Merge branch 'egil/maps/variable-keys/OTP-12218'

* egil/maps/variable-keys/OTP-12218: (22 commits)
  compiler: Update test for Maps aliasing
  compiler: Properly support Map aliasing
  compiler: Refactor Map pairs aliasing
  compiler: Fix harmless need_heap error for Maps
  stdlib: Update Map tests
  stdlib: Use environment bindings for Maps keys in erl_eval matching
  debugger: Update Map tests
  compiler: Update Map tests
  compiler: Fix v3_core Maps pair chains
  compiler: Use expressions in core patterns
  compiler: Use variables in Map cerl inliner
  compiler: Reintroduce binary limit for Map keys
  compiler: Shameless v3_core hack for variables
  compiler: Use variables in Map beam assmebler
  compiler: Use variables in Map kernel pass
  compiler: Use variables in Map core pass
  compiler: Normalize unary ops on Maps key literals
  stdlib: Update Map tests
  stdlib: erl_lint Map key variables
  compiler: Maps are always patterns never values in matching
  ...

3 files changed, 393 insertions, 12 deletions

diff --git a/lib/compiler/test/error_SUITE.erl b/lib/compiler/test/error_SUITE.erl
index bd877bb528..0d23f12fb5 100644
--- a/lib/compiler/test/error_SUITE.erl
+++ b/lib/compiler/test/error_SUITE.erl
@@ -23,7 +23,7 @@
 -export([all/0, suite/0,groups/0,init_per_suite/1, end_per_suite/1, 
 	 init_per_group/2,end_per_group/2,
 	 head_mismatch_line/1,warnings_as_errors/1, bif_clashes/1,
-	 transforms/1,forbidden_maps/1,bad_utf8/1]).
+	 transforms/1,maps_warnings/1,bad_utf8/1]).
 
 %% Used by transforms/1 test case.
 -export([parse_transform/2]).
@@ -37,7 +37,7 @@ all() ->
 groups() -> 
     [{p,test_lib:parallel(),
       [head_mismatch_line,warnings_as_errors,bif_clashes,
-       transforms,forbidden_maps,bad_utf8]}].
+       transforms,maps_warnings,bad_utf8]}].
 
 init_per_suite(Config) ->
     Config.
@@ -241,17 +241,30 @@ parse_transform(_, _) ->
     error(too_bad).
 
 
-forbidden_maps(Config) when is_list(Config) ->
-    Ts1 = [{map_illegal_use_of_pattern,
+maps_warnings(Config) when is_list(Config) ->
+    Ts1 = [{map_ok_use_of_pattern,
 	   <<"
-              -export([t/0]).
+              -export([t/1]).
+              t(K) ->
+                 #{K := 1 = V} = id(#{<<\"hi all\">> => 1}),
+		 V.
+              id(I) -> I.
+             ">>,
+	    [return],
+	    []},
+	{map_illegal_use_of_pattern,
+	   <<"
+              -export([t/0,t/2]).
+	      t(K,#{ K := V }) -> V.
               t() ->
                  V = 32,
                  #{<<\"hi\",V,\"all\">> := 1} = id(#{<<\"hi all\">> => 1}).
               id(I) -> I.
              ">>,
 	    [return],
-	    {error,[{5,erl_lint,{illegal_map_key_variable,'V'}}], []}}],
+	    {error,[{3,erl_lint,{unbound_var,'K'}},
+		    {6,erl_lint,illegal_map_key}],[]}}
+    ],
     [] = run2(Config, Ts1),
     ok.
 
diff --git a/lib/compiler/test/map_SUITE.erl b/lib/compiler/test/map_SUITE.erl
index 403b7e8405..75efce9d7b 100644
--- a/lib/compiler/test/map_SUITE.erl
+++ b/lib/compiler/test/map_SUITE.erl
@@ -21,6 +21,7 @@
     ]).
 
