Match host function returning -2 for non-existent sync call entry point

Author: linh2931

libraries/eosiolib/contracts/eosio/call.hpp

@@ -100,7 +100,7 @@ namespace eosio {
          uint64_t flags = read_only ? 0x01 : 0x00; // last bit indicating read only
          auto retval =  internal_use_do_not_use::call(receiver.value, flags, data.data(), data.size());
 
-         if (retval == -1) {  // sync call is not supported by the receiver contract
+         if (retval == -2) {  // sync call is not supported by the receiver contract
             check(no_op_if_receiver_not_support_sync_call, "receiver does not support sync call but no_op_if_receiver_not_support_sync_call flag is not set");
          }
          return retval;

tests/unit/test_contracts/call_tests.cpp

@@ -11,9 +11,9 @@ class [[eosio::contract]] call_tests : public eosio::contract{
       std::vector<char> data{};
 
       // For now, because sync_call entry point has not been implemented yet and
-      // no_op_if_receiver_no_support_sync_call is set to true, call should return -1
+      // no_op_if_receiver_no_support_sync_call is set to true, call should return -2
       auto rc = eosio::call("calltests"_n, data, false /* read_only */, true /* no_op_if_receiver_no_support_sync_call */)();
-      eosio::check(rc == -1, "call did not return -1");
+      eosio::check(rc == -2, "call did not return -2");
 
       // call was not executed. return value size should be 0
       std::vector<char> value(10);