetType, constantExpression );
+            if ( String.class.getCanonicalName().equals( sourceType.getFullyQualifiedName() ) ) {
+                // convert to string
+                constantExpression = "\"" + constantExpression + "\"";
+            }

            Assignment assignment = null;
            if ( !targetType.isEnumType() ) {
@ -808,6 +820,7 @@ public class PropertyMapping extends ModelElement {
            else {
                ctx.getMessager().printMessage(
                    method.getExecutable(),
+                    mirror,
                    Message.CONSTANTMAPPING_MAPPING_NOT_FOUND,
                    sourceType,
                    constantExpression,
--- a/processor/src/main/java/org/mapstruct/ap/internal/model/common/Type.java
+++ b/processor/src/main/java/org/mapstruct/ap/internal/model/common/Type.java
@ -89,6 +89,8 @@ public class Type extends ModelElement implements Comparable<Type> {
    private final boolean isImported;
    private final boolean isVoid;
    private final boolean isStream;
+    private final boolean isBoxed;
+    private final boolean isOriginatedFromConstant;

    private final List<String> enumConstants;

@ -111,7 +113,8 @@ public class Type extends ModelElement implements Comparable<Type> {
                BuilderInfo builderInfo,
                String packageName, String name, String qualifiedName,
                boolean isInterface, boolean isEnumType, boolean isIterableType,
-                boolean isCollectionType, boolean isMapType, boolean isStreamType, boolean isImported) {
+                boolean isCollectionType, boolean isMapType, boolean isStreamType, boolean isImported,
+                boolean isBoxed, boolean isOriginatedFromConstant ) {

        this.typeUtils = typeUtils;
        this.elementUtils = elementUtils;
@ -135,6 +138,8 @@ public class Type extends ModelElement implements Comparable<Type> {
        this.isStream = isStreamType;
        this.isImported = isImported;
        this.isVoid = typeMirror.getKind() == TypeKind.VOID;
+        this.isBoxed = isBoxed;
+        this.isOriginatedFromConstant = isOriginatedFromConstant;

        if ( isEnumType ) {
            enumConstants = new ArrayList<String>();
@ -384,7 +389,9 @@ public class Type extends ModelElement implements Comparable<Type> {
            isCollectionType,
            isMapType,
            isStream,
-            isImported
+            isImported,
+            isBoxed,
+            isOriginatedFromConstant
        );
    }

@ -913,4 +920,13 @@ public class Type extends ModelElement implements Comparable<Type> {

        return null;
    }
+
+    public boolean isBoxed() {
+        return isBoxed;
+    }
+
+    public boolean hasOriginatedFromConstant() {
+        return isOriginatedFromConstant;
+    }
+
 }
--- a/processor/src/main/java/org/mapstruct/ap/internal/model/common/TypeFactory.java
+++ b/processor/src/main/java/org/mapstruct/ap/internal/model/common/TypeFactory.java
@ -64,6 +64,7 @@ import org.mapstruct.ap.spi.BuilderInfo;
 import org.mapstruct.ap.spi.BuilderProvider;
 import org.mapstruct.ap.spi.DefaultBuilderProvider;
 import org.mapstruct.ap.spi.TypeHierarchyErroneousException;
+import org.mapstruct.ap.internal.util.NativeTypes;

 import static org.mapstruct.ap.internal.model.common.ImplementationType.withDefaultConstructor;
 import static org.mapstruct.ap.internal.model.common.ImplementationType.withInitialCapacity;
@ -131,6 +132,10 @@ public class TypeFactory {
    }

    public Type getType(String canonicalName) {
+        return getType( canonicalName, false );
+    }
+
+    private Type getType(String canonicalName, boolean isOriginatedFromConstant) {
        TypeElement typeElement = elementUtils.getTypeElement( canonicalName );

        if ( typeElement == null ) {
@ -139,7 +144,31 @@ public class TypeFactory {
            );
        }

-        return getType( typeElement );
+        return getType( typeElement, isOriginatedFromConstant );
+    }
+
+    public Type getTypeForConstant(Type targetType, String literal) {
+        Type result = null;
+        if ( targetType.isPrimitive() ) {
+            TypeKind kind = targetType.getTypeMirror().getKind();
+            boolean assignable = NativeTypes.isStringAssignable( kind, true, literal );
+            if ( assignable ) {
+                result = getType( targetType.getTypeMirror(), true );
+            }
+        }
+        else {
+            TypeKind boxedTypeKind = NativeTypes.getWrapperKind( targetType.getFullyQualifiedName() );
+            if ( boxedTypeKind != null ) {
+                boolean assignable = NativeTypes.isStringAssignable( boxedTypeKind, false, literal );
+                if ( assignable ) {
+                    result = getType( targetType.getTypeMirror(), true );
+                }
+            }
+        }
+        if ( result == null ) {
+            result = getType( String.class.getCanonicalName(), true );
+        }
+        return result;
    }

    /**
@ -165,7 +194,15 @@ public class TypeFactory {
        return getType( typeElement.asType() );
    }

