On 06/06/2016 14:50, Eduardo Habkost wrote: > # Makes the definition constant after the first expansion > DOCKER_SRC_COPY = $(eval DOCKER_SRC_COPY := > docker-src.$(CUR_TIME))$(DOCKER_SRC_COPY) > > $(shell echo DEBUG: src_copy: $(DOCKER_SRC_COPY) >&2) > > $(DOCKER_SRC_COPY): > @mkdir $@ > $(call make-archive-maybe, $(SRC_PATH), $@/qemu.tgz) > > and I still get a failure: https://travis-ci.org/ehabkost/qemu/jobs/135574871 > > $ make -j3 && ${TEST_CMD} > DEBUG: cur_time: 2016.13278 > /home/travis/build/ehabkost/qemu/tests/docker/Makefile.include:37: *** > unterminated variable reference. Stop. > > I am very confused by that code: using "=" to make a variable > reference itself is not allowed, but in this case no error is > reported because of the $(eval) trick. I have no idea what will > happen the second time the variable is expanded. Isn't $(eval) > going to be expanded again?
No, the second time you'll get the expansion of DOCKER_SRC_COPY := docker-src.$(CUR_TIME) > Why did you use this trick instead of just relying on ":=" to > expand the shell command only once? I think initially the $(mkdir) was in DOCKER_SRC_COPY too. Also, too many $(shell) end up slowing down make. Paolo
