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: phoad, luciang

Differential Revision: D28415741

fbshipit-source-id: ce083cec4c31a8cc98e956c247229ac765c7f983

Author: yfeldblum

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

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);
   }