exception_wrapper thrown variant via abi/runtime

Summary:
Reimplement `folly::exception_wrapper` thrown variant not to need to cache any pointers and rather to access the exception object and runtime type, and to perform runtime upcasting, via the platform runtime.

This both simplifies and extends the capability of the thrown variant.

Reviewed By: JunqiWang

Differential Revision: D28625444

fbshipit-source-id: 12409bc75794f5135cdb73563b07fafdf5cc44cd

Author: yfeldblum

Diff for: rsocket/test/transport/TcpDuplexConnectionTest.cpp

@@ -109,25 +109,5 @@ TEST(TcpDuplexConnection, ConnectionAndSubscribersAreUntied) {
       worker.getEventBase());
 }
 
-TEST(TcpDuplexConnection, ExceptionWrapperTest) {
-  folly::AsyncSocketException socketException(
-      folly::AsyncSocketException::AsyncSocketExceptionType::INVALID_STATE,
-      "test",
-      10);
-  folly::SSLException sslException(5, 10, 15, 20);
-
-  const folly::AsyncSocketException& socketExceptionRef = sslException;
-
-  folly::exception_wrapper ex1(socketException);
-  folly::exception_wrapper ex2(sslException);
-
-  // Slicing error:
-  // folly::exception_wrapper ex3(socketExceptionRef);
-
-  // Fixed version:
-  folly::exception_wrapper ex3(
-      std::make_exception_ptr(socketExceptionRef), socketExceptionRef);
-}
-
 } // namespace tests
 } // namespace rsocket

Diff for: rsocket/transports/tcp/TcpDuplexConnection.cpp

@@ -109,7 +109,7 @@ class TcpReaderWriter : public folly::AsyncTransportWrapper::WriteCallback,
 
   void writeErr(size_t, const folly::AsyncSocketException& exn) noexcept
       override {
-    closeErr(folly::exception_wrapper{std::make_exception_ptr(exn), exn});
+    closeErr(folly::exception_wrapper{folly::copy(exn)});
     intrusive_ptr_release(this);
   }
 
@@ -134,7 +134,7 @@ class TcpReaderWriter : public folly::AsyncTransportWrapper::WriteCallback,
   }
 
   void readErr(const folly::AsyncSocketException& exn) noexcept override {
-    closeErr(folly::exception_wrapper{std::make_exception_ptr(exn), exn});
+    closeErr(folly::exception_wrapper{folly::copy(exn)});
     intrusive_ptr_release(this);
   }