make_subcommands_cache

# http://qiita.com/ToQoz/items/848abdf90a0f40e70ce0
# http://stackoverflow.com/questions/3063507/list-goals-targets-in-gnu-make/9524878#9524878
_makefile_cache_updated_at() {
  echo $(stat .make_targets -c%Y)
}
_makefile_updated_at() {
  echo $(stat Makefile -c%Y)
}
_generate_makefile_cache() {
  [ -f .make_targets ] && rm .make_targets
  make -qp | awk -F':' '/^[a-zA-Z0-9][^$#\/\t=]*:([^=]|$)/ {split($1,A,/ /);for(i in A)print A[i]}' > .make_targets
}
_make() {
  if [ -f Makefile ]; then
    if [ ! -f .make_targets ] || \
       [ "`cat .make_targets | wc -l`" = "0" ] || \
       [ `_makefile_cache_updated_at` -lt `_makefile_updated_at` ] || \
       [ -f Makefile -a `_makefile_cache_updated_at` -lt `_makefile_updated_at` ]; then
      _generate_makefile_cache
    fi
    compadd `cat .make_targets`
  fi
}
compdef _make make