[gnote] Update ax_cxx_compile_stdcxx_11.m4

[Aurimas Černius <aurimasc src gnome org>]

commit 1f2742b679ba992a76c54234c9ed81d86598746d
Author: Aurimas Černius <aurisc4 gmail com>
Date:   Sun Oct 18 18:12:05 2015 +0300

    Update ax_cxx_compile_stdcxx_11.m4

 m4/ax_cxx_compile_stdcxx_11.m4 |   13 +++++++++++--
 1 files changed, 11 insertions(+), 2 deletions(-)
---
diff --git a/m4/ax_cxx_compile_stdcxx_11.m4 b/m4/ax_cxx_compile_stdcxx_11.m4
index 229de30..516da37 100644
--- a/m4/ax_cxx_compile_stdcxx_11.m4
+++ b/m4/ax_cxx_compile_stdcxx_11.m4
@@ -28,13 +28,14 @@
 #   Copyright (c) 2012 Zack Weinberg <zackw panix com>
 #   Copyright (c) 2013 Roy Stogner <roystgnr ices utexas edu>
 #   Copyright (c) 2014, 2015 Google Inc.; contributed by Alexey Sokolov <sokolov google com>
+#   Copyright (c) 2015 Paul Norman <penorman mac 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 9
+#serial 13
 
 m4_define([_AX_CXX_COMPILE_STDCXX_11_testbody], [[
   template <typename T>
@@ -61,6 +62,8 @@ m4_define([_AX_CXX_COMPILE_STDCXX_11_testbody], [[
 
     auto d = a;
     auto l = [](){};
+    // Prevent Clang error: unused variable 'l' [-Werror,-Wunused-variable]
+    struct use_l { use_l() { l(); } };
 
     // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
     // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function because of this
@@ -82,6 +85,9 @@ m4_define([_AX_CXX_COMPILE_STDCXX_11_testbody], [[
             func<foo>(0);
         }
     }
+
+    // Check for C++11 attribute support
+    void noret [[noreturn]] () { throw 0; }
 ]])
 
 AC_DEFUN([AX_CXX_COMPILE_STDCXX_11], [dnl
@@ -126,7 +132,10 @@ AC_DEFUN([AX_CXX_COMPILE_STDCXX_11], [dnl
 
   m4_if([$1], [ext], [], [dnl
   if test x$ac_success = xno; then
-    for switch in -std=c++11 -std=c++0x; do
+    dnl HP's aCC needs +std=c++11 according to:
+    dnl http://h21007.www2.hp.com/portal/download/files/unprot/aCxx/PDF_Release_Notes/769149-001.pdf
+    dnl Cray's crayCC needs "-h std=c++11"
+    for switch in -std=c++11 -std=c++0x +std=c++11 "-h std=c++11"; do
       cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx11_$switch])
       AC_CACHE_CHECK(whether $CXX supports C++11 features with $switch,
                      $cachevar,