From 05ebe83f2fdb8287f352c575ec8e43cdefc65905 Mon Sep 17 00:00:00 2001
From: levlam <levlam@telegram.org>
Date: Fri, 10 Sep 2021 17:38:27 +0300
Subject: [PATCH] Add TELEGRAM_BOT_API_ENABLE_LTO build option.

---
 CMakeLists.txt | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9c8cf79..2a33b9a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -8,6 +8,11 @@ endif()
 
 project(TelegramBotApi VERSION 5.3.2 LANGUAGES CXX)
 
+if (POLICY CMP0069)
+  option(TELEGRAM_BOT_API_ENABLE_LTO "Use \"ON\" to enable Link Time Optimization.")
+  set(TD_ENABLE_LTO "${TELEGRAM_BOT_API_ENABLE_LTO}" CACHE STRING "Enable LTO" FORCE)
+endif()
+
 add_subdirectory(td EXCLUDE_FROM_ALL)
 
 if (NOT DEFINED CMAKE_MODULE_PATH)
@@ -35,6 +40,19 @@ endif()
 include(PreventInSourceBuild)
 prevent_in_source_build()
 
+if (POLICY CMP0069 AND TELEGRAM_BOT_API_ENABLE_LTO)
+  cmake_policy(SET CMP0069 NEW)
+  include(CheckIPOSupported)
+  check_ipo_supported(RESULT IPO_SUPPORTED LANGUAGES CXX)
+  if (IPO_SUPPORTED)
+    string(REPLACE ";" " " CXX_FLAGS_IPO "${CMAKE_CXX_COMPILE_OPTIONS_IPO}")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${CXX_FLAGS_IPO}")
+
+    string(REPLACE ";" " " LINK_FLAGS_IPO "${CMAKE_CXX_LINK_OPTIONS_IPO}")
+    set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${LINK_FLAGS_IPO}")
+  endif()
+endif()
+
 set(CMAKE_THREAD_PREFER_PTHREAD ON)
 set(THREADS_PREFER_PTHREAD_FLAG ON)
 find_package(Threads REQUIRED)