path: root/lib/compiler/test/map_SUITE.erl

%% %CopyrightBegin%
%% 
%% Copyright Ericsson AB 2013. All Rights Reserved.
%% 
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%% 
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%% 
%% %CopyrightEnd%
%%
-module(map_SUITE).
-export([all/0, suite/0,groups/0,init_per_suite/1, end_per_suite/1, 
	init_per_group/2,end_per_group/2
    ]).

-export([
	t_build_and_match_literals/1,
	t_update_literals/1,t_match_and_update_literals/1,
	t_update_map_expressions/1,
	t_update_assoc/1,t_update_exact/1,
	t_guard_bifs/1, t_guard_sequence/1, t_guard_update/1,
	t_guard_receive/1, t_guard_fun/1,
	t_list_comprehension/1,
	t_map_sort_literals/1,
	t_map_size/1,
	t_build_and_match_aliasing/1,

	%% warnings
	t_warn_useless_build/1,
	t_warn_pair_key_overloaded/1,

	%% not covered in 17.0-rc1
	t_build_and_match_over_alloc/1,
	t_build_and_match_empty_val/1,
	t_build_and_match_val/1,

	%% errors in 17.0-rc1
	t_update_values/1
    ]).

suite() -> [].

all() -> [
	t_build_and_match_literals,
	t_update_literals, t_match_and_update_literals,
	t_update_map_expressions,
	t_update_assoc,t_update_exact,
	t_guard_bifs, t_guard_sequence, t_guard_update,
	t_guard_receive,t_guard_fun, t_list_comprehension,
	t_map_sort_literals,
	t_map_size,
	t_build_and_match_aliasing,

	%% warnings
	t_warn_useless_build,
	t_warn_pair_key_overloaded,

	%% not covered in 17.0-rc1
	t_build_and_match_over_alloc,
	t_build_and_match_empty_val,
	t_build_and_match_val,

	%% errors in 17.0-rc1
	t_update_values
    ].

groups() -> [].

init_per_suite(Config) -> Config.
end_per_suite(_Config) -> ok.

init_per_group(_GroupName, Config) -> Config.
end_per_group(_GroupName, Config) -> Config.

%% tests

t_build_and_match_literals(Config) when is_list(Config) ->
    #{} = id(#{}),
    #{1:=a} = id(#{1=>a}),
    #{1:=a,2:=b} = id(#{1=>a,2=>b}),
    #{1:=a,2:=b,3:="c"} = id(#{1=>a,2=>b,3=>"c"}),
    #{1:=a,2:=b,3:="c","4":="d"} = id(#{1=>a,2=>b,3=>"c","4"=>"d"}),
    #{1:=a,2:=b,3:="c","4":="d",<<"5">>:=<<"e">>} =
	id(#{1=>a,2=>b,3=>"c","4"=>"d",<<"5">>=><<"e">>}),
    #{1:=a,2:=b,3:="c","4":="d",<<"5">>:=<<"e">>,{"6",7}:="f"} =
	id(#{1=>a,2=>b,3=>"c","4"=>"d",<<"5">>=><<"e">>,{"6",7}=>"f"}),
    #{1:=a,2:=b,3:="c","4":="d",<<"5">>:=<<"e">>,{"6",7}:="f",8:=g} =
	id(#{1=>a,2=>b,3=>"c","4"=>"d",<<"5">>=><<"e">>,{"6",7}=>"f",8=>g}),

    #{<<"hi all">> := 1} = id(#{<<"hi",32,"all">> => 1}),

    #{a:=X,a:=X=3,b:=4} = id(#{a=>3,b=>4}), % weird but ok =)

    #{ a:=#{ b:=#{c := third, b:=second}}, b:=first} =
	id(#{ b=>first, a=>#{ b=>#{c => third, b=> second}}}),

    M = #{ map_1=>#{ map_2=>#{value_3 => third}, value_2=> second}, value_1=>first},
    M = #{ map_1:=#{ map_2:=#{value_3 := third}, value_2:= second}, value_1:=first} =
	 id(#{ map_1=>#{ map_2=>#{value_3 => third}, value_2=> second}, value_1=>first}),

