Python 3.13t crashes when constructing code objects with non-standard constants

[colesbury]

Bug report

PyTorch Dynamo constructs code objects with non-standard constants. This is unusual, but seems to work with the default (non-free threaded build) of CPython.

However, it crashes in the free threaded build due to a few assertions when we try to de-dupe (intern) and immortalize constants:

In compare_constants:

cpython/Objects/codeobject.c

Lines 2671 to 2672 in 3dd3675

	_Py_FatalErrorFormat("unexpected type in compare_constants: %s",
	Py_TYPE(op1)->tp_name);

In `hash_const:

cpython/Objects/codeobject.c

Lines 2692 to 2694 in 3dd3675

	// This should never happen: all the constants we support have
	// infallible hash functions.
	Py_FatalError("code: hash failed");

We should more gracefully handle unexpected code object constants in the free threading build. I think the interning code should behave like _PyCode_ConstantKey() where unhandled objects types are treated as unequal if they are not the same instance (i.e., identity comparison for unexpected types).

cc @williamwen42

Linked PRs

• gh-130851: Don't crash when deduping unusual code constants. #130853
• [3.13] gh-130851: Don't crash when deduping unusual code constants (GH-130853) #130880
• gh-130851: Skip test_unusual_constants under refleak checker #130899
• gh-130851: Only intern constants of types generated by the compiler #130901
• [3.13] gh-130851: Only intern constants of types generated by the compiler (GH-130901) #130953