Re: Meaning of @:

[Ewan Delanoy]

   If I understand correctly, the $(MAKE) after the colon will never get
   executed, so
   there's no point in putting it there (except perhaps as a somewhat
   cryptic comment)




   Envoyé: jeudi 26 novembre 2015 à 14:03
   De: "David Boyce" <address@hidden>
   À: "Ewan Delanoy" <address@hidden>
   Cc: help-make <address@hidden>
   Objet: Re: Meaning of @:
   The colon is not a make feature at all but a shell construct. It’s a
   “do-nothing” command; the result is similar to commenting out the
   line, except that in this case the $(unstage) action would still take
   place since it’s separated by a semicolon.
   BTW this is a badly written makefile because “;” should almost never
   be used in a make recipe since it throws away exit status. A good
   recipe uses && to separate commands which might fail. Consider the
   canonical typo example: “cd /tmpp; rm -rf *” vs “cd /tmpp && rm -rf
   *”.
   On Thu, Nov 26, 2015 at 4:55 AM, Ewan Delanoy <address@hidden>
   wrote:
   >
   >
   > Below is the "bootstrap" rule in gcc5.2.0's Makefile. What I don't
   > get is the meaning
   > of the @: at the beginning of the seventh line. I couldn't find it in
   > the manual.
   > I only know that @ before a shell command makes that command executed
   > but not displayed,
   > but why add the : ?
   >
   >
   > .PHONY: bootstrap bootstrap-lean
   > bootstrap:
   > echo stage3 > stage_final
   > @r=`${PWD_COMMAND}`; export r; \
   > s=`cd $(srcdir); ${PWD_COMMAND}`; export s; \
   > $(MAKE) $(RECURSE_FLAGS_TO_PASS) stage3-bubble
   > @: $(MAKE); $(unstage)
   > @r=`${PWD_COMMAND}`; export r; \
   > s=`cd $(srcdir); ${PWD_COMMAND}`; export s; \
   > TFLAGS="$(STAGE3_TFLAGS)"; \
   > $(MAKE) $(TARGET_FLAGS_TO_PASS) all-host all-target
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References

   1. https://lists.gnu.org/mailman/listinfo/help-make