# Utilities to produce errors inside Make
# Use this functions to produce friendlier error messages.

# Produce an error if the value is empty
#
# Parameters
#	value: a string which should not be empty
#	message: The error message to display.
# Returns:
#	the first argument, if it is not empty.
ensure_value = $(if $(1),$(1),$(error $(2)))

Add a function for checking that a string is not empty.
makefiles/utils: Add a function for checking that a string is not empty.

A call to `$(ensure_value x,y)` will fail with message y if x is empty, and
otherwise return x. This can be useto write more compact makefiles, while still
producing friendly error messages.
