4 files changed, 52 insertions, 6 deletions
diff --git a/lib/compiler/src/cerl.erl b/lib/compiler/src/cerl.erl
index b7e1f0b70b..9d6768b157 100644
--- a/lib/compiler/src/cerl.erl
+++ b/lib/compiler/src/cerl.erl
@@ -126,9 +126,11 @@
 	 map_es/1,
 	 map_arg/1,
 	 update_c_map/3,
+	 c_map/1, is_c_map_empty/1,
 	 ann_c_map/2, ann_c_map/3,
 	 map_pair_op/1,map_pair_key/1,map_pair_val/1,
 	 update_c_map_pair/4,
+	 c_map_pair/2,
 	 ann_c_map_pair/4
      ]).
 
@@ -1582,9 +1584,20 @@ map_es(#c_map{es = Es}) ->
 
 -spec map_arg(c_map()) -> c_map() | c_literal().
 
-map_arg(#c_map{arg = M}) ->
+map_arg(#c_map{arg=M}) ->
     M.
 
+-spec c_map([c_map_pair()]) -> c_map().
+
+c_map(Pairs) ->
+    #c_map{es=Pairs}.
+
+-spec is_c_map_empty(c_map() | c_literal()) -> boolean().
+
+is_c_map_empty(#c_map{ es=[] }) -> true;
+is_c_map_empty(#c_literal{val=M}) when is_map(M),map_size(M) =:= 0 -> true;
+is_c_map_empty(_) -> false.
+
 -spec ann_c_map([term()], [cerl()]) -> c_map() | c_literal().
 
 ann_c_map(As,Es) ->
@@ -1644,6 +1657,11 @@ map_pair_key(#c_map_pair{key=K}) -> K.
 map_pair_val(#c_map_pair{val=V}) -> V.
 map_pair_op(#c_map_pair{op=Op}) -> Op.
 
+-spec c_map_pair(cerl(), cerl()) -> c_map_pair().
+
+c_map_pair(Key,Val) ->
+    #c_map_pair{op=#c_literal{val=assoc},key=Key,val=Val}.
+
 -spec ann_c_map_pair([term()], cerl(), cerl(), cerl()) ->
         c_map_pair().
 
diff --git a/lib/dialyzer/test/small_SUITE_data/results/maps_difftype b/lib/dialyzer/test/small_SUITE_data/results/maps_difftype
new file mode 100644
index 0000000000..8980321135
--- /dev/null
+++ b/lib/dialyzer/test/small_SUITE_data/results/maps_difftype
@@ -0,0 +1,3 @@
+
+maps_difftype.erl:10: Function empty_mismatch/1 has no local return
+maps_difftype.erl:11: The pattern ~{}~ can never match the type tuple()
diff --git a/lib/dialyzer/test/small_SUITE_data/src/maps_difftype.erl b/lib/dialyzer/test/small_SUITE_data/src/maps_difftype.erl
new file mode 100644
index 0000000000..19e61a7944
--- /dev/null
+++ b/lib/dialyzer/test/small_SUITE_data/src/maps_difftype.erl
@@ -0,0 +1,11 @@
+%%
+%% File:    maps_difftype.erl
+%% Author:  Björn-Egil Dahlberg
+%% Created: 2014-04-29
+%%
+-module(maps_difftype).
+
+-export([empty_mismatch/1]).
+
+empty_mismatch(Tuple) when is_tuple(Tuple) ->
+    case Tuple of #{} -> ok end.
diff --git a/lib/hipe/cerl/cerl_prettypr.erl b/lib/hipe/cerl/cerl_prettypr.erl
index 22f5b8945a..9a3873f46d 100644
--- a/lib/hipe/cerl/cerl_prettypr.erl
+++ b/lib/hipe/cerl/cerl_prettypr.erl
@@ -63,7 +63,8 @@
 	       seq_arg/1, seq_body/1, string_lit/1, try_arg/1,
 	       try_body/1, try_vars/1, try_evars/1, try_handler/1,
 	       tuple_es/1, type/1, values_es/1, var_name/1,
-	       map_es/1, map_pair_key/1, map_pair_val/1, map_pair_op/1
+	       c_map/1, map_arg/1, map_es/1, is_c_map_empty/1,
+	       c_map_pair/2, map_pair_key/1, map_pair_val/1, map_pair_op/1
 	   ]).
 
 -define(PAPER, 76).
@@ -489,7 +490,13 @@ lay_literal(Node, Ctxt) ->
 	    %% `lay_cons' will check for strings.
 	    lay_cons(Node, Ctxt);
 	V when is_tuple(V) ->
-	    lay_tuple(Node, Ctxt)
+	    lay_tuple(Node, Ctxt);
+	M when is_map(M), map_size(M) =:= 0 ->
+	    text("~{}~");
+	M when is_map(M) ->
+	    lay_map(c_map([c_map_pair(abstract(K),abstract(V))
+			|| {K,V} <- maps:to_list(M)]),
+		       Ctxt)
     end.
 
 lay_var(Node, Ctxt) ->
@@ -596,10 +603,17 @@ lay_tuple(Node, Ctxt) ->
 		  floating(text("}")))).
 
 lay_map(Node, Ctxt) ->
+    Arg = map_arg(Node),
+    After = case is_c_map_empty(Arg) of
+	true -> floating(text("}~"));
+	false ->
+	    beside(floating(text(" | ")),
+		beside(lay(Arg,Ctxt),
+		    floating(text("}~"))))
+    end,
     beside(floating(text("~{")),
-	   beside(par(seq(map_es(Node), floating(text(",")),
-			  Ctxt, fun lay/2)),
-		  floating(text("}~")))).
+        beside(par(seq(map_es(Node), floating(text(",")), Ctxt, fun lay/2)),
+	    After)).
 
 lay_map_pair(Node, Ctxt) ->
     K = map_pair_key(Node),