From: Benjamin Peterson <benjamin@python.org>
Date: Sat, 27 Dec 2008 18:24:11 +0000 (+0000)
Subject: #4748 lambda generators shouldn't return values
X-Git-Tag: v2.7a1~2489
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=8d5934b25d7c3e636444428dc715316a08b8c94e;p=python

#4748 lambda generators shouldn't return values
---

diff --git a/Lib/test/test_generators.py b/Lib/test/test_generators.py
index 3702abc91a..b7c3fdcbe5 100644
--- a/Lib/test/test_generators.py
+++ b/Lib/test/test_generators.py
@@ -928,6 +928,16 @@ Test the __name__ attribute and the repr()
 'f'
 >>> repr(g)  # doctest: +ELLIPSIS
 '<generator object f at ...>'
+
+Lambdas shouldn't have their usual return behavior.
+
+>>> x = lambda: (yield 1)
+>>> list(x())
+[1]
+
+>>> x = lambda: ((yield 1), (yield 2))
+>>> list(x())
+[1, 2]
 """
 
 # conjoin is a simple backtracking generator, named in honor of Icon's
diff --git a/Misc/NEWS b/Misc/NEWS
index 4a15054eb5..64ff4062c8 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -83,6 +83,8 @@ Core and Builtins
 - Issue #4509: Various issues surrounding resize of bytearray objects to
   which there are buffer exports.
 
+- Issue #4748: Lambda generators no longer return a value.
+
 Library
 -------
 
diff --git a/Python/compile.c b/Python/compile.c
index 756a903340..8f0fd8d043 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -1534,7 +1534,12 @@ compiler_lambda(struct compiler *c, expr_ty e)
 	
 	c->u->u_argcount = asdl_seq_LEN(args->args);
 	VISIT_IN_SCOPE(c, expr, e->v.Lambda.body);
-	ADDOP_IN_SCOPE(c, RETURN_VALUE);
+	if (c->u->u_ste->ste_generator) {
+		ADDOP_IN_SCOPE(c, POP_TOP);
+	}
+	else {
+		ADDOP_IN_SCOPE(c, RETURN_VALUE);
+	}
 	co = assemble(c, 1);
 	compiler_exit_scope(c);
 	if (co == NULL)