[PATCH v6 1/4] libcpp: reject codepoints above 0x10FFFF

[Jason Merrill]

On 6/6/23 16:50, Ben Boeckel wrote:
> Unicode does not support such values because they are unrepresentable in
> UTF-16.

Pushed.

> libcpp/
> 
> 	* charset.cc: Reject encodings of codepoints above 0x10FFFF.
> 	UTF-16 does not support such codepoints and therefore all
> 	Unicode rejects such values.
> 
> Signed-off-by: Ben Boeckel <ben.boeckel@kitware.com>
> ---
>   libcpp/charset.cc | 7 +++++++
>   1 file changed, 7 insertions(+)
> 
> diff --git a/libcpp/charset.cc b/libcpp/charset.cc
> index d7f323b2cd5..3b34d804cf1 100644
> --- a/libcpp/charset.cc
> +++ b/libcpp/charset.cc
> @@ -1886,6 +1886,13 @@ cpp_valid_utf8_p (const char *buffer, size_t num_bytes)
>         int err = one_utf8_to_cppchar (&iter, &bytesleft, &cp);
>         if (err)
>   	return false;
> +
> +      /* Additionally, Unicode declares that all codepoints above 0010FFFF are
> +	 invalid because they cannot be represented in UTF-16.
> +
> +	 Reject such values.*/
> +      if (cp >= 0x10FFFF)
> +	return false;
>       }
>     /* No problems encountered.  */
>     return true;