+    private Type getType(TypeElement typeElement, boolean originatedFromConstant) {
+        return getType( typeElement.asType(), originatedFromConstant );
+    }
+
    public Type getType(TypeMirror mirror) {
+        return getType( mirror, false );
+    }
+
+    private Type getType(TypeMirror mirror, boolean originatedFromConstant) {
        if ( !canBeProcessed( mirror ) ) {
            throw new TypeHierarchyErroneousException( mirror );
        }
@ -186,6 +223,7 @@ public class TypeFactory {
        TypeElement typeElement;
        Type componentType;
        boolean isImported;
+        boolean isBoxed = false;

        if ( mirror.getKind() == TypeKind.DECLARED ) {
            DeclaredType declaredType = (DeclaredType) mirror;
@ -207,6 +245,7 @@ public class TypeFactory {

            componentType = null;
            isImported = isImported( name, qualifiedName );
+            isBoxed = NativeTypes.isWrapped( qualifiedName );
        }
        else if ( mirror.getKind() == TypeKind.ARRAY ) {
            TypeMirror componentTypeMirror = getComponentType( mirror );
@ -267,7 +306,9 @@ public class TypeFactory {
            isCollectionType,
            isMapType,
            isStreamType,
-            isImported
+            isImported,
+            isBoxed,
+            originatedFromConstant
        );
    }

@ -315,8 +356,8 @@ public class TypeFactory {
    }

    /**
-     * Get the Type for given method as part of usedMapper. Possibly parameterized types in method declaration
-     * will be evaluated to concrete types then.
+     * Get the Type for given method as part of usedMapper. Possibly parameterized types in method declaration will be
+     * evaluated to concrete types then.
     *
     * @param includingType the type on which's scope the method type shall be evaluated
     * @param method the method
@ -479,7 +520,9 @@ public class TypeFactory {
                implementationType.isCollectionType(),
                implementationType.isMapType(),
                implementationType.isStreamType(),
-                isImported( implementationType.getName(), implementationType.getFullyQualifiedName() )
+                isImported( implementationType.getName(), implementationType.getFullyQualifiedName() ),
+                implementationType.isBoxed(),
+                implementationType.hasOriginatedFromConstant()
            );
            return implementation.createNew( replacement );
        }
--- a/processor/src/main/java/org/mapstruct/ap/internal/processor/creation/MappingResolverImpl.java
+++ b/processor/src/main/java/org/mapstruct/ap/internal/processor/creation/MappingResolverImpl.java
@ -253,6 +253,18 @@ public class MappingResolverImpl implements MappingResolver {
                return simpleAssignment;
            }

+            // At this point the SourceType will either
+            // 1. be a String
+            // 2. or when its a primitive / wrapped type and analysis successful equal to its TargetType. But in that
+            //    case it should have been direct assignable.
+            // In case of 1. and the target type is still a wrapped or primitive type we must assume that the check
+            // in NativeType is not successful. We don't want to go through type conversion, double mappings etc.
+            // with something that we already know to be wrong.
+            if ( sourceType.hasOriginatedFromConstant() && ( targetType.isPrimitive() || targetType.isBoxed() ) ) {
+                // TODO: convey some error message
+                return null;
+            }
+
            // then type conversion
            Assignment conversion = resolveViaConversion( sourceType, targetType );
            if ( conversion != null ) {
--- a/processor/src/main/java/org/mapstruct/ap/internal/util/NativeTypes.java
+++ b/processor/src/main/java/org/mapstruct/ap/internal/util/NativeTypes.java
@ -25,6 +25,8 @@ import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
+import java.util.regex.Pattern;
+import javax.lang.model.type.TypeKind;

