From 6626b2a4ac67631bef3144bf9eca41b5f49c3176 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Thu, 12 Apr 2018 15:05:28 +0200
Subject: core_lint: Handle repeated variables in map patterns correctly

Keys in map patterns are input variables, not pattern variables.
---
 lib/compiler/test/map_SUITE.erl | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

(limited to 'lib/compiler/test/map_SUITE.erl')

diff --git a/lib/compiler/test/map_SUITE.erl b/lib/compiler/test/map_SUITE.erl
index f15917e3cb..3146c31c21 100644
--- a/lib/compiler/test/map_SUITE.erl
+++ b/lib/compiler/test/map_SUITE.erl
@@ -67,8 +67,10 @@
 
 	%% errors in 18
         t_register_corruption/1,
-	t_bad_update/1
+	t_bad_update/1,
 
+        %% new in OTP 21
+        t_reused_key_variable/1
     ]).
 
 suite() -> [].
@@ -120,7 +122,10 @@ all() ->
 
 	%% errors in 18
         t_register_corruption,
-        t_bad_update
+        t_bad_update,
+
+        %% new in OTP 21
+        t_reused_key_variable
     ].
 
 groups() -> [].
@@ -1980,6 +1985,16 @@ properly(Item) ->
 increase(Allows) ->
     catch fun() -> Allows end#{[] => +Allows, "warranty" => fun id/1}.
 
+t_reused_key_variable(Config) when is_list(Config) ->
+    Key = id(key),
+    Map1 = id(#{Key=>Config}),
+    Map2 = id(#{Key=>Config}),
+    case {Map1,Map2} of
+        %% core_lint treated Key as pattern variables, not input variables,
+        %% and complained about the variable being duplicated.
+        {#{Key:=Same},#{Key:=Same}} ->
+            ok
+    end.
 
 %% aux
 
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