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This PR is stale because it has been open for 30 days with no activity.

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This PR is stale because it has been open for 30 days with no activity.

@vstinner @serhiy-storchaka maybe you could take a look?

Fixes a pretty major malloc error in the docs.

Please elaborate. I don't understand which problem you are trying to solve.

The CPython API docs currently effectively suggest malloc(0 * sizeof(T)) when it should be malloc(1 * sizeof(T)) to create a new object. This PR fixes this.

The CPython API docs currently effectively suggest malloc(0 * sizeof(T)) when it should be malloc(1 * sizeof(T)) to create a new object. This PR fixes this.

tp_alloc(type, 0) doesn't call malloc().

The default allocator function is PyType_GenericAlloc() which uses:

    const size_t size = _PyObject_VAR_SIZE(type, nitems+1);

which is defined as:

#define _PyObject_VAR_SIZE(typeobj, nitems)     \
    _Py_SIZE_ROUND_UP((typeobj)->tp_basicsize + \
        (nitems)*(typeobj)->tp_itemsize,        \
        SIZEOF_VOID_P)

tp_alloc(type, 0) allocates types->tp_basicsize. In the tutorial, tp_basicsize is defined as:

.tp_basicsize = sizeof(CustomObject),

In short, IMO the current code is correct, and your change wastes memory.

Hmm nitems+1... curious. I had a code snippet which crashed and changing tp_alloc(type, 0) to tp_alloc(type, 1) fixed it. Will see if I can reproduce it again and post a minimal example.

Will see if I can reproduce it again and post a minimal example.

Open an issue at https://bugs.python.org/ in this case. In the meanwhile, I close your PR.