Re: Meaning of @:

[David Boyce]

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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