Remove /source-charset:utf-8 compile option.

[phprus]

Integrating fmt into my projects revealed the issue (https://godbolt.org/z/GqKEGexvo):

cl : Command line error D8016 : '/source-charset:utf-8' and '/utf-8' command-line options are incompatible

Compile options /utf-8, /source-charset:utf-8, /execution-charset:utf-8 are not compatible in any combination.
I'm using the globally set /utf-8 option, which results in an error when adding fmt with tests.

We can solve this problem globally by removing the '/source-charset:utf-8' option and replacing the string literal L"Файл.txt" with a wchar_t representation.

@vitaut, What do you think about this?

[fredemmott]

/utf-8 is /source-charset:utf-8 and /execution-charset:utf-8; perhaps specifying those separately for your project would work for you?

wchar_t's size (and UTF-16'ness) is Windows-specific; AIUI this approach isn't portable to the other platforms fmt supports

[ilyapopov]

wchar_t's size (and UTF-16'ness) is Windows-specific; AIUI this approach isn't portable to the other platforms fmt supports

This code is already guarded with #ifdef _WIN32

https://github.com/fmtlib/fmt/pull/2938/files#diff-d6fdd38fa0cc7a99925e7925eeae577c399747b4f8deb61a3aed03c0d56c007bR18

[vitaut]

This comment is a bit misleading because we actually use UTF-8 below. There is still a question whether it should be escaped or not but it's still UTF-8.

[phprus]

Comment updated.

[vitaut]

I think you can use UTF-8 without escape sequences here as we do in format-test:

fmt/test/format-test.cc

Line 175 in 2471875

auto u = fmt::detail::utf8_to_utf16("лошадка");

[vitaut]

In general looks good, a few comments inline.

[phprus]

@fredemmott,

fmt uses the /utf-8 flag in tests:

fmt/test/CMakeLists.txt

Lines 84 to 87 in fb991e9

	add_fmt_test(unicode-test HEADER_ONLY)
	if (MSVC)
	target_compile_options(unicode-test PRIVATE /utf-8)
	endif ()

Therefore, I cannot set the /source-charset:utf-8 /execution-charset:utf-8 option, it will conflict with /utf-8 from the tests (and several other third party libraries in my projects). And I cannot set the /utf-8 option, it will conflict with /source-charset:utf-8 from this test.

My mistake was choosing the /source-charset:utf-8 (PR ) option instead of using the wchar_t array.

wchar_t's size (and UTF-16'ness) is Windows-specific;
This test is only required for Windows. libstdc++ and libc++ use utf-8 in the std::filesystem::*.
This test will not reproduce the error when using the /utf-8 option or when there are utf-8 characters in the test source file.

[vitaut]

Merged, thanks!