From 6821a6e83ab2c68c895d807f0b2f6f00aa6667ac Mon Sep 17 00:00:00 2001
From: Noah Watkins <noahwatkins@gmail.com>
Date: Sat, 20 Jul 2013 18:41:38 -0700
Subject: [PATCH] assert: use feature test for static_cast

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
---
 configure.ac             |  2 ++
 m4/ax_cxx_static_cast.m4 | 43 ++++++++++++++++++++++++++++++++++++++++
 src/include/assert.h     |  2 +-
 3 files changed, 46 insertions(+), 1 deletion(-)
 create mode 100644 m4/ax_cxx_static_cast.m4

diff --git a/configure.ac b/configure.ac
index 66d8f2161c990..641bc93fac366 100644
--- a/configure.ac
+++ b/configure.ac
@@ -113,6 +113,8 @@ AM_CONDITIONAL([ENABLE_FPU_NEON], [case $target_cpu in arm*) true;; *) false;; e
 AX_CHECK_COMPILE_FLAG([-fvar-tracking-assignments], [HAS_VTA_SUPPORT=1], [HAS_VTA_SUPPORT=0])
 AM_CONDITIONAL(COMPILER_HAS_VTA, [test "$HAS_VTA_SUPPORT" = 1])
 
+AX_CXX_STATIC_CAST
+
 # Checks for libraries.
 ACX_PTHREAD
 AC_CHECK_LIB([uuid], [uuid_parse], [true], AC_MSG_FAILURE([libuuid not found]))
diff --git a/m4/ax_cxx_static_cast.m4 b/m4/ax_cxx_static_cast.m4
new file mode 100644
index 0000000000000..e09e6c46cb2da
--- /dev/null
+++ b/m4/ax_cxx_static_cast.m4
@@ -0,0 +1,43 @@
+# ===========================================================================
+#    http://www.gnu.org/software/autoconf-archive/ax_cxx_static_cast.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_CXX_STATIC_CAST
+#
+# DESCRIPTION
+#
+#   If the compiler supports static_cast<>, define HAVE_STATIC_CAST.
+#
+# 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 6
+
+AU_ALIAS([AC_CXX_STATIC_CAST], [AX_CXX_STATIC_CAST])
+AC_DEFUN([AX_CXX_STATIC_CAST],
+[AC_CACHE_CHECK(whether the compiler supports static_cast<>,
+ax_cv_cxx_static_cast,
+[AC_LANG_SAVE
+ AC_LANG_CPLUSPLUS
+ AC_TRY_COMPILE([#include <typeinfo>
+class Base { public : Base () {} virtual void f () = 0; };
+class Derived : public Base { public : Derived () {} virtual void f () {} };
+int g (Derived&) { return 0; }],[
+Derived d; Base& b = d; Derived& s = static_cast<Derived&> (b); return g (s);],
+ ax_cv_cxx_static_cast=yes, ax_cv_cxx_static_cast=no)
+ AC_LANG_RESTORE
+])
+if test "$ax_cv_cxx_static_cast" = yes; then
+  AC_DEFINE(HAVE_STATIC_CAST,,
+            [define if the compiler supports static_cast<>])
+fi
+])
diff --git a/src/include/assert.h b/src/include/assert.h
index 38c0eeb44a1ea..15952e50b710d 100644
--- a/src/include/assert.h
+++ b/src/include/assert.h
@@ -27,7 +27,7 @@ struct FailedAssertion {
 #endif
 
 
-#if defined __cplusplus && __GNUC_PREREQ (2,95)
+#ifdef HAVE_STATIC_CAST
 # define __CEPH_ASSERT_VOID_CAST static_cast<void>
 #else
 # define __CEPH_ASSERT_VOID_CAST (void)
-- 
2.39.5