 -export([
+	%% literals
 	t_build_and_match_literals/1,
 	t_update_literals/1,t_match_and_update_literals/1,
 	t_update_map_expressions/1,
@@ -32,6 +33,15 @@
 	t_map_size/1,
 	t_build_and_match_aliasing/1,
 
+	%% variables
+	t_build_and_match_variables/1,
+	t_update_assoc_variables/1,t_update_exact_variables/1,
+	t_nested_pattern_expressions/1,
+	t_guard_update_variables/1,
+	t_guard_sequence_variables/1,
+	t_guard_sequence_mixed/1,
+	t_frequency_table/1,
+
 	%% warnings
 	t_warn_useless_build/1,
 	t_warn_pair_key_overloaded/1,
@@ -52,6 +62,7 @@
 suite() -> [].
 
 all() -> [
+	%% literals
 	t_build_and_match_literals,
 	t_update_literals, t_match_and_update_literals,
 	t_update_map_expressions,
@@ -62,6 +73,15 @@ all() -> [
 	t_map_size,
 	t_build_and_match_aliasing,
 
+	%% variables
+	t_build_and_match_variables,
+	t_update_assoc_variables,t_update_exact_variables,
+	t_nested_pattern_expressions,
+	t_guard_update_variables,
+	t_guard_sequence_variables,
+	t_guard_sequence_mixed,
+	t_frequency_table,
+
 	%% warnings
 	t_warn_useless_build,
 	t_warn_pair_key_overloaded,
@@ -73,6 +93,7 @@ all() -> [
 	t_build_and_match_nil,
 	t_build_and_match_structure,
 
+
 	%% errors in 17.0-rc1
 	t_update_values,
         t_expand_map_update,
@@ -119,6 +140,11 @@ t_build_and_match_literals(Config) when is_list(Config) ->
 
     %% nil key
     #{[]:=ok,1:=2} = id(#{[]=>ok,1=>2}),
+    #{1:=2,[]:=ok,1:=2} = id(#{[]=>ok,1=>2}),
+
+    %% pseudo literals
+    #{ -3 := yep } = id(#{ -3 => yep }),
+    #{ <<0:358>> := "three" } = id(#{<<0:358>> =>"three"}),
 
     %% error case
     {'EXIT',{{badmatch,_},_}} = (catch (#{x:=3,x:=2} = id(#{x=>3}))),
@@ -126,10 +152,10 @@ t_build_and_match_literals(Config) when is_list(Config) ->
     {'EXIT',{{badmatch,_},_}} = (catch (#{x:=3} = id({a,b,c}))),
     {'EXIT',{{badmatch,_},_}} = (catch (#{x:=3} = id(#{y=>3}))),
     {'EXIT',{{badmatch,_},_}} = (catch (#{x:=3} = id(#{x=>"three"}))),
-    {'EXIT',{badarg,_}} = (catch id(#{<<0:258>> =>"three"})),
     {'EXIT',{{badmatch,_},_}} = (catch (#{#{"a"=>42} := 3}=id(#{#{"a"=>3}=>42}))),
     ok.
 
+
 t_build_and_match_aliasing(Config) when is_list(Config) ->
     M1 = id(#{a=>1,b=>2,c=>3,d=>4}),
     #{c:=C1=_=_=C2} = M1,
@@ -143,6 +169,19 @@ t_build_and_match_aliasing(Config) when is_list(Config) ->
     M2 = id(#{"a"=>1,"b"=>2,"c"=>3,"d"=>4}),
     #{"a":=A2,"a":=A2,"a":=A2,"b":=B2,"b":=B2,"b":=2} = M2,
     #{"a":=_,"a":=_,"a":=_,"b":=_,"b":=_,"b":=2} = M2,
+
+    #{a:=A1,a:=A1,a:=A1,b:=B1,b:=B1} = #{a:=A1,a:=A1,a:=A1,b:=B1,b:=B1,b:=2} = M1,
+    #{"a":=A3,"b":=B3} = #{"a":=A3,"a":=A3} = #{"b":=B3,"b":=2} = M2,
+
+    #{"a":=1,"b":=2,"c":=3,"d":=4} = #{"a":=A4,"b":=B4} = #{"a":=A4,"a":=A4} = #{"b":=B4,"d":=4} = M2,
+    #{"a":=A5,"b":=B5} = #{"a":=A5,"a":=A5} = #{"b":=B5,"d":=4} = #{"a":=1,"b":=2,"c":=3,"d":=4} = M2,
+    #{"a":=_,"b":=_} = #{"a":=_,"a":=_} = #{"b":=_,"d":=4} = #{"a":=1,"b":=2,"c":=3,"d":=4} = M2,
+
+    M3 = id(#{<<12:300>>=>1,<<13:300>>=>2}),
+    #{<<12:300>> := V1, <<13:300>> := V2} = #{<<13:300>> := V2, <<12:300>> := V1} = M3,
+    #{<<12:300>> := 1, <<13:300>> := 2} = #{<<13:300>> := _, <<12:300>> := _} = M3,
+    #{<<13:300>> := _, <<12:300>> := _} = #{<<12:300>> := 1, <<13:300>> := 2} = M3,
+
     ok.
 
