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# ===========================================================================
# https://www.gnu.org/software/autoconf-archive/ax_cxx_use_numtrait.html
# ===========================================================================
#
# SYNOPSIS
#
# AX_CXX_USE_NUMTRAIT
#
# DESCRIPTION
#
# If the compiler supports numeric traits promotions, define
# HAVE_USE_NUMTRAIT.
#
# LICENSE
#
# Copyright (c) 2008 Todd Veldhuizen
# Copyright (c) 2008 Luc Maisonobe <luc@spaceroots.org>
#
# 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 8
AU_ALIAS([AC_CXX_USE_NUMTRAIT], [AX_CXX_USE_NUMTRAIT])
AC_DEFUN([AX_CXX_USE_NUMTRAIT],
[AC_CACHE_CHECK(whether the compiler supports numeric traits promotions,
ax_cv_cxx_use_numtrait,
[AC_REQUIRE([AX_CXX_TYPENAME])
AC_LANG_PUSH([C++])
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
#ifndef HAVE_TYPENAME
#define typename
#endif
template<class T_numtype> class SumType { public : typedef T_numtype T_sumtype; };
template<> class SumType<char> { public : typedef int T_sumtype; };
template<class T> class A {};
template<class T> A<typename SumType<T>::T_sumtype> sum(A<T>)
{ return A<typename SumType<T>::T_sumtype>(); }
]], [[A<float> x; sum(x); return 0;]])],
[ax_cv_cxx_use_numtrait=yes], [ax_cv_cxx_use_numtrait=no])
AC_LANG_POP([C++])
])
if test "$ax_cv_cxx_use_numtrait" = yes; then
AC_DEFINE(HAVE_USE_NUMTRAIT,,[define if the compiler supports numeric traits promotions])
fi
])
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