<syncstream>: implement basic_syncbuf and basic_osyncstream

stl/CMakeLists.txt

@@ -186,6 +186,7 @@ set(HEADERS
     ${CMAKE_CURRENT_LIST_DIR}/inc/string
     ${CMAKE_CURRENT_LIST_DIR}/inc/string_view
     ${CMAKE_CURRENT_LIST_DIR}/inc/strstream
+    ${CMAKE_CURRENT_LIST_DIR}/inc/syncstream
     ${CMAKE_CURRENT_LIST_DIR}/inc/system_error
     ${CMAKE_CURRENT_LIST_DIR}/inc/thread
     ${CMAKE_CURRENT_LIST_DIR}/inc/tuple
@@ -396,6 +397,7 @@ set(SOURCES_SATELLITE_2
 set(SOURCES_SATELLITE_ATOMIC_WAIT
     ${CMAKE_CURRENT_LIST_DIR}/src/atomic_wait.cpp
     ${CMAKE_CURRENT_LIST_DIR}/src/parallel_algorithms.cpp
+    ${CMAKE_CURRENT_LIST_DIR}/src/syncstream.cpp
 )
 
 set(SOURCES_SATELLITE_CODECVT_IDS
@@ -495,7 +497,7 @@ function(add_stl_dlls D_SUFFIX THIS_CONFIG_DEFINITIONS THIS_CONFIG_COMPILE_OPTIO
     file(WRITE "${_ATOMIC_WAIT_DEF_NAME}" "${_ATOMIC_WAIT_DEF_CONTENTS}")
 
     add_library(msvcp${D_SUFFIX}_atomic_wait SHARED "${_ATOMIC_WAIT_DEF_NAME}")
-    target_link_libraries(msvcp${D_SUFFIX}_atomic_wait PRIVATE msvcp${D_SUFFIX}_atomic_wait_objects msvcp${D_SUFFIX}_satellite_objects "msvcp${D_SUFFIX}" "${TOOLSET_LIB}/vcruntime${D_SUFFIX}.lib" "${TOOLSET_LIB}/msvcrt${D_SUFFIX}.lib" "ucrt${D_SUFFIX}.lib")
+    target_link_libraries(msvcp${D_SUFFIX}_atomic_wait PRIVATE msvcp${D_SUFFIX}_atomic_wait_objects msvcp${D_SUFFIX}_satellite_objects msvcp${D_SUFFIX}_implib_objects "msvcp${D_SUFFIX}" "${TOOLSET_LIB}/vcruntime${D_SUFFIX}.lib" "${TOOLSET_LIB}/msvcrt${D_SUFFIX}.lib" "ucrt${D_SUFFIX}.lib")
     set_target_properties(msvcp${D_SUFFIX}_atomic_wait PROPERTIES ARCHIVE_OUTPUT_NAME "msvcp140_atomic_wait${D_SUFFIX}${VCLIBS_SUFFIX}")
     set_target_properties(msvcp${D_SUFFIX}_atomic_wait PROPERTIES ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}")
     set_target_properties(msvcp${D_SUFFIX}_atomic_wait PROPERTIES OUTPUT_NAME "${_ATOMIC_WAIT_OUTPUT_NAME}")

stl/inc/__msvc_all_public_headers.hpp

@@ -120,6 +120,7 @@
 #include <string>
 #include <string_view>
 #include <strstream>
+#include <syncstream>
 #include <system_error>
 #include <tuple>
 #include <typeindex>

stl/inc/header-units.json

@@ -96,6 +96,7 @@
         "string",
         "string_view",
         "strstream",
+        "syncstream",
         "system_error",
         "thread",
         "tuple",

stl/inc/iosfwd

@@ -200,6 +200,14 @@ template <class _Elem, class _Traits = char_traits<_Elem>>
 class basic_ofstream;
 template <class _Elem, class _Traits = char_traits<_Elem>>
 class basic_fstream;
+#if _HAS_CXX20
+template <class _Elem, class _Traits = char_traits<_Elem>>
+class _Basic_syncbuf_impl;
+template <class _Elem, class _Traits = char_traits<_Elem>, class _Alloc = allocator<_Elem>>
+class basic_syncbuf;
+template <class _Elem, class _Traits = char_traits<_Elem>, class _Alloc = allocator<_Elem>>
+class basic_osyncstream;
+#endif // _HAS_CXX20
 
