From 2735097a5595bdf06d9ac97275dfae82af3eb93d Mon Sep 17 00:00:00 2001
From: Jonathan Wakely <jwakely@redhat.com>
Date: Thu, 8 May 2014 19:30:14 +0100
Subject: [PATCH] re PR libstdc++/13860 (Poor error messages on invalid
 template parameters for basic_filebuf)

	PR libstdc++/13860
	* include/std/fstream (basic_filebuf): Enforce requirements on traits.

From-SVN: r210231
---
 libstdc++-v3/ChangeLog           |  3 +++
 libstdc++-v3/include/std/fstream | 14 ++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 20079f9b240b..9ee95da82803 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -11,6 +11,9 @@
 	(swap(basic_streambuf&)): Define for C++11.
 	* testsuite/27_io/basic_streambuf/cons/57394.cc: New.
 
+	PR libstdc++/13860
+	* include/std/fstream (basic_filebuf): Enforce requirements on traits.
+
 2014-05-08  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	* acinclude.m4 ([GLIBCXX_ENABLE_C99]): Avoid -Wwrite-strings warning.
diff --git a/libstdc++-v3/include/std/fstream b/libstdc++-v3/include/std/fstream
index 17ccac62868c..51db21b525c7 100644
--- a/libstdc++-v3/include/std/fstream
+++ b/libstdc++-v3/include/std/fstream
@@ -71,6 +71,20 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   template<typename _CharT, typename _Traits>
     class basic_filebuf : public basic_streambuf<_CharT, _Traits>
     {
+#if __cplusplus >= 201103L
+      template<typename _Tp>
+	using __chk_state = __and_<is_copy_assignable<_Tp>,
+				   is_copy_constructible<_Tp>,
+				   is_default_constructible<_Tp>>;
+
+      static_assert(__chk_state<typename _Traits::state_type>::value,
+		    "state_type must be CopyAssignable, CopyConstructible"
+		    " and DefaultConstructible");
+
+      static_assert(is_same<typename _Traits::pos_type,
+			    fpos<typename _Traits::state_type>>::value,
+		    "pos_type must be fpos<state_type>");
+#endif
     public:
       // Types:
       typedef _CharT                     	        char_type;
-- 
2.47.3