The vformat & vprint functions produce incorrect output when mixing named and positional arguments.

[calebkiage]

When using the dynamic_format_arg_store with both named and positional args on fmt, the output produced is incorrect.

A minimal reproduction of the issue is shown in the snippet below:

A minimal reproduction of the issue is shown in the snippet below:

#include <fmt/args.h>
#include <fmt/core.h>

int main() {
    fmt::dynamic_format_arg_store<fmt::format_context> store;
    store.push_back(1);
    store.push_back(fmt::arg("b", 2));
    store.push_back(3);

    // Prints 1 2 2 instead of 1 2 3
    fmt::vprint("{} {b} {}", store);
}

godbolt link

[calebkiage]

I've noticed the issue doesn't happen if the named arguments come after all the positional arguments.
godbolt link

[vitaut]

It was supposed to be an error similarly to mixing manual/automatic indexing but the check was missing. Fixed in 4c5b4af. Thanks for reporting.