<format>: Investigate objsize test

The MSVC compiler has an internal test (src\qa\VC\FE\compiler\tests\cxx\comp\regress\objsize\objsize.cpp) that includes STL headers without doing anything else, and verifies that the resulting object file is minimally small. <charconv> fails this test (because of its digit table), and <format> (which will be included by <chrono>, and includes <charconv>) causes more failures (due to strings used for exceptions, and possibly more). Here is the test:

C:\Temp>type objsize.cpp

#define _SILENCE_CXX17_C_HEADER_DEPRECATION_WARNING
#define _SILENCE_CXX17_STRSTREAM_DEPRECATION_WARNING
#define _SILENCE_EXPERIMENTAL_FILESYSTEM_DEPRECATION_WARNING
#define _SILENCE_STDEXT_HASH_DEPRECATION_WARNINGS

#include <algorithm>
#include <any>
#include <array>
#include <atomic>
#include <barrier>
#include <bit>
#include <bitset>
// #include <charconv>
#include <chrono>
#include <codecvt>
#include <compare>
#include <complex>
#include <concepts>
#include <condition_variable>
#include <coroutine>
#include <deque>
#include <exception>
#include <execution>
#include <filesystem>
#include <format>
#include <forward_list>
#include <fstream>
#include <functional>
#include <future>
#include <hash_map>
#include <hash_set>
#include <initializer_list>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <latch>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <memory_resource>
#include <mutex>
#include <new>
#include <numbers>
#include <numeric>
#include <optional>
#include <ostream>
#include <queue>
#include <random>
#include <ranges>
#include <ratio>
#include <regex>
#include <scoped_allocator>
#include <semaphore>
#include <set>
#include <shared_mutex>
#include <source_location>
#include <span>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <stop_token>
#include <streambuf>
#include <string>
#include <string_view>
#include <strstream>
#include <syncstream>
#include <system_error>
#include <thread>
#include <tuple>
#include <type_traits>
#include <typeindex>
#include <typeinfo>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <valarray>
#include <variant>
#include <vector>
#include <version>

#include <cassert>
#include <ccomplex>
#include <cctype>
#include <cerrno>
// #include <cfenv>
#include <cfloat>
#include <cinttypes>
#include <ciso646>
#include <climits>
#include <clocale>
#include <cmath>
#include <csetjmp>
#include <csignal>
#include <cstdalign>
#include <cstdarg>
#include <cstdbool>
#include <cstddef>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctgmath>
#include <ctime>
#include <cuchar>
#include <cwchar>
#include <cwctype>

#include <experimental/deque>
#include <experimental/filesystem>
#include <experimental/forward_list>
#include <experimental/list>
#include <experimental/map>
#include <experimental/set>
#include <experimental/string>
#include <experimental/unordered_map>
#include <experimental/unordered_set>
#include <experimental/vector>

#include <assert.h>
#include <complex.h>
#include <conio.h>
#include <crtdbg.h>
#include <ctype.h>
#include <direct.h>
#include <dos.h>
#include <errno.h>
#include <excpt.h>
#include <fcntl.h>
// #include <fenv.h>
#include <float.h>
#include <fpieee.h>
#include <intrin.h>
#include <inttypes.h>
#include <io.h>
#include <iso646.h>
#include <limits.h>
#include <locale.h>
#include <malloc.h>
#include <math.h>
#include <mbctype.h>
#include <mbstring.h>
#include <memory.h>
#include <minmax.h>
#include <new.h>
#include <process.h>
#include <safeint.h>
#include <sal.h>
#include <search.h>
#include <setjmp.h>
#include <share.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/locking.h>
#include <sys/stat.h>
#include <sys/timeb.h>
#include <sys/types.h>
#include <sys/utime.h>
#include <tchar.h>
#include <time.h>
#include <uchar.h>
#include <wchar.h>
#include <wctype.h>

C:\Temp>cl /EHsc /nologo /std:c++latest /c objsize.cpp
objsize.cpp

C:\Temp>(dumpbin /headers objsize.obj|findstr /C:" name"|findstr /V /C:".drectve"|findstr /V /C:".debug"|findstr /V /C:"chks64") && echo TEST FAILED || echo TEST PASSED
  .rdata name
   .data name
.text$mn name
   .data name
  .rdata name
.text$mn name
.text$di name
.text$di name
    .bss name
    .bss name
.CRT$XCU name
.CRT$XCU name
TEST FAILED

Note that if it's built in C++17 mode, it passes (the C++20-only headers emit informational messages as expected):

C:\Temp>cl /EHsc /nologo /std:c++17 /c objsize.cpp
objsize.cpp
The contents of <barrier> are available only with C++20 or later.
The contents of <bit> are available only with C++20 or later.
The contents of <compare> are available only with C++20 or later.
The contents of <concepts> are available only with C++20 concepts support.
The contents of <coroutine> are available only with C++20 or later or /await:strict.
The contents of <format> are available only with C++20 concepts support.
The contents of <latch> are available only with C++20 or later.
The contents of <numbers> are available only with C++20 or later.
The contents of <ranges> are available only with C++20 concepts support.
The contents of <semaphore> are available only with C++20 or later.
The contents of <source_location> are available only with C++20 consteval support.
The contents of <span> are available only with C++20 or later.
The contents of <stop_token> are available only with C++20 or later.
The contents of <syncstream> are available only with C++20 or later.

C:\Temp>(dumpbin /headers objsize.obj|findstr /C:" name"|findstr /V /C:".drectve"|findstr /V /C:".debug"|findstr /V /C:"chks64") && echo TEST FAILED || echo TEST PASSED
TEST PASSED

• We should see if we can get <charconv> and <format> to pass this test.
• Investigate whether /Zc:inline affects this.
• We should consider adding an improved version of this test (using <__msvc_all_public_headers.hpp>) to the STL.
• We should re-enable /std:c++latest coverage in this test - to unblock the <format> checkin, I'm going to change the compiler's test to cover /std:c++17 only.
• We should consider having coverage for /std:c++14, /std:c++17, /std:c++20, and /std:c++latest modes.

Reproduce the objsize test at src\qa\VC\FE\compiler\tests\cxx\comp\regress\objsize\objsize.cpp with /std:c++latest, then compare the C++17 result and investigate /Zc:inline. Review whether an improved test using <__msvc_all_public_headers.hpp> should cover the listed standard modes; done means the and coverage and the intended test matrix are resolved.