 /**
 * Provides functionality around the Java primitive data types and their wrapper
@ -37,6 +39,195 @@ public class NativeTypes {
    private static final Map<Class<?>, Class<?>> WRAPPER_TO_PRIMITIVE_TYPES;
    private static final Map<Class<?>, Class<?>> PRIMITIVE_TO_WRAPPER_TYPES;
    private static final Set<Class<?>> NUMBER_TYPES = new HashSet<Class<?>>();
+    private static final Map<String, TypeKind> WRAPPER_NAME_TO_PRIMITIVE_TYPES;
+
+    private static final Pattern PTRN_HEX = Pattern.compile( "^0[x|X].*" );
+    private static final Pattern PTRN_OCT = Pattern.compile( "^0_*[0-7].*" );
+    private static final Pattern PTRN_BIN = Pattern.compile( "^0[b|B].*" );
+    private static final Pattern PTRN_FLOAT_DEC_ZERO = Pattern.compile( "^[^eE]*[1-9].*[eE]?.*" );
+    private static final Pattern PTRN_FLOAT_HEX_ZERO = Pattern.compile( "^[^pP]*[1-9a-fA-F].*[pP]?.*" );
+
+    private static final Pattern PTRN_SIGN = Pattern.compile( "^[\\+|-]" );
+
+    private static final Pattern PTRN_LONG = Pattern.compile( "[l|L]$" );
+    private static final Pattern PTRN_FLOAT = Pattern.compile( "[f|F]$" );
+    private static final Pattern PTRN_DOUBLE = Pattern.compile( "[d|D]$" );
+
+    private static final Pattern PTRN_FAULTY_UNDERSCORE_INT = Pattern.compile( "^_|_$|-_|_-|\\+_|_\\+" );
+    private static final Pattern PTRN_FAULTY_UNDERSCORE_FLOAT = Pattern.compile( "^_|_$|-_|_-|\\+_|_\\+|\\._|_\\." );
+    private static final Pattern PTRN_FAULTY_DEC_UNDERSCORE_FLOAT = Pattern.compile( "_e|_E|e_|E_" );
+    private static final Pattern PTRN_FAULTY_HEX_UNDERSCORE_FLOAT = Pattern.compile( "_p|_P|p_|P_" );
+
+    private static final Map<TypeKind, NumberFormatValidator> VALIDATORS = initValidators();
+
+    private interface NumberFormatValidator {
+
+        boolean validate(boolean isPrimitive, String s);
+    }
+
+    private abstract static class NumberRepresentation {
+
+        int radix;
+        String val;
+        boolean isIntegralType;
+        boolean isLong;
+        boolean isFloat;
+        boolean isPrimitive;
+
+        NumberRepresentation(String in, boolean isIntegralType, boolean isLong, boolean isFloat, boolean isPrimitive) {
+            this.isLong = isLong;
+            this.isFloat = isFloat;
+            this.isIntegralType = isIntegralType;
+            this.isPrimitive = isPrimitive;
+
+            String valWithoutSign;
+            boolean isNegative = in.startsWith( "-" );
+            boolean hasSign = PTRN_SIGN.matcher( in ).find();
+            if ( hasSign ) {
+                valWithoutSign = in.substring( 1 );
+            }
+            else {
+                valWithoutSign = in;
+            }
+            if ( PTRN_HEX.matcher( valWithoutSign ).matches() ) {
+                // hex
+                radix = 16;
+                val = (isNegative ? "-" : "") + valWithoutSign.substring( 2 );
+            }
+            else if ( PTRN_BIN.matcher( valWithoutSign ).matches() ) {
+                // binary
+                radix = 2;
+                val = (isNegative ? "-" : "") + valWithoutSign.substring( 2 );
+            }
+            else if ( PTRN_OCT.matcher( valWithoutSign ).matches() ) {
+                // octal
+                radix = 8;
+                val = (isNegative ? "-" : "") + valWithoutSign.substring( 1 );
+            }
+            else {
+                // decimal
+                radix = 10;
+                val = (isNegative ? "-" : "") + valWithoutSign;
+            }
+        }
+
+        abstract boolean parse(String val, int radix);
+
+        boolean validate() {
+            try {
+                strip();
+                return parse( val, radix );
+            }
+            catch ( NumberFormatException ex ) {
+                return false;
+            }
+        }
+
+        void strip() {
+            if ( isIntegralType ) {
+                removeAndValidateIntegerLiteralSuffix();
+                removeAndValidateIntegerLiteralUnderscore();
+            }
+            else {
+                removeAndValidateFloatingPointLiteralSuffix();
+                removeAndValidateFloatingPointLiteralUnderscore();
+            }
+        }
+
+        /**
+         * remove java7+ underscores from the input
+         */
+        void removeAndValidateIntegerLiteralUnderscore() {
+            if ( PTRN_FAULTY_UNDERSCORE_INT.matcher( val ).find() ) {
+                throw new NumberFormatException("Improperly placed underscores");
+            }
+            else {
+                val = val.replace( "_", "" );
+            }
+        }
+
+        /**
+         * remove java7+ underscores from the input
+         */
+        void removeAndValidateFloatingPointLiteralUnderscore() {
+            boolean isHex = radix == 16;
+            if ( PTRN_FAULTY_UNDERSCORE_FLOAT.matcher( val ).find()
+                || !isHex && PTRN_FAULTY_DEC_UNDERSCORE_FLOAT.matcher( val ).find()
+                || isHex && PTRN_FAULTY_HEX_UNDERSCORE_FLOAT.matcher( val ).find() ) {
+                throw new NumberFormatException("Improperly placed underscores");
+            }
+            else {
+                val = val.replace( "_", "" );
+            }
+        }
+
+        /**
+         *
+         */
+        void removeAndValidateIntegerLiteralSuffix() {
+            boolean endsWithLSuffix = PTRN_LONG.matcher( val ).find();
+            // error handling
+            if (endsWithLSuffix && !isLong) {
+                throw new NumberFormatException("L/l not allowed for non-long types");
+            }
+            if (!isPrimitive && !endsWithLSuffix && isLong)  {
+                throw new NumberFormatException("L/l mandatory for boxed long");
+            }
+            // remove suffix
+            if ( endsWithLSuffix ) {
+                val = val.substring( 0, val.length() - 1 );
+            }
+
+        }
+
+        /**
+         * Double suffix forbidden for float.
+         *
+         * @param isFloat
+         */
+        void removeAndValidateFloatingPointLiteralSuffix() {
+            boolean endsWithLSuffix = PTRN_LONG.matcher( val ).find();
+            boolean endsWithFSuffix = PTRN_FLOAT.matcher( val ).find();
+            boolean endsWithDSuffix = PTRN_DOUBLE.matcher( val ).find();
+            // error handling
+            if ( isFloat && endsWithDSuffix ) {
+                throw new NumberFormatException("Assiging double to a float");
+            }
+            // remove suffix
+            if ( endsWithLSuffix || endsWithFSuffix || endsWithDSuffix ) {
+                val = val.substring( 0, val.length() - 1 );
+            }
+        }
+
+        boolean floatHasBecomeZero(float parsed) {
+            if ( parsed == 0f ) {
+                return floatHasBecomeZero();
+            }
+            else {
+                return false;
+            }
+        }
+
+        boolean doubleHasBecomeZero(double parsed) {
+            if ( parsed == 0d ) {
+                return floatHasBecomeZero();
+            }
+            else {
+                return false;
+            }
+        }
+
+        private boolean floatHasBecomeZero() {
+            if ( radix == 10 ) {
+                // decimal, should be at least some number before exponent (eE) unequal to 0.
+                return PTRN_FLOAT_DEC_ZERO.matcher( val ).matches();
+            }
+            else {
+                // hex, should be at least some number before exponent (pP) unequal to 0.
+                return PTRN_FLOAT_HEX_ZERO.matcher( val ).matches();
+            }
+        }
+    }