 t_map_size(Config) when is_list(Config) ->
@@ -241,11 +280,14 @@ t_update_assoc(Config) when is_list(Config) ->
     #{1:=a,2:=b,3.0:=new,4:=d,5:=e} = M2,
     M2 = M0#{3.0:=wrong,3.0=>new},
 
+    % Can't handle directly yet
+    Bin = <<0:257>>,
+    #{ Bin := val } = id(M0#{<<0:257>> => val}), %% binary limitation
+
     %% Errors cases.
     BadMap = id(badmap),
     {'EXIT',{badarg,_}} = (catch BadMap#{nonexisting=>val}),
     {'EXIT',{badarg,_}} = (catch <<>>#{nonexisting=>val}),
-    {'EXIT',{badarg,_}} = (catch M0#{<<0:257>> => val}), %% limitation
     ok.
 
 t_update_exact(Config) when is_list(Config) ->
@@ -281,8 +323,10 @@ t_update_values(Config) when is_list(Config) ->
     V0 = id(1337),
     M0 = #{ a => 1, val => V0},
     V1 = get_val(M0),
-    M1 = M0#{ val := [V0,V1], "wazzup" => 42 },
+    M1 = id(M0#{ val := [V0,V1], "wazzup" => 42 }),
     [1337, {some_val, 1337}] = get_val(M1),
+    M2 = id(M1#{ <<42:333>> => 1337 }),
+    {bin_key,1337} = get_val(M2),
 
     N = 110,
     List = [{[I,1,2,3,I],{1,2,3,"wat",I}}|| I <- lists:seq(1,N)],
@@ -308,6 +352,7 @@ t_export(Config) when is_list(Config) ->
 
 check_val(#{val1:=V1, val2:=V2},V1,V2) -> ok.
 
+get_val(#{ <<42:333>> := V }) -> {bin_key, V};
 get_val(#{ "wazzup" := _, val := V}) -> V;
 get_val(#{ val := V }) -> {some_val, V}.
 
@@ -437,7 +482,10 @@ guard_receive_loop() ->
 
 
 t_list_comprehension(Config) when is_list(Config) ->
-    [#{k:=1},#{k:=2},#{k:=3}] = [#{k=>I} || I <- [1,2,3]],
+    [#{k:=1},#{k:=2},#{k:=3}] = id([#{k=>I} || I <- [1,2,3]]),
+    Ls = id([#{<<2:301>> => I, "wat" => I + 1} || I <- [1,2,3]]),
+    [#{<<2:301>>:=1,"wat":=2},#{<<2:301>>:=2,"wat":=3},#{<<2:301>>:=3,"wat":=4}] = Ls,
+    [{1,2},{2,3},{3,4}] = id([{I2,I1} || #{"wat" := I1, <<2:301>> := I2} <- Ls]),
     ok.
 
 t_guard_fun(Config) when is_list(Config) ->
@@ -601,5 +649,325 @@ t_build_and_match_structure(Config) when is_list(Config) ->
     end,
     ok.
 
