Useless code block in math.trunc() ?

[skirpichev]

Bug report

Bug description:

The math.trunc function has:

cpython/Modules/mathmodule.c

Lines 2073 to 2076 in f013b47

	if (!_PyType_IsReady(Py_TYPE(x))){
	if (PyType_Ready(Py_TYPE(x)) < 0)
	return NULL;
	}

c.f. math.ceil or math.floor.

This seems to be a history artifact: the function was introduced in 400adb0 as a moved builtins.trunc(), while math.ceil/floor were here from the initial revision.

I think it's safe to remove mentioned block.

PS: Issue opened per @serhiy-storchaka suggestion in #110000.

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Linked PRs

• gh-111417: Remove unused code block in math.trunc() and builtin_round_impl #111454

[Jason-Y-Z]

Created a small PR to remove the unused code block - #111454

[serhiy-storchaka]

I suggested @skirpichev to open a separate issue for discussion and reference. Previously this change was hidden in a pile of unrelated changes.

Now I think that it is safe. This check is immediately followed by _PyObject_LookupSpecial() which calls _PyType_Lookup() which, after looking in the type cache, calls find_name_in_mro() which looks up tp_mro, and, if it has not yet been set, make the type ready.

I think that a similar code in the builtin round() can be removed as well. Other uses of _PyType_IsReady() and PyType_Ready() look more justified.

[skirpichev]

@serhiy-storchaka, in the end, it was your commit, that makes additional PyType_Ready() (since 15d3d04) call here useless: 8ef3460.

@Jason-Y-Z, I think you could reference that commit in you commit message. And remove similar code in round(), of course.