Sync from coreutils.

[gnulib.git] / m4 / lib-ignore.m4

diff --git a/m4/lib-ignore.m4 b/m4/lib-ignore.m4
new file mode 100644 (file)
index 0000000..319cf98
--- /dev/null
+++ b/m4/lib-ignore.m4
@@ -0,0 +1,43 @@
+# If possible, ignore libraries that are not depended on.
+
+dnl Copyright (C) 2006 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
+     AC_LINK_IFELSE([AC_LANG_PROGRAM()],
+       [gl_ldd_output0=`(ldd conftest$ac_exeext) 2>/dev/null` ||
+         gl_ldd_output0=])
+     if test "$gl_ldd_output0"; then
+       gl_saved_ldflags=$LDFLAGS
+       gl_saved_libs=$LIBS
+       LIBS="$LIBS -lm"
+       AC_LINK_IFELSE([AC_LANG_PROGRAM()],
+        [gl_ldd_output1=`(ldd conftest$ac_exeext) 2>/dev/null` ||
+           gl_ldd_output1=])
+       if test "$gl_ldd_output1" && test "$gl_ldd_output0" != "$gl_ldd_output1"
+       then
+        for gl_flags in '-Xlinker -zignore' '-zignore'; do
+          LDFLAGS="$gl_flags $LDFLAGS"
+          AC_LINK_IFELSE([AC_LANG_PROGRAM()],
+            [if gl_ldd_output2=`(ldd conftest$ac_exeext) 2>/dev/null` &&
+                test "$gl_ldd_output0" = "$gl_ldd_output2"; then
+               gl_cv_ignore_unused_libraries=$gl_flags
+             fi])
+          LDFLAGS=$gl_saved_ldflags
+          test "gl_cv_ignore_unused_libraries" != none && break
+        done
+       fi
+       LIBS=$gl_saved_LIBS
+     fi])
+
+  test "$gl_cv_ignore_unused_libraries" != none &&
+    LDFLAGS="$LDFLAGS $gl_cv_ignore_unused_libraries"
+])