configure: try to use -Wl,--as-needed if possible

This may be useful if net-snmp-config pulls a lot of dependencies
which are not really needed (like libperl, libpthread, libcrypto).

diff --git a/configure.ac b/configure.ac
index 6b0816680a3cd3259702affffdb867dce2ebfaaf..97dd94e0549cdc8eb0c943aab4989a8a0055fe71 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -50,6 +50,8 @@ AX_CFLAGS_GCC_OPTION([-D_FORTIFY_SOURCE=2])
 AX_CFLAGS_GCC_OPTION([-Wno-unused-parameter])
 AX_CFLAGS_GCC_OPTION([-Wno-sign-compare]) dnl Should be fixed later
 
+AX_LDFLAGS_OPTION([-Wl,--as-needed])
+
 AC_CACHE_SAVE
 
 # Checks for header files.

diff --git a/m4/ax_ld_check_flag.m4 b/m4/ax_ld_check_flag.m4
new file mode 100644 (file)
index 0000000..2f560c6
--- /dev/null
+++ b/m4/ax_ld_check_flag.m4
@@ -0,0 +1,97 @@
+# ===========================================================================
+#     http://www.gnu.org/software/autoconf-archive/ax_ld_check_flag.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_LD_CHECK_FLAG(FLAG-TO-CHECK,[PROLOGUE],[BODY],[ACTION-IF-SUCCESS],[ACTION-IF-FAILURE])
+#
+# DESCRIPTION
+#
+#   This macro tests if the C++ compiler supports the flag FLAG-TO-CHECK. If
+#   successfull execute ACTION-IF-SUCCESS otherwise ACTION-IF-FAILURE.
+#   PROLOGUE and BODY are optional and should be used as in AC_LANG_PROGRAM
+#   macro.
+#
+#   Example:
+#
+#     AX_LD_CHECK_FLAG([-Wl,-L/usr/lib],[],[],[
+#       ...
+#     ],[
+#       ...
+#     ])
+#
+#   This code is inspired from KDE_CHECK_COMPILER_FLAG macro. Thanks to
+#   Bogdan Drozdowski <bogdandr@op.pl> for testing and bug fixes.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Francesco Salvestrini <salvestrini@users.sourceforge.net>
+#
+#   This program is free software; you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by the
+#   Free Software Foundation; either version 2 of the License, or (at your
+#   option) any later version.
+#
+#   This program is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+#   Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License along
+#   with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+#   As a special exception, the respective Autoconf Macro's copyright owner
+#   gives unlimited permission to copy, distribute and modify the configure
+#   scripts that are the output of Autoconf when processing the Macro. You
+#   need not follow the terms of the GNU General Public License when using
+#   or distributing such scripts, even though portions of the text of the
+#   Macro appear in them. The GNU General Public License (GPL) does govern
+#   all other use of the material that constitutes the Autoconf Macro.
+#
+#   This special exception to the GPL applies to versions of the Autoconf
+#   Macro released by the Autoconf Archive. When you make and distribute a
+#   modified version of the Autoconf Macro, you may extend this special
+#   exception to the GPL to apply to your modified version as well.
+
+#serial 6
+
+AC_DEFUN([AX_LD_CHECK_FLAG],[
+  AC_PREREQ([2.61])
+  AC_REQUIRE([AC_PROG_CXX])
+  AC_REQUIRE([AC_PROG_SED])
+
+  flag=`echo "$1" | $SED 'y% .=/+-(){}<>:*,%_______________%'`
+
+  AC_CACHE_CHECK([whether the linker accepts the $1 flag],
+    [ax_cv_ld_check_flag_$flag],[
+
+    #AC_LANG_PUSH([C])
+
+    save_LDFLAGS="$LDFLAGS"
+    LDFLAGS="$LDFLAGS $1"
+    AC_LINK_IFELSE([
+      AC_LANG_PROGRAM([$2],[$3])
+    ],[
+      eval "ax_cv_ld_check_flag_$flag=yes"
+    ],[
+      eval "ax_cv_ld_check_flag_$flag=no"
+    ])
+
+    LDFLAGS="$save_LDFLAGS"
+
+    #AC_LANG_POP
+
+  ])
+
+  AS_IF([eval "test \"`echo '$ax_cv_ld_check_flag_'$flag`\" = yes"],[
+    :
+    $4
+  ],[
+    :
+    $5
+  ])
+])
+
+AC_DEFUN([AX_LDFLAGS_OPTION],[
+  AX_LD_CHECK_FLAG([$1],[],[],[LDFLAGS="$LDFLAGS $1"])])