Merge branch 'egil/maps-literals'

* egil/maps-literals:
  compiler: Transform M#{} to is_map(M)
  dialyzer: Do not native compile modules with Maps code
  hipe: Properly identify map() type form terms
  stdlib: Test Map key linting
  stdlib: Accept records as Map keys
  stdlib: Accept Maps as Map keys
  stdlib: Move map type to proper definition
  stdlib: Properly lint map key expressions
  compiler: Change #c_map{var} to #c_map{arg}
  compiler: Constant fold Maps that are safe
  compiler: Validate Map src
  compiler: Support literal maps in cerl_clauses:match/2
  compiler: Guard BIF is_map/1 is pure
  erts: Handle literals in is_map/1
  compiler: Change Maps Core Format
  compiler: Create literal Maps in creation if possible

13 files changed, 189 insertions, 48 deletions

diff --git a/lib/compiler/src/cerl.erl b/lib/compiler/src/cerl.erl
index 3c121f3b04..ecc4b2c9b1 100644
--- a/lib/compiler/src/cerl.erl
+++ b/lib/compiler/src/cerl.erl
@@ -124,9 +124,9 @@
 
 	 %% keep map exports here for now
 	 map_es/1,
-	 map_val/1,
+	 map_arg/1,
 	 update_c_map/3,
-	 ann_c_map/3,
+	 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,
 	 ann_c_map_pair/4
@@ -135,6 +135,9 @@
 -export_type([c_binary/0, c_call/0, c_clause/0, c_cons/0, c_fun/0, c_literal/0,
               c_module/0, c_tuple/0, c_values/0, c_var/0, cerl/0, var_name/0]).
 
+%% HiPE does not understand Maps
+%% (guard functions is_map/1 and map_size/1 in ann_c_map/3)
+-compile(no_native).
 %%
 %% needed by the include file below -- do not move
 %%
@@ -1575,20 +1578,70 @@ ann_make_list(_, [], Node) ->
 %% ---------------------------------------------------------------------
 %% maps
 
--spec map_es(c_map()) -> [cerl()].
+-spec map_es(c_map()) -> [c_map_pair()].
 
 map_es(#c_map{es = Es}) ->
     Es.
 
--spec map_val(c_map()) -> cerl().
-map_val(#c_map{var = M}) ->
+-spec map_arg(c_map()) -> c_map() | c_literal().
+
+map_arg(#c_map{arg = M}) ->
     M.
 
+-spec ann_c_map([term()], [cerl()]) -> c_map() | c_literal().
+
+ann_c_map(As,Es) ->
+    ann_c_map(As, #c_literal{val=#{}}, Es).
+
+-spec ann_c_map([term()], c_map() | c_literal(), [c_map_pair()]) -> c_map() | c_literal().
+
+ann_c_map(As,#c_literal{val=Mval}=M,Es) when is_map(Mval), map_size(Mval) =:= 0 ->
+    Pairs = [[Ck,Cv]||#c_map_pair{key=Ck,val=Cv}<-Es],
+    IsLit = lists:foldl(fun(Pair,Res) ->
+		Res andalso is_lit_list(Pair)
+	end, true, Pairs),
+    Fun = fun(Pair) -> [K,V] = lit_list_vals(Pair), {K,V} end,
+    case IsLit of
+	false ->
+	    #c_map{arg=M, es=Es, anno=As };
+	true ->
+	    #c_literal{anno=As, val=maps:from_list(lists:map(Fun, Pairs))}
+	end;
+ann_c_map(As,#c_literal{val=M},Es) when is_map(M) ->
+    fold_map_pairs(As,Es,M);
 ann_c_map(As,M,Es) ->
-    #c_map{var=M,es = Es, anno = As }.
+    #c_map{arg=M, es=Es, anno=As }.
+
+fold_map_pairs(As,[],M) -> #c_literal{anno=As,val=M};
+%% M#{ K => V}
+fold_map_pairs(As,[#c_map_pair{op=#c_literal{val=assoc},key=Ck,val=Cv}=E|Es],M) ->
+    case is_lit_list([Ck,Cv]) of
+	true ->
+	    [K,V] = lit_list_vals([Ck,Cv]),
+	    fold_map_pairs(As,Es,maps:put(K,V,M));
+	false ->
+	    #c_map{arg=#c_literal{val=M,anno=As}, es=[E|Es], anno=As }
+    end;
+%% M#{ K := V}
+fold_map_pairs(As,[#c_map_pair{op=#c_literal{val=exact},key=Ck,val=Cv}=E|Es],M) ->
+    case is_lit_list([Ck,Cv]) of
+	true ->
+	    [K,V] = lit_list_vals([Ck,Cv]),
+	    case maps:is_key(K,M) of
+		true -> fold_map_pairs(As,Es,maps:put(K,V,M));
+		false ->
+		    #c_map{arg=#c_literal{val=M,anno=As}, es=[E|Es], anno=As }
+	    end;
+	false ->
+	    #c_map{arg=#c_literal{val=M,anno=As}, es=[E|Es], anno=As }
+    end;
+fold_map_pairs(As,Es,M) ->
+    #c_map{arg=#c_literal{val=M,anno=As}, es=Es, anno=As }.
+
+%-spec update_c_map(c_map() | c_literal(), [c_map_pair()]) -> c_map() | c_literal().
 
