bug#5440: 23.1; buffer-file-format encoding temp buffers not reentrant

[Eli Zaretskii]

> From: Andrew Hyatt <ahyatt@gmail.com>
> Cc: user42@zip.com.au,  5440@debbugs.gnu.org
> Date: Mon, 25 Jul 2016 00:07:50 -0400
> 
> diff --git a/doc/lispref/files.texi b/doc/lispref/files.texi
> index f3650a4..5763380 100644
> --- a/doc/lispref/files.texi
> +++ b/doc/lispref/files.texi

Thanks.  A couple of comments:

> @@ -3238,7 +3238,9 @@ Format Conversion Round-Trip
>  
>  One responsibility of @var{from-fn} is to make sure that the beginning
>  of the file no longer matches @var{regexp}.  Otherwise it is likely to
> -get called again.
> +get called again.  Also, @var{from-fn} must not involve other buffers or
> +files other than the one being decoded

One of these 2 "others" should be deleted, I think.

>                                         or else formatting may happen
> +during formatting, leading to incorrect results.

I would say something like

  otherwise the internal buffer used for formatting might be
  overwritten.

> +@var{to-fn} must not involve other buffers or files other than the one
> +being encoded, or else formatting may happen during formatting,
> +leading to incorrect results.

Same here.