From 63c82ed8c60e0bd3694c48df2fdba4e2b3ef711e Mon Sep 17 00:00:00 2001
From: tamasmeszaros <meszaros.q@gmail.com>
Date: Thu, 14 May 2020 10:10:47 +0200
Subject: [PATCH] Modify PCH script to use builtin cmake function if possible.

---
 cmake/modules/PrecompiledHeader.cmake | 15 +++++++++++++++
 src/libslic3r/CMakeLists.txt          |  3 +--
 src/slic3r/CMakeLists.txt             |  3 +--
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/cmake/modules/PrecompiledHeader.cmake b/cmake/modules/PrecompiledHeader.cmake
index 2f62a7dbe..e5f01af21 100644
--- a/cmake/modules/PrecompiledHeader.cmake
+++ b/cmake/modules/PrecompiledHeader.cmake
@@ -101,7 +101,14 @@ function(export_all_flags _filename)
   file(GENERATE OUTPUT "${_filename}" CONTENT "${_compile_definitions}${_include_directories}${_compile_flags}${_compile_options}${_cxx_flags}\n")
 endfunction()
 
+# Use the new builtin CMake function if possible or fall back to the old one.
+if (CMAKE_VERSION VERSION_LESS 3.16)
+
 function(add_precompiled_header _target _input)
+
+  message(STATUS "Adding precompiled header ${_input} to target ${_target} with legacy method. "
+                 "Update your cmake instance to use the native PCH functions.")
+
   cmake_parse_arguments(_PCH "FORCEINCLUDE" "SOURCE_CXX;SOURCE_C" "" ${ARGN})
 
   get_filename_component(_input_we ${_input} NAME_WE)
@@ -241,3 +248,11 @@ function(add_precompiled_header _target _input)
     endforeach()
   endif(CMAKE_COMPILER_IS_GNUCXX)
 endfunction()
+
+else ()
+
+function(add_precompiled_header _target _input)
+    target_precompile_headers(${_target} PRIVATE ${_input})
+endfunction()
+
+endif (CMAKE_VERSION VERSION_LESS 3.16)
diff --git a/src/libslic3r/CMakeLists.txt b/src/libslic3r/CMakeLists.txt
index ae9087ed4..12e61d7f3 100644
--- a/src/libslic3r/CMakeLists.txt
+++ b/src/libslic3r/CMakeLists.txt
@@ -308,6 +308,5 @@ if(SLIC3R_PROFILE)
 endif()
 
 if (SLIC3R_PCH AND NOT SLIC3R_SYNTAXONLY)
-    #add_precompiled_header(libslic3r pchheader.hpp FORCEINCLUDE)
-    target_precompile_headers(libslic3r PRIVATE pchheader.hpp)
+    add_precompiled_header(libslic3r pchheader.hpp FORCEINCLUDE)
 endif ()
diff --git a/src/slic3r/CMakeLists.txt b/src/slic3r/CMakeLists.txt
index a110a82ed..ac6961990 100644
--- a/src/slic3r/CMakeLists.txt
+++ b/src/slic3r/CMakeLists.txt
@@ -231,6 +231,5 @@ if (SLIC3R_STATIC AND UNIX AND NOT APPLE)
 endif ()
 
 if (SLIC3R_PCH AND NOT SLIC3R_SYNTAXONLY)
-    #add_precompiled_header(libslic3r_gui pchheader.hpp FORCEINCLUDE)
-    target_precompile_headers(libslic3r_gui PRIVATE pchheader.hpp)
+    add_precompiled_header(libslic3r_gui pchheader.hpp FORCEINCLUDE)
 endif ()