-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 According to Jim Meyering on 9/22/2009 7:08 AM: > At first I wondered why it would be necessary to unlink sym, a file > named "conftest.sym" here, when right after this test, the usual > rm -fr conftest* would remove it for us? Then I looked, and see > that what I recalled is no longer the case. While in some places, > autoconf-generated configure files do indeed run > > rm -f conftest* > > it's not run after this sort of test. > Here, this is what's (now?) run: > > rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext \ > conftest.$ac_objext conftest.beam conftest.$ac_ext > > and that doesn't remove the carefully-named temporary file.
I think autoconf has always tried to only remove compiler files at the end of AC_*_IFELSE, leaving other files in place in case subsequent shell code needed to inspect the contents of the file. In other words, I don't think the rm -f conftest.* done by autoconf has ever been done throughout the configure script, but only once at the end. > Has autoconf changed this over the years? I'd have to research it further for a definitive answer, but if it changed, it was years ago. > Or is this accidental fall-out from some other change? I think this particular failure case has been latent, and was only recently exposed due to my change in semantics to link-follow.m4 to swap the sense of success. It used to be that failure to run the link-follow test was considered as success for the cache variable, while success in running the code set LINK_FOLLOWS_SYMLINK to nonzero; but now that we know we _want_ link that does not follow symlink, I reordered the test earlier this month, and that's where the latent use of conftest.sym finally changed the sense of the test on Linux. > I don't have time to investigate right now, > but will eventually audit for other assumptions like this. A good rule of thumb in writing autoconf macros is to clean up any files you directly created, which are unrelated to compiler side-effects. - -- Don't work too hard, make some time for fun as well! Eric Blake e...@byu.net -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (Cygwin) Comment: Public key at home.comcast.net/~ericblake/eblake.gpg Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkq5d/QACgkQ84KuGfSFAYCT9wCfeajOL82U58IzqtqCR58BE7oa LzEAn2nqXm1iy8ySkOOhiHSrQIKXg36C =Kb2n -----END PGP SIGNATURE-----
