Merge branch 'egil/compiler/maps-warn-repeated-keys/OTP-14058'

* egil/compiler/maps-warn-repeated-keys/OTP-14058:
  compiler: Test repeated map key warnings
  compiler: Warn for repeated identical map keys

2 files changed, 131 insertions, 8 deletions

diff --git a/lib/compiler/src/v3_core.erl b/lib/compiler/src/v3_core.erl
index f40cf97f57..14cd41ae27 100644
--- a/lib/compiler/src/v3_core.erl
+++ b/lib/compiler/src/v3_core.erl
@@ -883,19 +883,33 @@ badmap_term(Map, #core{in_guard=false}) ->
     c_tuple([#c_literal{val=badmap},Map]).
 
 map_build_pairs(Map, Es0, Ann, St0) ->
-    {Es,Pre,St1} = map_build_pairs_1(Es0, St0),
+    {Es,Pre,_,St1} = map_build_pairs_1(Es0, cerl_sets:new(), St0),
     {ann_c_map(Ann, Map, Es),Pre,St1}.
 
-map_build_pairs_1([{Op0,L,K0,V0}|Es], St0) ->
+map_build_pairs_1([{Op0,L,K0,V0}|Es], Used0, St0) ->
     {K,Pre0,St1} = safe(K0, St0),
     {V,Pre1,St2} = safe(V0, St1),
-    {Pairs,Pre2,St3} = map_build_pairs_1(Es, St2),
+    {Pairs,Pre2,Used1,St3} = map_build_pairs_1(Es, Used0, St2),
     As = lineno_anno(L, St3),
     Op = map_op(Op0),
+    {Used2,St4} = maybe_warn_repeated_keys(K, L, Used1, St3),
     Pair = cerl:ann_c_map_pair(As, Op, K, V),
-    {[Pair|Pairs],Pre0++Pre1++Pre2,St3};
-map_build_pairs_1([], St) ->
-    {[],[],St}.
+    {[Pair|Pairs],Pre0++Pre1++Pre2,Used2,St4};
+map_build_pairs_1([], Used, St) ->
+    {[],[],Used,St}.
+
+maybe_warn_repeated_keys(Ck,Line,Used,St) ->
+    case cerl:is_literal(Ck) of
+        false -> {Used,St};
+        true ->
+            K = cerl:concrete(Ck),
+            case cerl_sets:is_element(K,Used) of
+                true ->
+                    {Used, add_warning(Line, {map_key_repeated,K}, St)};
+                false ->
+                    {cerl_sets:add_element(K,Used), St}
+            end
+    end.
 
 map_op(map_field_assoc) -> #c_literal{val=assoc};
 map_op(map_field_exact) -> #c_literal{val=exact}.
@@ -2603,7 +2617,11 @@ format_error(nomatch) ->
 format_error(bad_binary) ->
     "binary construction will fail because of a type mismatch";
 format_error(badmap) ->
-    "map construction will fail because of a type mismatch".
+    "map construction will fail because of a type mismatch";
+format_error({map_key_repeated,Key}) when is_atom(Key) ->
+    io_lib:format("key '~w' will be overridden in expression", [Key]);
+format_error({map_key_repeated,Key}) ->
+    io_lib:format("key ~p will be overridden in expression", [Key]).
 
