[libc++][sstream] Explicitly delete special member functions (#80254)

The standard declares the copy constructors and copy assign operators as
deleted.

References:
- https://eel.is/c++draft/string.streams

Author: H-G-Hristov

libcxx/include/sstream

@@ -48,10 +48,12 @@ public:
     template <class SAlloc>
     explicit basic_stringbuf(const basic_string<char_type, traits_type, SAlloc>& s,
                              ios_base::openmode which = ios_base::in | ios_base::out); // C++20
+    basic_stringbuf(const basic_stringbuf&) = delete;
     basic_stringbuf(basic_stringbuf&& rhs);
     basic_stringbuf(basic_stringbuf&& rhs, const allocator_type& a);                   // C++20
 
     // [stringbuf.assign] Assign and swap:
+    basic_stringbuf& operator=(const basic_stringbuf&) = delete;
     basic_stringbuf& operator=(basic_stringbuf&& rhs);
     void swap(basic_stringbuf& rhs) noexcept(see below);                               // conditionally noexcept since C++20
 
@@ -119,9 +121,11 @@ public:
     template <class SAlloc>
     explicit basic_istringstream(const basic_string<char_type, traits_type, SAlloc>& s,
                                  ios_base::openmode which = ios_base::in);             // C++20
+    basic_istringstream(const basic_istringstream&) = delete;
     basic_istringstream(basic_istringstream&& rhs);
 
     // [istringstream.assign] Assign and swap:
+    basic_istringstream& operator=(const basic_istringstream&) = delete;
     basic_istringstream& operator=(basic_istringstream&& rhs);
     void swap(basic_istringstream& rhs);
 
@@ -178,9 +182,11 @@ public:
     template <class SAlloc>
     explicit basic_ostringstream(const basic_string<char_type, traits_type, SAlloc>& s,
                                  ios_base::openmode which = ios_base::out);            // C++20
+    basic_ostringstream(const basic_ostringstream&) = delete;                             
     basic_ostringstream(basic_ostringstream&& rhs);
 
     // [ostringstream.assign] Assign and swap:
+    basic_ostringstream& operator=(const basic_ostringstream&) = delete;
     basic_ostringstream& operator=(basic_ostringstream&& rhs);
     void swap(basic_ostringstream& rhs);
 
@@ -237,9 +243,11 @@ public:
     template <class SAlloc>
     explicit basic_stringstream(const basic_string<char_type, traits_type, SAlloc>& s,
                                 ios_base::openmode which = ios_base::out | ios_base::in); // C++20
+    basic_stringstream(const basic_stringstream&) = delete;
     basic_stringstream(basic_stringstream&& rhs);
 
     // [stringstream.assign] Assign and swap:
+    basic_stringstream& operator=(const basic_stringstream&) = delete;
     basic_stringstream& operator=(basic_stringstream&& rhs);
     void swap(basic_stringstream& rhs);
 
@@ -364,6 +372,7 @@ public:
   }
 #endif // _LIBCPP_STD_VER >= 20
 
+  basic_stringbuf(const basic_stringbuf&) = delete;
   basic_stringbuf(basic_stringbuf&& __rhs) : __mode_(__rhs.__mode_) { __move_init(std::move(__rhs)); }
 
 #if _LIBCPP_STD_VER >= 20
@@ -374,6 +383,7 @@ public:
 #endif
 
   // [stringbuf.assign] Assign and swap:
+  basic_stringbuf& operator=(const basic_stringbuf&) = delete;
   basic_stringbuf& operator=(basic_stringbuf&& __rhs);
   void swap(basic_stringbuf& __rhs)
 #if _LIBCPP_STD_VER >= 20
@@ -822,12 +832,14 @@ public:
       : basic_istream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__s, __wch | ios_base::in) {}
 #endif // _LIBCPP_STD_VER >= 20
 
+  basic_istringstream(const basic_istringstream&) = delete;
   _LIBCPP_HIDE_FROM_ABI basic_istringstream(basic_istringstream&& __rhs)
       : basic_istream<_CharT, _Traits>(std::move(__rhs)), __sb_(std::move(__rhs.__sb_)) {
     basic_istream<_CharT, _Traits>::set_rdbuf(&__sb_);
   }
 
   // [istringstream.assign] Assign and swap:
+  basic_istringstream& operator=(const basic_istringstream&) = delete;
   basic_istringstream& operator=(basic_istringstream&& __rhs) {
     basic_istream<char_type, traits_type>::operator=(std::move(__rhs));
     __sb_ = std::move(__rhs.__sb_);
@@ -929,12 +941,14 @@ public:
       : basic_ostream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__s, __wch | ios_base::out) {}
 #endif // _LIBCPP_STD_VER >= 20
 
