fix(cmake): avoid message if FINDPYTHON NEW (#5656)

Signed-off-by: Henry Schreiner <[email protected]>

Author: henryiii

tools/pybind11Common.cmake

@@ -200,19 +200,21 @@ elseif(
   else()
     include("${CMAKE_CURRENT_LIST_DIR}/pybind11NewTools.cmake")
 
-    message(
-      "Using compatibility mode for Python, set PYBIND11_FINDPYTHON to NEW/OLD to silence this message"
-    )
-    set(PYTHON_EXECUTABLE "${Python_EXECUTABLE}")
-    set(PYTHON_INCLUDE_DIR "${Python_INCLUDE_DIR}")
-    set(Python_INCLUDE_DIRS "${Python_INCLUDE_DIRS}")
-    set(PYTHON_LIBRARY "${Python_LIBRARY}")
-    set(PYTHON_LIBRARIES "${Python_LIBRARIES}")
-    set(PYTHON_VERSION "${Python_VERSION}")
-    set(PYTHON_VERSION_STRING "${Python_VERSION_STRING}")
-    set(PYTHON_VERSION_MAJOR "${Python_VERSION_MAJOR}")
-    set(PYTHON_VERSION_MINOR "${Python_VERSION_MINOR}")
-    set(PYTHON_VERSION_PATCH "${Python_VERSION_PATCH}")
+    if(PYBIND11_FINDPYTHON STREQUAL "COMPAT")
+      message(
+        "Using compatibility mode for Python, set PYBIND11_FINDPYTHON to NEW/OLD to silence this message"
+      )
+      set(PYTHON_EXECUTABLE "${Python_EXECUTABLE}")
+      set(PYTHON_INCLUDE_DIR "${Python_INCLUDE_DIR}")
+      set(Python_INCLUDE_DIRS "${Python_INCLUDE_DIRS}")
+      set(PYTHON_LIBRARY "${Python_LIBRARY}")
+      set(PYTHON_LIBRARIES "${Python_LIBRARIES}")
+      set(PYTHON_VERSION "${Python_VERSION}")
+      set(PYTHON_VERSION_STRING "${Python_VERSION_STRING}")
+      set(PYTHON_VERSION_MAJOR "${Python_VERSION_MAJOR}")
+      set(PYTHON_VERSION_MINOR "${Python_VERSION_MINOR}")
+      set(PYTHON_VERSION_PATCH "${Python_VERSION_PATCH}")
+    endif()
   endif()
 
 else()