From 5364066ff9096d22cf9c9dd1ba951759b7f245fb Mon Sep 17 00:00:00 2001
From: Aaron Barany <akb825@gmail.com>
Date: Fri, 29 Nov 2024 19:02:01 -0800
Subject: [PATCH] Added VFC_STATIC_RUNTIME CMake flag.

Allows for linking to the static runtime library on Windows.

Updated the minimum CMake version to 3.15 on Windows to support
CMAKE_MSVC_RUNTIME_LIBRARY. Other systems now require 3.10 to silence
warnings that newer versions will drop compatibility for a declared minimum
version < 3.10.
---
 CMakeLists.txt     | 11 ++++++++++-
 README.md          |  3 ++-
 cmake/config.cmake |  9 ++++++++-
 3 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4cbee2e..008b8ef 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,12 @@
-cmake_minimum_required(VERSION 3.5)
+if (WIN32)
+	# Needs 3.15 for CMAKE_MSVC_RUNTIME_LIBRARY.
+	cmake_minimum_required(VERSION 3.15)
+else()
+	cmake_minimum_required(VERSION 3.10)
+endif()
+if (POLICY CMP0144)
+	cmake_policy(SET CMP0144 NEW)
+endif()
 project(VFC)
 
 # Build options
@@ -9,6 +17,7 @@ else()
 	set(VFC_SHARED_DEFAULT OFF)
 endif()
 set(VFC_SHARED ${VFC_SHARED_DEFAULT} CACHE BOOL "Build VFC using shared libraries.")
+set(VFC_STATIC_RUNTIME OFF CACHE BOOL "Use static runtime library on Windows.")
 
 # Options for disabling portions of the build.
 set(VFC_BUILD_TESTS ON CACHE BOOL "Build unit tests.")
diff --git a/README.md b/README.md
index 0739e6e..cf74546 100644
--- a/README.md
+++ b/README.md
@@ -14,7 +14,7 @@ Example uses include:
 
 The following software is required to build VFC:
 
-* [CMake](https://cmake.org/) 3.1 or later
+* [CMake](https://cmake.org/) 3.10 or later
 * [GLM](https://glm.g-truc.net/) (required, included as a submodule)
 * [RapidJSON](https://rapidjson.org/) (required for tool, included as a submodule)
 * [doxygen](https://doxygen.nl/) (optional)
@@ -75,6 +75,7 @@ The following options may be used when running cmake:
 * `-DCMAKE_BUILD_TYPE=Debug|Release`: Building in `Debug` or `Release`. This should always be specified.
 * `-DCMAKE_INSTALL_PREFIX=path`: Sets the path to install to when running `make install`.
 * `-DVFC_SHARED=ON|OFF`: Set to `ON` to build with shared libraries, `OFF` to build with static libraries. Default is `OFF`.
+* `-DVFC_STATIC_RUNTIME=ON|OFF`: Set to `ON` to use the static runtime library on Windows. When `OFF`, it will respect the existing value of `CMAKE_MSVC_RUNTIME_LIBRARY`, or use dynamic runtime if otherwise unset. It is not recommended to set this to `ON` when `VFC_SHARED` is also `ON`. Default is `OFF`.
 
 ### Enabled Builds
 
diff --git a/cmake/config.cmake b/cmake/config.cmake
index 371d741..8fd9578 100644
--- a/cmake/config.cmake
+++ b/cmake/config.cmake
@@ -1,4 +1,4 @@
-# Copyright 2020-2022 Aaron Barany
+# Copyright 2020-2024 Aaron Barany
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -20,6 +20,13 @@ set(CMAKE_CXX_STANDARD 14)
 set(CMAKE_POSITION_INDEPENDENT_CODE ON)
 
 if (MSVC)
+	if (VFC_STATIC_RUNTIME)
+		set(CMAKE_MSVC_RUNTIME_LIBRARY "MultiThreaded$<$<CONFIG:Debug>:Debug>")
+		if (VFC_SHARED)
+			message(WARNING
+				"It is not recommended to have VFC_SHARED and VFC_STATIC_RUNTIME both set to ON.")
+		endif()
+	endif()
 	add_compile_options(/W3 /WX /wd4200 /MP)
 	add_definitions(-D_CRT_SECURE_NO_WARNINGS -D_CRT_NONSTDC_NO_WARNINGS)
 else()