From 2c12e75bfcae80aed0aa2674ccdf248280a6f4dc Mon Sep 17 00:00:00 2001
From: hduelme <46139144+hduelme@users.noreply.github.com>
Date: Sun, 3 Mar 2024 18:59:32 +0100
Subject: [PATCH] #3485 Exception for Mapping to target = "." without source

---
 .../internal/model/source/MappingOptions.java |  3 ++
 .../mapstruct/ap/internal/util/Message.java   |  1 +
 .../bugs/_3485/ErroneousIssue3485Mapper.java  | 35 +++++++++++++++++++
 .../ap/test/bugs/_3485/Issue3485Test.java     | 33 +++++++++++++++++
 4 files changed, 72 insertions(+)
 create mode 100644 processor/src/test/java/org/mapstruct/ap/test/bugs/_3485/ErroneousIssue3485Mapper.java
 create mode 100644 processor/src/test/java/org/mapstruct/ap/test/bugs/_3485/Issue3485Test.java

diff --git a/processor/src/main/java/org/mapstruct/ap/internal/model/source/MappingOptions.java b/processor/src/main/java/org/mapstruct/ap/internal/model/source/MappingOptions.java
index f60eba193..e0994d746 100644
--- a/processor/src/main/java/org/mapstruct/ap/internal/model/source/MappingOptions.java
+++ b/processor/src/main/java/org/mapstruct/ap/internal/model/source/MappingOptions.java
@@ -260,6 +260,9 @@ public class MappingOptions extends DelegatingOptions {
         else if ( ".".equals( gem.target().get() ) && gem.ignore().hasValue() && gem.ignore().getValue() ) {
             message = Message.PROPERTYMAPPING_TARGET_THIS_AND_IGNORE;
         }
+        else if ( ".".equals( gem.target().get() ) && !gem.source().hasValue() ) {
+            message = Message.PROPERTYMAPPING_TARGET_THIS_NO_SOURCE;
+        }
 
         if ( message == null ) {
             return true;
diff --git a/processor/src/main/java/org/mapstruct/ap/internal/util/Message.java b/processor/src/main/java/org/mapstruct/ap/internal/util/Message.java
index ab8fa0101..68c079cb9 100644
--- a/processor/src/main/java/org/mapstruct/ap/internal/util/Message.java
+++ b/processor/src/main/java/org/mapstruct/ap/internal/util/Message.java
@@ -71,6 +71,7 @@ public enum Message {
     PROPERTYMAPPING_DEFAULT_EXPERSSION_AND_NVPMS( "DefaultExpression and nullValuePropertyMappingStrategy are both defined in @Mapping, either define a defaultExpression or an nullValuePropertyMappingStrategy." ),
     PROPERTYMAPPING_IGNORE_AND_NVPMS( "Ignore and nullValuePropertyMappingStrategy are both defined in @Mapping, either define ignore or an nullValuePropertyMappingStrategy." ),
     PROPERTYMAPPING_TARGET_THIS_AND_IGNORE( "Using @Mapping( target = \".\", ignore = true ) is not allowed. You need to use @BeanMapping( ignoreByDefault = true ) if you would like to ignore all non explicitly mapped target properties." ),
+    PROPERTYMAPPING_TARGET_THIS_NO_SOURCE( "Using @Mapping( target = \".\") requires a source property. Expression or constant cannot be used as a source."),
     PROPERTYMAPPING_EXPRESSION_AND_QUALIFIER_BOTH_DEFINED("Expression and a qualifier both defined in @Mapping, either define an expression or a qualifier."),
     PROPERTYMAPPING_INVALID_EXPRESSION( "Value for expression must be given in the form \"java(<EXPRESSION>)\"." ),
     PROPERTYMAPPING_INVALID_DEFAULT_EXPRESSION( "Value for default expression must be given in the form \"java(<EXPRESSION>)\"." ),
diff --git a/processor/src/test/java/org/mapstruct/ap/test/bugs/_3485/ErroneousIssue3485Mapper.java b/processor/src/test/java/org/mapstruct/ap/test/bugs/_3485/ErroneousIssue3485Mapper.java
new file mode 100644
index 000000000..5714e0468
--- /dev/null
+++ b/processor/src/test/java/org/mapstruct/ap/test/bugs/_3485/ErroneousIssue3485Mapper.java
@@ -0,0 +1,35 @@
+/*
+ * 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._3485;
+
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+import org.mapstruct.ReportingPolicy;
+import org.mapstruct.factory.Mappers;
+
+/**
+ * @author hduelme
+ */
+@Mapper(unmappedTargetPolicy = ReportingPolicy.IGNORE)
+public interface ErroneousIssue3485Mapper {
+
+    ErroneousIssue3485Mapper INSTANCE = Mappers.getMapper( ErroneousIssue3485Mapper.class );
+    class Target {
+        private final String value;
+
+        public Target( String value ) {
+            this.value = value;
+        }
+
+        public String getValue() {
+            return value;
+        }
+
+    }
+
+    @Mapping(target = ".")
+    Target targetFromExpression(String s);
+}
diff --git a/processor/src/test/java/org/mapstruct/ap/test/bugs/_3485/Issue3485Test.java b/processor/src/test/java/org/mapstruct/ap/test/bugs/_3485/Issue3485Test.java
new file mode 100644
index 000000000..cf7e0563a
--- /dev/null
+++ b/processor/src/test/java/org/mapstruct/ap/test/bugs/_3485/Issue3485Test.java
@@ -0,0 +1,33 @@
+/*
+ * 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._3485;
+
+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;
+
+/**
+ * @author hduelme
+ */
+@IssueKey("3463")
+public class Issue3485Test {
+
+    @ProcessorTest
+    @WithClasses(ErroneousIssue3485Mapper.class)
+    @ExpectedCompilationOutcome(value = CompilationResult.FAILED,
+            diagnostics = {
+                    @Diagnostic(type = ErroneousIssue3485Mapper.class,
+                            kind = javax.tools.Diagnostic.Kind.ERROR,
+                            line = 33,
+                            message = "Using @Mapping( target = \".\") requires a source property. Expression or " +
+                                    "constant cannot be used as a source.")
+            })
+    void thisMappingWithoutSource() {
+    }
+}