Check contracts and entrypoints modifiers when implementing interfaces (#427)

* Check contracts and entrypoints modifiers when implementing interfaces

* Fix existing tests

* Add passing tests

* Add failing tests

* Update docs

* Update CHANGELOG

CHANGELOG.md

@@ -16,6 +16,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Return a mapping from variables to FATE registers in the compilation output.
 ### Changed
 - Type definitions serialised to ACI as `typedefs` field instead of `type_defs` to increase compatibility.
+- Check contracts and entrypoints modifiers when implementing interfaces.
 ### Removed
 ### Fixed
 - Typechecker crashes if Chain.create or Chain.clone are used without arguments.

docs/sophia_features.md

@@ -191,6 +191,17 @@ contract interface X : Z =
      entrypoint z() = 1
 ```
 
+#### Adding or removing modifiers
+
+When a `contract` or a `contract interface` implements another `contract interface`, the `payable` and `stateful` modifiers can be kept or changed, both in the contract and in the entrypoints, according to the following rules:
+
+1. A `payable` contract or interface can implement a `payable` interface or a non-`payable` interface.
+2. A non-`payable` contract or interface can only implement a non-`payable` interface, and cannot implement a `payable` interface.
+3. A `payable` entrypoint can implement a `payable` entrypoint or a non-`payable` entrypoint.
+4. A non-`payable` entrypoint can only implement a non-`payable` entrypoint, and cannot implement a `payable` entrypoint.
+5. A non-`stateful` entrypoint can implement a `stateful` entrypoint or a non-`stateful` entrypoint.
+6. A `stateful` entrypoint can only implement a `stateful` entrypoint, and cannot implement a non-`stateful` entrypoint.
+
 #### Subtyping and variance
 
 Subtyping in Sophia follows common rules that take type variance into account. As described by [Wikipedia](https://en.wikipedia.org/wiki/Covariance_and_contravariance_(computer_science)), 

src/aeso_ast_infer_types.erl

@@ -906,6 +906,7 @@ infer1(Env0, [Contract0 = {Contract, Ann, ConName, Impls, Code} | Rest], Acc, Op
         contract -> ets_insert(defined_contracts, {qname(ConName)});
         contract_interface -> ok
     end,
+    check_contract_preserved_payability(Env, ConName, Ann, Impls, Acc, What),
     populate_functions_to_implement(Env, ConName, Impls, Acc),
     Env1 = bind_contract(untyped, Contract0, Env),
     {Env2, Code1} = infer_contract_top(push_scope(contract, ConName, Env1), What, Code, Options),
@@ -931,6 +932,25 @@ infer1(Env, [{pragma, _, _} | Rest], Acc, Options) ->
     %% Pragmas are checked in check_modifiers
     infer1(Env, Rest, Acc, Options).
 
+-spec check_contract_preserved_payability(env(), Con, Ann, Impls, Contracts, Kind) -> ok | no_return() when
+      Con :: aeso_syntax:con(),
+      Ann :: aeso_syntax:ann(),
+      Impls :: [Con],
+      Contracts :: [aeso_syntax:decl()],
+      Kind :: contract | contract_interface.
+check_contract_preserved_payability(Env, ContractName, ContractAnn, Impls, DefinedContracts, Kind) ->
+    Payable = proplists:get_value(payable, ContractAnn, false),
+    ImplsNames = [ name(I) || I <- Impls ],
+    Interfaces = [ Con || I = {contract_interface, _, Con, _, _} <- DefinedContracts,
+                          lists:member(name(Con), ImplsNames),
+                          aeso_syntax:get_ann(payable, I, false) ],
+
+    create_type_errors(),
+    [ type_error({unpreserved_payablity, Kind, ContractName, I}) || I <- Interfaces, Payable == false ],
+    destroy_and_report_type_errors(Env),
+
+    ok.
+
