In my makefile I accumulate option values in variable hopc.
Running the makefile as follows results in
make -f antares.mk split=node trlfn ndf sm
make: *** No rule to make target 'trlfn'. Stop.
How can I avoid the problem with trlfn and ndf?
hopc :=
ifneq ($(css),)
hopc += --css-include=$(css)
endif
ifneq ($(css-ref),)
hopc += --css-ref=$(css-ref)
endif
ifneq ($(links),)
hopc += --internal-links=$(links)
endif
ifneq ($(split),)
hopc += --split=$(split)
endif
ifneq ($(trlfn),)
hopc += --transliterate-file-names
endif
ifneq ($(ndf),)
hopc += --node-files
endif
$(hmldir)/antares.html: $(srcs) | $$(@D)
makeinfo $(opts) --html $(hopc) -o $@ $<
