GH-96793: Implement PEP 479 in bytecode. (GH-99006)

* Handle converting StopIteration to RuntimeError in bytecode.

* Add custom instruction for converting StopIteration into RuntimeError.

1 files changed, 43 insertions, 0 deletions

diff --git a/Python/bytecodes.c b/Python/bytecodes.c
index 94a4e76..b0d5627 100644
--- a/Python/bytecodes.c
+++ b/Python/bytecodes.c
@@ -1085,6 +1085,49 @@ dummy_func(
             goto exception_unwind;
         }
 
+        inst(STOPITERATION_ERROR) {
+            assert(frame->owner == FRAME_OWNED_BY_GENERATOR);
+            PyObject *exc = TOP();
+            assert(PyExceptionInstance_Check(exc));
+            const char *msg = NULL;
+            if (PyErr_GivenExceptionMatches(exc, PyExc_StopIteration)) {
+                msg = "generator raised StopIteration";
+                if (frame->f_code->co_flags & CO_ASYNC_GENERATOR) {
+                    msg = "async generator raised StopIteration";
+                }
+                else if (frame->f_code->co_flags & CO_COROUTINE) {
+                    msg = "coroutine raised StopIteration";
+                }
+            }
+            else if ((frame->f_code->co_flags & CO_ASYNC_GENERATOR) &&
+                    PyErr_GivenExceptionMatches(exc, PyExc_StopAsyncIteration))
+            {
+                /* code in `gen` raised a StopAsyncIteration error:
+                raise a RuntimeError.
+                */
+                msg = "async generator raised StopAsyncIteration";
+            }
+            if (msg != NULL) {
+                PyObject *message = _PyUnicode_FromASCII(msg, strlen(msg));
+                if (message == NULL) {
+                    goto error;
+                }
+                PyObject *error = PyObject_CallOneArg(PyExc_RuntimeError, message);
+                if (error == NULL) {
+                    Py_DECREF(message);
+                    goto error;
+                }
+                assert(PyExceptionInstance_Check(error));
+                SET_TOP(error);
+                PyException_SetCause(error, exc);
+                Py_INCREF(exc);
+                PyException_SetContext(error, exc);
+                Py_DECREF(message);
+            }
+            DISPATCH();
+        }
+
+
         // stack effect: ( -- __0)
         inst(LOAD_ASSERTION_ERROR) {
             PyObject *value = PyExc_AssertionError;