change cmake_source_dir to project_source_dir so that FetchContent can work from other libraries

CMakeLists.txt

@@ -27,7 +27,7 @@ cmake_minimum_required(VERSION 3.10)
 project(tinycbor LANGUAGES C CXX VERSION 7.0)
 
 # Set path to additional cmake scripts
-set(CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/cmake ${CMAKE_MODULE_PATH})
+set(CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/cmake ${CMAKE_MODULE_PATH})
 
 set(TARGETS_EXPORT_NAME "TinyCBOR-targets")
 
@@ -142,14 +142,14 @@ endif()
 
 target_include_directories(tinycbor
   PUBLIC "$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/src>"
-  PUBLIC "$<BUILD_INTERFACE:${CMAKE_BINARY_DIR}>"
+  PUBLIC "$<BUILD_INTERFACE:${PROJECT_BINARY_DIR}>"
   PUBLIC "$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>"
 )
 
 install(FILES
-  src/cbor.h
-  ${CMAKE_BINARY_DIR}/tinycbor-version.h
-  ${CMAKE_BINARY_DIR}/tinycbor-export.h
+  ${PROJECT_SOURCE_DIR}/src/cbor.h
+  ${PROJECT_BINARY_DIR}/tinycbor-version.h
+  ${PROJECT_BINARY_DIR}/tinycbor-export.h
   TYPE INCLUDE
 )
 install(

cmake/PackageConfig.cmake

@@ -7,7 +7,7 @@
 include(CMakePackageConfigHelpers)
 
 configure_package_config_file(
-  "${CMAKE_SOURCE_DIR}/cmake/project-config.cmake.in"
+  "${PROJECT_SOURCE_DIR}/cmake/project-config.cmake.in"
   "${PROJECT_BINARY_DIR}/${PROJECT_NAME}-config.cmake"
   INSTALL_DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}
   #PATH_VARS CMAKE_INSTALL_DIR