diff --git a/Source/CMakeLists.txt b/Source/CMakeLists.txt
index 67d3d8d7a7..a8abb60963 100644
--- a/Source/CMakeLists.txt
+++ b/Source/CMakeLists.txt
@@ -426,6 +426,7 @@ add_library(
   cmStateTypes.h
   cmStringAlgorithms.cxx
   cmStringAlgorithms.h
+  cmSyntheticTargetCache.h
   cmSystemTools.cxx
   cmSystemTools.h
   cmTarget.cxx
diff --git a/Source/cmSyntheticTargetCache.h b/Source/cmSyntheticTargetCache.h
new file mode 100644
index 0000000000..22d1533b00
--- /dev/null
+++ b/Source/cmSyntheticTargetCache.h
@@ -0,0 +1,15 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#pragma once
+
+#include "cmConfigure.h" // IWYU pragma: keep
+
+#include <map>
+#include <string>
+
+class cmGeneratorTarget;
+
+struct cmSyntheticTargetCache
+{
+  std::map<std::string, cmGeneratorTarget const*> CxxModuleTargets;
+};