# Cleaning directories generated during a previous build,
# a failed previous build or even no previous build.
# Track build directories through 'cleanfiles'.

define _enum-parent-dirs
$(if $(1),$(1) $(if $(filter / ./,$(dir $(1))),,$(call enum-parent-dirs,$(dir $(1)))),)
endef

define enum-parent-dirs
$(call _enum-parent-dirs,$(patsubst %/,%,$(1)))
endef

define _reverse
$(if $(1),$(call _reverse,$(wordlist 2,$(words $(1)),$(1)))) $(firstword $(1))
endef

# Returns the list of all existing output directories up to $(O) including all
# intermediate levels, in depth first order so that rmdir can process them in
# order. May return an empty string.
# Example: if cleanfiles is "foo/a/file1 foo/b/c/d/file2" and O=foo, this will
# return "foo/b/c/d foo/b/c foo/b foo/a" (assuming all exist).
define cleandirs-for-rmdir
$(eval _O:=$(if $(O),$(O),.))$(wildcard $(addprefix $(_O)/,$(call _reverse,
	$(sort $(foreach d,$(patsubst $(_O)/%,%,$(dir $(cleanfiles))),
			   $(call enum-parent-dirs,$(d)))))))
endef