same _Storage_type for const string and string

fsb4000 · cpplearner · fsb4000 · commit 8caf0bd0e1c1 · 2022-06-08T16:48:25.000+07:00
Co-authored-by: S. B. Tam &lt;cpplearner@outlook.com&gt;
diff --git a/stl/inc/format b/stl/inc/format
@@ -1776,7 +1776,7 @@ struct _Format_arg_traits {
         -> basic_string_view<_Char_type>; // not defined
 
     template <class _Traits, class _Alloc>
-    static auto _Phony_basic_format_arg_constructor(const basic_string<_Char_type, _Traits, _Alloc>&)
+    static auto _Phony_basic_format_arg_constructor(basic_string<_Char_type, _Traits, _Alloc>)
         -> basic_string_view<_Char_type>; // not defined
 
     static auto _Phony_basic_format_arg_constructor(nullptr_t) -> const void*; // not defined
diff --git a/tests/std/tests/P0645R10_text_formatting_args/test.cpp b/tests/std/tests/P0645R10_text_formatting_args/test.cpp
@@ -7,6 +7,7 @@
 #include <cstdint>
 #include <format>
 #include <memory>
+#include <string>
 #include <string_view>
 #include <type_traits>
 #include <variant>
@@ -212,6 +213,9 @@ void test_format_arg_store() {
 static_assert(sizeof(_Format_arg_index) == sizeof(size_t));
 static_assert(is_same_v<_Format_arg_traits<format_context>::_Storage_type<void*>, const void*>);
 
+static_assert(is_same_v<_Format_arg_traits<format_context>::_Storage_type<string>, string_view>);
+static_assert(is_same_v<_Format_arg_traits<format_context>::_Storage_type<const string>, string_view>);
+
 template <class Context>
 void test_visit_monostate() {
     assert(visit_format_arg(visitor<Context>, basic_format_arg<Context>()) == Arg_type::none);
