fix for meta project

CMakeLists.txt

@@ -6,10 +6,10 @@
 # modification, are permitted provided that the following conditions are met:
 
 # 1. Redistributions of source code must retain the above copyright notice, this
-# list of conditions and the following disclaimer
+#    list of conditions and the following disclaimer
 # 2. Redistributions in binary form must reproduce the above copyright notice,
-# this list of conditions and the following disclaimer in the documentation
-# and/or other materials provided with the distribution.
+#    this list of conditions and the following disclaimer in the documentation
+#    and/or other materials provided with the distribution.
 
 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 # ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
@@ -103,7 +103,9 @@ set(CMAKE_THREAD_PREFER_PTHREAD)
 set(THREADS_PREFER_PTHREAD_FLAG)
 find_package(Threads)
 
-find_package(cifpp 5.0.0 REQUIRED)
+if(NOT PDB_REDO_META)
+	find_package(cifpp 5.0.0 REQUIRED)
+endif()
 
 # The DSSP code is in a separate library, optionally to be used by others
 add_library(dssp_library OBJECT ${PROJECT_SOURCE_DIR}/src/DSSP.cpp)

cmake/AddGitSubmodule.cmake

-cmake_minimum_required(VERSION 3.19)
+cmake_minimum_required(VERSION 3.16..3.19)
 
 function(add_git_submodule dir)
 	# add a Git submodule directory to CMake, assuming the
@@ -11,9 +11,14 @@ function(add_git_submodule dir)
 	find_package(Git REQUIRED)
 
 	if(NOT EXISTS ${dir}/CMakeLists.txt)
-		execute_process(COMMAND ${GIT_EXECUTABLE} submodule update --init --recursive -- ${dir}
-			WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
-			COMMAND_ERROR_IS_FATAL ANY)
+		if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.19)
+			execute_process(COMMAND ${GIT_EXECUTABLE} submodule update --init --recursive -- ${dir}
+				WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
+				COMMAND_ERROR_IS_FATAL ANY)
+		else()
+			execute_process(COMMAND ${GIT_EXECUTABLE} submodule update --init --recursive -- ${dir}
+				WORKING_DIRECTORY ${PROJECT_SOURCE_DIR})
+		endif()
 	endif()
 
 	set(ENABLE_TESTING OFF)