Add forward declarations for union types

Author: wravery

samples/today/separate/TodaySchema.h

@@ -64,6 +64,8 @@ namespace object {
 
 class Node;
 
+class UnionType;
+
 class Query;
 class PageInfo;
 class AppointmentEdge;

samples/today/separate_nointrospection/TodaySchema.h

@@ -64,6 +64,8 @@ namespace object {
 
 class Node;
 
+class UnionType;
+
 class Query;
 class PageInfo;
 class AppointmentEdge;

samples/today/unified/TodaySchema.h

@@ -64,6 +64,8 @@ namespace object {
 
 class Node;
 
+class UnionType;
+
 class Query;
 class PageInfo;
 class AppointmentEdge;

samples/today/unified_nointrospection/TodaySchema.h

@@ -64,6 +64,8 @@ namespace object {
 
 class Node;
 
+class UnionType;
+
 class Query;
 class PageInfo;
 class AppointmentEdge;

samples/validation/schema/ValidationSchema.h

@@ -44,6 +44,10 @@ namespace object {
 class Sentient;
 class Pet;
 
+class CatOrDog;
+class DogOrHuman;
+class HumanOrAlien;
+
 class Query;
 class Dog;
 class Alien;

src/SchemaGenerator.cpp

@@ -265,6 +265,23 @@ static_assert(graphql::internal::MinorVersion == )cpp"
 		headerFile << std::endl;
 	}
 
+	if (!_loader.getUnionTypes().empty())
+	{
+		if (objectNamespace.enter())
+		{
+			headerFile << std::endl;
+		}
+
+		// Forward declare all of the interface types
+		for (const auto& unionType : _loader.getUnionTypes())
+		{
+			headerFile << R"cpp(class )cpp" << unionType.cppType << R"cpp(;
+)cpp";
+		}
+
+		headerFile << std::endl;
+	}
+
 	if (!_loader.getObjectTypes().empty())
 	{
 		if (_loader.isIntrospection())