    private NativeTypes() {
    }
@ -80,6 +271,19 @@ public class NativeTypes {
        NUMBER_TYPES.add( Double.class );
        NUMBER_TYPES.add( BigInteger.class );
        NUMBER_TYPES.add( BigDecimal.class );
+
+        Map<String, TypeKind> tmp2 = new HashMap<String, TypeKind>();
+        tmp2.put( Boolean.class.getName(), TypeKind.BOOLEAN );
+        tmp2.put( Byte.class.getName(), TypeKind.BYTE );
+        tmp2.put( Character.class.getName(), TypeKind.CHAR );
+        tmp2.put( Double.class.getName(), TypeKind.DOUBLE );
+        tmp2.put( Float.class.getName(), TypeKind.FLOAT );
+        tmp2.put( Integer.class.getName(), TypeKind.INT );
+        tmp2.put( Long.class.getName(), TypeKind.LONG );
+        tmp2.put( Short.class.getName(), TypeKind.SHORT );
+
+        WRAPPER_NAME_TO_PRIMITIVE_TYPES = Collections.unmodifiableMap( tmp2 );
+
    }

    public static Class<?> getWrapperType(Class<?> clazz) {
@ -98,6 +302,14 @@ public class NativeTypes {
        return WRAPPER_TO_PRIMITIVE_TYPES.get( clazz );
    }

+    public static boolean isWrapped(String fullyQualifiedName) {
+        return WRAPPER_NAME_TO_PRIMITIVE_TYPES.containsKey( fullyQualifiedName );
+    }
+
+    public static TypeKind getWrapperKind(String fullyQualifiedName) {
+        return WRAPPER_NAME_TO_PRIMITIVE_TYPES.get( fullyQualifiedName );
+    }
+
    public static boolean isNumber(Class<?> clazz) {
        if ( clazz == null ) {
            return false;
@ -106,4 +318,125 @@ public class NativeTypes {
            return NUMBER_TYPES.contains( clazz );
        }
    }
+
+    public static boolean isStringAssignable(TypeKind kind, boolean isPrimitive, String in) {
+        NumberFormatValidator validator = VALIDATORS.get( kind );
+        return validator != null && validator.validate( isPrimitive, in );
+    }
+
+    private static Map<TypeKind, NumberFormatValidator> initValidators() {
+        Map<TypeKind, NumberFormatValidator> result = new HashMap<TypeKind, NumberFormatValidator>();
+        result.put( TypeKind.BOOLEAN, new NumberFormatValidator() {
+            @Override
+            public boolean validate(boolean isPrimitive, String s) {
+                return "true".equals( s ) || "false".equals( s );
+            }
+        } );
+        result.put( TypeKind.CHAR, new NumberFormatValidator() {
+            @Override
+            public boolean validate(boolean isPrimitive, String s) {
+                return s.length() == 3 && s.startsWith( "'" ) && s.endsWith( "'" );
+            }
+        } );
+        result.put( TypeKind.BYTE, new NumberFormatValidator() {
+            @Override
+            public boolean validate(boolean isPrimitive, String s) {
+                NumberRepresentation br = new NumberRepresentation( s, true, false, false, isPrimitive ) {
+
+                    @Override
+                    boolean parse(String val, int radix) {
+                        Byte.parseByte( val, radix );
+                        return true;
+                    }
+                };
+                return br.validate();
+            }
+        } );
+        result.put( TypeKind.DOUBLE, new NumberFormatValidator() {
+            @Override
+            public boolean validate(boolean isPrimitive, String s) {
+                NumberRepresentation br = new NumberRepresentation( s, false, false, false, isPrimitive ) {
+
+                    @Override
+                    boolean parse(String val, int radix) {
+                        Double d = Double.parseDouble( radix == 16 ? "0x" + val : val );
+                        return !d.isInfinite() && !doubleHasBecomeZero( d );
+                    }
+                };
+                return br.validate();
+            }
+        } );
+        result.put( TypeKind.FLOAT, new NumberFormatValidator() {
+            @Override
+            public boolean validate(boolean isPrimitive, String s) {
+
+                NumberRepresentation br = new NumberRepresentation( s, false, false, true, isPrimitive ) {
+                    @Override
+                    boolean parse(String val, int radix) {
+                        Float f = Float.parseFloat( radix == 16 ? "0x" + val : val );
+                        return !f.isInfinite() && !floatHasBecomeZero( f );
+                    }
+                };
+                return br.validate();
+            }
+        } );
+        result.put( TypeKind.INT, new NumberFormatValidator() {
+            @Override
+            public boolean validate(boolean isPrimitive, String s) {
+                NumberRepresentation br = new NumberRepresentation( s, true, false, false, isPrimitive ) {
+
+                    @Override
+                    boolean parse(String val, int radix) {
+                        if ( radix == 10 ) {
+                            // when decimal: treat like signed
+                            Integer.parseInt( val, radix );
+                            return true;
+                        }
+                        else {
+                            // when binary, octal or hex: treat like unsigned
+                            return new BigInteger( val, radix ).bitLength() <= 32;
+                        }
+                    }
+                };
+                return br.validate();
+            }
+        } );
+        result.put( TypeKind.LONG, new NumberFormatValidator() {
+            @Override
+            public boolean validate(boolean isPrimitive, String s) {
+                NumberRepresentation br = new NumberRepresentation( s, true, true, false, isPrimitive ) {
+
+                    @Override
+                    boolean parse(String val, int radix) {
+                        if ( radix == 10 ) {
+                            // when decimal: treat like signed
+                            Long.parseLong( val, radix );
+                            return true;
+                        }
+                        else {
+                            // when binary, octal or hex: treat like unsigned
+                            return new BigInteger( val, radix ).bitLength() <= 64;
+                        }
+                    }
+                };
+                return br.validate();
+            }
+        } );
+        result.put( TypeKind.SHORT, new NumberFormatValidator() {
+            @Override
+            public boolean validate(boolean isPrimitive, String s) {
+                NumberRepresentation br = new NumberRepresentation( s, true, false, false, isPrimitive ) {
+
+                    @Override
+                    boolean parse(String val, int radix) {
+                        Short.parseShort( val, radix );
+                        return true;
+                    }
+                };
+                return br.validate();
+            }
+        } );
+        return result;
+    }
+
 }
--- a/processor/src/test/java/org/mapstruct/ap/internal/model/common/DateFormatValidatorFactoryTest.java
+++ b/processor/src/test/java/org/mapstruct/ap/internal/model/common/DateFormatValidatorFactoryTest.java
@ -183,6 +183,8 @@ public class DateFormatValidatorFactoryTest {
                        false,
                        false,
                        false,
+                        false,
+                        false,
                        false );
    }

