#2132 Add unmappedTargetPolicy to @BeanMapping

core/src/main/java/org/mapstruct/BeanMapping.java

@@ -140,6 +140,17 @@ public @interface BeanMapping {
      */
     String[] ignoreUnmappedSourceProperties() default {};
 
+    /**
+     * How unmapped properties of the target type of a mapping should be reported.
+     * If no policy is configured, the policy given via {@link MapperConfig#unmappedTargetPolicy()} or
+     * {@link Mapper#unmappedTargetPolicy()} will be applied, using {@link ReportingPolicy#WARN} by default.
+     *
+     * @return The reporting policy for unmapped target properties.
+     *
+     * @since 1.5
+     */
+    ReportingPolicy unmappedTargetPolicy() default ReportingPolicy.WARN;
+
     /**
      * The information that should be used for the builder mappings. This can be used to define custom build methods
      * for the builder strategy that one uses.

documentation/src/main/asciidoc/chapter-2-set-up.asciidoc

@@ -245,6 +245,7 @@ Supported values are:
 * `IGNORE`: unmapped target properties are ignored
 
 If a policy is given for a specific mapper via `@Mapper#unmappedTargetPolicy()`, the value from the annotation takes precedence.
+If a policy is given for a specific bean mapping via `@BeanMapping#unmappedTargetPolicy()`, it takes precedence over both `@Mapper#unmappedTargetPolicy()` and the option.
 |`WARN`
 |===
 

processor/src/main/java/org/mapstruct/ap/internal/model/BeanMappingMethod.java

@@ -1390,6 +1390,9 @@ public class BeanMappingMethod extends NormalTypeMappingMethod {
             if ( mappingReferences.isForForgedMethods() ) {
                 return ReportingPolicyGem.IGNORE;
             }
+            if ( method.getOptions().getBeanMapping() != null ) {
+                return method.getOptions().getBeanMapping().unmappedTargetPolicy();
+            }
             return method.getOptions().getMapper().unmappedTargetPolicy();
         }
 

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

@@ -11,6 +11,8 @@ import java.util.Objects;
 import java.util.Optional;
 import javax.lang.model.element.AnnotationMirror;
 import javax.lang.model.element.ExecutableElement;
+
+import org.mapstruct.ap.internal.gem.ReportingPolicyGem;
 import org.mapstruct.ap.internal.util.ElementUtils;
 import org.mapstruct.ap.internal.util.TypeUtils;
 
@@ -88,6 +90,7 @@ public class BeanMappingOptions extends DelegatingOptions {
             && !gem.nullValueCheckStrategy().hasValue()
             && !gem.nullValuePropertyMappingStrategy().hasValue()
             && !gem.nullValueMappingStrategy().hasValue()
+            && !gem.unmappedTargetPolicy().hasValue()
             && !gem.ignoreByDefault().hasValue()
             && !gem.builder().hasValue() ) {
 
@@ -134,6 +137,15 @@ public class BeanMappingOptions extends DelegatingOptions {
             .orElse( next().getNullValueMappingStrategy() );
     }
 
+    @Override
+    public ReportingPolicyGem unmappedTargetPolicy() {
+        return Optional.ofNullable( beanMapping ).map( BeanMappingGem::unmappedTargetPolicy )
+                .filter( GemValue::hasValue )
+                .map( GemValue::getValue )
+                .map( ReportingPolicyGem::valueOf )
+                .orElse( next().unmappedTargetPolicy() );
+    }
+
     @Override
     public BuilderGem getBuilder() {
         return Optional.ofNullable( beanMapping ).map( BeanMappingGem::builder )

processor/src/test/java/org/mapstruct/ap/test/unmappedtarget/BeanMappingSourceTargetMapper.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.unmappedtarget;
+
+import org.mapstruct.BeanMapping;
+import org.mapstruct.Mapper;
+import org.mapstruct.ReportingPolicy;
+import org.mapstruct.factory.Mappers;
+
+@Mapper(unmappedTargetPolicy = ReportingPolicy.ERROR)
+public interface BeanMappingSourceTargetMapper {
+
+    BeanMappingSourceTargetMapper INSTANCE = Mappers.getMapper( BeanMappingSourceTargetMapper.class );
+
+    @BeanMapping(unmappedTargetPolicy = ReportingPolicy.WARN)
+    Target sourceToTarget(Source source);
+}

processor/src/test/java/org/mapstruct/ap/test/unmappedtarget/ErroneousBeanMappingStrictSourceTargetMapper.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.unmappedtarget;
+
+import org.mapstruct.BeanMapping;
+import org.mapstruct.Mapper;
+import org.mapstruct.ReportingPolicy;
+import org.mapstruct.factory.Mappers;
+
+@Mapper
+public interface ErroneousBeanMappingStrictSourceTargetMapper {
+
+    ErroneousBeanMappingStrictSourceTargetMapper INSTANCE =
+        Mappers.getMapper( ErroneousBeanMappingStrictSourceTargetMapper.class );
+
+    @BeanMapping(unmappedTargetPolicy = ReportingPolicy.ERROR)
+    Target sourceToTarget(Source source);
+
+    Source targetToSource(Target target);
+}

processor/src/test/java/org/mapstruct/ap/test/unmappedtarget/UnmappedProductTest.java

@@ -87,4 +87,38 @@ public class UnmappedProductTest {
     )
     public void shouldRaiseErrorDueToUnsetTargetPropertyWithPolicySetViaProcessorOption() {
     }
+
+    @ProcessorTest
+    @IssueKey("2132")
+    @WithClasses({ Source.class, Target.class, ErroneousBeanMappingStrictSourceTargetMapper.class })
+    @ExpectedCompilationOutcome(
+            value = CompilationResult.FAILED,
+            diagnostics = {
+                    @Diagnostic(type = ErroneousBeanMappingStrictSourceTargetMapper.class,
+                            kind = Kind.ERROR,
+                            line = 20,
+                            message = "Unmapped target property: \"bar\"."),
+                    @Diagnostic(type = ErroneousBeanMappingStrictSourceTargetMapper.class,
+                            kind = Kind.WARNING,
+                            line = 22,
+                            message = "Unmapped target property: \"qux\".")
+            }
+    )
+    public void shouldRaiseErrorDueToUnsetTargetPropertyWithPolicySetViaBeanMapping() {
+    }
+
+    @ProcessorTest
+    @IssueKey("2132")
+    @WithClasses({ Source.class, Target.class, BeanMappingSourceTargetMapper.class })
+    @ExpectedCompilationOutcome(
+        value = CompilationResult.SUCCEEDED,
+        diagnostics = {
+            @Diagnostic(type = BeanMappingSourceTargetMapper.class,
+                kind = Kind.WARNING,
+                line = 19,
+                message = "Unmapped target property: \"bar\".")
+        }
+    )
+    public void shouldLeaveUnmappedTargetPropertyUnsetWithWarnPolicySetViaBeanMapping() {
+    }
 }