Use gl_IGNORE_UNUSED_LIBRARIES

1 files changed, 115 insertions, 0 deletions

diff --git a/m4/lib-ignore.m4 b/m4/lib-ignore.m4
new file mode 100644
index 00000000..a67b002c
--- /dev/null
+++ b/m4/lib-ignore.m4
@@ -0,0 +1,115 @@
+# If possible, ignore libraries that are not depended on.
+
+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.
+
+dnl Written by Paul Eggert.
+
+# gl_IGNORE_UNUSED_LIBRARIES
+# --------------------------
+# Determines the option to be passed to the C/C++/Fortran compiler, so that it
+# omits unused libraries.
+# Example (on Solaris):
+# $ cc foo.c -lnsl; ldd ./a.out
+#         libnsl.so.1 =>   /lib/libnsl.so.1
+#         libc.so.1 =>     /lib/libc.so.1
+#         libmp.so.2 =>    /lib/libmp.so.2
+#         libmd.so.1 =>    /lib/libmd.so.1
+#         libscf.so.1 =>   /lib/libscf.so.1
+#         libdoor.so.1 =>  /lib/libdoor.so.1
+#         libuutil.so.1 =>         /lib/libuutil.so.1
+#         libgen.so.1 =>   /lib/libgen.so.1
+#         libm.so.2 =>     /lib/libm.so.2
+# $ cc foo.c -lnsl -Wl,-z,ignore; ldd ./a.out
+#         libc.so.1 =>     /lib/libc.so.1
+#         libm.so.2 =>     /lib/libm.so.2
+#
+# Note that the option works only for the C compiler, not for the C++
+# compiler:
+# - Sun C likes '-Wl,-z,ignore'.
+#   '-Qoption ld -z,ignore' is not accepted.
+#   '-z ignore' is accepted but has no effect.
+# - Sun C++ and Sun Fortran like '-Qoption ld -z,ignore'.
+#   '-Wl,-z,ignore' is not accepted.
+#   '-z ignore' is accepted but has no effect.
+#
+# Sets and substitutes a variable that depends on the current language:
+# - IGNORE_UNUSED_LIBRARIES_CFLAGS    for C
+# - IGNORE_UNUSED_LIBRARIES_CXXFLAGS  for C++
+# - IGNORE_UNUSED_LIBRARIES_FFLAGS    for Fortran
+#
+# Note that the option works only for direct invocation of the compiler, not
+# through libtool: When libtool is used to create a shared library, it will
+# honor and translate '-Wl,-z,ignore' to '-Qoption ld -z -Qoption ld ignore'
+# if needed, but it will drop a '-Qoption ld -z,ignore' on the command line.
+#
+AC_DEFUN([gl_IGNORE_UNUSED_LIBRARIES],
+[
+  AC_CACHE_CHECK([for []_AC_LANG[] compiler flag to ignore unused libraries],
+    [gl_cv_prog_[]_AC_LANG_ABBREV[]_ignore_unused_libraries],
+    [gl_cv_prog_[]_AC_LANG_ABBREV[]_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="$LIBS -lm"
+     # Use long option sequences like '-z ignore' to test for the feature,
+     # to forestall problems with linkers that have -z, -i, -g, -n, etc. flags.
+     # GCC + binutils likes '-Wl,--as-needed'.
+     # GCC + Solaris ld likes '-Wl,-z,ignore'.
+     # Sun C likes '-Wl,-z,ignore'. '-z ignore' is accepted but has no effect.
+     # Don't try bare '--as-needed'; nothing likes it and the HP-UX 11.11
+     # native cc issues annoying warnings and then ignores it,
+     # which would cause us to incorrectly conclude that it worked.
+     for gl_flags in _gl_IGNORE_UNUSED_LIBRARIES_OPTIONS
+     do
+       LDFLAGS="$gl_flags $LDFLAGS"
+       AC_LINK_IFELSE([AC_LANG_PROGRAM()],
+         [gl_cv_prog_[]_AC_LANG_ABBREV[]_ignore_unused_libraries=$gl_flags])
+       LDFLAGS=$gl_saved_ldflags
+       test "$gl_cv_prog_[]_AC_LANG_ABBREV[]_ignore_unused_libraries" != none &&
+         break
+     done
+     LIBS=$gl_saved_libs
+    ])
+  IGNORE_UNUSED_LIBRARIES_[]_AC_LANG_PREFIX[]FLAGS=
+  if test "$gl_cv_prog_[]_AC_LANG_ABBREV[]_ignore_unused_libraries" != none; then
+    IGNORE_UNUSED_LIBRARIES_[]_AC_LANG_PREFIX[]FLAGS="$gl_cv_prog_[]_AC_LANG_ABBREV[]_ignore_unused_libraries"
+  fi
+  AC_SUBST([IGNORE_UNUSED_LIBRARIES_]_AC_LANG_PREFIX[FLAGS])
+])
+
+# _gl_IGNORE_UNUSED_LIBRARIES_OPTIONS
+# -----------------------------------
+# Expands to the language dependent options to be tried.
+AC_DEFUN([_gl_IGNORE_UNUSED_LIBRARIES_OPTIONS],
+[_AC_LANG_DISPATCH([$0], _AC_LANG, $@)])
+
+# _gl_IGNORE_UNUSED_LIBRARIES_OPTIONS(C)
+# --------------------------------------
+m4_define([_gl_IGNORE_UNUSED_LIBRARIES_OPTIONS(C)],
+[ '-Wl,--as-needed' \
+  '-Wl,-z,ignore' \
+  '-z ignore'
+])
+
+# _gl_IGNORE_UNUSED_LIBRARIES_OPTIONS(C++)
+# ----------------------------------------
+m4_define([_gl_IGNORE_UNUSED_LIBRARIES_OPTIONS(C++)],
+[ '-Wl,--as-needed' \
+  '-Qoption ld -z,ignore' \
+  '-Wl,-z,ignore' \
+  '-z ignore'
+])
+
+# _gl_IGNORE_UNUSED_LIBRARIES_OPTIONS(Fortran 77)
+# -----------------------------------------------
+m4_copy([_gl_IGNORE_UNUSED_LIBRARIES_OPTIONS(C++)],
+        [_gl_IGNORE_UNUSED_LIBRARIES_OPTIONS(Fortran 77)])
+
+# _gl_IGNORE_UNUSED_LIBRARIES_OPTIONS(Fortran)
+# --------------------------------------------
+m4_copy([_gl_IGNORE_UNUSED_LIBRARIES_OPTIONS(Fortran 77)],
+        [_gl_IGNORE_UNUSED_LIBRARIES_OPTIONS(Fortran)])