pipe: Set errno upon failure.

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

diff --git a/m4/lib-ignore.m4 b/m4/lib-ignore.m4
index 348f6f4..0236cb5 100644 (file)
--- a/m4/lib-ignore.m4
+++ b/m4/lib-ignore.m4
@@ -1,6 +1,6 @@
 # If possible, ignore libraries that are not depended on.
 
-dnl Copyright (C) 2006 Free Software Foundation, Inc.
+dnl Copyright (C) 2006, 2009-2010 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.
@@ -13,15 +13,30 @@ 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="$LIBS -lm"
      # Use long option sequences like '-z ignore' to test for the feature,
      # to forestall problems with linkers that have -z, -i, -g, -n, etc. flags.
-     for gl_flags in '-Wl,-z,ignore' '-z ignore'; do
+     # GCC + binutils likes '-Wl,--as-needed'.
+     # GCC + Solaris ld likes '-Wl,-z,ignore'.
+     # Sun C likes '-z ignore'.
+     # Don't try bare '--as-needed'; nothing likes it and the HP-UX 11.11
+     # native cc issues annoying warnings and then ignores it,
+     # which would cause us to incorrectly conclude that it worked.
+     for gl_flags in \
+        '-Wl,--as-needed' \
+        '-Wl,-z,ignore' \
+        '-z ignore'
+     do
        LDFLAGS="$gl_flags $LDFLAGS"
        AC_LINK_IFELSE([AC_LANG_PROGRAM()],
-        [gl_cv_ignore_unused_libraries=$gl_flags])
+         [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"