Replace AC_TRY_COMPILE and AC_LANG_

Autoconf 2.50 in 2001 made several macros obsolete. These include macros
for temporary changing the language - AC_LANG_SAVE, AC_LANG_CPLUSPLUS,
AC_LANG_C, and AC_LANG_RESTORE. Instead of these the AC_LANG_PUSH and
AC_LANG_POP macros should be used with later Autoconf versions.

AC_TRY_COMPILE macros should be replaced with AC_COMPILE_IFELSE.

Refs:
- http://git.savannah.gnu.org/cgit/autoconf.git/tree/NEWS
- https://www.gnu.org/software/autoconf/manual/autoconf-2.69/html_node/Language-Choice.html
- https://www.gnu.org/software/autoconf/manual/autoconf-2.69/html_node/Obsolete-Macros.html

1 files changed, 6 insertions, 7 deletions

diff --git a/m4/ax_cxx_explicit_template_function_qualification.m4 b/m4/ax_cxx_explicit_template_function_qualification.m4
index 8d03522..2b25531 100644
--- a/m4/ax_cxx_explicit_template_function_qualification.m4
+++ b/m4/ax_cxx_explicit_template_function_qualification.m4
@@ -21,20 +21,19 @@
 #   and this notice are preserved. This file is offered as-is, without any
 #   warranty.
 
-#serial 7
+#serial 8
 
 AU_ALIAS([AC_CXX_EXPLICIT_TEMPLATE_FUNCTION_QUALIFICATION], [AX_CXX_EXPLICIT_TEMPLATE_FUNCTION_QUALIFICATION])
 AC_DEFUN([AX_CXX_EXPLICIT_TEMPLATE_FUNCTION_QUALIFICATION],
 [AC_CACHE_CHECK(whether the compiler supports explicit template function qualification,
 ax_cv_cxx_explicit_template_function_qualification,
-[AC_LANG_SAVE
- AC_LANG_CPLUSPLUS
- AC_TRY_COMPILE([
+[AC_LANG_PUSH([C++])
+ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
 template<class Z> class A { public : A() {} };
 template<class X, class Y> A<X> to (const A<Y>&) { return A<X>(); }
-],[A<float> x; A<double> y = to<double>(x); return 0;],
- ax_cv_cxx_explicit_template_function_qualification=yes, ax_cv_cxx_explicit_template_function_qualification=no)
- AC_LANG_RESTORE
+]], [[A<float> x; A<double> y = to<double>(x); return 0;]])],
+ [ax_cv_cxx_explicit_template_function_qualification=yes], [ax_cv_cxx_explicit_template_function_qualification=no])
+ AC_LANG_POP([C++])
 ])
 if test "$ax_cv_cxx_explicit_template_function_qualification" = yes; then
   AC_DEFINE(HAVE_EXPLICIT_TEMPLATE_FUNCTION_QUALIFICATION,,