From 68b7cd0820362667fe77f0065a2ac06989580eb5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Sat, 2 Dec 2017 07:40:42 +0100
Subject: v3_kernel: Make #k_break{} consistent with the code it follows

v3_kernel could generate a #k_break{} with only one variable, even if
the preceding code and succeding code expected more than one value. It
happened to work anyway because the value returned from the break was
not actually used.
---
 lib/compiler/src/v3_kernel.erl | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

(limited to 'lib/compiler')

diff --git a/lib/compiler/src/v3_kernel.erl b/lib/compiler/src/v3_kernel.erl
index 3eea058153..23625b1f2e 100644
--- a/lib/compiler/src/v3_kernel.erl
+++ b/lib/compiler/src/v3_kernel.erl
@@ -108,6 +108,7 @@ copy_anno(Kdst, Ksrc) ->
 -record(iclause, {anno=[],isub,osub,pats,guard,body}).
 -record(ireceive_accept, {anno=[],arg}).
 -record(ireceive_next, {anno=[],arg}).
+-record(ignored, {anno=[]}).
 
 -type warning() :: term().	% XXX: REFINE
 
@@ -489,7 +490,7 @@ make_alt(First0, Then0) ->
     Then1 = pre_seq(droplast(Then0), last(Then0)),
     First2 = make_protected(First1),
     Then2 = make_protected(Then1),
-    Body = #k_atom{val=ignored},
+    Body = #ignored{},
     First3 = #k_guard_clause{guard=First2,body=Body},
     Then3 = #k_guard_clause{guard=Then2,body=Body},
     First = #k_guard{clauses=[First3]},
@@ -2225,7 +2226,9 @@ ubody(E, return, St0) ->
 	    {Ea,Pa,St1} = force_atomic(E, St0),
 	    ubody(pre_seq(Pa, #ivalues{args=[Ea]}), return, St1)
     end;
-ubody(E, {break,_Rs} = Break, St0) ->
+ubody(#ignored{}, {break,_} = Break, St) ->
+    ubody(#ivalues{args=[]}, Break, St);
+ubody(E, {break,[_]} = Break, St0) ->
     %%ok = io:fwrite("ubody ~w:~p~n", [?LINE,{E,Br}]),
     %% Exiting expressions need no trailing break.
     case is_exit_expr(E) of
@@ -2233,6 +2236,16 @@ ubody(E, {break,_Rs} = Break, St0) ->
 	false ->
 	    {Ea,Pa,St1} = force_atomic(E, St0),
 	    ubody(pre_seq(Pa, #ivalues{args=[Ea]}), Break, St1)
+    end;
+ubody(E, {break,Rs}=Break, St0) ->
+    case is_exit_expr(E) of
+        true ->
+            uexpr(E, return, St0);
+        false ->
+            {Vs,St1} = new_vars(length(Rs), St0),
+            Iset = #iset{vars=Vs,arg=E},
+            PreSeq = pre_seq([Iset], #ivalues{args=Vs}),
+            ubody(PreSeq, Break, St1)
     end.
 
 iletrec_funs(#iletrec{defs=Fs}, St0) ->
-- 
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