From b944efa1f33770fe88c1fb54295a84f3db4b4d26 Mon Sep 17 00:00:00 2001
From: Vitaly Zaitsev <vitaly@easycoding.org>
Date: Fri, 24 Jan 2020 14:01:40 +0100
Subject: [PATCH] Added support of IPO optimizations.

Signed-off-by: Vitaly Zaitsev <vitaly@easycoding.org>
---
 init_target.cmake |  2 +-
 variables.cmake   | 14 ++++++++++----
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/init_target.cmake b/init_target.cmake
index 62f599e..bce754d 100644
--- a/init_target.cmake
+++ b/init_target.cmake
@@ -41,7 +41,7 @@ function(init_target target_name) # init_target(my_target folder_name)
         XCODE_ATTRIBUTE_GCC_OPTIMIZATION_LEVEL $<IF:$<CONFIG:Debug>,0,fast>
         XCODE_ATTRIBUTE_LLVM_LTO $<IF:$<CONFIG:Debug>,NO,YES>
     )
-    if (WIN32)
+    if (WIN32 OR DESKTOP_APP_ENABLE_IPO_OPTIMIZATIONS)
         set_target_properties(${target_name} PROPERTIES
             INTERPROCEDURAL_OPTIMIZATION_RELEASE True
             INTERPROCEDURAL_OPTIMIZATION_RELWITHDEBINFO True
diff --git a/variables.cmake b/variables.cmake
index 60e794e..9d3b075 100644
--- a/variables.cmake
+++ b/variables.cmake
@@ -25,6 +25,12 @@ option(DESKTOP_APP_DISABLE_CRASH_REPORTS "Disable crash report generation." ${DE
 option(DESKTOP_APP_USE_PACKAGED_RLOTTIE "Find rlottie using CMake instead of bundled one." ${DESKTOP_APP_USE_PACKAGED})
 option(DESKTOP_APP_USE_PACKAGED_FONTS "Use preinstalled fonts instead of bundled one." ${DESKTOP_APP_USE_PACKAGED})
 
+option(DESKTOP_APP_ENABLE_IPO_OPTIMIZATIONS "Enable IPO build optimizations." OFF)
+if (DESKTOP_APP_ENABLE_IPO_OPTIMIZATIONS AND CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+    message(WARNING "Clang cannot build Qt applications with IPO enabled due to upstream bug: https://bugreports.qt.io/browse/QTBUG-61710.")
+    set(DESKTOP_APP_ENABLE_IPO_OPTIMIZATIONS OFF)
+endif()
+
 if (DESKTOP_APP_SPECIAL_TARGET STREQUAL ""
     OR DESKTOP_APP_SPECIAL_TARGET STREQUAL "uwp"
     OR DESKTOP_APP_SPECIAL_TARGET STREQUAL "macstore")
@@ -59,10 +65,10 @@ else()
             report_bad_special_target()
         endif()
     endif()
-    if (NOT DESKTOP_APP_USE_PACKAGED)
-        set(CMAKE_AR /usr/bin/gcc-ar)
-        set(CMAKE_RANLIB /usr/bin/gcc-ranlib)
-        set(CMAKE_NM /usr/bin/gcc-nm)
+    if (NOT DESKTOP_APP_USE_PACKAGED OR DESKTOP_APP_ENABLE_IPO_OPTIMIZATIONS)
+        set(CMAKE_AR "gcc-ar")
+        set(CMAKE_RANLIB "gcc-ranlib")
+        set(CMAKE_NM "gcc-nm")
     endif()
 endif()