+%% simple build and match variables
+t_build_and_match_variables(Config) when is_list(Config) ->
+    K0 = id(#{}),
+    K1 = id(1),       V1 = id(a),
+    K2 = id(2),       V2 = id(b),
+    K3 = id(3),       V3 = id("c"),
+    K4 = id("4"),     V4 = id("d"),
+    K5 = id(<<"5">>), V5 = id(<<"e">>),
+    K6 = id({"6",7}), V6 = id("f"),
+    K7 = id(#{ "a" => 3 }),
+    #{K1:=V1} = id(#{K1=>V1}),
+    #{K1:=V1,K2:=V2} = id(#{K1=>V1,K2=>V2}),
+    #{K1:=V1,K2:=V2,K3:=V3} = id(#{K1=>V1,K2=>V2,K3=>V3}),
+    #{K1:=V1,K2:=V2,K3:=V3,K4:=V4} = id(#{K1=>V1,K2=>V2,K3=>V3,K4=>V4}),
+    #{K1:=V1,K2:=V2,K3:=V3,K4:=V4,K5:=V5} = id(#{K1=>V1,K2=>V2,K3=>V3,K4=>V4,K5=>V5}),
+    #{K1:=V1,K2:=V2,K3:=V3,K4:=V4,K5:=V5,K6:=V6} = id(#{K1=>V1,K2=>V2,K3=>V3,K4=>V4,K5=>V5,K6=>V6}),
+
+    #{K5:=X,K5:=X=3,K4:=4} = id(#{K5=>3,K4=>4}),
+    #{K5:=X,<<"5">>:=X=3,K4:=4} = id(#{K5=>3,K4=>4}),
+    #{K5:=X,<<"5">>:=X=3,K4:=4} = id(#{<<"5">>=>3,K4=>4}),
+
+    #{ K4:=#{ K3:=#{K1:=V1, K2:=V2}}, K5:=V5} =
+	id(#{ K5=>V5, K4=>#{ K3=>#{K2 => V2, K1 => V1}}}),
+    #{ K4 := #{ K5 := Res }, K6 := Res} = id(#{K4=>#{K5 => 99}, K6 => 99}),
+
+    %% has keys
+    #{a :=_,b :=_,K1:=_,K2:=_,K3:=V3,K4:=ResKey,K4:=ResKey,"4":=ResKey,"4":="ok"} =
+	id(#{ a=>1, b=>1, K1=>V1, K2=>V2, K3=>V3, K4=>"nope", "4"=>"ok" }),
+
+    %% function
+    ok = match_function_map_neg_keys(#{ -1 => a, -2 => b, -3 => c }),
+
+    %% map key
+    #{ K0 := 42 } = id(#{ K0 => 42 }),
+    #{ K7 := 42 } = id(#{ K7 => 42 }),
+
+    %% nil key
+    KNIL = id([]),
+    #{KNIL:=ok,1:=2} = id(#{KNIL=>ok,1=>2}),
+
+    Bin = <<0:258>>,
+    #{ Bin := "three" } = id(#{<<0:258>> =>"three"}),
+
+    %% error case
+    {'EXIT',{{badmatch,_},_}} = (catch (#{K5:=3,x:=2} = id(#{K5=>3}))),
+    {'EXIT',{{badmatch,_},_}} = (catch (#{K5:=2} = id(#{K5=>3}))),
+    {'EXIT',{{badmatch,_},_}} = (catch (#{K5:=3} = id({a,b,c}))),
+    {'EXIT',{{badmatch,_},_}} = (catch (#{K5:=3} = id(#{K6=>3}))),
+    {'EXIT',{{badmatch,_},_}} = (catch (#{K5:=3} = id(K7))),
+    {'EXIT',{{badmatch,_},_}} = (catch (#{K7:=3} = id(#{K7=>42}))),
+    ok.
+
+
+match_function_map_neg_keys(#{ -1 := a, -2 := b, -3 := c }) -> ok.
+
+t_update_assoc_variables(Config) when is_list(Config) ->
+    K1 = id(1),
+    K2 = id(2),
+    K3 = id(3.0),
+    K4 = id(4),
+    K5 = id(5),
+    K6 = id(2.0),
+
+    M0 = #{K1=>a,K2=>b,K3=>c,K4=>d,K5=>e},
+
+    M1 = M0#{K1=>42,K2=>100,K4=>[a,b,c]},
+    #{1:=42,2:=100,3.0:=c,4:=[a,b,c],5:=e} = M1,
+    #{1:=42,2:=b,4:=d,5:=e,2.0:=100,K3:=c,4.0:=[a,b,c]} = M0#{1.0=>float,1:=42,2.0=>wrong,K6=>100,4.0=>[a,b,c]},
+
+    M2 = M0#{K3=>new},
+    #{1:=a,2:=b,K3:=new,4:=d,5:=e} = M2,
+    M2 = M0#{3.0:=wrong,K3=>new},
+
+    #{ <<0:258>> := val } = id(M0#{<<0:258>> => val}), %% binary limitation
+
+    %% Errors cases.
+    BadMap = id(badmap),
