From ea73baecdd94deea5336c062647697448513a933 Mon Sep 17 00:00:00 2001
From: Jake Lishman <jake.lishman@ibm.com>
Date: Thu, 6 Jun 2024 13:54:09 +0100
Subject: [PATCH] Fix false positive in `use-yield-from` when using `yield`
 return (#9700)

If the return value from `yield` is inspected inline, such as by
(augmented) assignment, changing the looped `yield` to `yield from` is
very likely to change the semantics of the generator, since there is an
implicit use of `generator.send`.

Closes #9696
---
 doc/whatsnew/fragments/9696.false_positive        |  3 +++
 .../checkers/refactoring/refactoring_checker.py   | 15 +++++++++------
 tests/functional/u/use/use_yield_from.py          | 10 ++++++++++
 3 files changed, 22 insertions(+), 6 deletions(-)
 create mode 100644 doc/whatsnew/fragments/9696.false_positive

diff --git a/doc/whatsnew/fragments/9696.false_positive b/doc/whatsnew/fragments/9696.false_positive
new file mode 100644
index 0000000000..5d6e8cbf11
--- /dev/null
+++ b/doc/whatsnew/fragments/9696.false_positive
@@ -0,0 +1,3 @@
+Fix a false positive for ``use-yield-from`` when using the return value from the ``yield`` atom.
+
+Closes #9696
diff --git a/pylint/checkers/refactoring/refactoring_checker.py b/pylint/checkers/refactoring/refactoring_checker.py
index 94e722b177..9ffcecce12 100644
--- a/pylint/checkers/refactoring/refactoring_checker.py
+++ b/pylint/checkers/refactoring/refactoring_checker.py
@@ -1169,21 +1169,24 @@ def visit_yield(self, node: nodes.Yield) -> None:
         if not isinstance(node.value, nodes.Name):
             return
 
-        parent = node.parent.parent
+        loop_node = node.parent.parent
         if (
-            not isinstance(parent, nodes.For)
-            or isinstance(parent, nodes.AsyncFor)
-            or len(parent.body) != 1
+            not isinstance(loop_node, nodes.For)
+            or isinstance(loop_node, nodes.AsyncFor)
+            or len(loop_node.body) != 1
+            # Avoid a false positive if the return value from `yield` is used,
+            # (such as via Assign, AugAssign, etc).
+            or not isinstance(node.parent, nodes.Expr)
         ):
             return
 
-        if parent.target.name != node.value.name:
+        if loop_node.target.name != node.value.name:
             return
 
         if isinstance(node.frame(), nodes.AsyncFunctionDef):
             return
 
-        self.add_message("use-yield-from", node=parent, confidence=HIGH)
+        self.add_message("use-yield-from", node=loop_node, confidence=HIGH)
 
     @staticmethod
     def _has_exit_in_scope(scope: nodes.LocalsDictNodeNG) -> bool:
diff --git a/tests/functional/u/use/use_yield_from.py b/tests/functional/u/use/use_yield_from.py
index 2ccbb6d77e..f4dcdc6b9e 100644
--- a/tests/functional/u/use/use_yield_from.py
+++ b/tests/functional/u/use/use_yield_from.py
@@ -57,3 +57,13 @@ async def async_for_yield(agen):
 async def async_yield(agen):
     for item in agen:
         yield item
+
+
+# If the return from `yield` is used inline, don't suggest delegation.
+
+def yield_use_send():
+    for item in (1, 2, 3):
+        _ = yield item
+    total = 0
+    for item in (1, 2, 3):
+        total += yield item