v3_core: Fix variable incorrectly unbound after binary match

In the following code:

m(<<Sz:8,_:Sz/binary>>) ->
    Sz = wrong.

the Sz variable is supposed to be bound in the function header and the
matching "Sz = wrong" should cause a badarg exception.  But what
happens is that the Sz variables seems to be unbound and the matching
succeds and the m/1 function returns 'wrong'.

If the Sz variable is used directly (not matched), it will have
the expected value. Thus the following code:

m(<<Sz:8,_:Sz/binary>>) ->
    Sz.

will correctly return the value of Sz that was matched out from
the binary.

Reported-by: Bernard Duggan

1 files changed, 11 insertions, 0 deletions

diff --git a/lib/stdlib/test/erl_eval_SUITE.erl b/lib/stdlib/test/erl_eval_SUITE.erl
index 6b2eb78e2c..4b59cee99e 100644
--- a/lib/stdlib/test/erl_eval_SUITE.erl
+++ b/lib/stdlib/test/erl_eval_SUITE.erl
@@ -571,6 +571,17 @@ otp_5269(Config) when is_list(Config) ->
                                  B:A>> <- [<<16:8,19:16>>],
                                <<X:8>> <- [<<B:8>>]].",
                 [19]),
+    ?line check(fun() ->
+		(fun (<<A:1/binary, B:8/integer, _C:B/binary>>) ->
+			    case A of
+				B -> wrong;
+				_ -> ok
+			    end
+		 end)(<<1,2,3,4>>) end,
+		"(fun(<<A:1/binary, B:8/integer, _C:B/binary>>) ->"
+			    " case A of B -> wrong; _ -> ok end"
+		" end)(<<1, 2, 3, 4>>).",
+		ok),
     ok.
 
 otp_6539(doc) ->