    %% error case
    %V = 32,
    %{'EXIT',{{badmatch,_},_}} = (catch (#{<<"hi all">> => 1} = id(#{<<"hi",V,"all">> => 1}))),
    {'EXIT',{{badmatch,_},_}} = (catch (#{x:=3,x:=2} = id(#{x=>3}))),
    {'EXIT',{{badmatch,_},_}} = (catch (#{x:=2} = id(#{x=>3}))),
    {'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"}))),
    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,
    true = C1 =:= C2,
    #{a:=A,a:=A,a:=A,b:=B,b:=B} = M1,
    #{a:=A,a:=A,a:=A,b:=B,b:=B,b:=2} = M1,
    #{a:=A=1,a:=A,a:=A,b:=B=2,b:=B,b:=2} = M1,
    #{c:=C1, c:=_, c:=3, c:=_, c:=C2} = M1,
    #{c:=C=_=3=_=C} = M1,

    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,
    ok.

t_map_size(Config) when is_list(Config) ->
    0 = map_size(id(#{})),
    1 = map_size(id(#{a=>1})),
    1 = map_size(id(#{a=>"wat"})),
    2 = map_size(id(#{a=>1, b=>2})),
    3 = map_size(id(#{a=>1, b=>2, b=>"3","33"=><<"n">>})),

    true = map_is_size(#{a=>1}, 1),
    true = map_is_size(#{a=>1, a=>2}, 1),
    M = #{ "a" => 1, "b" => 2},
    true  = map_is_size(M, 2),
    false = map_is_size(M, 3),
    true  = map_is_size(M#{ "a" => 2}, 2),
    false = map_is_size(M#{ "c" => 2}, 2),

    %% Error cases.
    {'EXIT',{badarg,_}} = (catch map_size([])),
    {'EXIT',{badarg,_}} = (catch map_size(<<1,2,3>>)),
    {'EXIT',{badarg,_}} = (catch map_size(1)),
    ok.

map_is_size(M,N) when map_size(M) =:= N -> true;
map_is_size(_,_) -> false.

% test map updates without matching
t_update_literals(Config) when is_list(Config) ->
    Map = #{x=>1,y=>2,z=>3,q=>4},
    #{x:="d",q:="4"} = loop_update_literals_x_q(Map, [
		{"a","1"},{"b","2"},{"c","3"},{"d","4"}
	]),
    ok.

loop_update_literals_x_q(Map, []) -> Map;
loop_update_literals_x_q(Map, [{X,Q}|Vs]) ->
    loop_update_literals_x_q(Map#{q=>Q,x=>X},Vs).

% test map updates with matching
t_match_and_update_literals(Config) when is_list(Config) ->
    Map = #{x=>0,y=>"untouched",z=>"also untouched",q=>1},
    #{x:=16,q:=21,y:="untouched",z:="also untouched"} = loop_match_and_update_literals_x_q(Map, [
	    {1,2},{3,4},{5,6},{7,8}
	]),
    M0 = id(#{ "hi" => "hello", int => 3, <<"key">> => <<"value">>,
	    4 => number, 18446744073709551629 => wat}),
    M1 = id(#{}),
    M2 = M1#{ "hi" => "hello", int => 3, <<"key">> => <<"value">>,
	4 => number, 18446744073709551629 => wat},
    M0 = M2,

    #{ 4 := another_number, int := 3 } = M2#{ 4 => another_number },
    ok.

loop_match_and_update_literals_x_q(Map, []) -> Map;
loop_match_and_update_literals_x_q(#{q:=Q0,x:=X0} = Map, [{X,Q}|Vs]) ->
    loop_match_and_update_literals_x_q(Map#{q=>Q0+Q,x=>X0+X},Vs).


t_update_map_expressions(Config) when is_list(Config) ->
    M = maps:new(),
    #{ a := 1 } = M#{a => 1},

    #{ b := 2 } = (maps:new())#{ b => 2 },

    #{ a :=42, b:=42, c:=42 } = (maps:from_list([{a,1},{b,2},{c,3}]))#{ a := 42, b := 42, c := 42 },
    #{ "a" :=1, "b":=42, "c":=42 } = (maps:from_list([{"a",1},{"b",2}]))#{ "b" := 42, "c" => 42 },

