cygwin 1.5.20 introduced a static-only stub libdl.a so that users porting code
that linked against -ldl would not have to change their compilation. But dlopen
() was already available in cygwin1.dll, without ever having to fall back on
the crutch of -ldl. However, libtool was assuming that if libdl existed, dlopen
() must come from -ldl, and that if libdl.a is static-only, then shared
libraries could no longer be build if they depended on dlopen(). This
assumption basically breaks libltdl on cygwin:
http://lists.gnu.org/archive/html/libtool/2006-07/msg00059.html
This fixed things for me (at least, by installing this patch, then
bootstrapping m4 on cygwin, I was once again able to pass the testsuite where
it had been failing ever since I upgraded cygwin from 1.5.19). Okay to apply?
2006-07-18 Eric Blake <[EMAIL PROTECTED]>
* libltdl/m4/ltdl.m4 (LT_LIB_DLLOAD): Search for dlopen without
depending on -ldl, required by cygwin 1.5.20.
Index: libltdl/m4/ltdl.m4
===================================================================
RCS file: /sources/libtool/libtool/libltdl/m4/ltdl.m4,v
retrieving revision 1.27
diff -u -b -r1.27 ltdl.m4
--- libltdl/m4/ltdl.m4 17 May 2006 20:11:03 -0000 1.27
+++ libltdl/m4/ltdl.m4 18 Jul 2006 21:32:20 -0000
@@ -1,5 +1,5 @@
# ltdl.m4 - Configure ltdl for the target system. -*-Autoconf-*-
-# Copyright (C) 1999-2005 Free Software Foundation, Inc.
+# Copyright (C) 1999-2006 Free Software Foundation, Inc.
#
# This file is free software; the Free Software Foundation gives
# unlimited permission to copy and/or distribute it, with or without
@@ -108,7 +108,7 @@
dnl not yet using an explicit LT_CONFIG_LTDL_DIR.
m4_ifval([$1], [_LT_CONFIG_LTDL_DIR([$1])])dnl
-AC_CHECK_LIB(ltdl, lt_dlinit,
+AC_CHECK_LIB([ltdl], [lt_dlinit],
[test x"$enable_ltdl_install" != xyes && enable_ltdl_install=no],
[if test x"$enable_ltdl_install" = xno; then
AC_MSG_WARN([libltdl not installed, but installation disabled])
@@ -515,10 +515,13 @@
AC_LANG_PUSH([C])
LIBADD_DLOPEN=
-AC_CHECK_LIB([dl], [dlopen],
+AC_SEARCH_LIBS([dlopen], [dl],
[AC_DEFINE([HAVE_LIBDL], [1],
[Define if you have the libdl library or equivalent.])
- LIBADD_DLOPEN="-ldl" libltdl_cv_lib_dl_dlopen="yes"
+ if test "$ac_cv_search_dlopen" != "none required" ; then
+ LIBADD_DLOPEN="-ldl"
+ fi
+ libltdl_cv_lib_dl_dlopen="yes"
LT_DLLOADERS="$LT_DLLOADERS ${lt_dlopen_dir+$lt_dlopen_dir/}dlopen.la"],
[AC_LINK_IFELSE([AC_LANG_PROGRAM([[#if HAVE_DLFCN_H
# include <dlfcn.h>
