From 01f938e79938fd5b9bb6df2daeff95a625f6211f Mon Sep 17 00:00:00 2001
From: Boris Rasin <Boris-Rasin@users.noreply.github.com>
Date: Mon, 8 Nov 2021 01:35:25 +0200
Subject: [PATCH] fix: add missing std::forward calls (#3443)

* fix: add missing std::forward calls

Two of the four cpp_function overloads are missing std::forward calls, which seems like a simple oversight.

* add test for https://github.com/pybind/pybind11/pull/3443

* add py tests

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* fix test

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
---
 include/pybind11/pybind11.h           |  4 ++--
 tests/test_methods_and_attributes.cpp | 15 +++++++++++++++
 tests/test_methods_and_attributes.py  |  8 ++++++++
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/include/pybind11/pybind11.h b/include/pybind11/pybind11.h
index 124ea37e5..b8b7c7a02 100644
--- a/include/pybind11/pybind11.h
+++ b/include/pybind11/pybind11.h
@@ -115,7 +115,7 @@ public:
     template <typename Return, typename Class, typename... Arg, typename... Extra>
     // NOLINTNEXTLINE(google-explicit-constructor)
     cpp_function(Return (Class::*f)(Arg...)&, const Extra&... extra) {
-        initialize([f](Class *c, Arg... args) -> Return { return (c->*f)(args...); },
+        initialize([f](Class *c, Arg... args) -> Return { return (c->*f)(std::forward<Arg>(args)...); },
                    (Return (*) (Class *, Arg...)) nullptr, extra...);
     }
 
@@ -133,7 +133,7 @@ public:
     template <typename Return, typename Class, typename... Arg, typename... Extra>
     // NOLINTNEXTLINE(google-explicit-constructor)
     cpp_function(Return (Class::*f)(Arg...) const&, const Extra&... extra) {
-        initialize([f](const Class *c, Arg... args) -> Return { return (c->*f)(args...); },
+        initialize([f](const Class *c, Arg... args) -> Return { return (c->*f)(std::forward<Arg>(args)...); },
                    (Return (*)(const Class *, Arg ...)) nullptr, extra...);
     }
 
diff --git a/tests/test_methods_and_attributes.cpp b/tests/test_methods_and_attributes.cpp
index 2d303a44e..9e55452de 100644
--- a/tests/test_methods_and_attributes.cpp
+++ b/tests/test_methods_and_attributes.cpp
@@ -159,6 +159,14 @@ struct RefQualified {
     int constRefQualified(int other) const & { return value + other; }
 };
 
+// Test rvalue ref param
+struct RValueRefParam {
+    std::size_t func1(std::string&& s) { return s.size(); }
+    std::size_t func2(std::string&& s) const { return s.size(); }
+    std::size_t func3(std::string&& s) & { return s.size(); }
+    std::size_t func4(std::string&& s) const & { return s.size(); }
+};
+
 TEST_SUBMODULE(methods_and_attributes, m) {
     // test_methods_and_attributes
     py::class_<ExampleMandA> emna(m, "ExampleMandA");
@@ -409,4 +417,11 @@ TEST_SUBMODULE(methods_and_attributes, m) {
         .def_readonly("value", &RefQualified::value)
         .def("refQualified", &RefQualified::refQualified)
         .def("constRefQualified", &RefQualified::constRefQualified);
+
+    py::class_<RValueRefParam>(m, "RValueRefParam")
+        .def(py::init<>())
+        .def("func1", &RValueRefParam::func1)
+        .def("func2", &RValueRefParam::func2)
+        .def("func3", &RValueRefParam::func3)
+        .def("func4", &RValueRefParam::func4);
 }
diff --git a/tests/test_methods_and_attributes.py b/tests/test_methods_and_attributes.py
index 866b3cea1..fa026f9ed 100644
--- a/tests/test_methods_and_attributes.py
+++ b/tests/test_methods_and_attributes.py
@@ -515,3 +515,11 @@ def test_overload_ordering():
     assert "2. (arg0: {}) -> int".format(uni_name) in str(err.value)
     assert "3. (arg0: {}) -> int".format(uni_name) in str(err.value)
     assert "4. (arg0: int) -> int" in str(err.value)
+
+
+def test_rvalue_ref_param():
+    r = m.RValueRefParam()
+    assert r.func1("123") == 3
+    assert r.func2("1234") == 4
+    assert r.func3("12345") == 5
+    assert r.func4("123456") == 6