Re: Problem with symlinks and VPATH Builds

[Paul Eggert]

> From: "Mark D. Roth" <address@hidden>
> Date: Sat, 20 Jul 2002 20:31:13 -0500
> 
> I've attached a patch that does this.  It passes the test suite, so if
> I don't hear any objections in the next couple of days, I'll commit
> this to CVS.

I don't like this patch, for two reasons:

  * The output of "/bin/pwd" is often much uglier than the output of
    "pwd" (or $PWD).

  * Sometimes /bin/pwd fails when plain pwd would succeed.  Here's
    a contrived example:

          $ cd /tmp
          $ mkdir -p d/e
          $ cd d/e
          $ chmod 0 /tmp/d
          $ pwd
          /tmp/d/e
          $ /bin/pwd
          pwd: cannot determine current directory!

    More-realistic examples are quite common in practice.

I think this may help explain why "/bin/pwd" doesn't occur anywhere in
the existing Autoconf sources.  I'd rather avoid "/bin/pwd" if I can.

I went back to your original message
<http://mail.gnu.org/pipermail/autoconf/2002-July/013682.html>
and I could not reproduce the problem with autoconf 2.53 and Solaris 8
sparc, so I think there may be something else going on here.  Perhaps
the bug is somewhere else, and is not in Autoconf.

Here's how I tried to reproduce the problem.  I created the following
shell script and called it "/tmp/doit":

        R=/tmp # root directory
        cd $R || exit
        rm -fr projects usr
        mkdir -p projects/encap-src/psg/common
        mkdir -p projects/encap-src/psg/sparc-solaris8
        mkdir -p usr/local
        ln -s $R/projects/encap-src/psg/sparc-solaris8 usr/local/src

        (cd projects/encap-src/psg/common
         mkdir dummy-0.1
         cd dummy-0.1
         touch dummy.c Makefile.in
         cat >configure.ac <<'EOF'
        AC_INIT([dummy], [0.1])
        AC_CONFIG_HEADERS([config.h])
        AC_CONFIG_SRCDIR([dummy.c])
        AC_PROG_CC
        AC_CONFIG_FILES([Makefile])
        AC_OUTPUT
        EOF
         autoconf
         autoheader
        )

        (cd usr/local/src
         mkdir dummy-0.1
         cd dummy-0.1
         ../../common/dummy-0.1/configure
        )

I then ran "sh -x /tmp/doit", with the following results:

        R=/tmp
        + cd /tmp 
        + rm -fr projects usr 
        + mkdir -p projects/encap-src/psg/common 
        + mkdir -p projects/encap-src/psg/sparc-solaris8 
        + mkdir -p usr/local 
        + ln -s /tmp/projects/encap-src/psg/sparc-solaris8 usr/local/src 
        + cd projects/encap-src/psg/common 
        + mkdir dummy-0.1 
        + cd dummy-0.1 
        + touch dummy.c Makefile.in 
        + cat 
        + autoconf 
        + autoheader 
        autoheader: `config.h.in' is created
        + cd usr/local/src 
        + mkdir dummy-0.1 
        + cd dummy-0.1 
        + ../../common/dummy-0.1/configure 
        checking for gcc... gcc
        checking for C compiler default output... a.out
        checking whether the C compiler works... yes
        checking whether we are cross compiling... no
        checking for suffix of executables... 
        checking for suffix of object files... o
        checking whether we are using the GNU C compiler... yes
        checking whether gcc accepts -g... yes
        configure: creating ./config.status
        config.status: creating Makefile
        config.status: creating config.h

I did not see the failure that you reported.