+  basic_ostringstream(const basic_ostringstream&) = delete;
   _LIBCPP_HIDE_FROM_ABI basic_ostringstream(basic_ostringstream&& __rhs)
       : basic_ostream<_CharT, _Traits>(std::move(__rhs)), __sb_(std::move(__rhs.__sb_)) {
     basic_ostream<_CharT, _Traits>::set_rdbuf(&__sb_);
   }
 
   // [ostringstream.assign] Assign and swap:
+  basic_ostringstream& operator=(const basic_ostringstream&) = delete;
   basic_ostringstream& operator=(basic_ostringstream&& __rhs) {
     basic_ostream<char_type, traits_type>::operator=(std::move(__rhs));
     __sb_ = std::move(__rhs.__sb_);
@@ -1040,12 +1054,14 @@ public:
       : basic_iostream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__s, __wch) {}
 #endif // _LIBCPP_STD_VER >= 20
 
+  basic_stringstream(const basic_stringstream&) = delete;
   _LIBCPP_HIDE_FROM_ABI basic_stringstream(basic_stringstream&& __rhs)
       : basic_iostream<_CharT, _Traits>(std::move(__rhs)), __sb_(std::move(__rhs.__sb_)) {
     basic_istream<_CharT, _Traits>::set_rdbuf(&__sb_);
   }
 
   // [stringstream.assign] Assign and swap:
+  basic_stringstream& operator=(const basic_stringstream&) = delete;
   basic_stringstream& operator=(basic_stringstream&& __rhs) {
     basic_iostream<char_type, traits_type>::operator=(std::move(__rhs));
     __sb_ = std::move(__rhs.__sb_);

libcxx/test/std/input.output/string.streams/istringstream/types.compile.pass.cpp

@@ -0,0 +1,75 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// <sstream>
+
+// template <class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
+// class basic_istringstream
+//     : public basic_istream<charT, traits>
+// {
+// public:
+//     typedef charT                          char_type;
+//     typedef traits                         traits_type;
+//     typedef typename traits_type::int_type int_type;
+//     typedef typename traits_type::pos_type pos_type;
+//     typedef typename traits_type::off_type off_type;
+//     typedef Allocator                      allocator_type;
+//
+//     basic_istringstream(const basic_istringstream&) = delete;
+//     basic_istringstream& operator=(const basic_istringstream&) = delete;
+//
+//     basic_istringstream(basic_istringstream&& rhs);
+//     basic_istringstream& operator=(basic_istringstream&& rhs);
+
+#include <sstream>
+#include <type_traits>
+
+#include "test_macros.h"
+
+// Types
+
+static_assert(std::is_base_of<std::basic_istream<char>, std::basic_istringstream<char> >::value, "");
+static_assert(std::is_same<std::basic_istringstream<char>::char_type, char>::value, "");
+static_assert(std::is_same<std::basic_istringstream<char>::traits_type, std::char_traits<char> >::value, "");
+static_assert(std::is_same<std::basic_istringstream<char>::int_type, std::char_traits<char>::int_type>::value, "");
+static_assert(std::is_same<std::basic_istringstream<char>::pos_type, std::char_traits<char>::pos_type>::value, "");
+static_assert(std::is_same<std::basic_istringstream<char>::off_type, std::char_traits<char>::off_type>::value, "");
+static_assert(std::is_same<std::basic_istringstream<char>::allocator_type, std::allocator<char> >::value, "");
+
+#ifndef TEST_HAS_NO_WIDE_CHARACTERS
+static_assert(std::is_base_of<std::basic_istream<wchar_t>, std::basic_istringstream<wchar_t> >::value, "");
+static_assert(std::is_same<std::basic_istringstream<wchar_t>::char_type, wchar_t>::value, "");
+static_assert(std::is_same<std::basic_istringstream<wchar_t>::traits_type, std::char_traits<wchar_t> >::value, "");
+static_assert(std::is_same<std::basic_istringstream<wchar_t>::int_type, std::char_traits<wchar_t>::int_type>::value,
+              "");
+static_assert(std::is_same<std::basic_istringstream<wchar_t>::pos_type, std::char_traits<wchar_t>::pos_type>::value,
+              "");
+static_assert(std::is_same<std::basic_istringstream<wchar_t>::off_type, std::char_traits<wchar_t>::off_type>::value,
+              "");
+static_assert(std::is_same<std::basic_istringstream<wchar_t>::allocator_type, std::allocator<wchar_t> >::value, "");
+#endif
+
+// Copy properties
+
+static_assert(!std::is_copy_constructible<std::istringstream>::value, "");
+static_assert(!std::is_copy_assignable<std::istringstream>::value, "");
+
+#ifndef TEST_HAS_NO_WIDE_CHARACTERS
+static_assert(!std::is_copy_constructible<std::wistringstream>::value, "");
+static_assert(!std::is_copy_assignable<std::wistringstream>::value, "");
+#endif
+
+// Move properties
+
+static_assert(std::is_move_constructible<std::istringstream>::value, "");
+static_assert(std::is_move_assignable<std::istringstream>::value, "");
+
+#ifndef TEST_HAS_NO_WIDE_CHARACTERS
+static_assert(std::is_move_constructible<std::wistringstream>::value, "");
+static_assert(std::is_move_assignable<std::wistringstream>::value, "");
+#endif

