Contract compilation fails during elemental battles tutorial

Question

I have followed the elemental battles tutorial until lesson 2 step 4, and at the end of it, the tutorial instructs to compile the existing code with eosio-cpp -o destination.abi source.cpp -abigen (which makes no sense in that it seems to be putting a WASM into a .abi file)

I used eosio-cpp -o cardgame.wasm cardgame.cpp -abigen to try to compile but it did not work, giving me a long list of depreciation warnings (telling me to use eosio/* instead of eosiolib/*) and redefinition errors within the eosio files mostly.

At this point in the tutorial here is my code: cardgame.hpp

#include <eosiolib/eosio.hpp>

using namespace std;
using namespace eosio;
class [[eosio::contract]] cardgame : public eosio::contract {

  private:

    struct [[eosio::table]] user_info {
      name            username;
      uint16_t        win_count = 0;
      uint16_t        lost_count = 0;

      auto primary_key() const { return username.value; }
    };

    typedef eosio::multi_index<name("users"), user_info> users_table;

    users_table _users;

  public:

    cardgame( name receiver, name code, datastream<const char*> ds ):contract(receiver, code, ds),
                       _users(receiver, receiver.value) {}

    [[eosio::action]]
    void login(name username);

};

cardgame.cpp

#include "gameplay.cpp"

void cardgame::login(name username) {
  // Ensure this action is authorized by the player
  require_auth(username);

  // Create a record in the table if the player doesn't exist in our app yet
  auto user_iterator = _users.find(username.value);
  if (user_iterator == _users.end()) {
    user_iterator = _users.emplace(username,  [&](auto& new_user) {
      new_user.username = username;
    });
  } 
}

EOSIO_DISPATCH(cardgame, (login))

gameplay.cpp

#include "cardgame.hpp"

As hinted by the warning I tried to change eosiolib into eosio in my code:

#include <eosio/eosio.hpp>
// #include <eosiolib/eosio.hpp>

But that still gives me the following error:

$ eosio-cpp -o cardgame.wasm cardgame.cpp -abigen
Warning, empty ricardian clause file
Warning, empty ricardian clause file
Warning, action <login> does not have a ricardian contract
Warning, action <login> does not have a ricardian contract
In file included from /tmp/cardgame.cpp:1:
/tmp/./gameplay.cpp:6:7: error: redefinition of '__insert_eosio_abi'
        void __insert_eosio_abi(unsigned long long r, unsigned long long c, unsigned long long a){eosio_assert_code(false, 1);}
             ^
/tmp/./cardgame.hpp:34:7: note: previous definition is here
        void __insert_eosio_abi(unsigned long long r, unsigned long long c, unsigned long long a){eosio_assert_code(false, 1);}
             ^
1 error generated.
/usr/opt/eosio.cdt/1.6.1/bin/wasm-ld: error: cannot open /tmp/cardgame.cpp.o: No such file or directory

I however noticed that if I indicate the output wasm file to have a different name, the compilation would succeed(WHY?). However the .abi file is absent and therefore it is impossible to use this contract.

$ eosio-cpp -o cardgamee.wasm cardgame.cpp -abigen
Warning, empty ricardian clause file
Warning, empty ricardian clause file
$ ls
cardgame.cpp  cardgamee.wasm  cardgame.hpp  gameplay.cpp

What am I doing wrong in this case? How can I successfully compile this contract?

Answer 1

Okay, I have find the solution, it was a classic header include problems, so you just have to add -I. at the end like

eosio-cpp -o cardgame.wasm cardgame.cpp -abigen -I.

more information about the issue here:

https://github.com/EOSIO/eosio.cdt/issues/489

Answer 2

Here is a workaround for people who might have the same problem in the future (I do not consider this a real "solution"):

Simply put all the code into one file like so :

cardgame.cpp

// #include "gameplay.cpp"

#include <eosio/eosio.hpp>
// #include <eosiolib/eosio.hpp>

using namespace std;
using namespace eosio;
class [[eosio::contract]] cardgame : public eosio::contract {

  private:

    struct [[eosio::table]] user_info {
      name            username;
      uint16_t        win_count = 0;
      uint16_t        lost_count = 0;

      auto primary_key() const { return username.value; }
    };

    typedef eosio::multi_index<name("users"), user_info> users_table;

    users_table _users;

  public:

    cardgame( name receiver, name code, datastream<const char*> ds ):contract(receiver, code, ds),
                       _users(receiver, receiver.value) {}

    [[eosio::action]]
    void login(name username);

};

void cardgame::login(name username) {
  // Ensure this action is authorized by the player
  require_auth(username);

  // Create a record in the table if the player doesn't exist in our app yet
  auto user_iterator = _users.find(username.value);
  if (user_iterator == _users.end()) {
    user_iterator = _users.emplace(username,  [&](auto& new_user) {
      new_user.username = username;
    });
  } 
}

EOSIO_DISPATCH(cardgame, (login))

This probably betrays some programming best practice, but this is only a workaround and since smart contracts should be generally pretty simple and compact, it should not result in a monstrously large file.