    %% Test need to be in a fun.
    %% This tests that let expr optimisation in sys_core_fold
    %% covers maps correctly.
    F = fun() ->
	    M0 = id(#{ "a" => [1,2,3] }),
	    #{ "a" := _ } = M0,
	    M0#{ "a" := b }
    end,

    #{ "a" := b } = F(),

    %% Error cases, FIXME: should be 'badmap'?
    {'EXIT',{badarg,_}} = (catch (id(<<>>))#{ a := 42, b => 2 }),
    {'EXIT',{badarg,_}} = (catch (id([]))#{ a := 42, b => 2 }),
    ok.


t_update_assoc(Config) when is_list(Config) ->
    M0 = id(#{1=>a,2=>b,3.0=>c,4=>d,5=>e}),

    M1 = M0#{1=>42,2=>100,4=>[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:=100,3.0:=c,4.0:=[a,b,c]} = M0#{1.0=>float,1:=42,2.0=>wrong,2.0=>100,4.0=>[a,b,c]},

    M2 = M0#{3.0=>new},
    #{1:=a,2:=b,3.0:=new,4:=d,5:=e} = M2,
    M2 = M0#{3.0:=wrong,3.0=>new},

    %% Errors cases.
    BadMap = id(badmap),
    {'EXIT',{badarg,_}} = (catch BadMap#{nonexisting=>val}),

    ok.

t_update_exact(Config) when is_list(Config) ->
    M0 = id(#{1=>a,2=>b,3.0=>c,4=>d,5=>e}),

    M1 = M0#{1:=42,2:=100,4:=[a,b,c]},
    #{1:=42,2:=100,3.0:=c,4:=[a,b,c],5:=e} = M1,
    M1 = M0#{1:=wrong,1=>42,2=>wrong,2:=100,4:=[a,b,c]},

    M2 = M0#{3.0:=new},
    #{1:=a,2:=b,3.0:=new,4:=d,5:=e} = M2,
    M2 = M0#{3.0=>wrong,3.0:=new},
    true = M2 =/= M0#{3=>right,3.0:=new},
    #{ 3 := right, 3.0 := new } = M0#{3=>right,3.0:=new},

    M3 = id(#{ 1 => val}),
    #{1 := update2,1.0 := new_val4} = M3#{
	1.0 => new_val1, 1 := update, 1=> update3,
	1 := update2, 1.0 := new_val2, 1.0 => new_val3,
	1.0 => new_val4 },

    %% 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}),
    ok.

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 },
    [1337, {some_val, 1337}] = get_val(M1),

    N = 110,
    List = [{[I,1,2,3,I],{1,2,3,"wat",I}}|| I <- lists:seq(1,N)],

    {_,_,#{val2 := {1,2,3,"wat",N}, val1 := [N,1,2,3,N]}} = lists:foldl(fun
	    ({V2,V3},{Old2,Old3,Mi}) ->
		ok = check_val(Mi,Old2,Old3),
		#{ val1 := Old2, val2 := Old3 } = Mi,
		{V2,V3, Mi#{ val1 := id(V2), val2 := V1, val2 => id(V3)}}
	end, {none, none, #{val1=>none,val2=>none}},List),
    ok.

check_val(#{val1:=V1, val2:=V2},V1,V2) -> ok.

get_val(#{ "wazzup" := _, val := V}) -> V;
get_val(#{ val := V }) -> {some_val, V}.

t_guard_bifs(Config) when is_list(Config) ->
    true   = map_guard_head(#{a=>1}),
    false  = map_guard_head([]),
    true   = map_guard_body(#{a=>1}),
    false  = map_guard_body({}),
    true   = map_guard_pattern(#{a=>1, <<"hi">> => "hi" }),
    false  = map_guard_pattern("list"),
    ok.

map_guard_head(M) when is_map(M) -> true;
map_guard_head(_) -> false.

map_guard_body(M) -> is_map(M).

map_guard_pattern(#{}) -> true;
map_guard_pattern(_)   -> false.