+    {'EXIT',{badarg,_}} = (catch BadMap#{nonexisting=>val}),
+    {'EXIT',{badarg,_}} = (catch <<>>#{nonexisting=>val}),
+    ok.
+
+t_update_exact_variables(Config) when is_list(Config) ->
+    K1 = id(1),
+    K2 = id(2),
+    K3 = id(3.0),
+    K4 = id(4),
+
+    M0 = id(#{1=>a,2=>b,3.0=>c,4=>d,5=>e}),
+
+    M1 = M0#{K1:=42,K2:=100,K4:=[a,b,c]},
+    #{1:=42,2:=100,3.0:=c,K4:=[a,b,c],5:=e} = M1,
+    M1 = M0#{K1:=wrong,1:=also_wrong,K1=>42,2=>wrong,K2:=100,4:=[a,b,c]},
+
+    M2 = M0#{K3:=new},
+    #{1:=a,K2:=b,3.0:=new,K4:=d,5:=e} = M2,
+    M2 = M0#{3.0=>wrong,K3:=new},
+    true = M2 =/= M0#{3=>right,3.0:=new},
+    #{ 3 := right, 3.0 := new } = M0#{3=>right,K3:=new},
+
+    M3 = id(#{ 1 => val}),
+    #{1 := update2,1.0 := new_val4} = M3#{
+	1.0 => new_val1, K1 := update, K1=> update3,
+	K1 := update2, 1.0 := new_val2, 1.0 => new_val3,
+	1.0 => new_val4 },
+
+    #{ "wat" := 3, 2 := a } = id(#{ "wat" => 1, K2 => 2 }#{ K2 := a, "wat" := 3 }),
+
+    %% Errors cases.
+    {'EXIT',{badarg,_}} = (catch ((id(nil))#{ a := b })),
+    {'EXIT',{badarg,_}} = (catch M0#{nonexisting:=val}),
+    {'EXIT',{badarg,_}} = (catch M0#{1.0:=v,1.0=>v2}),
+    {'EXIT',{badarg,_}} = (catch M0#{42.0:=v,42:=v2}),
+    {'EXIT',{badarg,_}} = (catch M0#{42=>v1,42.0:=v2,42:=v3}),
+    {'EXIT',{badarg,_}} = (catch <<>>#{nonexisting:=val}),
+    {'EXIT',{badarg,_}} = (catch M0#{<<0:257>> := val}), %% limitation
+    ok.
+
+t_nested_pattern_expressions(Config) when is_list(Config) ->
+    K1 = id("hello"),
+    %K2 = id({ok}),
+    [_,_,#{ <<"hi">> := wat, K1 := 42 }|_] = id([k,k,#{<<"hi">> => wat, K1 => 42}]),
+    [_,_,#{ -1 := wat, K1 := 42 }|_] = id([k,k,#{-1 => wat, K1 => 42}]),
+    [_,_,{#{ -1 := #{ {-3,<<0:300>>} := V1 }, K1 := 42 },3}|_] = id([k,k,{#{-1 => #{{-3,<<0:300>>}=>"hi"}, K1 => 42},3}]),
+    "hi" = V1,
+    %[k,#{ {-1,K1,[]} := {wat,K1}, K2 := 42 }|_] = id([k,#{{-1,K1,[]} => {wat,K1}, K2 => 42}]),
+    %[k,#{ [-1,K2,[]] := {wat,K1}, K1 := 42 }|_] = id([k,#{[-1,K2,[]] => {wat,K1}, K1 => 42}]),
+
+    M0 = id(#{ <<33:333>> => 1, <<332:333>> => ok, a => ok, wat => yep, watzor => ok }),
+    F0 = map_nested_pattern_funs(M0),
+    F1 = F0(wat),
+    F2 = F1(watzor),
+    {yep,ok} = F2(M0),
+    ok.
+
+map_nested_pattern_funs(M) ->
+    K0 = id(a),
+    fun(K1) ->
+	    case M of
+		#{ K0 := ok, K1 := yep, <<33:333>> := 1 } ->
+		    fun(K2) ->
+			    case M of
+				#{ K2 := ok, K1 := yep, <<33:333>> := 1 } ->
+				    fun
+					(#{ <<332:333>> := ok, K1 := V1, K2 := V2 }) ->
+					    {V1,V2}
+				    end
+			    end
+		    end
+	    end
+    end.
+
+t_guard_update_variables(Config) when is_list(Config) ->
+    error  = map_guard_update_variables(n,#{},#{}),
+    first  = map_guard_update_variables(x,#{}, #{x=>first}),
