Add hint to error message on how to build with in-tree Irrlicht

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 65c6bf6c3f89bafad655a7fa92b3f6138102ee12..1995f34b88ebc8ea5a6ed20d0095e17329ba4385 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -86,7 +86,8 @@ else()
        if(NOT TARGET IrrlichtMt::IrrlichtMt)
                string(CONCAT explanation_msg
                        "The Minetest team has forked Irrlicht to make their own customizations. "
-                       "It can be found here: https://github.com/minetest/irrlicht")
+                       "It can be found here: https://github.com/minetest/irrlicht\n"
+                       "For example use: git clone --depth=1 https://github.com/minetest/irrlicht lib/irrlichtmt\n")
                if(BUILD_CLIENT)
                        message(FATAL_ERROR "IrrlichtMt is required to build the client, but it was not found.\n${explanation_msg}")
                endif()