From 2cbfcd232758967fa84794967d71d9584ec799ec Mon Sep 17 00:00:00 2001
From: glx22 <glx@openttd.org>
Date: Fri, 5 Feb 2021 02:00:36 +0100
Subject: [PATCH] Change: [CMake] Bump minimum version to 3.9

---
 CMakeLists.txt                 | 11 +++--------
 cmake/FindICU.cmake            |  5 +++++
 src/settingsgen/CMakeLists.txt |  2 +-
 src/strgen/CMakeLists.txt      |  2 +-
 4 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index be544316dd..8fbf3507d0 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.5)
+cmake_minimum_required(VERSION 3.9)
 
 if(NOT BINARY_NAME)
     set(BINARY_NAME openttd)
@@ -143,13 +143,8 @@ find_package(Xaudio2)
 
 find_package(Grfcodec)
 
-# IPO is only properly supported from CMake 3.9. Despite the fact we are
-# CMake 3.5, still enable IPO if we detect we are 3.9+.
-if(POLICY CMP0069)
-    cmake_policy(SET CMP0069 NEW)
-    include(CheckIPOSupported)
-    check_ipo_supported(RESULT IPO_FOUND)
-endif()
+include(CheckIPOSupported)
+check_ipo_supported(RESULT IPO_FOUND)
 
 show_options()
 
diff --git a/cmake/FindICU.cmake b/cmake/FindICU.cmake
index b110dbf404..d12f36b0ad 100644
--- a/cmake/FindICU.cmake
+++ b/cmake/FindICU.cmake
@@ -1,3 +1,8 @@
+# CMake provides a FindICU module since version 3.7.
+# But it doesn't use pkgconfig, doesn't set expected variables,
+# And it returns incomplete dependencies if only some modules are searched.
+
+
 #[=======================================================================[.rst:
 FindICU
 -------
diff --git a/src/settingsgen/CMakeLists.txt b/src/settingsgen/CMakeLists.txt
index 69b2092017..43d5284e62 100644
--- a/src/settingsgen/CMakeLists.txt
+++ b/src/settingsgen/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.5)
+cmake_minimum_required(VERSION 3.9)
 
 if (NOT HOST_BINARY_DIR)
     project(settingsgen)
diff --git a/src/strgen/CMakeLists.txt b/src/strgen/CMakeLists.txt
index 08c1223350..490f675f2e 100644
--- a/src/strgen/CMakeLists.txt
+++ b/src/strgen/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.5)
+cmake_minimum_required(VERSION 3.9)
 
 if (NOT HOST_BINARY_DIR)
     project(strgen)