--- a/processor/src/test/java/org/mapstruct/ap/internal/model/common/DefaultConversionContextTest.java
+++ b/processor/src/test/java/org/mapstruct/ap/internal/model/common/DefaultConversionContextTest.java
@ -134,6 +134,8 @@ public class DefaultConversionContextTest {
                        false,
                        false,
                        false,
+                        false,
+                        false,
                        false );
    }

--- a/processor/src/test/java/org/mapstruct/ap/test/source/constants/ConstantOptimizingTest.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/source/constants/ConstantOptimizingTest.java
@ -0,0 +1,342 @@
+/**
+ *  Copyright 2012-2017 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.source.constants;
+
+import javax.lang.model.type.TypeKind;
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mapstruct.ap.internal.util.NativeTypes.isStringAssignable;
+
+/**
+ *
+ * @author Sjaak Derksen
+ */
+public class ConstantOptimizingTest {
+
+    /**
+     * checkout https://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html
+     *
+     * The following example shows other ways you can use the underscore in numeric literals:
+     */
+    @Test
+    public void testUnderscorePlacement1() {
+        assertThat( isStringAssignable( TypeKind.LONG, true, "1234_5678_9012_3456L" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.LONG, true, "999_99_9999L" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.FLOAT, true, "3.14_15F" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.LONG, true, "0xFF_EC_DE_5EL" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.LONG, true, "0xCAFE_BABEL" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.LONG, true, "0x7fff_ffff_ffff_ffffL" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.BYTE, true, "0b0010_0101" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.LONG, true, "0b11010010_01101001_10010100_10010010L" ) ).isTrue();
+    }
+
+    /**
+     * checkout https://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html
+     *
+     * You can place underscores only between digits; you cannot place underscores in the following places:
+     * <ol>
+     * <li>At the beginning or end of a number</li>
+     * <li>Adjacent to a decimal point in a floating point literal</li>
+     * <li>Prior to an F or L suffix</li>
+     * <li>In positions where a string of digits is expected</li>
+     * </ol>
+     * The following examples demonstrate valid and invalid underscore placements (which are highlighted) in numeric
+     * literals:
+     */
+    @Test
+    public void testUnderscorePlacement2() {
+
+        // Invalid: cannot put underscores
+        // adjacent to a decimal point
+        assertThat( isStringAssignable( TypeKind.FLOAT, true, "3_.1415F" ) ).isFalse();
+
+        // Invalid: cannot put underscores
+        // adjacent to a decimal point
+        assertThat( isStringAssignable( TypeKind.FLOAT, true, "3._1415F" ) ).isFalse();
+
+        // Invalid: cannot put underscores
+        // prior to an L suffix
+        assertThat( isStringAssignable( TypeKind.LONG, true, "999_99_9999_L" ) ).isFalse();
+
+        // OK (decimal literal)
+        assertThat( isStringAssignable( TypeKind.INT, true, "5_2" ) ).isTrue();
+
+        // Invalid: cannot put underscores
+        // At the end of a literal
+        assertThat( isStringAssignable( TypeKind.INT, true, "52_" ) ).isFalse();
+
+        // OK (decimal literal)
+        assertThat( isStringAssignable( TypeKind.INT, true, "5_______2" ) ).isTrue();
+
+        // Invalid: cannot put underscores
+        // in the 0x radix prefix
+        assertThat( isStringAssignable( TypeKind.INT, true, "0_x52" ) ).isFalse();
+
+        // Invalid: cannot put underscores
+        // at the beginning of a number
+        assertThat( isStringAssignable( TypeKind.INT, true, "0x_52" ) ).isFalse();
+
+        // OK (hexadecimal literal)
+        assertThat( isStringAssignable( TypeKind.INT, true, "0x5_2" ) ).isTrue();
+
+        // Invalid: cannot put underscores
+        // at the end of a number
+        assertThat( isStringAssignable( TypeKind.INT, true, "0x52_" ) ).isFalse();
+    }
+
+    /**
+     * checkout https://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html
+     *
+     * The following example shows other ways you can use the underscore in numeric literals:
+     */
+    @Test
+    public void testIntegerLiteralFromJLS() {
+
+        // largest positive int: dec / octal / int / binary
+        assertThat( isStringAssignable( TypeKind.INT, true, "2147483647" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.INT, true, "0x7fff_ffff" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.INT, true, "0177_7777_7777" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.INT, true, "0b0111_1111_1111_1111_1111_1111_1111_1111" ) ).isTrue();
+
+        // most negative int: dec / octal / int / binary
+        // NOTE parseInt should be changed to parseUnsignedInt in Java, than the - sign can disssapear (java8)
+        // and the function will be true to what the compiler shows.
+        assertThat( isStringAssignable( TypeKind.INT, true, "-2147483648" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.INT, true, "0x8000_0000" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.INT, true, "0200_0000_0000" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.INT, true, "0b1000_0000_0000_0000_0000_0000_0000_0000" ) ).isTrue();
+
+        // -1 representation int: dec / octal / int / binary
+        assertThat( isStringAssignable( TypeKind.INT, true, "-1" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.INT, true, "0xffff_ffff" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.INT, true, "0377_7777_7777" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.INT, true, "0b1111_1111_1111_1111_1111_1111_1111_1111" ) ).isTrue();
+
+        // largest positive long: dec / octal / int / binary
+        assertThat( isStringAssignable( TypeKind.LONG, true, "9223372036854775807L" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.LONG, true, "0x7fff_ffff_ffff_ffffL" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.LONG, true, "07_7777_7777_7777_7777_7777L" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.LONG, true, "0b0111_1111_1111_1111_1111_1111_1111_1111_1111_1111_"
+            + "1111_1111_1111_1111_1111_1111L" ) ).isTrue();
+        // most negative long: dec / octal / int / binary
+        assertThat( isStringAssignable( TypeKind.LONG, true, "-9223372036854775808L" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.LONG, true, "0x8000_0000_0000_0000L" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.LONG, true, "010_0000_0000_0000_0000_0000L" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.LONG, true, "0b1000_0000_0000_0000_0000_0000_0000_0000_0000_0000_0000_"
+            + "0000_0000_0000_0000_0000L" ) ).isTrue();
+        // -1 representation long: dec / octal / int / binary
+        assertThat( isStringAssignable( TypeKind.LONG, true, "-1L" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.LONG, true, "0xffff_ffff_ffff_ffffL" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.LONG, true, "017_7777_7777_7777_7777_7777L" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.LONG, true, "0b1111_1111_1111_1111_1111_1111_1111_1111_1111_1111_1111_"
+            + "1111_1111_1111_1111_1111L" ) ).isTrue();
+
+        // some examples of ints
