Hello Autoconf patchers,
We have hit another bug in HEAD Libtool, for which we could use help
from Autoconf.
This is the setting: a third-party package (GraphicsMagick) that uses
libltdl in nonrecursive mode in a nonrecursive Makefile[1]. In this
Makefile, the library is given as
noinst_LTLIBRARIES = ltdl/libltdlc.la
however the dependency is given upon
LIBLTDL = ${top_builddir}/ltdl/libltdl.la
and in this case, top_builddir is `.'. LIBLTDL is computed as a
substitution of @LIBLTDL@ at configure time.
Now, AIX make (and others) fail to identify `./file' with `file' so the
build fails. It would be nice if Autoconf also substituted a variable
top_build_prefix that contained of zero or more runs of `../' and
otherwise behaved like top_builddir. The naming is not coincidental:
config.status already computes this value, it just doesn't make it
available.
This would make writing these kinds of things much easier also in
Automake, which has lots of special-cases of the kind
if ($directory ne '')
{
$object = $directory . '/' . $object;
}
Note that top_build_prefix cannot replace top_builddir: the former
requires the user _not_ to add a slash as separator.
[1] Yes, this is yet another instance where nonrecursive makefiles are
more difficult to realize for non-GNU makes.
Cheers,
Ralf
New config files output variable `top_build_prefix'.
* lib/autoconf/status.m4 (_AC_OUTPUT_FILE): Substitute
`top_build_prefix'.
* doc/autoconf.texi (Preset Output Variables): Document it.
* NEWS: Update.
Report by Bob Friesenhahn.
diff --git a/NEWS b/NEWS
index 77cd6f5..854c54a 100644
--- a/NEWS
+++ b/NEWS
@@ -13,6 +13,8 @@ GNU Autoconf NEWS - User visible changes.
Further, for config headers, the total size of values is not limited by
the POSIX length limit of text lines any more, only each single line.
+** New config variable `top_build_prefix'.
+
** Autoconf is now licensed under the General Public License version 3
or later (GPLv3+). As with earlier versions, the license includes
an exception clause so that you may release a configure script
diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 9025359..421056e 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -2436,6 +2436,16 @@ The relative name of the top level of the current build
tree. In the
top-level directory, this is the same as @code{builddir}.
@end defvar
[EMAIL PROTECTED] top_build_prefix
[EMAIL PROTECTED] top_build_prefix
+The relative name of the top level of the current build tree with final
+slash if nonemtpy. This is the same as @code{top_builddir}, except that
+it contains of zero of more runs of @code{../}, so it should not be
+appended with a slash for concatenation. This helps for @command{make}
+implementations that otherwise do not treat @file{./file} and @file{file}
+as equal in the toplevel build directory.
[EMAIL PROTECTED] defvar
+
@defvar abs_top_builddir
@ovindex abs_top_builddir
Absolute name of @code{top_builddir}.
diff --git a/lib/autoconf/status.m4 b/lib/autoconf/status.m4
index 350d370..4412df0 100644
--- a/lib/autoconf/status.m4
+++ b/lib/autoconf/status.m4
@@ -622,6 +622,7 @@ dnl configure_input is a somewhat special, so we don't call
AC_SUBST_TRACE.
s&@configure_input@&$configure_input&;t t
dnl During the transition period, this is a special case:
s&@top_builddir@&$ac_top_builddir_sub&;t t[]AC_SUBST_TRACE([top_builddir])
+s&@top_build_prefix@&$ac_top_build_prefix&;t
t[]AC_SUBST_TRACE([top_build_prefix])
m4_foreach([_AC_Var], [srcdir, abs_srcdir, top_srcdir, abs_top_srcdir,
builddir, abs_builddir,
abs_top_builddir]AC_PROVIDE_IFELSE([AC_PROG_INSTALL],
[[, INSTALL]])AC_PROVIDE_IFELSE([AC_PROG_MKDIR_P], [[, MKDIR_P]]),
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