[New-bugs-announce] [issue39109] [C-API] PyUnicode_FromString

Yannick report at bugs.python.org
Fri Dec 20 07:33:15 EST 2019

New submission from Yannick <schmetzyannick at gmail.com>:

Python version: 3.5
Tested with VS Studio 2017 in an C-API extension.

When you have a UTF-8 encoded char buffer which is filled with a 0 or empty, and you youse the PyUnicode_FromString() method on this buffer, you will get a PyObject*. The content looks good, but the refence counter looks strange. 

In case of an 0 as char in the buffer, the ob_refcnt Field is set to 100 and in case of an empty buffer, the ob_refcnt Field is set to something around 9xx. 

Example Code: 
      string s1 = u8"";
      string s2 = u8"0";

      PyObject *o1 = PyUnicode_FromString(s1.c_str());
      //o1->ob_refcnt = 9xx
      PyObject *o2 = PyUnicode_FromString(s2.c_str());
      //o2->ob_refcnt = 100

I think the ob_refcnt Field should be 1 in both cases. Or why is the refcnt here so high?

components: C API
messages: 358706
nosy: YannickSchmetz
priority: normal
severity: normal
status: open
title: [C-API] PyUnicode_FromString
type: behavior
versions: Python 3.5

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