t_guard_sequence(Config) when is_list(Config) ->
	{1, "a"} = map_guard_sequence_1(#{seq=>1,val=>id("a")}),
	{2, "b"} = map_guard_sequence_1(#{seq=>2,val=>id("b")}),
	{3, "c"} = map_guard_sequence_1(#{seq=>3,val=>id("c")}),
	{4, "d"} = map_guard_sequence_1(#{seq=>4,val=>id("d")}),
	{5, "e"} = map_guard_sequence_1(#{seq=>5,val=>id("e")}),

	{1,M1}       = map_guard_sequence_2(M1 = id(#{a=>3})),
	{2,M2}       = map_guard_sequence_2(M2 = id(#{a=>4, b=>4})),
	{3,gg,M3}    = map_guard_sequence_2(M3 = id(#{a=>gg, b=>4})),
	{4,sc,sc,M4} = map_guard_sequence_2(M4 = id(#{a=>sc, b=>3, c=>sc2})),
	{5,kk,kk,M5} = map_guard_sequence_2(M5 = id(#{a=>kk, b=>other, c=>sc2})),
	
	%% error case
	{'EXIT',{function_clause,_}} = (catch map_guard_sequence_1(#{seq=>6,val=>id("e")})),
	{'EXIT',{function_clause,_}} = (catch map_guard_sequence_2(#{b=>5})),
	ok.

map_guard_sequence_1(#{seq:=1=Seq, val:=Val}) -> {Seq,Val};
map_guard_sequence_1(#{seq:=2=Seq, val:=Val}) -> {Seq,Val};
map_guard_sequence_1(#{seq:=3=Seq, val:=Val}) -> {Seq,Val};
map_guard_sequence_1(#{seq:=4=Seq, val:=Val}) -> {Seq,Val};
map_guard_sequence_1(#{seq:=5=Seq, val:=Val}) -> {Seq,Val}.

map_guard_sequence_2(#{ a:=3 }=M) -> {1, M};
map_guard_sequence_2(#{ a:=4 }=M) -> {2, M};
map_guard_sequence_2(#{ a:=X, a:=X, b:=4 }=M) -> {3,X,M};
map_guard_sequence_2(#{ a:=X, a:=Y, b:=3 }=M) when X =:= Y -> {4,X,Y,M};
map_guard_sequence_2(#{ a:=X, a:=Y }=M) when X =:= Y -> {5,X,Y,M}.


t_guard_update(Config) when is_list(Config) ->
    error  = map_guard_update(#{},#{}),
    first  = map_guard_update(#{}, #{x=>first}),
    second = map_guard_update(#{y=>old}, #{x=>second,y=>old}),
    third  = map_guard_update(#{x=>old,y=>old}, #{x=>third,y=>old}),
    ok.

map_guard_update(M1, M2) when M1#{x=>first}  =:= M2 -> first;
map_guard_update(M1, M2) when M1#{x=>second} =:= M2 -> second;
map_guard_update(M1, M2) when M1#{x:=third}  =:= M2 -> third;
map_guard_update(_, _) -> error.

t_guard_receive(Config) when is_list(Config) ->
    M0  = #{ id => 0 },
    Pid = spawn_link(fun() -> guard_receive_loop() end),
    Big = 36893488147419103229,
    B1  = <<"some text">>,
    B2  = <<"was appended">>,
    B3  = <<B1/binary, B2/binary>>,

    #{id:=1, res:=Big} = M1 = call(Pid, M0#{op=>sub,in=>{1 bsl 65, 3}}),
    #{id:=2, res:=26}  = M2 = call(Pid, M1#{op=>idiv,in=>{53,2}}),
    #{id:=3, res:=832} = M3 = call(Pid, M2#{op=>imul,in=>{26,32}}),
    #{id:=4, res:=4}   = M4 = call(Pid, M3#{op=>add,in=>{1,3}}),
    #{id:=5, res:=Big} = M5 = call(Pid, M4#{op=>sub,in=>{1 bsl 65, 3}}),
    #{id:=6, res:=B3}  = M6 = call(Pid, M5#{op=>"append",in=>{B1,B2}}),
    #{id:=7, res:=4}   = _  = call(Pid, M6#{op=>add,in=>{1,3}}),


