<chrono>: incorrect estimated string width when formatting year_month_day into fullwidth character #2002
Description
Command-line test case
Active code page: 65001
D:\cpptest>type repro.cpp
#include <format>
#include <iostream>
#include <chrono>
#include <locale>
int main()
{
using namespace std::chrono;
std::locale loc{ "chinese.UTF-8" };
std::locale::global(loc);
const year_month_day date = 2021y / June / 1d;
std::cout << std::format("+{:-^60}+\n", "");
std::cout << std::format("|{:^60}|\n", "English & 中文");
std::cout << std::format("|{:^60%Y %B %d %A}|\n", date);
std::cout << std::format("|{:^60}|\n", std::format("{:%Y %B %d %A}", date));
std::cout << std::format("+{:-^60}+\n", "");
return 0;
}
D:\cpptest>cl /std:c++20 /utf-8 .\repro.cpp
Microsoft (R) C/C++ Optimizing Compiler Version 19.29.30129.3 for x86
Copyright (C) Microsoft Corporation. All rights reserved.
repro.cpp
D:\Program Files (x86)\Microsoft Visual Studio\2019\Preview\VC\Tools\MSVC\14.29.30129\include\chrono(2879): warning C4530: C++ exception handler used, but unwind semantics are not enabled. Specify /EHsc
Microsoft (R) Incremental Linker Version 14.29.30129.3
Copyright (C) Microsoft Corporation. All rights reserved.
/out:repro.exe
repro.obj
D:\cpptest>repro.exe
+------------------------------------------------------------+
| English & 中文 |
| 2021 六月 01 星期二 |
| 2021 六月 01 星期二 |
+------------------------------------------------------------+
Expected behavior
I expect the output to be like:
+------------------------------------------------------------+
| English & 中文 |
| 2021 六月 01 星期二 |
| 2021 六月 01 星期二 |
+------------------------------------------------------------+
i.e. the two lines of "2021 六月 01 星期二" should have the same width.
STL version
Microsoft Visual Studio Enterprise 2019 Preview
版本 16.11.0 Preview 1.0