 #if defined(_DLL_CPPLIB)
 template <class _Elem, class _InIt>
@@ -224,6 +232,10 @@ using filebuf       = basic_filebuf<char, char_traits<char>>;
 using ifstream      = basic_ifstream<char, char_traits<char>>;
 using ofstream      = basic_ofstream<char, char_traits<char>>;
 using fstream       = basic_fstream<char, char_traits<char>>;
+#if _HAS_CXX20
+using syncbuf     = basic_syncbuf<char>;
+using osyncstream = basic_osyncstream<char>;
+#endif // _HAS_CXX20
 
 // wchar_t TYPEDEFS
 using wios           = basic_ios<wchar_t, char_traits<wchar_t>>;
@@ -239,6 +251,10 @@ using wfilebuf       = basic_filebuf<wchar_t, char_traits<wchar_t>>;
 using wifstream      = basic_ifstream<wchar_t, char_traits<wchar_t>>;
 using wofstream      = basic_ofstream<wchar_t, char_traits<wchar_t>>;
 using wfstream       = basic_fstream<wchar_t, char_traits<wchar_t>>;
+#if _HAS_CXX20
+using wsyncbuf     = basic_syncbuf<wchar_t>;
+using wosyncstream = basic_osyncstream<wchar_t>;
+#endif // _HAS_CXX20
 
 #if defined(_CRTBLD)
 // unsigned short TYPEDEFS

stl/inc/ostream

@@ -993,6 +993,45 @@ basic_ostream<_Elem, _Traits>& __CLRCALL_OR_CDECL flush(basic_ostream<_Elem, _Tr
     return _Ostr;
 }
 
+#if _HAS_CXX20
+#ifdef _CPPRTTI
+template <class _Elem, class _Traits>
+basic_ostream<_Elem, _Traits>& emit_on_flush(basic_ostream<_Elem, _Traits>& _Ostr) {
+    const auto _Sync_buf_ptr = dynamic_cast<_Basic_syncbuf_impl<_Elem, _Traits>*>(_Ostr.rdbuf());
+    if (_Sync_buf_ptr) {
+        _Sync_buf_ptr->set_emit_on_sync(true);
+    }
+    return _Ostr;
+}
+
+template <class _Elem, class _Traits>
+basic_ostream<_Elem, _Traits>& noemit_on_flush(basic_ostream<_Elem, _Traits>& _Ostr) {
+    const auto _Sync_buf_ptr = dynamic_cast<_Basic_syncbuf_impl<_Elem, _Traits>*>(_Ostr.rdbuf());
+    if (_Sync_buf_ptr) {
+        _Sync_buf_ptr->set_emit_on_sync(false);
+    }
+    return _Ostr;
+}
+
+template <class _Elem, class _Traits>
+basic_ostream<_Elem, _Traits>& flush_emit(basic_ostream<_Elem, _Traits>& _Ostr) {
+    _Ostr.flush();
+    const auto _Sync_buf_ptr = dynamic_cast<_Basic_syncbuf_impl<_Elem, _Traits>*>(_Ostr.rdbuf());
+    if (_Sync_buf_ptr) {
+        _Sync_buf_ptr->_Do_emit();
+    }
+    return _Ostr;
+}
+#else // _CPPRTTI
+template <class _Elem, class _Traits>
+basic_ostream<_Elem, _Traits>& emit_on_flush(basic_ostream<_Elem, _Traits>&) = delete; // requires /GR option
+template <class _Elem, class _Traits>
+basic_ostream<_Elem, _Traits>& noemit_on_flush(basic_ostream<_Elem, _Traits>&) = delete; // requires /GR option
+template <class _Elem, class _Traits>
+basic_ostream<_Elem, _Traits>& flush_emit(basic_ostream<_Elem, _Traits>&) = delete; // requires /GR option
+#endif // _CPPRTTI
+#endif // _HAS_CXX20
+
 // INSERTER FOR error_category
 template <class _Elem, class _Traits>
 basic_ostream<_Elem, _Traits>& operator<<(basic_ostream<_Elem, _Traits>& _Ostr,