Unconsistent command-line parsing in case of UTF-8 quoted arguments

[Jérôme Froissart]

Thanks for your replies.
This issue only happens when a program is run from cmd.exe, not from a
Cygwin bash shell.
This is important for me, since I discovered this bug in a project
that must be run from Windows graphical shell (i.e. there is no
sensible way to run it through Cygwin and Bash).

> Please show us the output from "uname -a" and "locale" run from the bash prompt.

> Please provide the results of "locale" command right before running your test
> binary.
Here are the more detailed steps to reproduce the issue (along with
answers to your requests about `uname`, `locale`, etc.).
(I mostly reproduced what billziss-gh had done before, I do not take
all the credits :D)

Here is an example C file
    $ cat example.c
    #include <stdio.h>

    const char *GetCommandLineA(void);

    int main(int argc, char *argv[])
    {
        const char *s = GetCommandLineA();
        printf("C=%s\n", s);

        for (int i = 0; argc > i; i++)
            printf("%d=%s\n", i, argv[i]);

        return 0;
    }

I have built it with gcc from Cygwin
    $ gcc -o binary example.c

Running it from the same Cygwin bash prompt works as expected
    $ uname -a
    CYGWIN_NT-10.0 XPS 3.1.5(0.340/5/3) 2020-06-01 08:59 x86_64 Cygwin
    # (XPS is my Windows machine name)

    $ locale
    LANG=fr_FR.UTF-8
    LC_CTYPE="fr_FR.UTF-8"
    LC_NUMERIC="fr_FR.UTF-8"
    LC_TIME="fr_FR.UTF-8"
    LC_COLLATE="fr_FR.UTF-8"
    LC_MONETARY="fr_FR.UTF-8"
    LC_MESSAGES="fr_FR.UTF-8"
    LC_ALL=

    $ which gcc
    /usr/bin/gcc

    # The following runs as expected
    $ ./binary.exe "foo bar" "Jérôme"
    C="C:\Users\Public\binary.exe"
    0=./binary
    1=foo bar
    2=Jérôme

Now, let's start a Windows shell (cmd.exe)
Note that I had to copy cygwin1.dll from my Cygwin installation
directory, otherwise binary.exe would not start.
I do not know whether there is a `locale` equivalent in Windows
command prompt, so I merely ran my program.
    C:\Users\Public>binary.exe "foo bar" "Jérôme"
    C=binary.exe  "foo bar" "J□r□me"
    0=binary
    1=foo bar
    2="Jérôme"

This behaviour is not expected and is quite inconsistent with what
happened through Bash.
Besides the "strange squares" that appear on the first line, and the
extra space after binary.exe, I especially did not expect "Jérôme" to
remain quoted as a second argument.

Sorry for the delay in my answer. I hope this is now clear, please ask
me for more examples or investigation if you need.
Thanks for your help.

Jérôme