In function 'test':
tests/cpychecker/refcounts/PyString_Concat/basic/input.c:30:nn: warning: future use-after-free: ob_refcnt of return value is 1 too low [enabled by default]
tests/cpychecker/refcounts/PyString_Concat/basic/input.c:29:nn: note: return value was allocated at:     PyString_Concat(lhs, rhs);
tests/cpychecker/refcounts/PyString_Concat/basic/input.c:30:nn: note: was expecting final owned ob_refcnt of return value to be 2 due to object being referenced by: return value, heap-region-0 but final ob_refcnt is refs: 1 owned
tests/cpychecker/refcounts/PyString_Concat/basic/input.c:29:nn: note: when treating unknown struct PyObject * * from tests/cpychecker/refcounts/PyString_Concat/basic/input.c:27 as non-NULL at:     PyString_Concat(lhs, rhs);
tests/cpychecker/refcounts/PyString_Concat/basic/input.c:29:nn: note: when treating unknown struct PyObject * from tests/cpychecker/refcounts/PyString_Concat/basic/input.c:29 as non-NULL at:     PyString_Concat(lhs, rhs);
tests/cpychecker/refcounts/PyString_Concat/basic/input.c:30:nn: note: when PyString_Concat() succeeds (Py_DECREF() without deallocation on *LHS) at:     return *lhs;
tests/cpychecker/refcounts/PyString_Concat/basic/input.c:30:nn: note: return value is now referenced by 1 non-stack value(s): heap-region-0
tests/cpychecker/refcounts/PyString_Concat/basic/input.c:30:nn: note: returning at:     return *lhs;
tests/cpychecker/refcounts/PyString_Concat/basic/input.c:30:nn: note: found 1 similar trace(s) to this
tests/cpychecker/refcounts/PyString_Concat/basic/input.c:30:nn: warning: returning (PyObject*)NULL without setting an exception [enabled by default]
tests/cpychecker/refcounts/PyString_Concat/basic/input.c:29:nn: note: when treating unknown struct PyObject * * from tests/cpychecker/refcounts/PyString_Concat/basic/input.c:27 as non-NULL at:     PyString_Concat(lhs, rhs);
tests/cpychecker/refcounts/PyString_Concat/basic/input.c:29:nn: note: when treating unknown struct PyObject * from tests/cpychecker/refcounts/PyString_Concat/basic/input.c:29 as NULL at:     PyString_Concat(lhs, rhs);
tests/cpychecker/refcounts/PyString_Concat/basic/input.c:29:nn: note: when PyString_Concat() does nothing due to NULL *lhs at:     PyString_Concat(lhs, rhs);
tests/cpychecker/refcounts/PyString_Concat/basic/input.c:30:nn: note: returning at:     return *lhs;
tests/cpychecker/refcounts/PyString_Concat/basic/input.c:28:nn: note: graphical error report for function 'test' written out to 'tests/cpychecker/refcounts/PyString_Concat/basic/input.c.test-refcount-errors.html'