 update_c_map(Old,M,Es) ->
-    #c_map{var=M, es = Es, anno = get_ann(Old)}.
+    #c_map{arg=M, es = Es, anno = get_ann(Old)}.
 
 map_pair_key(#c_map_pair{key=K}) -> K.
 map_pair_val(#c_map_pair{val=V}) -> V.
diff --git a/lib/compiler/src/cerl_clauses.erl b/lib/compiler/src/cerl_clauses.erl
index 76d70dcabf..87bd47c08b 100644
--- a/lib/compiler/src/cerl_clauses.erl
+++ b/lib/compiler/src/cerl_clauses.erl
@@ -356,14 +356,19 @@ match(P, E, Bs) ->
 	    end;
     map ->
         %% The most we can do is to say "definitely no match" if a
-        %% binary pattern is matched against non-binary data.
+        %% map pattern is matched against non-map data.
         case E of
             any ->
                 {false, Bs};
             _ ->
                 case type(E) of
-                    literal ->
-                        none;
+		    literal ->
+			case is_map(concrete(E)) of
+			    false ->
+				none;
+			    true ->
+				{false, Bs}
+			end;
                     cons ->
                         none;
                     tuple ->
diff --git a/lib/compiler/src/cerl_inline.erl b/lib/compiler/src/cerl_inline.erl
index fa1d34cc9b..75740e8b9d 100644
--- a/lib/compiler/src/cerl_inline.erl
+++ b/lib/compiler/src/cerl_inline.erl
@@ -64,7 +64,7 @@
 	       seq_body/1, set_ann/2, try_arg/1, try_body/1, try_vars/1,
 	       try_evars/1, try_handler/1, tuple_es/1, tuple_arity/1,
 	       type/1, values_es/1, var_name/1,
-	       map_val/1, map_es/1, update_c_map/3,
+	       map_arg/1, map_es/1, update_c_map/3,
 	       update_c_map_pair/4,
 	       map_pair_op/1, map_pair_key/1, map_pair_val/1
 	   ]).
@@ -1343,7 +1343,7 @@ i_bitstr(E, Ren, Env, S) ->
 
 i_map(E, Ctx, Ren, Env, S) ->
     %% Visit the segments for value.
-    {M1, S1} = i(map_val(E), value, Ren, Env, S),
+    {M1, S1} = i(map_arg(E), value, Ren, Env, S),
     {Es, S2} = mapfoldl(fun (E, S) ->
 		i_map_pair(E, Ctx, Ren, Env, S)
 	end, S1, map_es(E)),
@@ -1420,8 +1420,8 @@ i_pattern(E, Ren, Env, Ren0, Env0, S) ->
 	    S2 = count_size(weight(binary), S1),
 	    {update_c_binary(E, Es), S2};
 	map ->
-	    %% map patterns should not have vals
-	    M = map_val(E),
+	    %% map patterns should not have args
+	    M = map_arg(E),
 
