add_custom_command(OUTPUT output1 [output2 ...]
  COMMAND command1 [ARGS] [args1...]
  [COMMAND command2 [ARGS] [args2...] ...]
  [MAIN_DEPENDENCY depend]
  [DEPENDS [depends...]]
  [BYPRODUCTS [files...]]
  [IMPLICIT_DEPENDS <lang1> depend1
  [<lang2> depend2] ...]
  [WORKING_DIRECTORY dir]
  [COMMENT comment]
  [DEPFILE depfile]
  [JOB_POOL job_pool]
  [JOB_SERVER_AWARE <bool>]
  [VERBATIM] [APPEND] [USES_TERMINAL]
  [COMMAND_EXPAND_LISTS]
[DEPENDS_EXPLICIT_ONLY])