From 76378c8990f9e5aa87998f7a7bf73108aa294e2e Mon Sep 17 00:00:00 2001
From: Sam Edwards <CFSworks@gmail.com>
Date: Sun, 19 Aug 2018 23:10:20 -0600
Subject: [PATCH] CMake: Ask Python for preferred binary extension suffix

---
 cmake/macros/Interrogate.cmake         |  4 +---
 dtool/Package.cmake                    | 29 +++++++++++++++++++-------
 dtool/src/interrogatedb/CMakeLists.txt |  1 +
 3 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/cmake/macros/Interrogate.cmake b/cmake/macros/Interrogate.cmake
index 5cbecfb626..44d2aed8e1 100644
--- a/cmake/macros/Interrogate.cmake
+++ b/cmake/macros/Interrogate.cmake
@@ -297,9 +297,7 @@ function(add_python_module module)
     LIBRARY_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/panda3d"
     PREFIX ""
   )
-  if(WIN32 AND NOT CYGWIN)
-    set_target_properties(${module} PROPERTIES SUFFIX ".pyd")
-  endif()
+  set_target_properties(${module} PROPERTIES SUFFIX "${PYTHON_EXTENSION_SUFFIX}")
 
   install(TARGETS ${module} DESTINATION "${PYTHON_ARCH_INSTALL_DIR}/panda3d")
 
diff --git a/dtool/Package.cmake b/dtool/Package.cmake
index 468b123ea5..43b9fdc23b 100644
--- a/dtool/Package.cmake
+++ b/dtool/Package.cmake
@@ -22,13 +22,29 @@ if(HAVE_PYTHON)
   execute_process(
     COMMAND ${PYTHON_EXECUTABLE}
       -c "from distutils.sysconfig import get_python_lib; print(get_python_lib(False))"
-      OUTPUT_VARIABLE _LIB_DIR
-      OUTPUT_STRIP_TRAILING_WHITESPACE)
+    OUTPUT_VARIABLE _LIB_DIR
+    OUTPUT_STRIP_TRAILING_WHITESPACE)
   execute_process(
     COMMAND ${PYTHON_EXECUTABLE}
       -c "from distutils.sysconfig import get_python_lib; print(get_python_lib(True))"
-      OUTPUT_VARIABLE _ARCH_DIR
-      OUTPUT_STRIP_TRAILING_WHITESPACE)
+    OUTPUT_VARIABLE _ARCH_DIR
+    OUTPUT_STRIP_TRAILING_WHITESPACE)
+  execute_process(
+    COMMAND ${PYTHON_EXECUTABLE}
+      -c "from sysconfig import get_config_var as g; print((g('EXT_SUFFIX') or g('SO'))[:])"
+    OUTPUT_VARIABLE _EXT_SUFFIX
+    ERROR_QUIET
+    OUTPUT_STRIP_TRAILING_WHITESPACE)
+
+  if(NOT _EXT_SUFFIX)
+    if(CYGWIN)
+      set(_EXT_SUFFIX ".dll")
+    elseif(WIN32)
+      set(_EXT_SUFFIX ".pyd")
+    else()
+      set(_EXT_SUFFIX ".so")
+    endif()
+  endif()
 
   set(PYTHON_LIB_INSTALL_DIR "${_LIB_DIR}" CACHE STRING
     "Path to the Python architecture-independent package directory.")
@@ -36,9 +52,8 @@ if(HAVE_PYTHON)
   set(PYTHON_ARCH_INSTALL_DIR "${_ARCH_DIR}" CACHE STRING
     "Path to the Python architecture-dependent package directory.")
 
-  # Always include Python, because we include it pretty much everywhere
-  # though we don't usually want to link it in as well.
-  include_directories(${PYTHON_INCLUDE_DIRS})
+  set(PYTHON_EXTENSION_SUFFIX "${_EXT_SUFFIX}" CACHE STRING
+    "Suffix for Python binary extension modules.")
 endif()
 
 #
diff --git a/dtool/src/interrogatedb/CMakeLists.txt b/dtool/src/interrogatedb/CMakeLists.txt
index c4d02f25a0..305e64efbe 100644
--- a/dtool/src/interrogatedb/CMakeLists.txt
+++ b/dtool/src/interrogatedb/CMakeLists.txt
@@ -67,6 +67,7 @@ add_custom_command(
 
 add_library(interrogatedb ${MODULE_TYPE}
   "${CMAKE_CURRENT_BINARY_DIR}/interrogatedb_module.cxx")
+set_target_properties(interrogatedb PROPERTIES SUFFIX "${PYTHON_EXTENSION_SUFFIX}")
 target_use_packages(interrogatedb PYTHON)
 target_link_libraries(interrogatedb p3dtoolconfig)