    %% update old maps and check id update
    #{id:=2, res:=B3} = call(Pid, M1#{op=>"append",in=>{B1,B2}}),
    #{id:=5, res:=99} = call(Pid, M4#{op=>add,in=>{33, 66}}),

    %% cleanup
    done = call(Pid, done),
    ok.

call(Pid, M) ->
    Pid ! {self(), M}, receive {Pid, Res} -> Res end.

guard_receive_loop() ->
    receive
	{Pid, #{ id:=Id, op:="append", in:={X,Y}}=M} when is_binary(X), is_binary(Y) ->
	    Pid ! {self(), M#{ id=>Id+1, res=><<X/binary,Y/binary>>}},
	    guard_receive_loop();
	{Pid, #{ id:=Id, op:=add, in:={X,Y}}} ->
	    Pid ! {self(), #{ id=>Id+1, res=>X+Y}},
	    guard_receive_loop();
	{Pid, #{ id:=Id, op:=sub,  in:={X,Y}}=M} ->
	    Pid ! {self(), M#{ id=>Id+1, res=>X-Y}},
	    guard_receive_loop();
	{Pid, #{ id:=Id, op:=idiv, in:={X,Y}}=M} ->
	    Pid ! {self(), M#{ id=>Id+1, res=>X div Y}},
	    guard_receive_loop();
	{Pid, #{ id:=Id, op:=imul, in:={X,Y}}=M} ->
	    Pid ! {self(), M#{ id=>Id+1, res=>X * Y}},
	    guard_receive_loop();
	{Pid, done} ->
	    Pid ! {self(), done};
	{Pid, Other} ->
	    Pid ! {error, Other},
	    guard_receive_loop()
    end.


t_list_comprehension(Config) when is_list(Config) ->
    [#{k:=1},#{k:=2},#{k:=3}] = [#{k=>I} || I <- [1,2,3]],
    ok.

t_guard_fun(Config) when is_list(Config) ->
    F1 = fun
	    (#{s:=v,v:=V})     -> {v,V};
	    (#{s:=t,v:={V,V}}) -> {t,V};
	    (#{s:=l,v:=[V,V]}) -> {l,V}
    end,
    
    F2 = fun
	    (#{s:=T,v:={V,V}}) -> {T,V};
	    (#{s:=T,v:=[V,V]}) -> {T,V};
	    (#{s:=T,v:=V})     -> {T,V}
    end,
    V = <<"hi">>,

    {v,V} = F1(#{s=>v,v=>V}),
    {t,V} = F1(#{s=>t,v=>{V,V}}),
    {l,V} = F1(#{s=>l,v=>[V,V]}),

    {v,V} = F2(#{s=>v,v=>V}),
    {t,V} = F2(#{s=>t,v=>{V,V}}),
    {l,V} = F2(#{s=>l,v=>[V,V]}),

    %% error case
    {'EXIT', {function_clause,[{?MODULE,_,[#{s:=none,v:=none}],_}|_]}} = (catch F1(#{s=>none,v=>none})),
    ok.


t_map_sort_literals(Config) when is_list(Config) ->
    % test relation

    %% size order
    true  = #{ a => 1, b => 2} < id(#{ a => 1, b => 1, c => 1}),
    true  = #{ b => 1, a => 1} < id(#{ c => 1, a => 1, b => 1}),
    false = #{ c => 1, b => 1, a => 1} < id(#{ c => 1, a => 1}),

    %% key order
    true  = id(#{ a => 1 }) < id(#{ b => 1}),
    false = id(#{ b => 1 }) < id(#{ a => 1}),
    true  = id(#{ a => 1, b => 1, c => 1 }) < id(#{ b => 1, c => 1, d => 1}),
    true  = id(#{ b => 1, c => 1, d => 1 }) > id(#{ a => 1, b => 1, c => 1}),
    true  = id(#{ c => 1, b => 1, a => 1 }) < id(#{ b => 1, c => 1, d => 1}),
    true  = id(#{ "a" => 1 }) < id(#{ <<"a">> => 1}),
    false = id(#{ <<"a">> => 1 }) < id(#{ "a" => 1}),
    false = id(#{ 1 => 1 }) < id(#{ 1.0 => 1}),
    false = id(#{ 1.0 => 1 }) < id(#{ 1 => 1}),

