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, 7 insertions, 8 deletions

diff --git a/m4/ax_cxx_full_specialization_syntax.m4 b/m4/ax_cxx_full_specialization_syntax.m4
index 3fff48a..c245891 100644
--- a/m4/ax_cxx_full_specialization_syntax.m4
+++ b/m4/ax_cxx_full_specialization_syntax.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_FULL_SPECIALIZATION_SYNTAX], [AX_CXX_FULL_SPECIALIZATION_SYNTAX])
 AC_DEFUN([AX_CXX_FULL_SPECIALIZATION_SYNTAX],
 [AC_CACHE_CHECK(whether the compiler recognizes the full specialization syntax,
 ax_cv_cxx_full_specialization_syntax,
-[AC_LANG_SAVE
- AC_LANG_CPLUSPLUS
- AC_TRY_COMPILE([
+[AC_LANG_PUSH([C++])
+ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
 template<class T> class A        { public : int f () const { return 1; } };
-template<>        class A<float> { public:  int f () const { return 0; } };],[
-A<float> a; return a.f();],
- ax_cv_cxx_full_specialization_syntax=yes, ax_cv_cxx_full_specialization_syntax=no)
- AC_LANG_RESTORE
+template<>        class A<float> { public:  int f () const { return 0; } };]], [[
+A<float> a; return a.f();]])],
+ [ax_cv_cxx_full_specialization_syntax=yes], [ax_cv_cxx_full_specialization_syntax=no])
+ AC_LANG_POP([C++])
 ])
 if test "$ax_cv_cxx_full_specialization_syntax" = yes; then
   AC_DEFINE(HAVE_FULL_SPECIALIZATION_SYNTAX,,