How to distinguish yield of a value vs exhaustion of the generator

[smontanaro]

In Objects/genobject.c, it distinguishes between a simple yield and exhaustion of the generator by testing f->f_stacktop:

if (result && f->f_stacktop == NULL) {
... exhausted ...
}
else ... {
... normal yield ...
}

Need a way to signal the distinction without relying on f->f_stacktop.

[smontanaro]

Perhaps we set f->f_stacktop in the typical case and null it upon return? Where would those two happen?

[smontanaro]

Could it be as simple as setting f->f_stacktop to a non-NULL value when yielding and to NULL when returning?

[smontanaro]

Tried that. Set it to f->f_valuestack in YIELD_VALUE_REG and to NULL in RETURN_VALUE_REG. That provoked an abort while exiting.