+        assertThat( isStringAssignable( TypeKind.INT, true, "0" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.INT, true, "2" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.INT, true, "0372" ) ).isTrue();
+        //assertThat( isStringAssignable( TypeKind.INT, true, "0xDada_Cafe" ) ).isTrue(); java8
+        assertThat( isStringAssignable( TypeKind.INT, true, "1996" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.INT, true, "0x00_FF__00_FF" ) ).isTrue();
+
+        // some examples of longs
+        assertThat( isStringAssignable( TypeKind.LONG, true, "0777l" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.LONG, true, "0x100000000L" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.LONG, true, "2_147_483_648L" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.LONG, true, "0xC0B0L" ) ).isTrue();
+    }
+
+    /**
+     * checkout https://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html
+     *
+     * The following example shows other ways you can use the underscore in numeric literals:
+     */
+    @Test
+    public void testFloatingPoingLiteralFromJLS() {
+
+        // The largest positive finite literal of type float is 3.4028235e38f.
+        assertThat( isStringAssignable( TypeKind.FLOAT, true, "3.4028235e38f" ) ).isTrue();
+        // The smallest positive finite non-zero literal of type float is 1.40e-45f.
+        assertThat( isStringAssignable( TypeKind.FLOAT, true, "1.40e-45f" ) ).isTrue();
+        // The largest positive finite literal of type double is 1.7976931348623157e308.
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "1.7976931348623157e308" ) ).isTrue();
+        // The smallest positive finite non-zero literal of type double is 4.9e-324
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "4.9e-324" ) ).isTrue();
+
+        // some floats
+        assertThat( isStringAssignable( TypeKind.FLOAT, true, "3.1e1F" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.FLOAT, true, "2.f" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.FLOAT, true, ".3f" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.FLOAT, true, "0f" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.FLOAT, true, "3.14f" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.FLOAT, true, "6.022137e+23f" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.FLOAT, true, "-3.14f" ) ).isTrue();
+
+        // some doubles
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "1e1" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "1e+1" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "2." ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, ".3" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "0.0" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "3.14" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "-3.14" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "1e-9D" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "1e137" ) ).isTrue();
+
+        // too large (infinitve)
+        assertThat( isStringAssignable( TypeKind.FLOAT, true, "3.4028235e38f" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "1.7976931348623157e308" ) ).isTrue();
+
+        // too large (infinitve)
+        assertThat( isStringAssignable( TypeKind.FLOAT, true, "3.4028235e39f" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "1.7976931348623159e308" ) ).isFalse();
+
+        // small
+        assertThat( isStringAssignable( TypeKind.FLOAT, true, "1.40e-45f" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.FLOAT, true, "0x1.0p-149" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "4.9e-324" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "0x0.001P-1062d" ) ).isTrue();
+
+        // too small
+        assertThat( isStringAssignable( TypeKind.FLOAT, true, "1.40e-46f" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.FLOAT, true, "0x1.0p-150" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "4.9e-325" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "0x0.001p-1063d" ) ).isFalse();
+    }
+
+    /**
+     * checkout https://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html
+     *
+     * The following example shows other ways you can use the underscore in numeric literals:
+     */
+    @Test
+    public void testBooleanLiteralFromJLS() {
+        assertThat( isStringAssignable( TypeKind.BOOLEAN, true, "true" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.BOOLEAN, true, "false" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.BOOLEAN, true, "FALSE" ) ).isFalse();
+    }
+
+    /**
+     * checkout https://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html
+     *
+     * The following example shows other ways you can use the underscore in numeric literals:
+     */
+    @Test
+    public void testCharLiteralFromJLS() {
+
+        assertThat( isStringAssignable( TypeKind.CHAR, true, "'a'" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.CHAR, true, "'%'" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.CHAR, true, "'\t'" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.CHAR, true, "'\\'" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.CHAR, true, "'\''" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.CHAR, true, "'\u03a9'" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.CHAR, true, "'\uFFFF'" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.CHAR, true, "'\177'" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.CHAR, true, "'Ω'" ) ).isTrue();
+
+    }
+
+    @Test
+    public void testShortAndByte() {
+        assertThat( isStringAssignable( TypeKind.SHORT, true, "0xFE" ) ).isTrue();
+
+        // some examples of ints
+        assertThat( isStringAssignable( TypeKind.BYTE, true, "0" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.BYTE, true, "2" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.BYTE, true, "127" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.BYTE, true, "-128" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.SHORT, true, "1996" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.SHORT, true, "-1996" ) ).isTrue();
+    }
+
+    @Test
+    public void testMiscellaneousErroneousPatterns() {
+        assertThat( isStringAssignable( TypeKind.INT, true, "1F" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.FLOAT, true, "1D" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.INT, true, "_1" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.INT, true, "1_" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.INT, true, "0x_1" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.INT, true, "0_x1" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "4.9e_-3" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "4.9_e-3" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "4._9e-3" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "4_.9e-3" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "_4.9e-3" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "4.9E-3_" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "4.9E_-3" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "4.9E-_3" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "4.9E+-3" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "4.9E+_3" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "4.9_E-3" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "0x0.001_P-10d" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "0x0.001P_-10d" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "0x0.001_p-10d" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.DOUBLE, true, "0x0.001p_-10d" ) ).isFalse();
