Fix SUBSCR_LIST_INT/STORE_SUBSCR_LIST_INT asserting on wide ints

_GUARD_TOS_INT only checks PyLong_CheckExact, so wide (non-compact) ints can reach _BINARY_OP_SUBSCR_LIST_INT and _STORE_SUBSCR_LIST_INT, both of which call _PyLong_CompactValue unconditionally. The specializer correctly gates on _PyLong_IsNonNegativeCompact, but the runtime guard did not enforce that invariant. Add EXIT_IF / DEOPT_IF(!_PyLong_IsNonNegativeCompact) before each _PyLong_CompactValue call so wide-int indices fall back to the slow path instead of hitting the assertion. The bug was latent before this branch because BINARY_OP_ADD_INT would deopt on wide-int operands, so wide results rarely appeared as list subscripts that had already been specialised for compact ints.
KRRT7 · May 20, 2026 · May 25, 2026 · May 25, 2026 · May 25, 2026 · May 25, 2026
commit 5e018400515a9c2c41a2d4afdc9c908db9211211
diff --git a/Modules/_testinternalcapi/test_cases.c.h b/Modules/_testinternalcapi/test_cases.c.h
@@ -1135,6 +1135,7 @@ dummy_func(
 
             assert(PyLong_CheckExact(sub));
             assert(PyList_CheckExact(list));
+            EXIT_IF(!_PyLong_IsNonNegativeCompact((PyLongObject *)sub));
 
             Py_ssize_t index = _PyLong_CompactValue((PyLongObject *)sub);
             if (index < 0) {
@@ -1413,6 +1414,7 @@ dummy_func(
 
             assert(PyLong_CheckExact(sub));
             assert(PyList_CheckExact(list));
+            DEOPT_IF(!_PyLong_IsNonNegativeCompact((PyLongObject *)sub));
 
             Py_ssize_t index = _PyLong_CompactValue((PyLongObject *)sub);
             DEOPT_IF(!LOCK_OBJECT(list));

diff --git a/Python/executor_cases.c.h b/Python/executor_cases.c.h
diff --git a/Python/generated_cases.c.h b/Python/generated_cases.c.h