 	    {Es, S1} = mapfoldl(fun (E, S) ->
 			i_map_pair_pattern(E, Ren, Env, Ren0, Env0, S)
diff --git a/lib/compiler/src/cerl_trees.erl b/lib/compiler/src/cerl_trees.erl
index 2ebeab243f..e53bdd4efb 100644
--- a/lib/compiler/src/cerl_trees.erl
+++ b/lib/compiler/src/cerl_trees.erl
@@ -57,7 +57,7 @@
 	       update_c_try/6, update_c_tuple/2, update_c_tuple_skel/2,
 	       update_c_values/2, values_es/1, var_name/1,
 
-	       map_val/1, map_es/1,
+	       map_arg/1, map_es/1,
 	       ann_c_map/3,
 	       update_c_map/3,
 	       map_pair_key/1,map_pair_val/1,map_pair_op/1,
@@ -138,7 +138,7 @@ map_1(F, T) ->
  	tuple ->
 	    update_c_tuple_skel(T, map_list(F, tuple_es(T)));
  	map ->
-	    update_c_map(T, map(F,map_val(T)), map_list(F, map_es(T)));
+	    update_c_map(T, map(F, map_arg(T)), map_list(F, map_es(T)));
 	map_pair ->
 	    update_c_map_pair(T, map(F, map_pair_op(T)),
                                  map(F, map_pair_key(T)),
@@ -372,7 +372,7 @@ mapfold(F, S0, T) ->
 	    {Ts, S1} = mapfold_list(F, S0, tuple_es(T)),
 	    F(update_c_tuple_skel(T, Ts), S1);
 	map ->
-	    {M , S1} = mapfold(F, S0, map_val(T)),
+	    {M , S1} = mapfold(F, S0, map_arg(T)),
 	    {Ts, S2} = mapfold_list(F, S1, map_es(T)),
 	    F(update_c_map(T, M, Ts), S2);
 	map_pair ->
@@ -724,7 +724,7 @@ label(T, N, Env) ->
 	    {As, N2} = label_ann(T, N1),
 	    {ann_c_tuple_skel(As, Ts), N2};
  	map ->
-	    {M,  N1} = label(map_val(T), N, Env),
+	    {M,  N1} = label(map_arg(T), N, Env),
 	    {Ts, N2} = label_list(map_es(T), N1, Env),
 	    {As, N3} = label_ann(T, N2),
 	    {ann_c_map(As, M, Ts), N3};
diff --git a/lib/compiler/src/core_lib.erl b/lib/compiler/src/core_lib.erl
index ed181e3baa..93ec3bbad5 100644
--- a/lib/compiler/src/core_lib.erl
+++ b/lib/compiler/src/core_lib.erl
@@ -105,7 +105,7 @@ vu_expr(V, #c_cons{hd=H,tl=T}) ->
     vu_expr(V, H) orelse vu_expr(V, T);
 vu_expr(V, #c_tuple{es=Es}) ->
     vu_expr_list(V, Es);
-vu_expr(V, #c_map{var=M,es=Es}) ->
+vu_expr(V, #c_map{arg=M,es=Es}) ->
     vu_expr(V, M) orelse vu_expr_list(V, Es);
 vu_expr(V, #c_map_pair{key=Key,val=Val}) ->
     vu_expr_list(V, [Key,Val]);
diff --git a/lib/compiler/src/core_parse.hrl b/lib/compiler/src/core_parse.hrl
index d54715ef59..20f3a46991 100644
--- a/lib/compiler/src/core_parse.hrl
+++ b/lib/compiler/src/core_parse.hrl
@@ -103,5 +103,5 @@
 		     val}).
 
 -record(c_map, {anno=[],
-		var=#c_literal{val=[]} :: #c_var{} | #c_literal{},
+		arg=#c_literal{val=#{}} :: #c_var{} | #c_literal{},
 		es :: [#c_map_pair{}]}).
diff --git a/lib/compiler/src/core_parse.yrl b/lib/compiler/src/core_parse.yrl
index b8db0f683a..a66ad4235f 100644
--- a/lib/compiler/src/core_parse.yrl
+++ b/lib/compiler/src/core_parse.yrl
@@ -21,7 +21,7 @@
 %% Have explicit productions for annotated phrases named anno_XXX.
 %% This just does an XXX and adds the annotation.
 
-Expect 1.
+Expect 0.
 
