diff --git a/llvm/include/llvm/ADT/STLExtras.h b/llvm/include/llvm/ADT/STLExtras.h --- a/llvm/include/llvm/ADT/STLExtras.h +++ b/llvm/include/llvm/ADT/STLExtras.h @@ -75,6 +75,75 @@ typename std::add_const::type>::type; }; +/// Utilities for detecting if a given trait holds for some set of arguments +/// 'Args'. For example, the given trait could be used to detect if a given type +/// has a copy assignment operator: +/// template +/// using has_copy_assign_t = decltype(std::declval() +/// = std::declval()); +/// bool fooHasCopyAssign = is_detected::value; +namespace detail { +template using void_t = void; +template class Op, class... Args> struct detector { + using value_t = std::false_type; +}; +template