#2781 Remove unmapped source properties when source parameter is directly mapped

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

@@ -1295,8 +1295,16 @@ public class BeanMappingMethod extends NormalTypeMappingMethod {
                             .options( mapping )
                             .build();
                         handledTargets.add( targetPropertyName );
-                        unprocessedSourceParameters.remove( sourceRef.getParameter() );
+                        Parameter sourceParameter = sourceRef.getParameter();
-                        unprocessedSourceProperties.remove( sourceRef.getShallowestPropertyName() );
+                        unprocessedSourceParameters.remove( sourceParameter );
+                        // If the source parameter was directly mapped
+                        if ( sourceRef.getPropertyEntries().isEmpty() ) {
+                            // Ignore all of its source properties completely
+                            ignoreSourceProperties( sourceParameter );
+                        }
+                        else {
+                            unprocessedSourceProperties.remove( sourceRef.getShallowestPropertyName() );
+                        }
                     }
                     else {
                         errorOccured = true;
@@ -1471,23 +1479,25 @@ public class BeanMappingMethod extends NormalTypeMappingMethod {
                         sourceParameters.remove();
                         unprocessedDefinedTargets.remove( targetProperty.getKey() );
                         unprocessedSourceProperties.remove( targetProperty.getKey() );
-
-                        // The source parameter was directly mapped so ignore all of its source properties completely
-                        if ( !sourceParameter.getType().isPrimitive() && !sourceParameter.getType().isArrayType() ) {
-                            // We explicitly ignore source properties from primitives or array types
-                            Map<String, ReadAccessor> readAccessors = sourceParameter.getType()
-                                .getPropertyReadAccessors();
-                            for ( String sourceProperty : readAccessors.keySet() ) {
-                                unprocessedSourceProperties.remove( sourceProperty );
-                            }
-                        }
-
                         unprocessedConstructorProperties.remove( targetProperty.getKey() );
+                        ignoreSourceProperties( sourceParameter );
                     }
                 }
             }
         }
 
+        private void ignoreSourceProperties(Parameter sourceParameter) {
+            // The source parameter was directly mapped so ignore all of its source properties completely
+            if ( !sourceParameter.getType().isPrimitive() && !sourceParameter.getType().isArrayType() ) {
+                // We explicitly ignore source properties from primitives or array types
+                Map<String, ReadAccessor> readAccessors = sourceParameter.getType()
+                    .getPropertyReadAccessors();
+                for ( String sourceProperty : readAccessors.keySet() ) {
+                    unprocessedSourceProperties.remove( sourceProperty );
+                }
+            }
+        }
+
         private SourceReference getSourceRefByTargetName(Parameter sourceParameter, String targetPropertyName) {
 
             SourceReference sourceRef = null;

processor/src/test/java/org/mapstruct/ap/test/bugs/_2781/Issue2781Mapper.java

@@ -0,0 +1,53 @@
+/*
+ * 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._2781;
+
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+import org.mapstruct.ReportingPolicy;
+import org.mapstruct.factory.Mappers;
+
+/**
+ * @author Mengxing Yuan
+ */
+@Mapper(unmappedSourcePolicy = ReportingPolicy.ERROR)
+public interface Issue2781Mapper {
+
+    Issue2781Mapper INSTANCE = Mappers.getMapper( Issue2781Mapper.class );
+
+    @Mapping(target = "nested", source = "source")
+    Target map(Source source);
+
+    class Target {
+        private Source nested;
+
+        public Source getNested() {
+            return nested;
+        }
+
+        public void setNested(Source nested) {
+            this.nested = nested;
+        }
+    }
+
+    class Source {
+        private String field1;
+        private String field2;
+
+        public Source(String field1, String field2) {
+            this.field1 = field1;
+            this.field2 = field2;
+        }
+
+        public String getField1() {
+            return field1;
+        }
+
+        public String getField2() {
+            return field2;
+        }
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/bugs/_2781/Issue2781Test.java

@@ -0,0 +1,24 @@
+/*
+ * 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._2781;
+
+import org.mapstruct.ap.testutil.IssueKey;
+import org.mapstruct.ap.testutil.ProcessorTest;
+import org.mapstruct.ap.testutil.WithClasses;
+
+/**
+ * @author Mengxing Yuan
+ */
+@IssueKey("2781")
+@WithClasses({
+    Issue2781Mapper.class
+})
+class Issue2781Test {
+
+    @ProcessorTest
+    void shouldCompileWithoutErrors() {
+    }
+}