+    }
+
+    @Test
+    public void testNegatives() {
+        assertThat( isStringAssignable( TypeKind.INT, true, "-0xffaa" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.INT, true, "-0377_7777" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.INT, true, "-0b1111_1111" ) ).isTrue();
+    }
+
+    @Test
+    public void testFaultyChar() {
+        assertThat( isStringAssignable( TypeKind.CHAR, true, "''" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.CHAR, true, "'a" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.CHAR, true, "'aa" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.CHAR, true, "a'" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.CHAR, true, "aa'" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.CHAR, true, "'" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.CHAR, true, "a" ) ).isFalse();
+    }
+
+    @Test
+    public void testFloatWithLongLiteral() {
+        assertThat( isStringAssignable( TypeKind.FLOAT, true, "156L" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.FLOAT, true, "156l" ) ).isTrue();
+    }
+
+    @Test
+    public void testLongPrimitivesAndNonRequiredLongSuffix() {
+        assertThat( isStringAssignable( TypeKind.LONG, true, "156" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.LONG, true, "156l" ) ).isTrue();
+        assertThat( isStringAssignable( TypeKind.LONG, true, "156L" ) ).isTrue();
+    }
+
+    @Test
+    public void testIntPrimitiveWithLongSuffix() {
+        assertThat( isStringAssignable( TypeKind.INT, true, "156l" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.INT, true, "156L" ) ).isFalse();
+    }
+
+    @Test
+    public void testTooBigIntegersAndBigLongs() {
+        assertThat( isStringAssignable( TypeKind.INT, true, "0xFFFF_FFFF_FFFF" ) ).isFalse();
+        assertThat( isStringAssignable( TypeKind.LONG, true, "0xFFFF_FFFF_FFFF_FFFF_FFFF" ) ).isFalse();
+    }
+
+    @Test
+    public void testNonSupportedPrimitiveType() {
+        assertThat( isStringAssignable( TypeKind.VOID, true, "0xFFFF_FFFF_FFFF" ) ).isFalse();
+    }
+
+}
--- a/processor/src/test/java/org/mapstruct/ap/test/source/constants/ErroneousMapper1.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/source/constants/ErroneousMapper1.java
@ -35,7 +35,7 @@ public interface ErroneousMapper1 {
        @Mapping(target = "stringConstant", constant = "stringConstant"),
        @Mapping(target = "emptyStringConstant", constant = ""),
        @Mapping(source = "test", target = "integerConstant", constant = "14"),
-        @Mapping(target = "longWrapperConstant", constant = "3001"),
+        @Mapping(target = "longWrapperConstant", constant = "3001L"),
        @Mapping(target = "dateConstant", dateFormat = "dd-MM-yyyy", constant = "09-01-2014"),
        @Mapping(target = "nameConstants", constant = "jack-jill-tom"),
        @Mapping(target = "country", constant = "THE_NETHERLANDS")
--- a/processor/src/test/java/org/mapstruct/ap/test/source/constants/ErroneousMapper3.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/source/constants/ErroneousMapper3.java
@ -35,7 +35,7 @@ public interface ErroneousMapper3 {
        @Mapping(target = "stringConstant", constant = "stringConstant"),
        @Mapping(target = "emptyStringConstant", constant = ""),
        @Mapping(target = "integerConstant", expression = "java('test')", constant = "14"),
-        @Mapping(target = "longWrapperConstant", constant = "3001"),
+        @Mapping(target = "longWrapperConstant", constant = "3001L"),
        @Mapping(target = "dateConstant", dateFormat = "dd-MM-yyyy", constant = "09-01-2014"),
        @Mapping(target = "nameConstants", constant = "jack-jill-tom"),
        @Mapping(target = "country", constant = "THE_NETHERLANDS")
--- a/processor/src/test/java/org/mapstruct/ap/test/source/constants/ErroneousMapper4.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/source/constants/ErroneousMapper4.java
@ -35,7 +35,7 @@ public interface ErroneousMapper4 {
        @Mapping(target = "stringConstant", constant = "stringConstant"),
        @Mapping(target = "emptyStringConstant", constant = ""),
        @Mapping(source = "test", target = "integerConstant", expression = "java('test')"),
-        @Mapping(target = "longWrapperConstant", constant = "3001"),
+        @Mapping(target = "longWrapperConstant", constant = "3001L"),
        @Mapping(target = "dateConstant", dateFormat = "dd-MM-yyyy", constant = "09-01-2014"),
        @Mapping(target = "nameConstants", constant = "jack-jill-tom"),
        @Mapping(target = "country", constant = "THE_NETHERLANDS")
--- a/processor/src/test/java/org/mapstruct/ap/test/source/constants/ErroneousMapper5.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/source/constants/ErroneousMapper5.java
@ -35,7 +35,7 @@ public interface ErroneousMapper5 {
        @Mapping(target = "stringConstant", constant = "stringConstant"),
        @Mapping(target = "emptyStringConstant", constant = ""),
        @Mapping(target = "integerConstant", constant = "14"),
-        @Mapping(target = "longWrapperConstant", constant = "3001"),
+        @Mapping(target = "longWrapperConstant", constant = "3001L"),
        @Mapping(target = "dateConstant", dateFormat = "dd-MM-yyyy", constant = "09-01-2014"),
        @Mapping(target = "nameConstants", constant = "jack-jill-tom"),
        @Mapping(target = "country", constant = "DENMARK")
--- a/processor/src/test/java/org/mapstruct/ap/test/source/constants/ErroneousMapper6.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/source/constants/ErroneousMapper6.java
@ -0,0 +1,46 @@
+/**
+ *  Copyright 2012-2017 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.source.constants;
+
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+import org.mapstruct.Mappings;
+import org.mapstruct.factory.Mappers;
+
+/**
+ * @author Sjaak Derksen
+ */
+@Mapper(uses = StringListMapper.class)
+public interface ErroneousMapper6 {
+
+    ErroneousMapper6 INSTANCE = Mappers.getMapper( ErroneousMapper6.class );
+
+    @Mappings({
+        @Mapping(target = "stringConstant", constant = "stringConstant"),
+        @Mapping(target = "emptyStringConstant", constant = ""),
+        @Mapping(target = "integerConstant", constant = "14"),
+        @Mapping(target = "longWrapperConstant", constant = "3001"),
+        @Mapping(target = "dateConstant", dateFormat = "dd-MM-yyyy", constant = "09-01-2014"),
+        @Mapping(target = "nameConstants", constant = "jack-jill-tom"),
+        @Mapping(target = "country", constant = "THE_NETHERLANDS")
+    })
+    Target sourceToTarget(Source s);
+
+    Source targetToSource(Target t);
+}
--- a/processor/src/test/java/org/mapstruct/ap/test/source/constants/SourceConstantsTest.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/source/constants/SourceConstantsTest.java
@ -209,7 +209,7 @@ public class SourceConstantsTest {
                    + "constants.CountryEnum for property \"country\".$"),
            @Diagnostic(type = ErroneousMapper5.class,
                kind = Kind.ERROR,
-                line = 43,
+                line = 41,
                messageRegExp = "^Can't map \"java.lang.String \"DENMARK\"\" to \"org.mapstruct.ap.test.source."
                    + "constants.CountryEnum country\".$")
        }
@ -217,6 +217,28 @@ public class SourceConstantsTest {
    public void errorOnNonExistingEnumConstant() throws ParseException {
    }