 Nonterminals
 
@@ -285,9 +285,9 @@ tuple -> '{' '}' : c_tuple([]).
 tuple -> '{' anno_expressions '}' : c_tuple('$2').
 
 map_expr -> '~' '{' '}' '~' : #c_map{es=[]}.
-map_expr -> '~' '{' map_pairs  '}' '~' : #c_map{es='$3'}.
-map_expr -> variable '~' '{' '}' '~' : #c_map{var='$1',es=[]}.
-map_expr -> variable '~' '{' map_pairs  '}' '~' : #c_map{var='$1',es='$4'}.
+map_expr -> '~' '{' map_pairs '}' '~' : #c_map{es='$3'}.
+map_expr -> '~' '{' map_pairs '|' variable '}' '~' : #c_map{arg='$5',es='$3'}.
+map_expr -> '~' '{' map_pairs '|' map_expr '}' '~' : #c_map{arg='$5',es='$3'}.
 
 map_pairs -> map_pair : ['$1'].
 map_pairs -> map_pair ',' map_pairs : ['$1' | '$3'].
diff --git a/lib/compiler/src/core_pp.erl b/lib/compiler/src/core_pp.erl
index faa26ec6df..a76327457d 100644
--- a/lib/compiler/src/core_pp.erl
+++ b/lib/compiler/src/core_pp.erl
@@ -118,6 +118,12 @@ format_1(#c_literal{val=Tuple}, Ctxt) when is_tuple(Tuple) ->
 format_1(#c_literal{anno=A,val=Bitstring}, Ctxt) when is_bitstring(Bitstring) ->
     Segs = segs_from_bitstring(Bitstring),
     format_1(#c_binary{anno=A,segments=Segs}, Ctxt);
+format_1(#c_literal{anno=A,val=M},Ctxt) when is_map(M) ->
+    Pairs = maps:to_list(M),
+    Cpairs = [#c_map_pair{op=#c_literal{val=assoc},
+			  key=#c_literal{val=V},
+			  val=#c_literal{val=K}} || {K,V} <- Pairs],
+	format_1(#c_map{anno=A,arg=#c_literal{val=#{}},es=Cpairs},Ctxt);
 format_1(#c_var{name={I,A}}, _) ->
     [core_atom(I),$/,integer_to_list(A)];
 format_1(#c_var{name=V}, _) ->
@@ -161,15 +167,15 @@ format_1(#c_tuple{es=Es}, Ctxt) ->
      format_hseq(Es, ",", add_indent(Ctxt, 1), fun format/2),
      $}
     ];
-format_1(#c_map{var=#c_var{}=Var,es=Es}, Ctxt) ->
-    [format_1(Var, Ctxt),
-     "~{",
+format_1(#c_map{arg=#c_literal{val=M},es=Es}, Ctxt) when is_map(M),map_size(M)=:=0 ->
+    ["~{",
      format_hseq(Es, ",", add_indent(Ctxt, 1), fun format/2),
      "}~"
     ];
-format_1(#c_map{es=Es}, Ctxt) ->
+format_1(#c_map{arg=Var,es=Es}, Ctxt) ->
     ["~{",
      format_hseq(Es, ",", add_indent(Ctxt, 1), fun format/2),
+     "|",format(Var, add_indent(Ctxt, 1)),
      "}~"
     ];
 format_1(#c_map_pair{op=#c_literal{val=assoc},key=K,val=V}, Ctxt) ->
diff --git a/lib/compiler/src/erl_bifs.erl b/lib/compiler/src/erl_bifs.erl
index 3ad3c8c690..6c75538194 100644
--- a/lib/compiler/src/erl_bifs.erl
+++ b/lib/compiler/src/erl_bifs.erl
@@ -91,6 +91,7 @@ is_pure(erlang, is_float, 1) -> true;
 is_pure(erlang, is_function, 1) -> true;
 is_pure(erlang, is_integer, 1) -> true;
 is_pure(erlang, is_list, 1) -> true;
+is_pure(erlang, is_map, 1) -> true;
 is_pure(erlang, is_number, 1) -> true;
 is_pure(erlang, is_pid, 1) -> true;
 is_pure(erlang, is_port, 1) -> true;
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl
index 058abd3357..52d6dfe184 100644
--- a/lib/compiler/src/sys_core_fold.erl
+++ b/lib/compiler/src/sys_core_fold.erl
@@ -72,7 +72,7 @@
 -import(lists, [map/2,foldl/3,foldr/3,mapfoldl/3,all/2,any/2,
 		reverse/1,reverse/2,member/2,nth/2,flatten/1,unzip/1]).
 
