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# If possible, ignore libraries that are not depended on.
dnl Copyright (C) 2006, 2009 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
dnl Written by Paul Eggert.
AC_DEFUN([gl_IGNORE_UNUSED_LIBRARIES],
[
AC_CACHE_CHECK([for flag to ignore unused libraries],
[gl_cv_ignore_unused_libraries],
[gl_cv_ignore_unused_libraries=none
gl_saved_ldflags=$LDFLAGS
gl_saved_libs=$LIBS
# Link with -lm to detect binutils 2.16 bug with --as-needed; see
# <http://lists.gnu.org/archive/html/bug-gnulib/2006-06/msg00131.html>.
LIBS="$LIBS -lm"
# Use long option sequences like '-z ignore' to test for the feature,
# to forestall problems with linkers that have -z, -i, -g, -n, etc. flags.
# GCC + binutils likes '-Wl,--as-needed'.
# GCC + Solaris ld likes '-Wl,-z,ignore'.
# Sun C likes '-z ignore'.
# Don't try bare '--as-needed'; nothing likes it and the HP-UX 11.11
# native cc issues annoying warnings and then ignores it,
# which would cause us to incorrectly conclude that it worked.
for gl_flags in \
'-Wl,--as-needed' \
'-Wl,-z,ignore' \
'-z ignore'
do
LDFLAGS="$gl_flags $LDFLAGS"
AC_LINK_IFELSE([AC_LANG_PROGRAM()],
[gl_cv_ignore_unused_libraries=$gl_flags])
LDFLAGS=$gl_saved_ldflags
test "$gl_cv_ignore_unused_libraries" != none && break
done
LIBS=$gl_saved_libs])
test "$gl_cv_ignore_unused_libraries" != none &&
LDFLAGS="$LDFLAGS $gl_cv_ignore_unused_libraries"
])
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