# util.mk - Miscellaneous utility functions for use in Makefiles
# Throws an error if the value of the variable named by $(1) is not in the list given by $(2)
define validate-option
# value must be part of the list
ifeq ($$(filter $($(1)),$(2)),)
$$(error Value of $(1) must be one of the following: $(2))
endif
# value must be a single word (no whitespace)
ifneq ($$(words $($(1))),1)
$$(error Value of $(1) must be one of the following: $(2))
endif
endef
# Returns the path to the command $(1) if exists. Otherwise returns an empty string.
find-command = $(shell which $(1) 2>/dev/null)
