Update copyright years.

[thirdparty/gcc.git] / libstdc++-v3 / include / std / istream

diff --git a/libstdc++-v3/include/std/istream b/libstdc++-v3/include/std/istream
index d4e5d71177e56a359c2f25555a10d3476ef77abf..407c1ccda499ea0ca00138586525193af1878f1a 100644 (file)
--- a/libstdc++-v3/include/std/istream
+++ b/libstdc++-v3/include/std/istream
@@ -1,6 +1,6 @@
 // Input streams -*- C++ -*-
 
-// Copyright (C) 1997-2014 Free Software Foundation, Inc.
+// Copyright (C) 1997-2020 Free Software Foundation, Inc.
 //
 // This file is part of the GNU ISO C++ Library.  This library is free
 // software; you can redistribute it and/or modify it under the
@@ -150,9 +150,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        *  whatever data is appropriate for the type of the argument.
        *
        *  If an exception is thrown during extraction, ios_base::badbit
-       *  will be turned on in the stream's error state without causing an
-       *  ios_base::failure to be thrown.  The original exception will then
-       *  be rethrown.
+       *  will be turned on in the stream's error state (without causing an
+       *  ios_base::failure to be thrown) and the original exception will
+       *  be rethrown if badbit is set in the exceptions mask.
       */
 
       //@{
@@ -286,9 +286,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        *  by gcount().
        *
        *  If an exception is thrown during extraction, ios_base::badbit
-       *  will be turned on in the stream's error state without causing an
-       *  ios_base::failure to be thrown.  The original exception will then
-       *  be rethrown.
+       *  will be turned on in the stream's error state (without causing an
+       *  ios_base::failure to be thrown) and the original exception will
+       *  be rethrown if badbit is set in the exceptions mask.
       */
 
       /**
@@ -908,7 +908,57 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     ws(basic_istream<_CharT, _Traits>& __is);
 
 #if __cplusplus >= 201103L
+  template<typename _Ch, typename _Up>
+    basic_istream<_Ch, _Up>&
+    __is_convertible_to_basic_istream_test(basic_istream<_Ch, _Up>*);
+
+  template<typename _Tp, typename = void>
+    struct __is_convertible_to_basic_istream_impl
+    {
+      using __istream_type = void;
+    };
+
+  template<typename _Tp>
+    using __do_is_convertible_to_basic_istream_impl =
+    decltype(__is_convertible_to_basic_istream_test
+            (declval<typename remove_reference<_Tp>::type*>()));
+
+  template<typename _Tp>
+    struct __is_convertible_to_basic_istream_impl
+    <_Tp,
+     __void_t<__do_is_convertible_to_basic_istream_impl<_Tp>>>
+    {
+      using __istream_type =
+       __do_is_convertible_to_basic_istream_impl<_Tp>;
+    };
+
+  template<typename _Tp>
+    struct __is_convertible_to_basic_istream
+    : __is_convertible_to_basic_istream_impl<_Tp>
+    {
+    public:
+      using type = __not_<is_void<
+        typename __is_convertible_to_basic_istream_impl<_Tp>::__istream_type>>;
+      constexpr static bool value = type::value;
+    };
+
+  template<typename _Istream, typename _Tp, typename = void>
+    struct __is_extractable : false_type {};
+
+  template<typename _Istream, typename _Tp>
+    struct __is_extractable<_Istream, _Tp,
+                           __void_t<decltype(declval<_Istream&>()
+                                             >> declval<_Tp>())>>
+    : true_type {};
+
+  template<typename _Istream>
+    using __rvalue_istream_type =
+      typename __is_convertible_to_basic_istream<
+       _Istream>::__istream_type;
+
   // [27.7.1.6] Rvalue stream extraction
+  // _GLIBCXX_RESOLVE_LIB_DEFECTS
+  // 2328. Rvalue stream extraction should use perfect forwarding
   /**
    *  @brief  Generic extractor for rvalue stream
    *  @param  __is  An input stream.
@@ -919,10 +969,20 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
    *  rvalue streams since they won't bind to the extractor functions
    *  that take an lvalue reference.
   */
-  template<typename _CharT, typename _Traits, typename _Tp>
-    inline basic_istream<_CharT, _Traits>&
-    operator>>(basic_istream<_CharT, _Traits>&& __is, _Tp& __x)
-    { return (__is >> __x); }
+  template<typename _Istream, typename _Tp>
+    inline
+    typename enable_if<__and_<__not_<is_lvalue_reference<_Istream>>,
+                             __is_convertible_to_basic_istream<_Istream>,
+                             __is_extractable<
+                               __rvalue_istream_type<_Istream>,
+                               _Tp&&>>::value,
+                      __rvalue_istream_type<_Istream>>::type
+    operator>>(_Istream&& __is, _Tp&& __x)
+    {
+      __rvalue_istream_type<_Istream> __ret_is = __is;
+      __ret_is >> std::forward<_Tp>(__x);
+      return __ret_is;
+    }
 #endif // C++11
 
 _GLIBCXX_END_NAMESPACE_VERSION