From a617a6469d2b3657e7fa9ef990ebef551517285c Mon Sep 17 00:00:00 2001
From: Hans Svensson <hans.svensson@quviq.com>
Date: Thu, 27 Jun 2019 14:19:39 +0200
Subject: [PATCH] Change Chain.block_hash to return option(hash)

---
 rebar.lock                     | 2 +-
 src/aeso_ast_infer_types.erl   | 4 ++--
 src/aeso_ast_to_icode.erl      | 2 +-
 src/aeso_builtins.erl          | 7 +++++++
 test/contracts/environment.aes | 2 +-
 5 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/rebar.lock b/rebar.lock
index a3392b5..83e3967 100644
--- a/rebar.lock
+++ b/rebar.lock
@@ -11,7 +11,7 @@
   {git,"https://github.com/aeternity/erl-base58.git",
        {ref,"60a335668a60328a29f9731b67c4a0e9e3d50ab6"}},
   2},
- {<<"eblake2">>,{pkg,<<"eblake2">>,<<"1.0.0">>},1},
+ {<<"eblake2">>,{pkg,<<"eblake2">>,<<"1.0.0">>},0},
  {<<"getopt">>,{pkg,<<"getopt">>,<<"1.0.1">>},0},
  {<<"jsx">>,
   {git,"https://github.com/talentdeficit/jsx.git",
diff --git a/src/aeso_ast_infer_types.erl b/src/aeso_ast_infer_types.erl
index e222f8d..54da3f8 100644
--- a/src/aeso_ast_infer_types.erl
+++ b/src/aeso_ast_infer_types.erl
@@ -136,7 +136,7 @@ on_current_scope(Env = #env{ namespace = NS, scopes = Scopes }, Fun) ->
     Env#env{ scopes = Scopes#{ NS => Fun(Scope) } }.
 
 -spec on_scopes(env(), fun((scope()) -> scope())) -> env().
-on_scopes(Env = #env{ namespace = NS, scopes = Scopes }, Fun) ->
+on_scopes(Env = #env{ scopes = Scopes }, Fun) ->
     Env#env{ scopes = maps:map(fun(_, Scope) -> Fun(Scope) end, Scopes) }.
 
 -spec bind_var(aeso_syntax:id(), type(), env()) -> env().
@@ -401,7 +401,7 @@ global_env() ->
                     [{"spend",        StateFun([Address, Int], Unit)},
                      %% Chain environment
                      {"balance",      Fun1(Address, Int)},
-                     {"block_hash",   Fun1(Int, Int)},
+                     {"block_hash",   Fun1(Int, Option(Hash))},
                      {"coinbase",     Address},
                      {"timestamp",    Int},
                      {"block_height", Int},
diff --git a/src/aeso_ast_to_icode.erl b/src/aeso_ast_to_icode.erl
index 5542354..c495d2f 100644
--- a/src/aeso_ast_to_icode.erl
+++ b/src/aeso_ast_to_icode.erl
@@ -141,7 +141,7 @@ ast_body(?qid_app([Con, "Chain", "event"], [Event], _, _), Icode = #{ contract_n
 ast_body(?qid_app(["Chain", "balance"], [Address], _, _), Icode) ->
     #prim_balance{ address = ast_body(Address, Icode) };
 ast_body(?qid_app(["Chain", "block_hash"], [Height], _, _), Icode) ->
-    #prim_block_hash{ height = ast_body(Height, Icode) };
+    builtin_call(block_hash, [ast_body(Height, Icode)]);
 ast_body(?qid_app(["Call", "gas_left"], [], _, _), _Icode) ->
     prim_gas_left;
 ast_body({qid, _, ["Contract", "address"]}, _Icode)      -> prim_contract_address;
diff --git a/src/aeso_builtins.erl b/src/aeso_builtins.erl
index 93c1c57..b913db9 100644
--- a/src/aeso_builtins.erl
+++ b/src/aeso_builtins.erl
@@ -130,6 +130,7 @@ builtin_function(BF) ->
     case BF of
         {event, EventT}            -> bfun(BF, builtin_event(EventT));
         abort                      -> bfun(BF, builtin_abort());
+        block_hash                 -> bfun(BF, builtin_block_hash());
         require                    -> bfun(BF, builtin_require());
         {map_lookup, Type}         -> bfun(BF, builtin_map_lookup(Type));
         map_put                    -> bfun(BF, builtin_map_put());
@@ -211,6 +212,12 @@ builtin_abort() ->
                    A(?REVERT)]}, %% Stack: 0,Ptr
      {tuple,[]}}.
 
+builtin_block_hash() ->
+    {[{"height", word}],
+     ?LET(hash, #prim_block_hash{ height = ?V(height)},
+          {ifte, ?EQ(hash, 0), option_none(), option_some(?V(hash))}),
+     aeso_icode:option_typerep(word)}.
+
 builtin_require() ->
     {[{"c", word}, {"msg", string}],
      {ifte, ?V(c), {tuple, []}, ?call(abort, [?V(msg)])},
diff --git a/test/contracts/environment.aes b/test/contracts/environment.aes
index 3f7f721..085b683 100644
--- a/test/contracts/environment.aes
+++ b/test/contracts/environment.aes
@@ -50,7 +50,7 @@ contract Environment =
   function get_balance(acct : address) : int = Chain.balance(acct)
 
   // Block hash
-  function block_hash(height : int) : int = Chain.block_hash(height)
+  function block_hash(height : int) : option(hash) = Chain.block_hash(height)
 
   // Coinbase
   function coinbase() : address = Chain.coinbase