(gl_IGNORE_UNUSED_LIBRARIES):

Use -Wl,--as-needed, not bare --as-needed, since HP-UX 11.11
cc merely issues a bunch of annoying warnings for --as-needed
(this problem was reported by Bob Proulx).  Also, try linking with
-lm to detect a bug in binutils 2.16 (this problem was reported
by Ralf Wildenhues).

1 files changed, 12 insertions, 2 deletions

diff --git a/m4/lib-ignore.m4 b/m4/lib-ignore.m4
index deaaee8e6..e518f8113 100644
--- a/m4/lib-ignore.m4
+++ b/m4/lib-ignore.m4
@@ -13,12 +13,21 @@ AC_DEFUN([gl_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="$LIBS -lm"
      # Use long option sequences like '-z ignore' to test for the feature,
      # to forestall problems with linkers that have -z, -i, -g, -n, etc. flags.
+     # GCC + binutils likes '-Wl,--as-needed'.
+     # GCC + Solaris ld likes '-Wl,-z,ignore'.
+     # Sun C likes '-z ignore'.
+     # Don't try bare '--as-needed'; nothing likes it and the HP-UX 11.11
+     # native cc issues annoying warnings and then ignores it,
+     # which would cause us to incorrectly conclude that it worked.
      for gl_flags in \
 	'-Wl,--as-needed' \
 	'-Wl,-z,ignore' \
-	'--as-needed' \
 	'-z ignore'
      do
        LDFLAGS="$gl_flags $LDFLAGS"
@@ -26,7 +35,8 @@ AC_DEFUN([gl_IGNORE_UNUSED_LIBRARIES],
 	 [gl_cv_ignore_unused_libraries=$gl_flags])
        LDFLAGS=$gl_saved_ldflags
        test "$gl_cv_ignore_unused_libraries" != none && break
-     done])
+     done
+     LIBS=$gl_saved_libs])
 
   test "$gl_cv_ignore_unused_libraries" != none &&
     LDFLAGS="$LDFLAGS $gl_cv_ignore_unused_libraries"