CMake: Use LTO on all compilers where supported (#330)

* CMakeLists.txt: Fix indentation

* CMake: Bump minimum required version: 3.7 -> 3.10

This simplifies LTO support

.circleci/config.yml

@@ -7,8 +7,8 @@ jobs:
     steps:
       - checkout
       - run: apt-get update -y
-      - run: apt-get install -y cmake g++ libsdl2-dev libsdl2-mixer-dev libsdl2-ttf-dev
-      - run: apt-get install -y -t stretch-backports libsodium-dev
+      - run: apt-get install -y g++ libsdl2-dev libsdl2-mixer-dev libsdl2-ttf-dev
+      - run: apt-get install -y -t stretch-backports cmake libsodium-dev
       - run: mkdir build
       - run: cd build && cmake ..
       - run: cd build && make -j$(nproc)
@@ -20,8 +20,8 @@ jobs:
     steps:
       - checkout
       - run: apt-get update -y
-      - run: apt-get install -y cmake g++ libsdl-dev libsdl-mixer1.2-dev libsdl-ttf2.0-dev
-      - run: apt-get install -y -t stretch-backports libsodium-dev
+      - run: apt-get install -y g++ libsdl-dev libsdl-mixer1.2-dev libsdl-ttf2.0-dev
+      - run: apt-get install -y -t stretch-backports cmake libsodium-dev
       - run: mkdir build
       - run: cd build && cmake .. -DUSE_SDL1=ON
       - run: cd build && make -j$(nproc)
@@ -34,8 +34,8 @@ jobs:
       - checkout
       - run: dpkg --add-architecture i386
       - run: apt-get update -y
-      - run: apt-get install -y cmake g++-multilib libsdl2-dev:i386 libsdl2-mixer-dev:i386 libsdl2-ttf-dev:i386 libsodium-dev
-      - run: apt-get install -y -t stretch-backports libsodium-dev:i386
+      - run: apt-get install -y g++-multilib libsdl2-dev:i386 libsdl2-mixer-dev:i386 libsdl2-ttf-dev:i386 libsodium-dev
+      - run: apt-get install -y -t stretch-backports cmake libsodium-dev:i386
       - run: mkdir build
       - run: cd build && cmake -DCMAKE_TOOLCHAIN_FILE=../CMake/32bit.cmake ..
       - run: cd build && make -j$(nproc)

.editorconfig

@@ -16,3 +16,10 @@ end_of_line = lf
 
 [.clang-format]
 end_of_line = lf
+
+[.gitignore]
+end_of_line = lf
+
+[CMakeLists.txt]
+indent_style = space
+indent_size = 2

CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.7)
+cmake_minimum_required(VERSION 3.10)
 
 include(CMake/out_of_tree.cmake)
 
@@ -28,7 +28,16 @@ if(BINARY_RELEASE)
   set(DEBUG OFF)
   set(DIST ON)
   set(FASTER OFF)
-  set(CMAKE_INTERPROCEDURAL_OPTIMIZATION ON)
+
+  # Use LTO on all compilers where it is supported.
+  include(CheckIPOSupported)
+  check_ipo_supported(RESULT result)
+  if(result)
+    set(CMAKE_INTERPROCEDURAL_OPTIMIZATION ON)
+    message(STATUS "LTO enabled")
+  else()
+    message(WARNING "LTO not supported by this compiler and/or CMake version")
+  endif()
 endif()
 
 if(NIGHTLY_BUILD)
@@ -69,17 +78,17 @@ if(NOT NONET)
 endif()
 
 if(USE_SDL1)
-	find_package(SDL REQUIRED)
-	find_package(SDL_ttf REQUIRED)
-	find_package(SDL_mixer REQUIRED)
-	include_directories(${SDL_INCLUDE_DIR})
+  find_package(SDL REQUIRED)
+  find_package(SDL_ttf REQUIRED)
+  find_package(SDL_mixer REQUIRED)
+  include_directories(${SDL_INCLUDE_DIR})
 else()
-	find_package(SDL2 CONFIG QUIET)
-	if (NOT SDL2_FOUND)
-		find_package(SDL2 REQUIRED)
-	endif()
-	find_package(SDL2_ttf REQUIRED)
-	find_package(SDL2_mixer REQUIRED)
+  find_package(SDL2 CONFIG QUIET)
+  if (NOT SDL2_FOUND)
+    find_package(SDL2 REQUIRED)
+  endif()
+  find_package(SDL2_ttf REQUIRED)
+  find_package(SDL2_mixer REQUIRED)
 endif()
 
 add_library(smacker STATIC