+    second = map_guard_update_variables(x,#{y=>old}, #{x=>second,y=>old}),
+    third  = map_guard_update_variables(x,#{x=>old,y=>old}, #{x=>third,y=>old}),
+    fourth = map_guard_update_variables(x,#{x=>old,y=>old}, #{x=>4,y=>new}),
+    ok.
+
+map_guard_update_variables(K,M1,M2) when M1#{K=>first}    =:= M2 -> first;
+map_guard_update_variables(K,M1,M2) when M1#{K=>second}   =:= M2 -> second;
+map_guard_update_variables(K,M1,M2) when M1#{K:=third}    =:= M2 -> third;
+map_guard_update_variables(K,M1,M2) when M1#{K:=4,y=>new} =:= M2 -> fourth;
+map_guard_update_variables(_,_,_) -> error.
+
+t_guard_sequence_variables(Config) when is_list(Config) ->
+    {1,"a"} = map_guard_sequence_var_1(a,#{seq=>1,a=>id("a"),b=>no}),
+    {2,"b"} = map_guard_sequence_var_1(b,#{seq=>2,b=>id("b"),a=>no}),
+    {3,"c"} = map_guard_sequence_var_1(a,#{seq=>3,a=>id("c"),b=>no}),
+    {4,"d"} = map_guard_sequence_var_1(b,#{seq=>4,b=>id("d"),a=>no}),
+    {4,4}   = map_guard_sequence_var_1(seq,#{seq=>4}),
+    {4,4,y} = map_guard_sequence_var_1(seq,#{seq=>4,b=>id("d"),a=>y}),
+    {5,"d"} = map_guard_sequence_var_1(b,#{seq=>5,b=>id("d"),a=>y}),
+
+    %% error case
+    {'EXIT',{{case_clause,_},_}} = (catch map_guard_sequence_var_1("a",#{seq=>4,val=>id("e")})),
+    ok.
+
+
+map_guard_sequence_var_1(K,M) ->
+    case M of
+	#{seq:=1=Seq, K:=Val} -> {Seq,Val};
+	#{seq:=2=Seq, K:=Val} -> {Seq,Val};
+	#{seq:=3=Seq, K:=Val} -> {Seq,Val};
+	#{K:=4=Seq,   K:=Val1,a:=Val2} -> {Seq,Val1,Val2};
+	#{seq:=4=Seq, K:=Val} -> {Seq,Val};
+	#{K:=4=Seq,   K:=Val} -> {Seq,Val};
+	#{seq:=5=Seq, K:=Val} -> {Seq,Val}
+    end.
+
+
+t_guard_sequence_mixed(Config) when is_list(Config) ->
+    M0 = id(#{ a=>1, b=>1, c=>1, d=>1, e=>1, f=>1, g=>1, h=>1 }),
+    M1 = id(M0#{ d := 3 }),
+    1 = map_guard_sequence_mixed(a,d,M1),
+    M2 = id(M1#{ b := 2, d := 4, h := 2 }),
+    2 = map_guard_sequence_mixed(a,d,M2),
+    M3 = id(M2#{ b := 3, e := 5, g := 3 }),
+    3 = map_guard_sequence_mixed(a,e,M3),
+    M4 = id(M3#{ c := 4, e := 6, h := 1 }),
+    4 = map_guard_sequence_mixed(a,e,M4),
+    M5 = id(M4#{ c := 5, f := 7, g := 2 }),
+    5 = map_guard_sequence_mixed(a,f,M5),
+    M6 = id(M5#{ c := 6, f := 8, h := 3 }),
+    6 = map_guard_sequence_mixed(a,f,M6),
+
+    %% error case
+    {'EXIT',{{case_clause,_},_}} = (catch map_guard_sequence_mixed(a,b,M0)),
+    ok.
+
+map_guard_sequence_mixed(K1,K2,M) ->
+    case M of
+	#{ K1 := 1, b := 1, K2 := 3, g := 1} -> 1;
+	#{ K1 := 1, b := 2, K2 := 4, h := 2} -> 2;
+	#{ K1 := 1, b := 3, K2 := 5, g := 3} -> 3;
+	#{ K1 := 1, c := 4, K2 := 6, h := 1} -> 4;
+	#{ K1 := 1, c := 5, K2 := 7, g := 2} -> 5;
+	#{ K1 := 1, c := 6, K2 := 8, h := 3} -> 6
+    end.
+
+
+
+t_frequency_table(Config) when is_list(Config) ->
+    random:seed({13,1337,54}),  % pseudo random
+    N = 100000,