 %% Report all functions that were not implemented by the contract ContractName.
 -spec report_unimplemented_functions(env(), ContractName) -> ok | no_return() when
       ContractName :: aeso_syntax:con().
@@ -1487,19 +1507,37 @@ check_reserved_entrypoints(Funs) ->
 check_fundecl(Env, {fun_decl, Ann, Id = {id, _, Name}, Type = {fun_t, _, _, _, _}}) ->
     Type1 = {fun_t, _, Named, Args, Ret} = check_type(Env, Type),
     TypeSig = {type_sig, Ann, none, Named, Args, Ret},
-    register_implementation(Name),
+    register_implementation(Id, TypeSig),
     {{Name, TypeSig}, {fun_decl, Ann, Id, Type1}};
 check_fundecl(Env, {fun_decl, Ann, Id = {id, _, Name}, Type}) ->
     type_error({fundecl_must_have_funtype, Ann, Id, Type}),
     {{Name, {type_sig, Ann, none, [], [], Type}}, check_type(Env, Type)}.
 
-%% Register the function FunName as implemented by deleting it from the functions
+%% Register the function FunId as implemented by deleting it from the functions
 %% to be implemented table if it is included there, or return true otherwise.
--spec register_implementation(FunName) -> true | no_return() when
-      FunName :: string().
-register_implementation(Name) ->
+-spec register_implementation(FunId, FunSig) -> true | no_return() when
+      FunId :: aeso_syntax:id(),
+      FunSig :: typesig().
+register_implementation(Id, Sig) ->
+    Name = name(Id),
     case ets_lookup(functions_to_implement, Name) of
-        [{Name, _, {fun_decl, _, _, _}}] ->
+        [{Name, Interface, Decl = {fun_decl, _, DeclId, _}}] ->
+            DeclStateful   = aeso_syntax:get_ann(stateful,   Decl, false),
+            DeclPayable    = aeso_syntax:get_ann(payable,    Decl, false),
+
+            SigEntrypoint = aeso_syntax:get_ann(entrypoint, Sig, false),
+            SigStateful   = aeso_syntax:get_ann(stateful,   Sig, false),
+            SigPayable    = aeso_syntax:get_ann(payable,    Sig, false),
+
+            [ type_error({function_should_be_entrypoint, Id, DeclId, Interface})
+                || not SigEntrypoint ],
+
+            [ type_error({entrypoint_cannot_be_stateful, Id, DeclId, Interface})
+                || SigStateful andalso not DeclStateful ],
+
+            [ type_error({entrypoint_must_be_payable, Id, DeclId, Interface})
+                || not SigPayable andalso DeclPayable ],
+
             ets_delete(functions_to_implement, Name);
         [] ->
             true;
@@ -1509,9 +1547,9 @@ register_implementation(Name) ->
 
 infer_nonrec(Env, LetFun) ->
     create_constraints(),
-    NewLetFun = {{FunName, _}, _} = infer_letfun(Env, LetFun),
+    NewLetFun = {{_, Sig}, _} = infer_letfun(Env, LetFun),
     check_special_funs(Env, NewLetFun),
-    register_implementation(FunName),
+    register_implementation(get_letfun_id(LetFun), Sig),
     solve_then_destroy_and_report_unsolved_constraints(Env),
     Result = {TypeSig, _} = instantiate(NewLetFun),
     print_typesig(TypeSig),
@@ -1540,8 +1578,8 @@ infer_letrec(Env, Defs) ->
     ExtendEnv = bind_funs(Funs, Env),
     Inferred =
         [ begin
-            Res    = {{Name, TypeSig}, _} = infer_letfun(ExtendEnv, LF),
-            register_implementation(Name),
+            Res    = {{Name, TypeSig}, LetFun} = infer_letfun(ExtendEnv, LF),
+            register_implementation(get_letfun_id(LetFun), TypeSig),
             Got    = proplists:get_value(Name, Funs),
             Expect = typesig_to_fun_t(TypeSig),
             unify(Env, Got, Expect, {check_typesig, Name, Got, Expect}),
@@ -1593,6 +1631,9 @@ infer_letfun1(Env0 = #env{ namespace = NS }, {letfun, Attrib, Fun = {id, NameAtt
     {{Name, TypeSig},
