From 6d6a82c78e6d3064e32e6686b4ac32d48cefed95 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20H=C3=B6gberg?= <john@erlang.org>
Date: Mon, 4 Mar 2019 12:34:51 +0100
Subject: beam_validator: Fix element/2 BIF handling

The element type can not be extracted before the tuple type has
been updated.
---
 lib/compiler/src/beam_validator.erl | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

(limited to 'lib/compiler')

diff --git a/lib/compiler/src/beam_validator.erl b/lib/compiler/src/beam_validator.erl
index 164007548c..472bb1b22e 100644
--- a/lib/compiler/src/beam_validator.erl
+++ b/lib/compiler/src/beam_validator.erl
@@ -683,12 +683,15 @@ valfun_4({make_fun2,_,_,_,Live}, Vst) ->
     call(make_fun, Live, Vst);
 %% Other BIFs
 valfun_4({bif,element,{f,Fail},[Pos,Tuple],Dst}, Vst0) ->
+    Vst1 = branch_state(Fail, Vst0),
+
     PosType = get_term_type(Pos, Vst0),
-    ElementType = get_element_type(PosType, Tuple, Vst0),
     InferredType = {tuple,[get_tuple_size(PosType)],#{}},
-    Vst1 = branch_state(Fail, Vst0),
+
     Vst2 = update_type(fun meet/2, InferredType, Tuple, Vst1),
     Vst = update_type(fun meet/2, {integer,[]}, Pos, Vst2),
+
+    ElementType = get_element_type(PosType, Tuple, Vst),
     extract_term(ElementType, {bif,element}, [Pos,Tuple], Dst, Vst);
 valfun_4({bif,raise,{f,0},Src,_Dst}, Vst) ->
     validate_src(Src, Vst),
@@ -2082,11 +2085,10 @@ assert_type(Needed, Actual) ->
 get_element_type(Key, Src, Vst) ->
     get_element_type_1(Key, get_term_type(Src, Vst)).
 
-get_element_type_1({integer,Index}=Key, {tuple,Sz,Es}) ->
+get_element_type_1({integer,_}=Key, {tuple,_Sz,Es}) ->
     case Es of
         #{ Key := Type } -> Type;
-        #{} when Index =< Sz -> term;
-        #{} -> none
+        #{} -> term
     end;
 get_element_type_1(_Index, _Type) ->
     term.
-- 
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