Clean up tests + remove ifdef guards

include/pybind11/functional.h

@@ -38,15 +38,14 @@ struct type_caster<std::function<Return(Args...)>> {
 
         auto func = reinterpret_borrow<function>(src);
 
-/*
-   When passing a C++ function as an argument to another C++
-   function via Python, every function call would normally involve
-   a full C++ -> Python -> C++ roundtrip, which can be prohibitive.
-   Here, we try to at least detect the case where the function is
-   stateless (i.e. function pointer or lambda function without
-   captured variables), in which case the roundtrip can be avoided.
- */
-#ifndef BAD
+        /*
+           When passing a C++ function as an argument to another C++
+           function via Python, every function call would normally involve
+           a full C++ -> Python -> C++ roundtrip, which can be prohibitive.
+           Here, we try to at least detect the case where the function is
+           stateless (i.e. function pointer or lambda function without
+           captured variables), in which case the roundtrip can be avoided.
+         */
         if (auto cfunc = func.cpp_function()) {
             auto *cfunc_self = PyCFunction_GET_SELF(cfunc.ptr());
             if (cfunc_self == nullptr) {
@@ -80,7 +79,6 @@ struct type_caster<std::function<Return(Args...)>> {
             // Raising an fail exception here works to prevent the segfault, but only on gcc.
             // See PR #1413 for full details
         }
-#endif
 
         // ensure GIL is held during functor destruction
         struct func_handle {

tests/test_callbacks.cpp

@@ -245,8 +245,15 @@ TEST_SUBMODULE(callbacks, m) {
 
     def.ml_name = "example_name";
     def.ml_doc = "Example doc";
-    def.ml_meth = [](PyObject *, PyObject *) -> PyObject * {
-        auto result = py::cast(20);
+    def.ml_meth = [](PyObject *, PyObject *args) -> PyObject * {
+        if (PyTuple_Size(args) != 1) {
+            throw std::runtime_error("Invalid number of arguments for example_name");
+        }
+        PyObject *first = PyTuple_GetItem(args, 0);
+        if (!PyLong_Check(first)) {
+            throw std::runtime_error("Invalid argument to example_name");
+        }
+        auto result = py::cast(PyLong_AsLong(first) * 9);
         return result.release().ptr();
     };
     def.ml_flags = METH_VARARGS;
@@ -255,6 +262,9 @@ TEST_SUBMODULE(callbacks, m) {
     constexpr const char *rec_capsule_name = "CUSTOM_REC_CAPSULE";
     py::capsule rec_capsule(std::malloc(1), [](void *data) { std::free(data); });
     rec_capsule.set_name(rec_capsule_name);
-    py::handle m_ptr = PyCFunction_New(&def, rec_capsule.ptr());
-    m.add_object("custom_function", m_ptr);
+    m.add_object("custom_function", PyCFunction_New(&def, rec_capsule.ptr()));
+
+    // rec_capsule with nullptr name
+    py::capsule rec_capsule2(std::malloc(1), [](void *data) { std::free(data); });
+    m.add_object("custom_function2", PyCFunction_New(&def, rec_capsule2.ptr()));
 }

tests/test_callbacks.py

@@ -196,6 +196,8 @@ def test_callback_num_times():
 
 
 def test_custom_func():
-    func = m.custom_function
-    assert func() == 20
-    _ = m.roundtrip(func)
+    assert m.custom_function(4) == 36
+    assert m.roundtrip(m.custom_function)(4) == 36
+
+    assert m.custom_function2(3) == 27
+    assert m.roundtrip(m.custom_function2)(3) == 27