Re: [PATCH] system-type cygwin with window-system w32

[Eli Zaretskii]

Could you please explain this part of the patch:

>    /* Create the dialog with PROMPT as title, using DIR as initial
>       directory and using "*" as pattern.  */
> -  dir = Fexpand_file_name (dir, Qnil);
> -  strncpy (init_dir, SDATA (ENCODE_FILE (dir)), MAX_PATH);
> -  init_dir[MAX_PATH] = '\0';
> -  unixtodos_filename (init_dir);
> -
> -  if (STRINGP (default_filename))
> -    {
> -      char *file_name_only;
> -      char *full_path_name = SDATA (ENCODE_FILE (default_filename));
> -
> -      unixtodos_filename (full_path_name);
> -
> -      file_name_only = strrchr (full_path_name, '\\');
> -      if (!file_name_only)
> -        file_name_only = full_path_name;
> -      else
> -     file_name_only++;
> -
> -      strncpy (filename, file_name_only, MAX_PATH);
> -      filename[MAX_PATH] = '\0';
> -    }
> -  else
> -    filename[0] = '\0';
> -
> -  /* The code in file_dialog_callback that attempts to set the text
> -     of the file name edit window when handling the CDN_INITDONE
> -     WM_NOTIFY message does not work.  Setting filename to "Current
> -     Directory" in the only_dir_p case here does work however.  */
> -  if (filename[0] == 0 && ! NILP (only_dir_p))
> -    strcpy (filename, "Current Directory");
> +  to_unicode (Fexpand_file_name (dir, Qnil), &dir);
> +
> +  to_unicode (build_string ("All Files (*.*)\0*.*\0Directories\0*|*\0\0"),
> +              &filter);

AFAICT, to_unicode encodes the file name in UTF-16.  If so, this will
not work in the native Windows build, because it does not use Unicode
APIs for file names.  In the original code, ENCODE_FILE would use the
ANSI encoding, not UTF-16.  So, unless I'm missing something, the
replacement is not equivalent to the original, and could break the
native build.

If my analysis is correct, could you please explain the rationale for
this change?