Fix multiple definition error caused by forward declarations

CMakeLists.txt

@@ -10,7 +10,7 @@ set(META_APP_CATEGORIES "Utility;")
 set(META_GUI_OPTIONAL false)
 set(META_VERSION_MAJOR 0)
 set(META_VERSION_MINOR 0)
-set(META_VERSION_PATCH 6)
+set(META_VERSION_PATCH 7)
 set(META_APP_VERSION ${META_VERSION_MAJOR}.${META_VERSION_MINOR}.${META_VERSION_PATCH})
 set(META_CXX_STANDARD 17)
 

generator/serializationcodegenerator.cpp

@@ -67,6 +67,11 @@ void SerializationCodeGenerator::addDeclaration(clang::Decl *decl)
 SerializationCodeGenerator::IsRelevant SerializationCodeGenerator::isQualifiedNameIfRelevant(
     clang::CXXRecordDecl *record, const std::string &qualifiedName) const
 {
+    // skip all classes which are only forward-declared
+    if (!record->isCompleteDefinition()) {
+        return IsRelevant::No;
+    }
+
     // consider all classes for which a specialization of the "AdaptedJsonSerializable" struct is available
     for (const auto &adaptionRecord : m_adaptionRecords) {
         // skip all adaption records which are only included

generator/tests/structs.h

@@ -37,6 +37,11 @@ private:
     string privateString = "not going to be serialized";
 };
 
+// forward declarations shouldn't cause the generator to emit the code multiple times
+struct TestStruct;
+struct TestStruct;
+struct TestStruct;
+
 class JsonGeneratorTests;
 
 /*!