# Run at build time (cmake -P): writes keel_version.h from git — the commit, its date, and
# whether the tree had changes. Not __DATE__: Nix's build shell pins SOURCE_DATE_EPOCH to 1980
# (reproducible builds), and that's what the compiler's date said.
execute_process(COMMAND git -C ${SRC} log -1 --format=%h OUTPUT_VARIABLE commit OUTPUT_STRIP_TRAILING_WHITESPACE ERROR_QUIET)
execute_process(COMMAND git -C ${SRC} log -1 --format=%cd --date=format:%Y-%m-%d\ %H:%M OUTPUT_VARIABLE date OUTPUT_STRIP_TRAILING_WHITESPACE ERROR_QUIET)
execute_process(COMMAND git -C ${SRC} status --porcelain --untracked-files=no OUTPUT_VARIABLE dirty OUTPUT_STRIP_TRAILING_WHITESPACE ERROR_QUIET)
if(NOT commit)
  set(commit "unknown")
  set(date "unknown")
endif()
if(dirty)
  set(commit "${commit}+changes")
endif()
set(text "#pragma once\n#define KEEL_COMMIT \"${commit}\"\n#define KEEL_COMMIT_DATE \"${date}\"\n")
if(EXISTS ${OUT})
  file(READ ${OUT} old)
endif()
if(NOT "${old}" STREQUAL "${text}")
  file(WRITE ${OUT} "${text}")
endif()