Fixed issue with formatting to an array of chars

[stryku]

It should fix #1169. Added a couple of tests to prevent such issues in the future. Please, let me know if I forgot about any prepared_format::format_to use case.

[vitaut]

Thanks for the PR! Mostly looks good, just two comments inline.

[vitaut]

vformat* functions should take basic_format_args not format_arg_store.

[stryku]

Those are private methods. I've introduced the overload that takes format_arg_store, because calling prepared_format::format_to() with char* as an output iterator, introduced compilation error could not match 'basic_format_args' against 'format_arg_store'. That's why I decided to create the overload, explicitly create basic_format_args there and pass it to the proper vformat implementation.

Does it resolve your doubts or it's still wrong? If it's wrong, what do you propose?

[vitaut]

The matching error is because template argument deduction doesn't play well with implicit conversion from format_arg_store to format_args. I suggest removing the extra overload and adding braces to force the conversion as it is done in

fmt/include/fmt/core.h

Line 1357 in 87fbc6f

{internal::make_args_checked(format_str, args...)});

[stryku]

Hmm, I think that's not exactly the case. Braces help here because with such call, compiler doesn't need to deduce context for basic_format_args, thus whole basic_format_args<context> type is known. It's known because Char type known, as well.

fmt/include/fmt/core.h

Line 1317 in 87fbc6f

basic_format_args<buffer_context<Char>> args) {

In my case, the context type is not known and needs to be deduced, so basic_format_args is not known and can not be deduced because compiler would need to perform implicit conversion.

To handle this, I've added explicit call to basic_format_args ctors. Please check it and let me know if it looks reasonable.

[vitaut]

Thanks!