# If possible, ignore libraries that are not depended on.
-dnl Copyright (C) 2006 Free Software Foundation, Inc.
+dnl Copyright (C) 2006, 2009-2013 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 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="$LIBS -lm"
+ AC_CACHE_CHECK([for []_AC_LANG[] compiler flag to ignore unused libraries],
+ [gl_cv_prog_[]_AC_LANG_ABBREV[]_ignore_unused_libraries],
+ [gl_cv_prog_[]_AC_LANG_ABBREV[]_ignore_unused_libraries=none
+ gl_saved_ldflags=$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 $LDFLAGS"
AC_LINK_IFELSE([AC_LANG_PROGRAM()],
- [gl_ldd_output1=`(ldd conftest$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 $gl_cv_ignore_unused_libraries"
+ [gl_cv_prog_[]_AC_LANG_ABBREV[]_ignore_unused_libraries=$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)])
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