# ===========================================================================
# http://www.gnu.org/software/autoconf-archive/ax_check_vscript.html
# ===========================================================================
#
# SYNOPSIS
#
# AX_CHECK_VSCRIPT
#
# DESCRIPTION
#
# Check whether the linker supports version scripts. Version scripts are
# used when building shared libraries to bind symbols to version nodes
# (helping to detect incompatibilities) or to limit the visibility of
# non-public symbols.
#
# Output:
#
# If version scripts are supported, VSCRIPT_LDFLAGS will contain the
# appropriate flag to pass to the linker. On GNU systems this would
# typically be "-Wl,--version-script", and on Solaris it would typically
# be "-Wl,-M".
#
# Two Automake conditionals are also set:
#
# HAVE_VSCRIPT is true if the linker supports version scripts with
# entries that use simple wildcards, like "local: *".
#
# HAVE_VSCRIPT_COMPLEX is true if the linker supports version scripts with
# pattern matching wildcards, like "global: Java_*".
#
# On systems that do not support symbol versioning, such as Mac OS X, both
# conditionals will be false. They will also be false if the user passes
# "--disable-symvers" on the configure command line.
#
# Example:
#
# configure.ac:
#
# AX_CHECK_VSCRIPT
#
# Makefile.am:
#
# if HAVE_VSCRIPT
# libfoo_la_LDFLAGS += $(VSCRIPT_LDFLAGS),@srcdir@/libfoo.map
# endif
#
# if HAVE_VSCRIPT_COMPLEX
# libbar_la_LDFLAGS += $(VSCRIPT_LDFLAGS),@srcdir@/libbar.map
# endif
#
# LICENSE
#
# Copyright (c) 2014 Kevin Cernekee <cernekee@gmail.com>
#
# Copying and distribution of this file, with or without modification, are
# permitted in any medium without royalty provided the copyright notice
# and this notice are preserved. This file is offered as-is, without any
# warranty.
#serial 1
# _AX_CHECK_VSCRIPT(flag, global-sym, action-if-link-succeeds, [junk-file=no])
AC_DEFUN([_AX_CHECK_VSCRIPT], [
AC_LANG_PUSH([C])
ax_check_vscript_save_flags="$LDFLAGS"
echo "V1 { global: $2; local: *; };" > conftest.map
AS_IF([test x$4 = xyes], [
echo "{" >> conftest.map
])
LDFLAGS="$LDFLAGS -Wl,$1,conftest.map"
AC_LINK_IFELSE([AC_LANG_PROGRAM([[int show, hide;]], [])], [$3])
LDFLAGS="$ax_check_vscript_save_flags"
rm -f conftest.map
AC_LANG_POP([C])
]) dnl _AX_CHECK_VSCRIPT
AC_DEFUN([AX_CHECK_VSCRIPT], [
AC_ARG_ENABLE([symvers],
AS_HELP_STRING([--disable-symvers],
[disable library symbol versioning [default=auto]]),
[want_symvers=$enableval],
[want_symvers=yes]
)
AS_IF([test x$want_symvers = xyes], [
dnl First test --version-script and -M with a simple wildcard.
AC_CACHE_CHECK([linker version script flag], ax_cv_check_vscript_flag, [
ax_cv_check_vscript_flag=unsupported
_AX_CHECK_VSCRIPT([--version-script], [show], [
ax_cv_check_vscript_flag=--version-script
])
AS_IF([test x$ax_cv_check_vscript_flag = xunsupported], [
_AX_CHECK_VSCRIPT([-M], [show], [ax_cv_check_vscript_flag=-M])
])
dnl The linker may interpret -M (no argument) as "produce a load map."
dnl If "-M conftest.map" doesn't fail when conftest.map contains
dnl obvious syntax errors, assume this is the case.
AS_IF([test x$ax_cv_check_vscript_flag != xunsupported], [
_AX_CHECK_VSCRIPT([$ax_cv_check_vscript_flag], [show],
[ax_cv_check_vscript_flag=unsupported], [yes])
])
])
dnl If the simple wildcard worked, retest with a complex wildcard.
AS_IF([test x$ax_cv_check_vscript_flag != xunsupported], [
ax_check_vscript_flag=$ax_cv_check_vscript_flag
AC_CACHE_CHECK([if version scripts can use complex wildcards],
ax_cv_check_vscript_complex_wildcards, [
ax_cv_check_vscript_complex_wildcards=no
_AX_CHECK_VSCRIPT([$ax_cv_check_vscript_flag], [sh*], [
ax_cv_check_vscript_complex_wildcards=yes])
])
ax_check_vscript_complex_wildcards="$ax_cv_check_vscript_complex_wildcards"
], [
ax_check_vscript_flag=
ax_check_vscript_complex_wildcards=no
])
], [
AC_MSG_CHECKING([linker version script flag])
AC_MSG_RESULT([disabled])
ax_check_vscript_flag=
ax_check_vscript_complex_wildcards=no
])
AS_IF([test x$ax_check_vscript_flag != x], [
VSCRIPT_LDFLAGS="-Wl,$ax_check_vscript_flag"
AC_SUBST([VSCRIPT_LDFLAGS])
])
AM_CONDITIONAL([HAVE_VSCRIPT],
[test x$ax_check_vscript_flag != x])
AM_CONDITIONAL([HAVE_VSCRIPT_COMPLEX],
[test x$ax_check_vscript_complex_wildcards = xyes])
]) dnl AX_CHECK_VSCRIPT
