Use FetchContent

Author: TartanLlama

CMakeLists.txt

@@ -1,10 +1,19 @@
-cmake_minimum_required(VERSION 3.8)
+cmake_minimum_required(VERSION 3.11)
 
 project(tl-optional VERSION 1.0.0 LANGUAGES CXX)
 
 option(OPTIONAL_ENABLE_TESTS "Enable tests." ON)
 
-set(CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake/tl-cmake" ${CMAKE_MODULE_PATH})
+include(FetchContent)
+FetchContent_Declare(
+  tl_cmake
+  GIT_REPOSITORY https://github.com/TartanLlama/tl-cmake.git
+)
+FetchContent_GetProperties(tl_cmake)
+if(NOT tl_cmake_POPULATED)
+  FetchContent_Populate(tl_cmake)
+  set(CMAKE_MODULE_PATH ${tl_cmake_SOURCE_DIR} ${CMAKE_MODULE_PATH})
+endif()
 include(add-tl)
 
 tl_add_library(optional SOURCES