Update ax_cxx_compile_stdcxx_11 from upstream 3cb2915

build/autotools/includes/ax_cxx_compile_stdcxx_11.m4

@@ -27,21 +27,29 @@
 #   Copyright (c) 2008 Benjamin Kosnik <bkoz@redhat.com>
 #   Copyright (c) 2012 Zack Weinberg <zackw@panix.com>
 #   Copyright (c) 2013 Roy Stogner <roystgnr@ices.utexas.edu>
+#   Copyright (c) 2014 Alexey Sokolov <sokolov@google.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 3
+#serial 4
 
-m4_define([_AX_CXX_COMPILE_STDCXX_11_testbody], [
+m4_define([_AX_CXX_COMPILE_STDCXX_11_testbody], [[
   template <typename T>
     struct check
     {
       static_assert(sizeof(int) <= sizeof(T), "not big enough");
     };
 
+    struct Base {
+    virtual void f() {}
+    };
+    struct Child : public Base {
+    virtual void f() override {}
+    };
+
     typedef check<check<bool>> right_angle_brackets;
 
     int a;
@@ -52,7 +60,8 @@ m4_define([_AX_CXX_COMPILE_STDCXX_11_testbody], [
     check_type&& cr = static_cast<check_type&&>(c);
 
     auto d = a;
-])
+    auto l = [](){};
+]])
 
 AC_DEFUN([AX_CXX_COMPILE_STDCXX_11], [dnl
   m4_if([$1], [], [],
@@ -62,7 +71,7 @@ AC_DEFUN([AX_CXX_COMPILE_STDCXX_11], [dnl
   m4_if([$2], [], [ax_cxx_compile_cxx11_required=true],
         [$2], [mandatory], [ax_cxx_compile_cxx11_required=true],
         [$2], [optional], [ax_cxx_compile_cxx11_required=false],
-        [m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX_11])])dnl
+        [m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX_11])])
   AC_LANG_PUSH([C++])dnl
   ac_success=no
   AC_CACHE_CHECK(whether $CXX supports C++11 features by default,