From c8ed14a9209fcb742579da711ee309e463abe186 Mon Sep 17 00:00:00 2001
From: HNeitzel <hauke.neitzel@googlemail.com>
Date: Tue, 18 Feb 2025 00:16:26 +0100
Subject: [PATCH] LWG-3899 co_yielding elements of an lvalue generator is
 unnecessarily inefficient #5111

---
 stl/inc/generator | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/stl/inc/generator b/stl/inc/generator
index 09c16afc339..3374d9bb589 100644
--- a/stl/inc/generator
+++ b/stl/inc/generator
@@ -286,6 +286,13 @@ namespace _Gen_detail {
             return _Nested_awaitable{_STD move(_Elem.range)};
         }
 
+        template <class _Rty, class _Vty, class _Alloc, class _Unused>
+            requires same_as<_Yield_t<_Reference_t<_Rty, _Vty>>, _Yielded>
+        _NODISCARD auto yield_value(_RANGES elements_of<generator<_Rty, _Vty, _Alloc>&, _Unused> _Elem) noexcept {
+            using _Nested_awaitable = _Nested_awaitable_provider<_Rty, _Vty, _Alloc>::_Awaitable;
+            return _Nested_awaitable{_STD move(_Elem.range)};
+        }
+
         template <_RANGES input_range _Rng, class _Alloc>
             requires convertible_to<_RANGES range_reference_t<_Rng>, _Yielded>
         _NODISCARD auto yield_value(_RANGES elements_of<_Rng, _Alloc> _Elem) {