remove _v that are not yet supported

Summary:
fixed some compile errors when building SMC with pushmi as a dependency

some _v traits do not exist

a specialization of ManualLifetime<void> was required

Reviewed By: yfeldblum

Differential Revision: D14939161

fbshipit-source-id: 76a1f05d7ce889d00fdf4a264e5e719fdb12d4ac

folly/experimental/coro/detail/ManualLifetime.h

@@ -36,9 +36,9 @@ class ManualLifetime {
 
   template <
       typename... Args,
-      std::enable_if_t<std::is_constructible_v<T, Args...>, int> = 0>
+      std::enable_if_t<std::is_constructible<T, Args...>::value, int> = 0>
   void construct(Args&&... args) noexcept(
-      noexcept(std::is_nothrow_constructible_v<T, Args...>)) {
+      noexcept(std::is_nothrow_constructible<T, Args...>::value)) {
     new (static_cast<void*>(std::addressof(value_)))
         T(static_cast<Args&&>(args)...);
   }
@@ -110,6 +110,16 @@ class ManualLifetime<T&&> {
   T* ptr_;
 };
 
+template <>
+class ManualLifetime<void> {
+ public:
+  void construct() noexcept {}
+
+  void destruct() noexcept {}
+
+  void get() const noexcept {}
+};
+
 } // namespace detail
 } // namespace coro
 } // namespace folly

folly/experimental/pushmi/awaitable/senders.h

@@ -75,7 +75,7 @@ private:
       requires ConvertibleTo<U, value_type> //
     )                                       //
     void value(U&& value)
-      noexcept(std::is_nothrow_constructible_v<value_type, U>) {
+      noexcept(std::is_nothrow_constructible<value_type, U>::value) {
       this_->value_.construct(static_cast<U&&>(value));
       this_->state_ = state::value;
     }
@@ -96,7 +96,7 @@ private:
     template<typename Error>
     void error(Error error) noexcept {
       assert(this_->state_ != state::value);
-      PUSHMI_IF_CONSTEXPR( (std::is_same_v<Error, std::exception_ptr>) (
+      PUSHMI_IF_CONSTEXPR( (std::is_same<Error, std::exception_ptr>::value) (
         this_->exception_.construct(std::move(error));
       ) else (
         this_->exception_.construct(std::make_exception_ptr(std::move(error)));
@@ -113,13 +113,13 @@ public:
   : sender_(std::addressof(sender))
   {}
   sender_awaiter(sender_awaiter &&that)
-    noexcept(std::is_nothrow_move_constructible_v<value_type> ||
-      std::is_void_v<value_type>)
+    noexcept(std::is_nothrow_move_constructible<value_type>::value ||
+      std::is_void<value_type>::value)
   : sender_(std::exchange(that.sender_, nullptr))
   , continuation_{std::exchange(that.continuation_, {})}
   , state_(that.state_) {
     if (that.state_ == state::value) {
-      PUSHMI_IF_CONSTEXPR( (!std::is_void_v<value_type>) (
+      PUSHMI_IF_CONSTEXPR( (!std::is_void<value_type>::value) (
         id(value_).construct(std::move(that.value_).get());
       ) else (
       ))

folly/experimental/pushmi/sender/detail/concepts.h

@@ -118,7 +118,7 @@ PUSHMI_CONCEPT_DEF(
 //     template<typename...Args>
 //     using result_t =
 //       std::conditional_t<
-//         std::is_void_v<result_t<Args...>>,
+//         std::is_void<result_t<Args...>>::value,
 //         Tuple<>,
 //         Tuple<result_t<Args...>>>;
 //   };