--import(cerl, [ann_c_cons/3,ann_c_tuple/2]).
+-import(cerl, [ann_c_cons/3,ann_c_map/3,ann_c_tuple/2]).
 
 -include("core_parse.hrl").
 
@@ -246,7 +246,7 @@ expr(#c_tuple{anno=Anno,es=Es0}=Tuple, Ctxt, Sub) ->
 	value ->
 	    ann_c_tuple(Anno, Es)
     end;
-expr(#c_map{var=V0,es=Es0}=Map, Ctxt, Sub) ->
+expr(#c_map{anno=Anno,arg=V0,es=Es0}=Map, Ctxt, Sub) ->
     Es = pair_list(Es0, Ctxt, Sub),
     case Ctxt of
 	effect ->
@@ -254,7 +254,7 @@ expr(#c_map{var=V0,es=Es0}=Map, Ctxt, Sub) ->
 	    expr(make_effect_seq(Es, Sub), Ctxt, Sub);
 	value ->
 	    V = expr(V0, Ctxt, Sub),
-	    Map#c_map{var=V,es=Es}
+	    ann_c_map(Anno,V,Es)
     end;
 expr(#c_binary{segments=Ss}=Bin0, Ctxt, Sub) ->
     %% Warn for useless building, but always build the binary
@@ -1378,6 +1378,7 @@ eval_is_record(Call, _, _, _, _) -> Call.
 is_not_integer(#c_literal{val=Val}) when not is_integer(Val) -> true;
 is_not_integer(#c_tuple{}) -> true;
 is_not_integer(#c_cons{}) -> true;
+is_not_integer(#c_map{}) -> true;
 is_not_integer(_) -> false.
 
 %% is_not_tuple(Core) -> true | false.
@@ -1385,6 +1386,7 @@ is_not_integer(_) -> false.
 
 is_not_tuple(#c_literal{val=Val}) when not is_tuple(Val) -> true;
 is_not_tuple(#c_cons{}) -> true;
+is_not_tuple(#c_map{}) -> true;
 is_not_tuple(_) -> false.
 
 %% eval_setelement(Call, Pos, Tuple, NewVal) -> Core.
diff --git a/lib/compiler/src/v3_core.erl b/lib/compiler/src/v3_core.erl
index 3d17557e01..082809b8a0 100644
--- a/lib/compiler/src/v3_core.erl
+++ b/lib/compiler/src/v3_core.erl
@@ -77,7 +77,8 @@
 		splitwith/2,keyfind/3,sort/1,foreach/2,droplast/1,last/1]).
 -import(ordsets, [add_element/2,del_element/2,is_element/2,
 		  union/1,union/2,intersection/2,subtract/2]).
--import(cerl, [ann_c_cons/3,ann_c_cons_skel/3,ann_c_tuple/2,c_tuple/1]).
+-import(cerl, [ann_c_cons/3,ann_c_cons_skel/3,ann_c_tuple/2,c_tuple/1,
+	       ann_c_map/2, ann_c_map/3]).
 
 -include("core_parse.hrl").
 
