SZEDER Gábor <szeder.dev@xxxxxxxxx> writes: > The rules creating the $(LIB_FILE) and $(XDIFF_LIB) archives used to > be: > > $(QUIET_AR)$(RM) $@ && $(AR) $(ARFLAGS) $@ $^ > > until commit 7b76d6bf22 (Makefile: add and use the ".DELETE_ON_ERROR" > flag, 2021-06-29) removed the '$(RM) $@' part, claiming that "we can > rely on the "c" (create) being present in ARFLAGS", and (I presume) > assuming that it means that the named archive is created from scratch. > > Unfortunately, that's not what the 'c' flag does, it merely "Suppress > the diagnostic message that is written to standard error by default > when the archive is created" [1]. Consequently, all object files that > are already present in an existing archive and are not replaced will > remain there. This leads to linker errors in back-to-back builds of > different revisions without a 'make clean' between them if source > files going into these archives are renamed in between: > > # The last commit renaming files that go into 'libgit.a': > # bc62692757 (hash-lookup: rename from sha1-lookup, 2020-12-31) > # sha1-lookup.c => hash-lookup.c | 14 +++++++------- > # sha1-lookup.h => hash-lookup.h | 12 ++++++------ > $ git checkout bc62692757^ > HEAD is now at 7a7d992d0d sha1-lookup: rename `sha1_pos()` as `hash_pos()` > $ make > [...] > $ git checkout 7b76d6bf22 > HEAD is now at 7b76d6bf22 Makefile: add and use the ".DELETE_ON_ERROR" flag > $ make > [...] > AR libgit.a > LINK git > /usr/bin/ld: libgit.a(hash-lookup.o): in function `bsearch_hash': > /home/szeder/src/git/hash-lookup.c:105: multiple definition of `bsearch_hash'; libgit.a(sha1-lookup.o):/home/szeder/src/git/sha1-lookup.c:105: first defined here > collect2: error: ld returned 1 exit status > make: *** [Makefile:2213: git] Error 1 > > Restore the original make rules to first remove $(LIB_FILE) and > $(XDIFF_LIB) and then create them from scratch to avoid these build > errors. Thanks. I think I've seen a similar breakage around hook.o but didn't dig into it. Will queue. > > [1] Quoting POSIX at: > https://pubs.opengroup.org/onlinepubs/9699919799/utilities/ar.html > > Signed-off-by: SZEDER Gábor <szeder.dev@xxxxxxxxx> > --- > Makefile | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/Makefile b/Makefile > index 157293b555..20a0fe6e88 100644 > --- a/Makefile > +++ b/Makefile > @@ -2594,10 +2594,10 @@ $(REMOTE_CURL_PRIMARY): remote-curl.o http.o http-walker.o GIT-LDFLAGS $(GITLIBS > $(CURL_LIBCURL) $(EXPAT_LIBEXPAT) $(LIBS) > > $(LIB_FILE): $(LIB_OBJS) > - $(QUIET_AR)$(AR) $(ARFLAGS) $@ $^ > + $(QUIET_AR)$(RM) $@ && $(AR) $(ARFLAGS) $@ $^ > > $(XDIFF_LIB): $(XDIFF_OBJS) > - $(QUIET_AR)$(AR) $(ARFLAGS) $@ $^ > + $(QUIET_AR)$(RM) $@ && $(AR) $(ARFLAGS) $@ $^ > > export DEFAULT_EDITOR DEFAULT_PAGER
