[Python-Dev] When val=b'', but val == b'' returns False - bytes initialization

[Antoine Pitrou]

On Wed, 27 Dec 2017 14:19:16 +0000
Jonathan Underwood <jonathan.underwood at gmail.com> wrote:
> Hello,
> 
> I am not sure if this is expected behaviour, or a bug.
> 
> In a C extension module, if I create and return an empty bytes object like this:
> 
>     val = PyBytes_FromStringAndSize (NULL, 20);
>     Py_SIZE(val) = 0;

I wouldn't call it "expected", but bytes objects are supposed to be
NULL-terminated internally, so your code technically creates an invalid
bytes object.  The NULL-terminated constraint may be relied on by some
code, for example when the string gets passed to a third-party C
function.

Perhaps that should be mentioned in the C API docs.

Regards

Antoine.