@@ -515,12 +516,20 @@ expr({map,L,Es0}, St0) ->
     % in map construction.
     {Es1,Eps,St1} = map_pair_list(Es0, St0),
     A = lineno_anno(L, St1),
-    {#c_map{anno=A,es=Es1},Eps,St1};
+    {ann_c_map(A,Es1),Eps,St1};
 expr({map,L,M0,Es0}, St0) ->
-    {M1,Mps,St1} = safe(M0, St0),
-    {Es1,Eps,St2} = map_pair_list(Es0, St1),
-    A = lineno_anno(L, St2),
-    {#c_map{anno=A,var=M1,es=Es1},Mps++Eps,St2};
+    try expr_map(M0,Es0,lineno_anno(L, St0),St0) of
+	{_,_,_}=Res -> Res
+    catch
+	throw:bad_map ->
+	    St = add_warning(L, bad_map, St0),
+	    LineAnno = lineno_anno(L, St),
+	    As = [#c_literal{anno=LineAnno,val=badarg}],
+	    {#icall{anno=#a{anno=LineAnno},	%Must have an #a{}
+		    module=#c_literal{anno=LineAnno,val=erlang},
+		    name=#c_literal{anno=LineAnno,val=error},
+		    args=As},[],St}
+    end;
 expr({bin,L,Es0}, St0) ->
     try expr_bin(Es0, lineno_anno(L, St0), St0) of
 	{_,_,_}=Res -> Res
@@ -730,6 +739,37 @@ make_bool_switch_guard(L, E, V, T, F) ->
       {clause,NegL,[V],[],[V]}
      ]}.
 
+expr_map(M0,Es0,A,St0) ->
+    {M1,Mps,St1} = safe(M0, St0),
+    case is_valid_map_src(M1) of
+	true ->
+	    case {M1,Es0} of
+		{#c_var{}, []} ->
+		    %% transform M#{} to is_map(M)
+		    {Vpat,St2} = new_var(St1),
+		    {Fpat,St3} = new_var(St2),
+		    Cs = [#iclause{
+			   anno=A,
+			   pats=[Vpat],
+			   guard=[#icall{anno=#a{anno=A},
+				   module=#c_literal{anno=A,val=erlang},
+			           name=#c_literal{anno=A,val=is_map},
+				   args=[Vpat]}],
+			   body=[Vpat]}],
+		    Fc = fail_clause([Fpat], A, #c_literal{val=badarg}),
+		    {#icase{anno=#a{anno=A},args=[M1],clauses=Cs,fc=Fc},Mps,St3};
+		{_,_} ->
+		    {Es1,Eps,St2} = map_pair_list(Es0, St1),
+		    {ann_c_map(A,M1,Es1),Mps++Eps,St2}
+	    end;
+	false -> throw(bad_map)
+    end.
+
+is_valid_map_src(#c_literal{val = M}) when is_map(M) -> true;
+is_valid_map_src(#c_map{})  -> true;
+is_valid_map_src(#c_var{})  -> true;
+is_valid_map_src(_)         -> false.
+
 map_pair_list(Es, St) ->
     foldr(fun
 	    ({map_field_assoc,L,K0,V0}, {Ces,Esp,St0}) ->
@@ -2256,7 +2296,9 @@ is_simple_list(Es) -> lists:all(fun is_simple/1, Es).
 format_error(nomatch) ->
     "pattern cannot possibly match";
 format_error(bad_binary) ->
-    "binary construction will fail because of a type mismatch".
+    "binary construction will fail because of a type mismatch";
+format_error(bad_map) ->
+    "map construction will fail because of a type mismatch".
 
 add_warning(Line, Term, #core{ws=Ws,file=[{file,File}]}=St) when Line >= 0 ->
     St#core{ws=[{File,[{location(Line),?MODULE,Term}]}|Ws]};
diff --git a/lib/compiler/src/v3_kernel.erl b/lib/compiler/src/v3_kernel.erl
index d00dd56f30..d3b785aa14 100644
--- a/lib/compiler/src/v3_kernel.erl
+++ b/lib/compiler/src/v3_kernel.erl
@@ -272,9 +272,18 @@ expr(#c_cons{anno=A,hd=Ch,tl=Ct}, Sub, St0) ->
 expr(#c_tuple{anno=A,es=Ces}, Sub, St0) ->
     {Kes,Ep,St1} = atomic_list(Ces, Sub, St0),
     {#k_tuple{anno=A,es=Kes},Ep,St1};
-expr(#c_map{anno=A,var=Var0,es=Ces}, Sub, St0) ->
-    {Var,[],St1} = expr(Var0, Sub, St0),
-    map_split_pairs(A, Var, Ces, Sub, St1);
+expr(#c_map{anno=A,arg=Var,es=Ces}, Sub, St0) ->
+    try expr_map(A,Var,Ces,Sub,St0) of
+	{_,_,_}=Res -> Res
+    catch
+	throw:bad_map ->
+	    St1 = add_warning(get_line(A), bad_map, A, St0),
+	    Erl = #c_literal{val=erlang},
+	    Name = #c_literal{val=error},
+	    Args = [#c_literal{val=badarg}],
+	    Error = #c_call{anno=A,module=Erl,name=Name,args=Args},
+	    expr(Error, Sub, St1)
+    end;
 expr(#c_binary{anno=A,segments=Cv}, Sub, St0) ->
     try atomic_bin(Cv, Sub, St0) of
 	{Kv,Ep,St1} ->
@@ -496,6 +505,21 @@ translate_match_fail_1(Anno, As, Sub, #kern{ff=FF}) ->
 translate_fc(Args) ->
     [#c_literal{val=function_clause},make_list(Args)].
 
