Fix evaluation of map updates in the debugger and erl_eval

Reported-by: José Valim

2 files changed, 11 insertions, 4 deletions

diff --git a/lib/stdlib/src/erl_eval.erl b/lib/stdlib/src/erl_eval.erl
index acde3ad5d6..3cfedfee97 100644
--- a/lib/stdlib/src/erl_eval.erl
+++ b/lib/stdlib/src/erl_eval.erl
@@ -244,17 +244,17 @@ expr({record,_,_,Name,_}, _Bs, _Lf, _Ef, _RBs) ->
     erlang:raise(error, {undef_record,Name}, stacktrace());
 
 %% map
-expr({map,_, Binding,Es}, Bs0, Lf, Ef, RBs) ->
-    {value, Map0, Bs1} = expr(Binding, Bs0, Lf, Ef, RBs),
+expr({map,_,Binding,Es}, Bs0, Lf, Ef, RBs) ->
+    {value, Map0, Bs1} = expr(Binding, Bs0, Lf, Ef, none),
     case Map0 of
         #{} ->
-            {Vs,Bs} = eval_map_fields(Es, Bs1, Lf, Ef),
+            {Vs,Bs2} = eval_map_fields(Es, Bs0, Lf, Ef),
             Map1 = lists:foldl(fun ({map_assoc,K,V}, Mi) ->
                                        maps:put(K, V, Mi);
                                    ({map_exact,K,V}, Mi) ->
                                        maps:update(K, V, Mi)
                                end, Map0, Vs),
-            ret_expr(Map1, Bs, RBs);
+            ret_expr(Map1, merge_bindings(Bs2, Bs1), RBs);
         _ ->
             erlang:raise(error, {badarg,Map0}, stacktrace())
     end;
diff --git a/lib/stdlib/test/erl_eval_SUITE.erl b/lib/stdlib/test/erl_eval_SUITE.erl
index b91d14b5b8..b55324161b 100644
--- a/lib/stdlib/test/erl_eval_SUITE.erl
+++ b/lib/stdlib/test/erl_eval_SUITE.erl
@@ -1451,6 +1451,13 @@ eep43(Config) when is_list(Config) ->
           "    {Map#{a := B},Map#{a => c},Map#{d => e}} "
           "end.",
           {#{a => b},#{a => c},#{a => b,d => e}}),
+    check(fun () ->
+                  lists:map(fun (X) -> X#{price := 0} end,
+                            [#{hello => 0, price => nil}])
+          end,
+          "lists:map(fun (X) -> X#{price := 0} end,
+                     [#{hello => 0, price => nil}]).",
+          [#{hello => 0, price => 0}]),
     error_check("[camembert]#{}.", {badarg,[camembert]}),
     error_check("#{} = 1.", {badmatch,1}),
     ok.