mapstruct · zyberzebra · Apr 28, 2024 · Apr 29, 2024 · May 7, 2024 · May 25, 2024
diff --git a/processor/src/main/java/org/mapstruct/ap/internal/model/BeanMappingMethod.java b/processor/src/main/java/org/mapstruct/ap/internal/model/BeanMappingMethod.java
@@ -152,7 +152,7 @@ public Builder forgedMethod(ForgedMethod forgedMethod) {
             method( forgedMethod );
             mappingReferences = forgedMethod.getMappingReferences();
             Parameter sourceParameter = first( Parameter.getSourceParameters( forgedMethod.getParameters() ) );
-            for ( MappingReference mappingReference : mappingReferences.getMappingReferences() ) {
+            for ( MappingReference mappingReference: mappingReferences.getMappingReferences() ) {
                 SourceReference sourceReference = mappingReference.getSourceReference();
                 if ( sourceReference != null ) {
                     mappingReference.setSourceReference( new SourceReference.BuilderFromSourceReference()
@@ -2110,7 +2110,15 @@ private boolean doesNotNeedPresenceCheckForSourceParameter(PropertyMapping mappi
             return false;
         }
 
-        return mapping.getAssignment().isSourceReferenceParameter();
+        return mapping.getAssignment().isSourceReferenceParameter()
+            || isCheckedByGuardClause( mapping );
+    }
+
+    private boolean isCheckedByGuardClause(PropertyMapping mapping) {
+        boolean isUpdateMethod = getReturnTypeToConstruct() == null && isMapNullToDefault();
+        return !isUpdateMethod
+            && presenceChecksByParameter.size() == 1
+            && presenceChecksByParameter.containsKey( mapping.getSourceBeanName() );
     }
 
     @Override

diff --git a/processor/src/test/java/org/mapstruct/ap/test/nullcheck/redundant/FooMapper.java b/processor/src/test/java/org/mapstruct/ap/test/nullcheck/redundant/FooMapper.java
@@ -0,0 +1,26 @@
+/*
+ * 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.nullcheck.redundant;
+
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+import org.mapstruct.MappingTarget;
+import org.mapstruct.factory.Mappers;
+
+@Mapper
+public interface FooMapper {
+
+    FooMapper INSTANCE = Mappers.getMapper( FooMapper.class );
+
+    void updateFoo(FooSource input, @MappingTarget FooTarget toUpdate, boolean baz);
+
+    void updateFoo(FooSource input, @MappingTarget FooTarget toUpdate, boolean baz, int bay);
+
+    FooTarget getUpdatedFooTarget(FooSource input, @MappingTarget FooTarget toUpdate, boolean baz);
+
+    @Mapping(source = "input.nested.bar", target = "bar")
+    FooTarget map(FooSourceNested input, @MappingTarget FooTarget toUpdate, boolean baz);
+}
diff --git a/processor/src/test/java/org/mapstruct/ap/test/nullcheck/redundant/FooSource.java b/processor/src/test/java/org/mapstruct/ap/test/nullcheck/redundant/FooSource.java
@@ -0,0 +1,18 @@
+/*
+ * 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.nullcheck.redundant;
+
+public class FooSource {
+    private String bar;
+
+    public String getBar() {
+        return bar;
+    }
+
+    public void setBar(String bar) {
+        this.bar = bar;
+    }
+}
diff --git a/processor/src/test/java/org/mapstruct/ap/test/nullcheck/redundant/FooSourceNested.java b/processor/src/test/java/org/mapstruct/ap/test/nullcheck/redundant/FooSourceNested.java
@@ -0,0 +1,27 @@
+/*
+ * 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.nullcheck.redundant;
+
+public class FooSourceNested {
+    private String bar;
+    private FooSource nested;
+
+    public FooSource getNested() {
+        return nested;
+    }
+
+    public void setNested(FooSource nested) {
+        this.nested = nested;
+    }
+
+    public String getBar() {
+        return bar;
+    }
+
+    public void setBar(String bar) {
+        this.bar = bar;
+    }
+}
diff --git a/processor/src/test/java/org/mapstruct/ap/test/nullcheck/redundant/FooTarget.java b/processor/src/test/java/org/mapstruct/ap/test/nullcheck/redundant/FooTarget.java
@@ -0,0 +1,18 @@
+/*
+ * 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.nullcheck.redundant;
+
+public class FooTarget {
+    private String bar;
+
+    public String getBar() {
+        return bar;
+    }
+
+    public void setBar(String bar) {
+        this.bar = bar;
+    }
+}
diff --git a/...essor/src/test/java/org/mapstruct/ap/test/nullcheck/redundant/RedundantNullCheckTest.java b/...essor/src/test/java/org/mapstruct/ap/test/nullcheck/redundant/RedundantNullCheckTest.java
@@ -0,0 +1,31 @@
+/*
+ * 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.nullcheck.redundant;
+
+import org.junit.jupiter.api.extension.RegisterExtension;
+import org.mapstruct.ap.testutil.IssueKey;
+import org.mapstruct.ap.testutil.ProcessorTest;
+import org.mapstruct.ap.testutil.WithClasses;
+import org.mapstruct.ap.testutil.runner.GeneratedSource;
+
+@WithClasses({
+    FooMapper.class,
+    FooSource.class,
+    FooTarget.class,
+    FooSourceNested.class
+})
+@IssueKey("3133")
+class RedundantNullCheckTest {
+
+    @RegisterExtension
+    final GeneratedSource generatedSource = new GeneratedSource();
+
+    @ProcessorTest
+    void generatedMapperShouldNotContainAnyRedundantNullChecks() {
+        generatedSource.addComparisonToFixtureFor( FooMapper.class );
+    }
+
+}
diff --git a/.../src/test/resources/fixtures/org/mapstruct/ap/test/nullcheck/redundant/FooMapperImpl.java b/.../src/test/resources/fixtures/org/mapstruct/ap/test/nullcheck/redundant/FooMapperImpl.java
@@ -0,0 +1,64 @@
+/*
+ * 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.nullcheck.redundant;
+
+import javax.annotation.processing.Generated;
+
+@Generated(
+    value = "org.mapstruct.ap.MappingProcessor",
+    date = "2024-05-07T18:50:27+0200",
+    comments = "version: , compiler: javac, environment: Java 21.0.2 (Azul Systems, Inc.)"
+)
+public class FooMapperImpl implements FooMapper {
+
+    @Override
+    public void updateFoo(FooSource input, FooTarget toUpdate, boolean baz) {
+        if ( input == null ) {
+            return;
+        }
+
+        toUpdate.setBar( input.getBar() );
+    }
+
+    @Override
+    public void updateFoo(FooSource input, FooTarget toUpdate, boolean baz, int bay) {
+        if ( input == null ) {
+            return;
+        }
+
+        toUpdate.setBar( input.getBar() );
+    }
+
+    @Override
+    public FooTarget getUpdatedFooTarget(FooSource input, FooTarget toUpdate, boolean baz) {
+        if ( input == null ) {
+            return toUpdate;
+        }
+
+        toUpdate.setBar( input.getBar() );
+
+        return toUpdate;
+    }
+
+    @Override
+    public FooTarget map(FooSourceNested input, FooTarget toUpdate, boolean baz) {
+        if ( input == null ) {
+            return toUpdate;
+        }
+
+        toUpdate.setBar( inputNestedBar( input ) );
+
+        return toUpdate;
+    }
+
+    private String inputNestedBar(FooSourceNested fooSourceNested) {
+        FooSource nested = fooSourceNested.getNested();
+        if ( nested == null ) {
+            return null;
+        }
+        return nested.getBar();
+    }
+}