Properly sort map pairs in v3_codegen

Literal nil values aren't tagged tuple but the bare atom nil.

The function lists:sort/2 expects the passed function to return true if the first
element is less than or equal to the second, not strictly less than. The original
base clause is changed accordingly.

Reported-by: Ulf Norell

2 files changed, 8 insertions, 1 deletions

diff --git a/lib/compiler/src/v3_codegen.erl b/lib/compiler/src/v3_codegen.erl
index e00ee1f3ad..f1331d1fe7 100644
--- a/lib/compiler/src/v3_codegen.erl
+++ b/lib/compiler/src/v3_codegen.erl
@@ -1551,7 +1551,11 @@ map_pair_strip_and_termsort(Es) ->
     %%    [{map_pair,K,V}]
     %% where K is for example {integer, 1} and we want to sort on 1.
     Ls = [{K,V}||{_,K,V}<-Es],
-    lists:sort(fun({{_,A},_},{{_,B},_}) -> erts_internal:cmp_term(A,B) < 0 end, Ls).
+    lists:sort(fun ({{_,A},_}, {{_,B},_}) -> erts_internal:cmp_term(A,B) =< 0;
+                   ({nil,_},   {{_,B},_}) -> [] =< B;
+                   ({{_,A},_}, {nil,_})   -> A =< [];
+                   ({nil,_},   {nil,_})   -> true
+               end, Ls).
 
 %%%
 %%% Code generation for constructing binaries.
diff --git a/lib/compiler/test/map_SUITE.erl b/lib/compiler/test/map_SUITE.erl
index b4baef461b..23c47ca5f4 100644
--- a/lib/compiler/test/map_SUITE.erl
+++ b/lib/compiler/test/map_SUITE.erl
@@ -105,6 +105,9 @@ t_build_and_match_literals(Config) when is_list(Config) ->
     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}),
 
+    %% nil key
+    #{[]:=ok,1:=2} = id(#{[]=>ok,1=>2}),
+
     %% error case
     {'EXIT',{{badmatch,_},_}} = (catch (#{x:=3,x:=2} = id(#{x=>3}))),
     {'EXIT',{{badmatch,_},_}} = (catch (#{x:=2} = id(#{x=>3}))),