libcxx/test/std/input.output/string.streams/istringstream/types.pass.cpp

@@ -0,0 +1,75 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// <sstream>
+
+// template <class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
+// class basic_ostringstream
+//     : public basic_ostream<charT, traits>
+// {
+// public:
+//     typedef charT                          char_type;
+//     typedef traits                         traits_type;
+//     typedef typename traits_type::int_type int_type;
+//     typedef typename traits_type::pos_type pos_type;
+//     typedef typename traits_type::off_type off_type;
+//     typedef Allocator                      allocator_type;
+//
+//     basic_ostringstream(const basic_ostringstream&) = delete;
+//     basic_ostringstream& operator=(const basic_ostringstream&) = delete;
+//
+//     basic_ostringstream(basic_ostringstream&& rhs);
+//     basic_ostringstream& operator=(basic_ostringstream&& rhs);
+
+#include <sstream>
+#include <type_traits>
+
+#include "test_macros.h"
+
+// Types
+
+static_assert(std::is_base_of<std::basic_ostream<char>, std::basic_ostringstream<char> >::value, "");
+static_assert(std::is_same<std::basic_ostringstream<char>::char_type, char>::value, "");
+static_assert(std::is_same<std::basic_ostringstream<char>::traits_type, std::char_traits<char> >::value, "");
+static_assert(std::is_same<std::basic_ostringstream<char>::int_type, std::char_traits<char>::int_type>::value, "");
+static_assert(std::is_same<std::basic_ostringstream<char>::pos_type, std::char_traits<char>::pos_type>::value, "");
+static_assert(std::is_same<std::basic_ostringstream<char>::off_type, std::char_traits<char>::off_type>::value, "");
+static_assert(std::is_same<std::basic_ostringstream<char>::allocator_type, std::allocator<char> >::value, "");
+
+#ifndef TEST_HAS_NO_WIDE_CHARACTERS
+static_assert(std::is_base_of<std::basic_ostream<wchar_t>, std::basic_ostringstream<wchar_t> >::value, "");
+static_assert(std::is_same<std::basic_ostringstream<wchar_t>::char_type, wchar_t>::value, "");
+static_assert(std::is_same<std::basic_ostringstream<wchar_t>::traits_type, std::char_traits<wchar_t> >::value, "");
+static_assert(std::is_same<std::basic_ostringstream<wchar_t>::int_type, std::char_traits<wchar_t>::int_type>::value,
+              "");
+static_assert(std::is_same<std::basic_ostringstream<wchar_t>::pos_type, std::char_traits<wchar_t>::pos_type>::value,
+              "");
+static_assert(std::is_same<std::basic_ostringstream<wchar_t>::off_type, std::char_traits<wchar_t>::off_type>::value,
+              "");
+static_assert(std::is_same<std::basic_ostringstream<wchar_t>::allocator_type, std::allocator<wchar_t> >::value, "");
+#endif
+
+// Copy properties
+
+static_assert(!std::is_copy_constructible<std::ostringstream>::value, "");
+static_assert(!std::is_copy_assignable<std::ostringstream>::value, "");
+
+#ifndef TEST_HAS_NO_WIDE_CHARACTERS
+static_assert(!std::is_copy_constructible<std::wostringstream>::value, "");
+static_assert(!std::is_copy_assignable<std::wostringstream>::value, "");
+#endif
+
+// Move properties
+
+static_assert(std::is_move_constructible<std::ostringstream>::value, "");
+static_assert(std::is_move_assignable<std::ostringstream>::value, "");
+
+#ifndef TEST_HAS_NO_WIDE_CHARACTERS
+static_assert(std::is_move_constructible<std::wostringstream>::value, "");
+static_assert(std::is_move_assignable<std::wostringstream>::value, "");
+#endif