fix: possible help in #2355

Author: henryiii

tools/pybind11Tools.cmake

@@ -184,6 +184,11 @@ function(pybind11_add_module target_name)
   if(CMAKE_VERSION VERSION_LESS 3.9 OR PYBIND11_CLASSIC_LTO)
     _pybind11_add_lto_flags(${target_name} ${ARG_THIN_LTO})
   elseif(NOT DEFINED CMAKE_INTERPROCEDURAL_OPTIMIZATION)
+    cmake_policy(GET CMP0069 IPO_POL)
+    if(CMP0069 STREQUAL "NEW")
+      cmake_policy(SET CMP0069 NEW)
+    endif()
+
     include(CheckIPOSupported)
     check_ipo_supported(RESULT supported OUTPUT error)
     if(supported)