From 54e43764ca6e5f4edb61ac387d8ff16a2ebdea1c Mon Sep 17 00:00:00 2001
From: radrow <radrowicki@gmail.com>
Date: Fri, 15 May 2020 19:09:08 +0200
Subject: [PATCH] Ban empty contracts, ban function blocks with mismatched
 declarations

---
 src/aeso_ast_infer_types.erl          | 20 ++++++++++++++++----
 src/aeso_syntax.erl                   | 10 ++++++----
 test/aeso_compiler_tests.erl          | 10 ++++++++++
 test/contracts/bad_function_block.aes |  5 +++++
 test/contracts/just_an_empty_file.aes |  0
 5 files changed, 37 insertions(+), 8 deletions(-)
 create mode 100644 test/contracts/bad_function_block.aes
 create mode 100644 test/contracts/just_an_empty_file.aes

diff --git a/src/aeso_ast_infer_types.erl b/src/aeso_ast_infer_types.erl
index 84f8683..d85b3f6 100644
--- a/src/aeso_ast_infer_types.erl
+++ b/src/aeso_ast_infer_types.erl
@@ -564,6 +564,10 @@ init_env(_Options) -> global_env().
 
 -spec infer(aeso_syntax:ast(), list(option())) ->
     aeso_syntax:ast() | {env(), aeso_syntax:ast()}.
+infer([], Options) ->
+    create_type_errors(),
+    type_error({no_decls, proplists:get_value(src_file, Options, no_file)}),
+    destroy_and_report_type_errors(init_env(Options));
 infer(Contracts, Options) ->
     ets_init(), %% Init the ETS table state
     try
@@ -626,7 +630,9 @@ infer_contract_top(Env, Kind, Defs0, _Options) ->
 %% a list of definitions.
 -spec infer_contract(env(), main_contract | contract | namespace, [aeso_syntax:decl()]) -> {env(), [aeso_syntax:decl()]}.
 infer_contract(Env0, What, Defs0) ->
+    create_type_errors(),
     Defs = process_blocks(Defs0),
+    destroy_and_report_type_errors(Env0),
     Env  = Env0#env{ what = What },
     Kind = fun({type_def, _, _, _, _})    -> type;
               ({letfun, _, _, _, _, _})   -> function;
@@ -679,12 +685,12 @@ process_block(Ann, [Decl | Decls]) ->
     case Decl of
         {fun_decl, Ann1, Id = {id, _, Name}, Type} ->
             {Clauses, Rest} = lists:splitwith(IsThis(Name), Decls),
-            [{fun_clauses, Ann1, Id, Type, Clauses} |
-             process_block(Ann, Rest)];
+            [type_error({mismatched_decl_in_funblock, Name, D1}) || D1 <- Rest],
+            [{fun_clauses, Ann1, Id, Type, Clauses}];
         {letfun, Ann1, Id = {id, _, Name}, _, _, _} ->
             {Clauses, Rest} = lists:splitwith(IsThis(Name), [Decl | Decls]),
-            [{fun_clauses, Ann1, Id, {id, [{origin, system} | Ann1], "_"}, Clauses} |
-             process_block(Ann, Rest)]
+            [type_error({mismatched_decl_in_funblock, Name, D1}) || D1 <- Rest],
+            [{fun_clauses, Ann1, Id, {id, [{origin, system} | Ann1], "_"}, Clauses}]
     end.
 
 -spec check_typedefs(env(), [aeso_syntax:decl()]) -> {env(), [aeso_syntax:decl()]}.
@@ -2266,6 +2272,12 @@ mk_t_err(Pos, Msg) ->
 mk_t_err(Pos, Msg, Ctxt) ->
     aeso_errors:new(type_error, Pos, lists:flatten(Msg), lists:flatten(Ctxt)).
 
+mk_error({no_decls, File}) ->
+    Pos = aeso_errors:pos(File, 0, 0),
+    mk_t_err(Pos, "Empty contract\n");
+mk_error({mismatched_decl_in_funblock, Name, Decl}) ->
+    Msg = io_lib:format("Mismatch in the function block. Expected implementation/type declaration of ~s function\n", [Name]),
+    mk_t_err(pos(Decl), Msg);
 mk_error({higher_kinded_typevar, T}) ->
     Msg = io_lib:format("Type ~s is a higher kinded type variable\n"
                         "(takes another type as an argument)\n", [pp(instantiate(T))]
diff --git a/src/aeso_syntax.erl b/src/aeso_syntax.erl
index 30d4d67..1d01ef0 100644
--- a/src/aeso_syntax.erl
+++ b/src/aeso_syntax.erl
@@ -39,9 +39,9 @@
               | {pragma, ann(), pragma()}
               | {type_decl, ann(), id(), [tvar()]} % Only for error msgs
               | {type_def, ann(), id(), [tvar()], typedef()}
-              | {fun_decl, ann(), id(), type()}
-              | {fun_clauses, ann(), id(), type(), [letbind()]}
+              | {fun_clauses, ann(), id(), type(), [letfun() | fundecl()]}
               | {block, ann(), [decl()]}
+              | fundecl()
               | letfun()
               | letval(). % Only for error msgs
 
@@ -50,8 +50,10 @@
 -type pragma() :: {compiler, '==' | '<' | '>' | '=<' | '>=', compiler_version()}.
 
 
--type letval() :: {letval, ann(), pat(), expr()}.
--type letfun() :: {letfun, ann(), id(), [pat()], type(), expr()}.
+-type letval()  :: {letval, ann(), pat(), expr()}.
+-type letfun()  :: {letfun, ann(), id(), [pat()], type(), expr()}.
+-type fundecl() :: {fun_decl, ann(), id(), type()}.
+
 -type letbind()
     :: letfun()
      | letval().
diff --git a/test/aeso_compiler_tests.erl b/test/aeso_compiler_tests.erl
index c6f5b9f..e8f5931 100644
--- a/test/aeso_compiler_tests.erl
+++ b/test/aeso_compiler_tests.erl
@@ -665,6 +665,16 @@ failing_contracts() ->
            "Empty record/map update\n"
            "  r {}">>
         ])
+    , ?TYPE_ERROR(bad_function_block,
+                  [<<?Pos(4, 5)
+                     "Mismatch in the function block. Expected implementation/type declaration of g function">>,
+                   <<?Pos(5, 5)
+                     "Mismatch in the function block. Expected implementation/type declaration of g function">>
+                  ])
+    , ?TYPE_ERROR(just_an_empty_file,
+                  [<<?Pos(0, 0)
+                     "Empty contract">>
+                  ])
     , ?TYPE_ERROR(bad_number_of_args,
                   [<<?Pos(3, 39)
                      "Cannot unify () => unit\n"
diff --git a/test/contracts/bad_function_block.aes b/test/contracts/bad_function_block.aes
new file mode 100644
index 0000000..53f93b1
--- /dev/null
+++ b/test/contracts/bad_function_block.aes
@@ -0,0 +1,5 @@
+contract C =
+  function
+    g(1) = 2
+    f(2) = 3
+    h(1) = 123
\ No newline at end of file
diff --git a/test/contracts/just_an_empty_file.aes b/test/contracts/just_an_empty_file.aes
new file mode 100644
index 0000000..e69de29