diff options
Diffstat (limited to 'base/callback_internal.h')
| -rw-r--r-- | base/callback_internal.h | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/base/callback_internal.h b/base/callback_internal.h index aa8542c..a2adbf9 100644 --- a/base/callback_internal.h +++ b/base/callback_internal.h @@ -9,6 +9,7 @@ #define BASE_CALLBACK_INTERNAL_H_ #include <stddef.h> +#include <memory> #include <type_traits> #include "base/atomic_ref_count.h" @@ -94,7 +95,13 @@ class BASE_EXPORT CallbackBase { // A helper template to determine if given type is non-const move-only-type, // i.e. if a value of the given type should be passed via std::move() in a -// destructive way. +// destructive way. Types are considered to be move-only if they have a +// sentinel MoveOnlyTypeForCPP03 member: a class typically gets this from using +// the DISALLOW_COPY_AND_ASSIGN_WITH_MOVE_FOR_BIND macro. +// It would be easy to generalize this trait to all move-only types... but this +// confuses template deduction in VS2013 with certain types such as +// std::unique_ptr. +// TODO(dcheng): Revisit this when Windows switches to VS2015 by default. template <typename T> struct IsMoveOnlyType { template <typename U> static YesType Test(const typename U::MoveOnlyTypeForCPP03*); @@ -106,6 +113,11 @@ template <typename T> struct IsMoveOnlyType { !is_const<T>::value; }; +// Specialization of IsMoveOnlyType so that std::unique_ptr is still considered +// move-only, even without the sentinel member. +template <typename T> +struct IsMoveOnlyType<std::unique_ptr<T>> : std::true_type {}; + template <typename> struct CallbackParamTraitsForMoveOnlyType; |