    %% value order
    true  = id(#{ a => 1 }) < id(#{ a => 2}),
    false = id(#{ a => 2 }) < id(#{ a => 1}),
    false = id(#{ a => 2, b => 1 }) < id(#{ a => 1, b => 3}),
    true  = id(#{ a => 1, b => 1 }) < id(#{ a => 1, b => 3}),

    true  = id(#{ "a" => "hi", b => 134 }) == id(#{ b => 134,"a" => "hi"}),

    %% lists:sort

    SortVs = [#{"a"=>1},#{a=>2},#{1=>3},#{<<"a">>=>4}],
    [#{1:=ok},#{a:=ok},#{"a":=ok},#{<<"a">>:=ok}] = lists:sort([#{"a"=>ok},#{a=>ok},#{1=>ok},#{<<"a">>=>ok}]),
    [#{1:=3},#{a:=2},#{"a":=1},#{<<"a">>:=4}] = lists:sort(SortVs),
    [#{1:=3},#{a:=2},#{"a":=1},#{<<"a">>:=4}] = lists:sort(lists:reverse(SortVs)),

    ok.

t_warn_pair_key_overloaded(Config) when is_list(Config) ->
    #{ "hi1" := 42 } = id(#{ "hi1" => 1, "hi1" => 42 }),

    #{ "hi1" := 1337, "hi2" := [2], "hi3" := 3 } = id(#{
	    "hi1" => erlang:atom_to_binary(?MODULE,utf8),
	    "hi1" => erlang:binary_to_atom(<<"wazzup">>,utf8),
	    "hi1" => erlang:binary_to_float(<<"3.1416">>),
	    "hi1" => erlang:float_to_binary(3.1416),
	    "hi2" => erlang:pid_to_list(self()),
	    "hi3" => erlang:float_to_binary(3.1416),
	    "hi2" => lists:subtract([1,2],[1]),
	    "hi3" => +3,
	    "hi1" => erlang:min(1,2),
	    "hi1" => erlang:hash({1,2},35),
	    "hi1" => erlang:phash({1,2},33),
	    "hi1" => erlang:phash2({1,2},34),
	    "hi1" => erlang:integer_to_binary(1337),
	    "hi1" => erlang:binary_to_integer(<<"1337">>),
	    "hi4" => erlang:float_to_binary(3.1416)
	}),
    ok.

t_warn_useless_build(Config) when is_list(Config) ->
    [#{ a => id(I)} || I <- [1,2,3]],
    ok.

t_build_and_match_over_alloc(Config) when is_list(Config) ->
    Ls = id([1,2,3]),
    V0 = [a|Ls],
    M0 = id(#{ "a" => V0 }),
    #{ "a" := V1 } = M0,
    V2 = id([c|Ls]),
    M2 = id(#{ "a" => V2 }),
    #{ "a" := V3 } = M2,
    {[a,1,2,3],[c,1,2,3]} = id({V1,V3}),
    ok.

t_build_and_match_empty_val(Config) when is_list(Config) ->
    F = fun(#{ "hi":=_,{1,2}:=_,1337:=_}) -> ok end,
    ok = F(id(#{"hi"=>ok,{1,2}=>ok,1337=>ok})),

    %% error case
    {'EXIT',{function_clause,_}} = (catch (F(id(#{"hi"=>ok})))),
    ok.

t_build_and_match_val(Config) when is_list(Config) ->
    F = fun
	(#{ "hi" := first,  v := V}) -> {1,V};
	(#{ "hi" := second, v := V}) -> {2,V}
    end,


    {1,"hello"}  = F(id(#{"hi"=>first,v=>"hello"})),
    {2,"second"} = F(id(#{"hi"=>second,v=>"second"})),

    %% error case
    {'EXIT',{function_clause,_}} = (catch (F(id(#{"hi"=>ok})))),
    ok.


%% Use this function to avoid compile-time evaluation of an expression.
id(I) -> I.