Re: Dynamic rules : $< and $@ empty?

[Paul D. Smith]

%% Jon Chatten <address@hidden> writes:

  jc> Hi,
  jc> I'm using GNU make 3.80 on Windows, but am having some
  jc> issues with Dynamic Rules.  This is probably down to
  jc> my own misunderstanding, but consider the following
  jc> (contrived!  I do have a reason for trying this :-))
  jc> example:


  jc> ALL : TEST

  jc> define test-rule
  jc> $(1)/%.o : %.c
  jc>   @echo test-rule
  jc>   @echo Arg 1 : $(1)
  jc>   @echo Target : $@
  jc>   @echo Dependent : $<
  jc> endef

  jc> TEST : bin/File.o
  jc> bin/File.o : File.c

  jc> $(eval $(call test-rule,bin))

  jc> Which leads me to believe the rule is created
  jc> correctly and invoked as you'd expect, but why are $<
  jc> and $@ empty?

Because call is evaluating them, and at that time they have no value.

You have to escape them ($$@ etc.) if you want the references to the
variable to survive into the eval step.

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