From 03f79ba054b5509a05b164220f7d218d278298df Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Wed, 4 Feb 2015 08:05:09 +0100
Subject: Clean up evaluation of setelement/3

The 'try' ... 'catch' is problematic. Firstly, if no optimization
is possible, an exception will always be thrown. Secondly, bugs
in the code will go unnoticed.
---
 lib/compiler/src/sys_core_fold.erl    | 40 +++++++++++++++++++----------------
 lib/compiler/test/core_fold_SUITE.erl |  1 +
 2 files changed, 23 insertions(+), 18 deletions(-)

diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl
index b9ce6476c3..8299c6a415 100644
--- a/lib/compiler/src/sys_core_fold.erl
+++ b/lib/compiler/src/sys_core_fold.erl
@@ -1014,28 +1014,32 @@ eval_is_record(Call, _, _, _, _) -> Call.
 
 %% eval_setelement(Call, Pos, Tuple, NewVal) -> Core.
 %%  Evaluates setelement/3 if position Pos is an integer
-%%  the shape of the tuple Tuple is known.
+%%  and the shape of the tuple Tuple is known.
 %%
-eval_setelement(Call, Pos, Tuple, NewVal) ->
-    try
-	eval_setelement_1(Pos, Tuple, NewVal)
-    catch
-	error:_ ->
-	    Call
-    end.
-
-eval_setelement_1(#c_literal{val=Pos}, #c_tuple{anno=A,es=Es}, NewVal)
-  when is_integer(Pos) ->
-    ann_c_tuple(A, eval_setelement_2(Pos, Es, NewVal));
-eval_setelement_1(#c_literal{val=Pos}, #c_literal{anno=A,val=Es0}, NewVal)
+eval_setelement(Call, #c_literal{val=Pos}, Tuple, NewVal)
   when is_integer(Pos) ->
-    Es = [#c_literal{anno=A,val=E} || E <- tuple_to_list(Es0)],
-    ann_c_tuple(A, eval_setelement_2(Pos, Es, NewVal)).
+    case cerl:is_data(Tuple) of
+	false ->
+	    Call;
+	true ->
+	    Es0 = case cerl:is_c_tuple(Tuple) of
+		      false -> [];
+		      true -> cerl:tuple_es(Tuple)
+		  end,
+	    if
+		1 =< Pos, Pos =< length(Es0) ->
+		    Es = eval_setelement_1(Pos, Es0, NewVal),
+		    cerl:update_c_tuple(Tuple, Es);
+		true ->
+		    eval_failure(Call, badarg)
+	    end
+    end;
+eval_setelement(Call, _, _, _) -> Call.
 
-eval_setelement_2(1, [_|T], NewVal) ->
+eval_setelement_1(1, [_|T], NewVal) ->
     [NewVal|T];
-eval_setelement_2(Pos, [H|T], NewVal) when Pos > 1 ->
-    [H|eval_setelement_2(Pos-1, T, NewVal)].
+eval_setelement_1(Pos, [H|T], NewVal) when Pos > 1 ->
+    [H|eval_setelement_1(Pos-1, T, NewVal)].
 
 %% eval_failure(Call, Reason) -> Core.
 %%  Warn for a call that will fail and replace the call with
diff --git a/lib/compiler/test/core_fold_SUITE.erl b/lib/compiler/test/core_fold_SUITE.erl
index 9228aa7fd1..bc82eaf5aa 100644
--- a/lib/compiler/test/core_fold_SUITE.erl
+++ b/lib/compiler/test/core_fold_SUITE.erl
@@ -107,6 +107,7 @@ setelement(Config) when is_list(Config) ->
     ?line error = setelement_crash_2({a,b,c,d,e,f}, <<42>>),
 
     {'EXIT',{badarg,_}} = (catch setelement(1, not_a_tuple, New)),
+    {'EXIT',{badarg,_}} = (catch setelement(3, {a,b}, New)),
 
     ok.
 
-- 
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