#2863 Add validation of String type to @TargetPropertyName

processor/src/main/java/org/mapstruct/ap/internal/processor/MethodRetrievalProcessor.java

@@ -28,6 +28,7 @@ import org.mapstruct.ap.internal.gem.MappingsGem;
 import org.mapstruct.ap.internal.gem.ObjectFactoryGem;
 import org.mapstruct.ap.internal.gem.SubclassMappingGem;
 import org.mapstruct.ap.internal.gem.SubclassMappingsGem;
+import org.mapstruct.ap.internal.gem.TargetPropertyNameGem;
 import org.mapstruct.ap.internal.gem.ValueMappingGem;
 import org.mapstruct.ap.internal.gem.ValueMappingsGem;
 import org.mapstruct.ap.internal.model.common.Parameter;
@@ -230,7 +231,7 @@ public class MethodRetrievalProcessor implements ModelElementProcessor<Void, Lis
         // otherwise add reference to existing mapper method
         else if ( isValidReferencedMethod( parameters ) || isValidFactoryMethod( method, parameters, returnType )
             || isValidLifecycleCallbackMethod( method )
-            || isValidPresenceCheckMethod( method, returnType ) ) {
+            || isValidPresenceCheckMethod( method, parameters, returnType ) ) {
             return getReferencedMethod( usedMapper, methodType, method, mapperToImplement, parameters );
         }
         else {
@@ -407,7 +408,17 @@ public class MethodRetrievalProcessor implements ModelElementProcessor<Void, Lis
         return ObjectFactoryGem.instanceOn( method ) != null;
     }
 
-    private boolean isValidPresenceCheckMethod(ExecutableElement method, Type returnType) {
+    private boolean isValidPresenceCheckMethod(ExecutableElement method, List<Parameter> parameters, Type returnType) {
+        for ( Parameter param : parameters ) {
+            if ( param.isTargetPropertyName() && !param.getType().isString() ) {
+                messager.printMessage(
+                    param.getElement(),
+                    TargetPropertyNameGem.instanceOn( param.getElement() ).mirror(),
+                    Message.RETRIEVAL_TARGET_PROPERTY_NAME_WRONG_TYPE
+                );
+                return false;
+            }
+        }
         return isBoolean( returnType ) && hasConditionAnnotation( method );
     }
 

processor/src/main/java/org/mapstruct/ap/internal/util/Message.java

@@ -176,6 +176,7 @@ public enum Message {
     RETRIEVAL_MAPPER_USES_CYCLE( "The mapper %s is referenced itself in Mapper#uses.", Diagnostic.Kind.WARNING ),
     RETRIEVAL_AFTER_METHOD_NOT_IMPLEMENTED( "@AfterMapping can only be applied to an implemented method." ),
     RETRIEVAL_BEFORE_METHOD_NOT_IMPLEMENTED( "@BeforeMapping can only be applied to an implemented method." ),
+    RETRIEVAL_TARGET_PROPERTY_NAME_WRONG_TYPE( "@TargetPropertyName can only by applied to a String parameter." ),
 
     INHERITINVERSECONFIGURATION_DUPLICATES( "Several matching inverse methods exist: %s(). Specify a name explicitly." ),
     INHERITINVERSECONFIGURATION_INVALID_NAME( "None of the candidates %s() matches given name: \"%s\"." ),

processor/src/test/java/org/mapstruct/ap/test/conditional/targetpropertyname/ErroneousNonStringTargetPropertyNameParameter.java

@@ -0,0 +1,21 @@
+/*
+ * 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.conditional.targetpropertyname;
+
+import org.mapstruct.Condition;
+import org.mapstruct.Mapper;
+import org.mapstruct.TargetPropertyName;
+
+@Mapper
+public interface ErroneousNonStringTargetPropertyNameParameter {
+
+    Employee map(EmployeeDto employee);
+
+    @Condition
+    default boolean isNotBlank(String value, @TargetPropertyName int propName) {
+        return value != null && !value.trim().isEmpty();
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/conditional/targetpropertyname/TargetPropertyNameTest.java

@@ -9,6 +9,9 @@ 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.compilation.annotation.CompilationResult;
+import org.mapstruct.ap.testutil.compilation.annotation.Diagnostic;
+import org.mapstruct.ap.testutil.compilation.annotation.ExpectedCompilationOutcome;
 import org.mapstruct.ap.testutil.runner.GeneratedSource;
 
 import java.util.Collections;
@@ -278,4 +281,24 @@ public class TargetPropertyNameTest {
                 "addresses.street"
             );
     }
+
+    @IssueKey("2863")
+    @ProcessorTest
+    @WithClasses({
+        ErroneousNonStringTargetPropertyNameParameter.class
+    })
+    @ExpectedCompilationOutcome(
+        value = CompilationResult.FAILED,
+        diagnostics = {
+            @Diagnostic(
+                kind = javax.tools.Diagnostic.Kind.ERROR,
+                type = ErroneousNonStringTargetPropertyNameParameter.class,
+                line = 18,
+                message = "@TargetPropertyName can only by applied to a String parameter."
+            )
+        }
+    )
+    public void nonStringTargetPropertyNameParameter() {
+
+    }
 }