aboutsummaryrefslogtreecommitdiffstats
path: root/lib/compiler/test/map_SUITE.erl
diff options
context:
space:
mode:
Diffstat (limited to 'lib/compiler/test/map_SUITE.erl')
-rw-r--r--lib/compiler/test/map_SUITE.erl467
1 files changed, 467 insertions, 0 deletions
diff --git a/lib/compiler/test/map_SUITE.erl b/lib/compiler/test/map_SUITE.erl
new file mode 100644
index 0000000000..dc880a7a9d
--- /dev/null
+++ b/lib/compiler/test/map_SUITE.erl
@@ -0,0 +1,467 @@
+%% %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,
+
+ %% 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
+
+ ]).
+
+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,
+
+ %% 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
+
+ ].
+
+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_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 },
+
+ %% 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},
+ M2 = M0#{3=>wrong,3.0:=new},
+
+ %% 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_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.
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-05 09:52:50 +0000