From 94b36c7c2534f92e1d1ce768fb63d9012bb0c630 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Mon, 2 Feb 2015 13:01:10 +0100
Subject: Be more careful about map patterns when evalutating element/2

We must not convert map patterns to map expressions.
---
 lib/compiler/src/sys_core_fold.erl    | 9 ++++++---
 lib/compiler/test/core_fold_SUITE.erl | 6 ++++++
 2 files changed, 12 insertions(+), 3 deletions(-)

(limited to 'lib/compiler')

diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl
index 2158c29576..f4f5c3f361 100644
--- a/lib/compiler/src/sys_core_fold.erl
+++ b/lib/compiler/src/sys_core_fold.erl
@@ -1338,9 +1338,12 @@ eval_element(Call, #c_literal{val=Pos}, #c_var{name=V}, Types)
 	{ok,#c_tuple{es=Elements}} ->
 	    if
 		1 =< Pos, Pos =< length(Elements) ->
-		    case lists:nth(Pos, Elements) of
-			#c_alias{var=Alias} -> Alias;
-			Res -> Res
+		    El = lists:nth(Pos, Elements),
+		    try
+			pat_to_expr(El)
+		    catch
+			throw:impossible ->
+			    Call
 		    end;
 		true ->
 		    eval_failure(Call, badarg)
diff --git a/lib/compiler/test/core_fold_SUITE.erl b/lib/compiler/test/core_fold_SUITE.erl
index 6a7036d728..9c7e97a1bf 100644
--- a/lib/compiler/test/core_fold_SUITE.erl
+++ b/lib/compiler/test/core_fold_SUITE.erl
@@ -60,6 +60,12 @@ t_element(Config) when is_list(Config) ->
     X = make_ref(),
     ?line X = id(element(1, {X,y,z})),
     ?line b = id(element(2, {a,b,c,d})),
+    (fun() ->
+	    case {a,#{k=>X}} of
+		{a,#{k:=X}}=Tuple ->
+		    #{k:=X} = id(element(2, Tuple))
+	    end
+    end)(),
 
     %% No optimization, but should work.
     Tuple = id({x,y,z}),
-- 
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