freebsd-dev/sys/contrib/libsodium/m4/ax_check_link_flag.m4
Conrad Meyer 0ac341f145 Bring in libsodium to sys/contrib
Bring in https://github.com/jedisct1/libsodium at
461ac93b260b91db8ad957f5a576860e3e9c88a1 (August 7, 2018), unmodified.

libsodium is derived from Daniel J. Bernstein et al.'s 2011 NaCl
("Networking and Cryptography Library," pronounced "salt") software library.
At the risk of oversimplifying, libsodium primarily exists to make it easier
to use NaCl.  NaCl and libsodium provide high quality implementations of a
number of useful cryptographic concepts (as well as the underlying
primitics) seeing some adoption in newer network protocols.

I considered but dismissed cleaning up the directory hierarchy and
discarding artifacts of other build systems in favor of remaining close to
upstream (and easing future updates).

Nothing is integrated into the build system yet, so in that sense, no
functional change.
2018-08-17 00:23:50 +00:00

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# ===========================================================================
# https://www.gnu.org/software/autoconf-archive/ax_check_link_flag.html
# ===========================================================================
#
# SYNOPSIS
#
# AX_CHECK_LINK_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
#
# DESCRIPTION
#
# Check whether the given FLAG works with the linker or gives an error.
# (Warnings, however, are ignored)
#
# ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on
# success/failure.
#
# If EXTRA-FLAGS is defined, it is added to the linker's default flags
# when the check is done. The check is thus made with the flags: "LDFLAGS
# EXTRA-FLAGS FLAG". This can for example be used to force the linker to
# issue an error when a bad flag is given.
#
# INPUT gives an alternative input source to AC_LINK_IFELSE.
#
# NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
# macro in sync with AX_CHECK_{PREPROC,COMPILE}_FLAG.
#
# LICENSE
#
# Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
# Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
#
# This program is free software: you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation, either version 3 of the License, or (at your
# option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
# Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program. If not, see <https://www.gnu.org/licenses/>.
#
# As a special exception, the respective Autoconf Macro's copyright owner
# gives unlimited permission to copy, distribute and modify the configure
# scripts that are the output of Autoconf when processing the Macro. You
# need not follow the terms of the GNU General Public License when using
# or distributing such scripts, even though portions of the text of the
# Macro appear in them. The GNU General Public License (GPL) does govern
# all other use of the material that constitutes the Autoconf Macro.
#
# This special exception to the GPL applies to versions of the Autoconf
# Macro released by the Autoconf Archive. When you make and distribute a
# modified version of the Autoconf Macro, you may extend this special
# exception to the GPL to apply to your modified version as well.
#serial 5
AC_DEFUN([AX_CHECK_LINK_FLAG],
[AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_IF
AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_ldflags_$4_$1])dnl
AC_CACHE_CHECK([whether the linker accepts $1], CACHEVAR, [
ax_check_save_flags=$LDFLAGS
LDFLAGS="$LDFLAGS $4 $1"
AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <time.h>]],
[[time_t x; int fodder = 0; if (fodder > -1000 && time(&x)) return (int) x]])],
[AS_VAR_SET(CACHEVAR,[yes])],
[AS_VAR_SET(CACHEVAR,[no])])
LDFLAGS=$ax_check_save_flags])
AS_VAR_IF(CACHEVAR,yes,
[m4_default([$2], :)],
[m4_default([$3], :)])
AS_VAR_POPDEF([CACHEVAR])dnl
])dnl AX_CHECK_LINK_FLAGS