+    Ts = rand_terms(N),
+    #{ n:=N, tf := Tf } = frequency_table(Ts,#{ n=>0, tf => #{}}),
+    ok = check_frequency(Ts,Tf),
+    ok.
+
+
+frequency_table([T|Ts], M) ->
+    case M of
+	#{ n := N, tf := #{ T := C } = F } ->
+	    frequency_table(Ts,M#{ n := N + 1, tf := F#{ T := C + 1 }});
+	#{ n := N, tf := F } ->
+	    frequency_table(Ts,M#{ n := N + 1, tf := F#{ T => 1 }})
+    end;
+frequency_table([], M) -> M.
+
+
+check_frequency(Ts,Tf) ->
+    check_frequency(Ts,Tf,dict:new()).
+
+check_frequency([T|Ts],Tf,D) ->
+    case dict:find(T,D) of
+	error  -> check_frequency(Ts,Tf,dict:store(T,1,D));
+	{ok,C} -> check_frequency(Ts,Tf,dict:store(T,C+1,D))
+    end;
+check_frequency([],Tf,D) ->
+    validate_frequency(dict:to_list(D),Tf).
+
+validate_frequency([{T,C}|Fs],Tf) ->
+    case Tf of
+	#{ T := C } -> validate_frequency(Fs,Tf);
+	_ -> error
+    end;
+validate_frequency([], _) -> ok.
+
+
+%% aux
+
+rand_terms(0) -> [];
+rand_terms(N) -> [rand_term()|rand_terms(N-1)].
+
+rand_term() ->
+    case random:uniform(6) of
+	1 -> rand_binary();
+	2 -> rand_number();
+	3 -> rand_atom();
+	4 -> rand_tuple();
+	5 -> rand_list();
+	6 -> rand_map()
+    end.
+
+rand_binary() ->
+    case random:uniform(3) of
+	1 -> <<>>;
+	2 -> <<"hi">>;
+	3 -> <<"message text larger than 64 bytes. yep, message text larger than 64 bytes.">>
+    end.
+
+rand_number() ->
+    case random:uniform(3) of
+	1 -> random:uniform(5);
+	2 -> float(random:uniform(5));
+	3 -> 1 bsl (63 + random:uniform(3))
+    end.
+
+rand_atom() ->
+    case random:uniform(3) of
+	1 -> hi;
+	2 -> some_atom;
+	3 -> some_other_atom
+    end.
+
+
+rand_tuple() ->
+    case random:uniform(3) of
+	1 -> {ok, rand_term()}; % careful
+	2 -> {1, 2, 3};
+	3 -> {<<"yep">>, 1337}
+    end.
+
+rand_list() ->
+    case random:uniform(3) of
+	1 -> "hi";
+	2 -> [1,rand_term()]; % careful
+	3 -> [improper|list]
+    end.
+
+rand_map() ->
+    case random:uniform(3) of
+	1 -> #{ hi => 3 };
+	2 -> #{ wat => rand_term(), other => 3 };  % careful
+	3 -> #{ hi => 42, other => 42, yet_anoter => 1337 }
+    end.
+
+
+
 %% Use this function to avoid compile-time evaluation of an expression.
 id(I) -> I.
diff --git a/lib/compiler/test/warnings_SUITE.erl b/lib/compiler/test/warnings_SUITE.erl
index 0637041873..be0348a92d 100644
--- a/lib/compiler/test/warnings_SUITE.erl
+++ b/lib/compiler/test/warnings_SUITE.erl
@@ -601,7 +601,7 @@ maps(Config) when is_list(Config) ->
            ">>,
            [],
 	   {warnings,[{3,v3_core,bad_map}]}},
-	   {bad_map_literal_key,
+	   {ok_map_literal_key,
            <<"
              t() ->
 		 V = id(1),
@@ -614,7 +614,7 @@ maps(Config) when is_list(Config) ->
 	     id(I) -> I.
            ">>,
            [],
-	   {warnings,[{6,v3_core,nomatch}]}}],
+	   []}],
     run(Config, Ts),
     ok.