On 29 January 2015 at 15:38, Thiago Macieira <thi...@macieira.org> wrote: > On Thursday 29 January 2015 15:30:43 Lubomir I. Ivanov wrote: >> this is what i would do: >> ----------------- >> >> all: main.exe >> >> .PHONY: persist >> >> version.h: persist >> cat $@ 2> /dev/null || git rev-parse HEAD > $@ >> git rev-parse HEAD > $@.tmp >> git diff --quiet $@ $@.tmp || cp $@.tmp $@ >> rm -f $@.tmp >> >> main.o: main.c version.h >> gcc -c main.c -o main.o >> >> main.exe: main.o >> gcc main.o -o main.exe >> >> ------------------- >> >> what it does is, it writes the output of "git rev-parse" to a TMP file >> and if that TMP file differs to the previous version.h file it updates >> version.h >> but since version.h may not change, main is not recompiled. > > The way I read this, persist is phony, so it will always be found to be out- > of-date. Therefore, version.h is always out of date, so is main.o and > therefore main.exe will too. > > Are you saying that if the version.h command doesn't actually touch version.h, > then Make does not find it to be out of date? >
it works for me, version.h is not updated with "persist", because the diff fails. and main.o is only recompiled if i change the HEAD (e.g. add a commit, change branch etc..). but i may be missing something. lubomir -- _______________________________________________ subsurface mailing list subsurface@subsurface-divelog.org http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface
