cmake_minimum_required(VERSION 3.29)
cmake_policy(SET CMP0168 ${CMP0168})

include(FetchContent)

file(WRITE tmpFile.txt "Generated contents, not important")

FetchContent_Populate(
  t1
  DOWNLOAD_COMMAND ${CMAKE_COMMAND} -E copy
                   ${CMAKE_CURRENT_BINARY_DIR}/tmpFile.txt
                   <SOURCE_DIR>/done1.txt
)
if(NOT EXISTS ${CMAKE_CURRENT_BINARY_DIR}/t1-src/done1.txt)
  message(FATAL_ERROR "Default SOURCE_DIR doesn't contain done1.txt")
endif()
if(CMP0168 STREQUAL "NEW" AND EXISTS ${CMAKE_CURRENT_BINARY_DIR}/t1-subbuild)
  message(FATAL_ERROR "t1 sub-build used when expected direct population")
elseif(CMP0168 STREQUAL "OLD" AND NOT EXISTS ${CMAKE_CURRENT_BINARY_DIR}/t1-subbuild)
  message(FATAL_ERROR "t1 used direct population when a sub-build was expected")
endif()

FetchContent_Populate(
  t2
  SOURCE_DIR       ${CMAKE_CURRENT_BINARY_DIR}/mysrc
  DOWNLOAD_COMMAND ${CMAKE_COMMAND} -E copy
                   ${CMAKE_CURRENT_BINARY_DIR}/tmpFile.txt
                   <SOURCE_DIR>/done2.txt
)
if(NOT EXISTS ${CMAKE_CURRENT_BINARY_DIR}/mysrc/done2.txt)
  message(FATAL_ERROR "Specified SOURCE_DIR doesn't contain done2.txt")
endif()
if(CMP0168 STREQUAL "NEW" AND EXISTS ${CMAKE_CURRENT_BINARY_DIR}/t2-subbuild)
  message(FATAL_ERROR "t2 sub-build used when expected direct population")
elseif(CMP0168 STREQUAL "OLD" AND NOT EXISTS ${CMAKE_CURRENT_BINARY_DIR}/t2-subbuild)
  message(FATAL_ERROR "t2 used direct population when a sub-build was expected")
endif()

FetchContent_Populate(
  t3
  SOURCE_DIR       myrelsrc
  DOWNLOAD_COMMAND ${CMAKE_COMMAND} -E copy
                   ${CMAKE_CURRENT_BINARY_DIR}/tmpFile.txt
                   <SOURCE_DIR>/done3.txt
)
if(NOT EXISTS ${CMAKE_CURRENT_BINARY_DIR}/myrelsrc/done3.txt)
  message(FATAL_ERROR "Relative SOURCE_DIR doesn't contain done3.txt")
endif()
if(CMP0168 STREQUAL "NEW" AND EXISTS ${CMAKE_CURRENT_BINARY_DIR}/t3-subbuild)
  message(FATAL_ERROR "t3 sub-build used when expected direct population")
elseif(CMP0168 STREQUAL "OLD" AND NOT EXISTS ${CMAKE_CURRENT_BINARY_DIR}/t3-subbuild)
  message(FATAL_ERROR "t3 used direct population when a sub-build was expected")
endif()