Bug in libtoolize

[Jeff Squyres]

I have found a bug in libtoolize which has bit me for a long, long time 
but I've never gotten around to checking it out (it was a minor 
annoyance).  But today, it bit one of my other developers in a rather 
awkward moment.  So I guess it's time to investigate and report this 
bug.  :-)

The problem is with "libtoolize --copy --ltdl".  libtoolize makes the 
subdirectory libltdl/ and copies all the relevant files over.  However, 
the problem is that it simply globs the files from the source directory 
and then copies them over one-by-one.  This can violate the strict 
ordering of files required by Automake and can cause needless 
re-building of files, even after a successful run of libltdl's 
"configure" script.

In my developer's case, the following happened:

------
libtoolize --copy --ltdl
cd libltdl
./configure .....
[configure runs successfully]
make -d
------

Here's the end of the output from "make -d":

-----
     No need to remake target `configure.ac'.
     Considering target file `aclocal.m4'.
       Pruning file `acinclude.m4'.
       Pruning file `configure.ac'.
      Finished prerequisites of target file `aclocal.m4'.
      Prerequisite `acinclude.m4' is older than target `aclocal.m4'.
      Prerequisite `configure.ac' is newer than target `aclocal.m4'.
     Must remake target `aclocal.m4'.
cd . && /bin/bash [/path/to]/libltdl/missing --run aclocal-1.8
-----

Doh!  That shouldn't be!

Checking the fine-grained timestamps, we can see that yes, indeed, 
acinclude.m4 is older than aclocal.m4.  So let's try a controlled 
experiment:

-----
$ rm -rf libltdl
$ libtoolize --automake --copy --ltdl
$ cd libltdl/
$ /usr/local/gnu/bin/ls --full-time ac*
-rw-r--r--  1 jsquyres lam 226073 2005-02-15 18:48:58.458929000 -0500 
acinclude.m4
-rw-r--r--  1 jsquyres lam  35379 2005-02-15 18:48:58.478986000 -0500 
aclocal.m4
-----

Yowza!

Looking in the code for libtoolize (v1.5.14), I see the following:

-----
if test "x$ltdl" = xyes; then
  test -d libltdl || $mkdir libltdl
  ltdlfiles=`cd $pkgdatadir && ls libltdl/*`
else
  ltdlfiles=
fi

for file in $ltdlfiles; do
  if test -f "$file" && test -z "$force"; then
    test -z "$automake" && echo "$progname: \`$file' exists: use 
\`--force' to overwrite" 1>&2
    continue
  fi

  $rm $file
  if test -n "$ln_s" && $ln_s $pkgdatadir/$file $file; then :
  elif $cp $pkgdatadir/$file $file; then :
  else
    echo "$progname: cannot copy \`$pkgdatadir/$file' to \`$file'" 1>&2
    status=1
  fi
done
-----

This quite definitely does not honor any ordering of the copy -- so the 
dependencies that Automake sets up in its Makefiles are potentially 
going to be violated (as it is in my case).

Some suggestions for a fix:

1. Do the copy as now, but then have a series of "touch" statements to 
modify the mtime/ctime all the relevant AM-specific files in the Right 
Order so that the timestamps will be proper.

2. Copy the files over in order in the first place (i.e., don't use a 
glob).

3. Tar up the source directory and untar it in the destination.

Each of the three has benefits and drawbacks -- I guess I'd lean 
towards #1.  It's probably the least elegant, but it guarantees to get 
it Right with the least amount of work.

Thanks!

--
{+} Jeff Squyres
{+} address@hidden
{+} http://www.lam-mpi.org/