+   @Test
+    @IssueKey("1401")
+    @WithClasses({
+        Source.class,
+        Target.class,
+        CountryEnum.class,
+        ErroneousMapper6.class,
+        StringListMapper.class
+    })
+    @ExpectedCompilationOutcome(
+        value = CompilationResult.FAILED,
+        diagnostics = {
+            @Diagnostic(type = ErroneousMapper6.class,
+                kind = Kind.ERROR,
+                line = 38,
+                messageRegExp = "^.*Can't map \"java.lang.String \"3001\"\" to \"java.lang.Long "
+                    + "longWrapperConstant\".*$")
+        }
+    )
+    public void cannotMapIntConstantToLong() throws ParseException {
+    }
+
    private Date getDate(String format, String date) throws ParseException {
        SimpleDateFormat dateFormat = new SimpleDateFormat( format );
        Date result = dateFormat.parse( date );
--- a/processor/src/test/java/org/mapstruct/ap/test/source/constants/SourceTargetMapper.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/source/constants/SourceTargetMapper.java
@ -35,7 +35,7 @@ public interface SourceTargetMapper {
        @Mapping(target = "stringConstant", constant = "stringConstant"),
        @Mapping(target = "emptyStringConstant", constant = ""),
        @Mapping(target = "integerConstant", constant = "14"),
-        @Mapping(target = "longWrapperConstant", constant = "3001"),
+        @Mapping(target = "longWrapperConstant", constant = "3001L"),
        @Mapping(target = "dateConstant", dateFormat = "dd-MM-yyyy", constant = "09-01-2014"),
        @Mapping(target = "nameConstants", constant = "jack-jill-tom"),
        @Mapping(target = "country", constant = "THE_NETHERLANDS")