 add_warning(Anno, Term, #core{ws=Ws,file=[{file,File}]}=St) ->
     case erl_anno:generated(Anno) of
diff --git a/lib/compiler/test/warnings_SUITE.erl b/lib/compiler/test/warnings_SUITE.erl
index 72ead22191..7c27750556 100644
--- a/lib/compiler/test/warnings_SUITE.erl
+++ b/lib/compiler/test/warnings_SUITE.erl
@@ -628,7 +628,112 @@ maps(Config) when is_list(Config) ->
 	     id(I) -> I.
            ">>,
            [],
-	   []}],
+	   []},
+           {repeated_keys1,
+           <<"
+             foo1() ->
+                 #{a=>1,
+                   b=> 2,
+                   a=>3}.
+             
+             bar1(M) ->
+                 M#{a=>1, b=> 2, a:=3}.
+             
+             baz1(M) ->
+                 M#{a=>1, b=> 2, a:=3}.
+             
+             foo2() ->
+                 #{\"a\"=>1, \"b\"=> 2, \"a\"=>3}.
+             
+             bar2(M) ->
+                 M#{\"a\"=>1, \"b\"=> 2, \"a\":=3}.
+             
+             baz2(M) ->
+                 M#{\"a\"=>1, \"b\"=> 2, \"a\":=3}.
+             
+             foo3() ->
+                 #{\"a\"=>1,
+                   \"b\"=> 2,
+                   \"a\"=>3}.
+             
+             bar3(M) ->
+                 M#{\"a\"=>1, \"b\"=> 2, \"a\":=3}.
+             
+             baz3(M) ->
+                 M#{<<\"a\">>=>1, <<\"b\">>=> 2, <<\"a\">>:=3}.
+           ">>,
+           [],
+           {warnings,[{3,v3_core,{map_key_repeated,a}},
+                      {8,v3_core,{map_key_repeated,a}},
+                      {11,v3_core,{map_key_repeated,a}},
+                      {14,v3_core,{map_key_repeated,"a"}},
+                      {17,v3_core,{map_key_repeated,"a"}},
+                      {20,v3_core,{map_key_repeated,"a"}},
+                      {23,v3_core,{map_key_repeated,"a"}},
+                      {28,v3_core,{map_key_repeated,"a"}},
+                      {31,v3_core,{map_key_repeated,<<"a">>}}]}},
+           {repeated_keys2,
+           <<"
+             foo4(K) ->
+                 #{\"a\"=>1, K => 1, \"b\"=> 2, \"a\"=>3, K=>2}.
+             
+             bar4(M,K) ->
+                 M#{a=>1, K =>1, b=> 2, a:=3, K=>2}.
+             
+             baz4(M,K) ->
+                 M#{<<\"a\">>=>1,
+                     K => 1, <<\"b\">>=> 2,
+                     <<\"a\">>:=3, K=>2}.
+             
+             foo5(K) ->
+                 #{{\"a\",1}=>1, K => 1, \"b\"=> 2, {\"a\",1}=>3, K=>2}.
+             
+             bar5(M,K) ->
+                 M#{{\"a\",<<\"b\">>}=>1, K =>1,
+                    \"b\"=> 2, {\"a\",<<\"b\">>}:=3, K=>2}.
+             
+             baz5(M,K) ->
+                 M#{{<<\"a\">>,1}=>1, K => 1,
+                    <<\"b\">>=> 2, {<<\"a\">>,1}:=3,K=>2}.
+             
+             foo6(K) ->
+                 #{#{\"a\"=>1}=>1, K => 1, \"b\"=> 2, #{\"a\"=>1}=>3, K=>2}.
+             
+             bar6(M,K) ->
+                 M#{#{\"a\"=><<\"b\">>}=>1, K =>1,
+                    \"b\"=> 2, #{\"a\"=><<\"b\">>}:=3, K=>2}.
+             
+             baz6(M,K) ->
+                 M#{#{<<\"a\">>=>1}=>1,
+                    K => 1,
+                    <<\"b\">>=> 2,
+                    #{<<\"a\">>=>1}:=3,K=>2}.
+             
+             foo7(K) ->
+                 M1 = #{#{\"a\"=>1}=>1, K => 1, \"b\"=> 2},
+                 M1#{#{\"a\"=>1}=>3, K=>2}.
+             
+             bar7(M,K) ->
+                 M1 = M#{#{\"a\"=><<\"b\">>}=>1, K =>1, \"b\"=> 2},
+                 M1#{#{\"a\"=><<\"b\">>}:=3, K=>2}.
+             
+             baz7(M,K) ->
+                 M1 = M#{#{<<\"a\">>=>1}=>1,
+                    K => 1,
+                    <<\"b\">>=> 2},
+                 M1#{#{<<\"a\">>=>1}:=3,K=>2}.
+          ">>,
+           [],
+           {warnings,[{3,v3_core,{map_key_repeated,"a"}},
+                      {6,v3_core,{map_key_repeated,a}},
+                      {9,v3_core,{map_key_repeated,<<"a">>}},
+                      {14,v3_core,{map_key_repeated,{"a",1}}},
+                      {17,v3_core,{map_key_repeated,{"a",<<"b">>}}},
+                      {21,v3_core,{map_key_repeated,{<<"a">>,1}}},
+                      {25,v3_core,{map_key_repeated,#{"a" => 1}}},
+                      {28,v3_core,{map_key_repeated,#{"a" => <<"b">>}}},
+                      {32,v3_core,{map_key_repeated,#{<<"a">> => 1}}}]}}
+         ],
     run(Config, Ts),
     ok.