Reduce move constructions

Author: rhaschke

include/pybind11/cast.h

@@ -783,7 +783,7 @@ template <typename T> using cast_op_type_for_moving =
 template <typename T> using cast_op_type_for_byvalue =
     conditional_t<std::is_copy_constructible<intrinsic_t<T>>::value,
         typename std::add_lvalue_reference<intrinsic_t<T>>::type,
-        cast_op_type_for_moving<T> >;
+        typename std::add_rvalue_reference<intrinsic_t<T>>::type >;
 
 /**
  * Determine suitable casting operator for movable types.

tests/test_copy_move.cpp

@@ -80,9 +80,9 @@ static_assert(std::is_same<movable_cast_op_type<MoveOrCopyInt&&>, MoveOrCopyInt>
 static_assert(std::is_same<movable_cast_op_type<MoveOnlyInt&&>, MoveOnlyInt>::value, "requesting move semantics");
 static_assert(std::is_same<movable_cast_op_type<CopyOnlyInt&&>, CopyOnlyInt>::value, "requesting move semantics");
 
-// casting type for plain arguments is chose to yield copy semantics by default, but move semantics for move-only types
+// casting type for by-value arguments is chosen to yield copy semantics by default, but move semantics for move-only types
 static_assert(std::is_same<movable_cast_op_type<MoveOrCopyInt>, MoveOrCopyInt&>::value, "default to copy semantics");
-static_assert(std::is_same<movable_cast_op_type<MoveOnlyInt>, MoveOnlyInt>::value, "only move semantics supported");
+static_assert(std::is_same<movable_cast_op_type<MoveOnlyInt>, MoveOnlyInt&&>::value, "only move semantics supported");
 static_assert(std::is_same<movable_cast_op_type<CopyOnlyInt>, CopyOnlyInt&>::value, "copy semantics");
 
 template <> struct type_caster<MoveOnlyInt> {

tests/test_copy_move.py

@@ -62,7 +62,7 @@ def test_move_and_copy_loads():
 
     assert c_m.copy_assignments + c_m.copy_constructions == 0
     assert c_m.move_assignments == 6
-    assert c_m.move_constructions == 14
+    assert c_m.move_constructions == 9
     assert c_mc.copy_assignments == 0
     assert c_mc.copy_constructions == 1
     assert c_mc.move_assignments == 6
@@ -123,7 +123,7 @@ def test_move_and_copy_load_optional():
 
     assert c_m.copy_assignments + c_m.copy_constructions == 0
     assert c_m.move_assignments == 2
-    assert c_m.move_constructions == 7
+    assert c_m.move_constructions == 6
     assert c_mc.copy_assignments == 0
     assert c_mc.copy_constructions == 1
     assert c_mc.move_assignments == 3