+expr_map(A,Var0,Ces,Sub,St0) ->
+    %% An extra pass of validation of Map src because of inlining
+    {Var,Mps,St1} = expr(Var0, Sub, St0),
+    case is_valid_map_src(Var) of
+	true ->
+	    {Km,Eps,St2} = map_split_pairs(A, Var, Ces, Sub, St1),
+	    {Km,Eps++Mps,St2};
+	false -> throw(bad_map)
+    end.
+
+is_valid_map_src(#k_map{}) -> true;
+is_valid_map_src(#k_literal{val=M}) when is_map(M) -> true;
+is_valid_map_src(#k_var{}) -> true;
+is_valid_map_src(_) -> false.
+
 map_split_pairs(A, Var, Ces, Sub, St0) ->
     %% two steps
     %% 1. force variables
@@ -1986,7 +2010,9 @@ format_error(nomatch_shadow) ->
 format_error(bad_call) ->
     "invalid module and/or function name; this call will always fail";
 format_error(bad_segment_size) ->
-    "binary construction will fail because of a type mismatch".
+    "binary construction will fail because of a type mismatch";
+format_error(bad_map) ->
+    "map construction will fail because of a type mismatch".
 
 add_warning(none, Term, Anno, #kern{ws=Ws}=St) ->
     File = get_file(Anno),
diff --git a/lib/compiler/src/v3_kernel_pp.erl b/lib/compiler/src/v3_kernel_pp.erl
index b4e486f97c..b33eba50eb 100644
--- a/lib/compiler/src/v3_kernel_pp.erl
+++ b/lib/compiler/src/v3_kernel_pp.erl
@@ -104,20 +104,26 @@ format_1(#k_tuple{es=Es}, Ctxt) ->
      format_hseq(Es, ",", ctxt_bump_indent(Ctxt, 1), fun format/2),
      $}
     ];
-format_1(#k_map{var=#k_var{}=Var,es=Es}, Ctxt) ->
-    [$~,${,
+format_1(#k_map{var=#k_literal{val=M},op=assoc,es=Es}, Ctxt) when is_map(M), map_size(M) =:= 0 ->
+    ["~{",
      format_hseq(Es, ",", ctxt_bump_indent(Ctxt, 1), fun format/2),
-     " | ",format_1(Var, Ctxt),
-     $},$~
+     "}~"
     ];
-format_1(#k_map{op=assoc,es=Es}, Ctxt) ->
+format_1(#k_map{var=#k_literal{val=M},op=exact,es=Es}, Ctxt) when is_map(M), map_size(M) =:= 0 ->
+    ["::{",
+     format_hseq(Es, ",", ctxt_bump_indent(Ctxt, 1), fun format/2),
+     "}::"
+    ];
+format_1(#k_map{var=Var,op=assoc,es=Es}, Ctxt) ->
     ["~{",
      format_hseq(Es, ",", ctxt_bump_indent(Ctxt, 1), fun format/2),
+     " | ",format_1(Var, Ctxt),
      "}~"
     ];
-format_1(#k_map{es=Es}, Ctxt) ->
+format_1(#k_map{var=Var,op=exact,es=Es}, Ctxt) ->
     ["::{",
      format_hseq(Es, ",", ctxt_bump_indent(Ctxt, 1), fun format/2),
+     " | ",format_1(Var, Ctxt),
      "}::"
     ];
 format_1(#k_map_pair{key=K,val=V}, Ctxt) ->