      {letfun, Attrib, {id, NameAttrib, Name}, TypedArgs, ResultType, NewGuardedBodies}}.
 
+get_letfun_id({fun_clauses, _, Id, _, _}) -> Id;
+get_letfun_id({letfun, _, Id, _, _, _})   -> Id.
+
 desugar_clauses(Ann, Fun, {type_sig, _, _, _, ArgTypes, RetType}, Clauses) ->
     NeedDesugar =
         case Clauses of
@@ -3659,7 +3700,7 @@ mk_error({empty_record_definition, Ann, Name}) ->
     Msg = io_lib:format("Empty record definitions are not allowed. Cannot define the record `~s`", [Name]),
     mk_t_err(pos(Ann), Msg);
 mk_error({unimplemented_interface_function, ConId, InterfaceName, FunName}) ->
-    Msg = io_lib:format("Unimplemented function `~s` from the interface `~s` in the contract `~s`", [FunName, InterfaceName, pp(ConId)]),
+    Msg = io_lib:format("Unimplemented entrypoint `~s` from the interface `~s` in the contract `~s`", [FunName, InterfaceName, pp(ConId)]),
     mk_t_err(pos(ConId), Msg);
 mk_error({referencing_undefined_interface, InterfaceId}) ->
     Msg = io_lib:format("Trying to implement or extend an undefined interface `~s`", [pp(InterfaceId)]),
@@ -3707,6 +3748,29 @@ mk_error({interface_implementation_conflict, Contract, I1, I2, Fun}) ->
                         "the contract `~s` have a function called `~s`",
                         [name(I1), name(I2), name(Contract), name(Fun)]),
     mk_t_err(pos(Contract), Msg);
+mk_error({function_should_be_entrypoint, Impl, Base, Interface}) ->
+    Msg = io_lib:format("`~s` must be declared as an entrypoint instead of a function "
+                        "in order to implement the entrypoint `~s` from the interface `~s`",
+                        [name(Impl), name(Base), name(Interface)]),
+    mk_t_err(pos(Impl), Msg);
+mk_error({entrypoint_cannot_be_stateful, Impl, Base, Interface}) ->
+    Msg = io_lib:format("`~s` cannot be stateful because the entrypoint `~s` in the "
+                        "interface `~s` is not stateful",
+                        [name(Impl), name(Base), name(Interface)]),
+    mk_t_err(pos(Impl), Msg);
+mk_error({entrypoint_must_be_payable, Impl, Base, Interface}) ->
+    Msg = io_lib:format("`~s` must be payable because the entrypoint `~s` in the "
+                        "interface `~s` is payable",
+                        [name(Impl), name(Base), name(Interface)]),
+    mk_t_err(pos(Impl), Msg);
+mk_error({unpreserved_payablity, Kind, ContractCon, InterfaceCon}) ->
+    KindStr = case Kind of
+                  contract -> "contract";
+                  contract_interface -> "interface"
+              end,
+    Msg = io_lib:format("Non-payable ~s `~s` cannot implement payable interface `~s`",
+                        [KindStr, name(ContractCon), name(InterfaceCon)]),
+    mk_t_err(pos(ContractCon), Msg);
 mk_error(Err) ->
     Msg = io_lib:format("Unknown error: ~p", [Err]),
     mk_t_err(pos(0, 0), Msg).

test/aeso_compiler_tests.erl

@@ -205,6 +205,9 @@ compilable_contracts() ->
      "polymorphism_variance_switching_chain_create",
      "polymorphism_variance_switching_void_supertype",
      "polymorphism_variance_switching_unify_with_interface_decls",
+     "polymorphism_preserve_or_add_payable_contract",
+     "polymorphism_preserve_or_add_payable_entrypoint",
+     "polymorphism_preserve_or_remove_stateful_entrypoint",
      "missing_init_fun_state_unit",
      "complex_compare_leq",
      "complex_compare",
@@ -868,7 +871,7 @@ failing_contracts() ->
                      "  - line 9, column 5">>])
     , ?TYPE_ERROR(polymorphism_contract_missing_implementation,
                   [<<?Pos(4,20)
-                     "Unimplemented function `f` from the interface `I1` in the contract `I2`">>
