[issue23192] Generator return value ignored in lambda function

[Bruno Cauet]

Bruno Cauet added the comment:

Here are the operations being emitted (line, macro used and eventual argument):

>>> f = lambda: (yield 5)
3487: ADDOP_O LOAD_CONST e->v.Num.n
3472: ADDOP YIELD_VALUE
1907: ADDOP_IN_SCOPE POP_TOP
4349: ADDOP_O LOAD_CONST Py_None
4350: ADDOP RETURN_VALUE
1457: ADDOP_O LOAD_CONST (PyObject*)co
1458: ADDOP_O LOAD_CONST qualname
1459: ADDOP_I MAKE_FUNCTION args
4349: ADDOP_O LOAD_CONST Py_None
4350: ADDOP RETURN_VALUE
>>> def g(): return (yield 5)
... 
3487: ADDOP_O LOAD_CONST e->v.Num.n
3472: ADDOP YIELD_VALUE
2533: ADDOP RETURN_VALUE
1457: ADDOP_O LOAD_CONST (PyObject*)co
1458: ADDOP_O LOAD_CONST qualname
1459: ADDOP_I MAKE_FUNCTION args
4349: ADDOP_O LOAD_CONST Py_None
4350: ADDOP RETURN_VALUE

So there's an extra POP_TOP + LOAD_CONST Py_NONE for the lambda version that throws away the "123" (in the exemple).

The attached patch (0001-...) fixes it. However please note that I'm not knowledgable about that part of the code and devised the patch empirically.
Moreover a test should probably added but I did not know where (test_dis? tried and failed... see patch 0002-...).

----------
keywords: +patch
nosy: +bru
Added file: http://bugs.python.org/file38298/0001-lambda-generators-don-t-throw-away-stack-top.patch

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue23192>
_______________________________________