+                     "Unimplemented entrypoint `f` from the interface `I1` in the contract `I2`">>
                   ])
     , ?TYPE_ERROR(polymorphism_contract_same_decl_multi_interface,
                   [<<?Pos(7,10)
@@ -1152,6 +1155,26 @@ failing_contracts() ->
                      "to arguments\n"
                      "  `Chain.create : (value : int, var_args) => 'c`">>
                   ])
+    , ?TYPE_ERROR(polymorphism_add_stateful_entrypoint,
+                  [<<?Pos(5,25)
+                     "`f` cannot be stateful because the entrypoint `f` in the interface `I` is not stateful">>
+                  ])
+    , ?TYPE_ERROR(polymorphism_change_entrypoint_to_function,
+                  [<<?Pos(6,14)
+                     "`f` must be declared as an entrypoint instead of a function in order to implement the entrypoint `f` from the interface `I`">>
+                  ])
+    , ?TYPE_ERROR(polymorphism_non_payable_contract_implement_payable,
+                  [<<?Pos(4,10)
+                     "Non-payable contract `C` cannot implement payable interface `I`">>
+                  ])
+    , ?TYPE_ERROR(polymorphism_non_payable_interface_implement_payable,
+                  [<<?Pos(4,20)
+                     "Non-payable interface `H` cannot implement payable interface `I`">>
+                  ])
+    , ?TYPE_ERROR(polymorphism_remove_payable_entrypoint,
+                  [<<?Pos(5,16)
+                     "`f` must be payable because the entrypoint `f` in the interface `I` is payable">>
+                  ])
     ].
 
 validation_test_() ->

test/contracts/polymorphism_add_stateful_entrypoint.aes

@@ -0,0 +1,5 @@
+contract interface I =
+    entrypoint f : () => int
+
+contract C : I =
+    stateful entrypoint f() = 1

test/contracts/polymorphism_change_entrypoint_to_function.aes

@@ -0,0 +1,6 @@
+contract interface I =
+    entrypoint f : () => int
+
+contract C : I =
+    entrypoint init() = ()
+    function f() = 1

test/contracts/polymorphism_non_payable_contract_implement_payable.aes

@@ -0,0 +1,5 @@
+payable contract interface I =
+    payable entrypoint f : () => int
+
+contract C : I =
+    entrypoint f() = 123

test/contracts/polymorphism_non_payable_interface_implement_payable.aes

@@ -0,0 +1,8 @@
+payable contract interface I =
+    payable entrypoint f : () => int
+
+contract interface H : I =
+    payable entrypoint f : () => int
+
+payable contract C : H =
+    entrypoint f() = 123

test/contracts/polymorphism_preserve_or_add_payable_contract.aes

@@ -0,0 +1,14 @@
+contract interface F =
+    entrypoint f : () => int
+
+payable contract interface G : F =
+    payable entrypoint f : () => int
+    entrypoint g : () => int
+
+payable contract interface H =
+    payable entrypoint h : () => int
+
+payable contract C : G, H =
+    payable entrypoint f() = 1
+    payable entrypoint g() = 2
+    payable entrypoint h() = 3

test/contracts/polymorphism_preserve_or_add_payable_entrypoint.aes

@@ -0,0 +1,7 @@
+contract interface I =
+    payable entrypoint f : () => int
+    entrypoint g : () => int
+
+contract C : I =
+    payable entrypoint f() = 1
+    payable entrypoint g() = 2

test/contracts/polymorphism_preserve_or_remove_stateful_entrypoint.aes

@@ -0,0 +1,7 @@
+contract interface I =
+    stateful entrypoint f : () => int
+    stateful entrypoint g : () => int
+
+contract C : I =
+    stateful entrypoint f() = 1
+    entrypoint g() = 2

test/contracts/polymorphism_remove_payable_entrypoint.aes

@@ -0,0 +1,5 @@
+contract interface I =
+    payable entrypoint f : () => int
+
+contract C : I =
+    entrypoint f() = 1