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-rw-r--r--lib/compiler/src/v3_core.erl16
-rw-r--r--lib/compiler/test/bs_match_SUITE.erl9
2 files changed, 23 insertions, 2 deletions
diff --git a/lib/compiler/src/v3_core.erl b/lib/compiler/src/v3_core.erl
index 54f6834dd5..e1a593fffa 100644
--- a/lib/compiler/src/v3_core.erl
+++ b/lib/compiler/src/v3_core.erl
@@ -1820,7 +1820,21 @@ upattern_list([], _, St) -> {[],[],[],[],St}.
%% upat_bin([Pat], [KnownVar], State) ->
%% {[Pat],[GuardTest],[NewVar],[UsedVar],State}.
upat_bin(Es0, Ks, St0) ->
- upat_bin(Es0, Ks, [], St0).
+ {Es1,Pg,Pv,Pu0,St1} = upat_bin(Es0, Ks, [], St0),
+
+ %% In a clause such as <<Sz:8,V:Sz>> in a function head, Sz will both
+ %% be new and used; a situation that is not handled properly by
+ %% uclause/4. (Basically, since Sz occurs in two sets that are
+ %% subtracted from each other, Sz will not be added to the list of
+ %% known variables and will seem to be new the next time it is
+ %% used in a match.)
+ %% Since the variable Sz really is new (it does not use a
+ %% value bound prior to the binary matching), Sz should only be
+ %% included in the set of new variables. Thus we should take it
+ %% out of the set of used variables.
+
+ Pu1 = subtract(Pu0, intersection(Pv, Pu0)),
+ {Es1,Pg,Pv,Pu1,St1}.
%% upat_bin([Pat], [KnownVar], [LocalVar], State) ->
%% {[Pat],[GuardTest],[NewVar],[UsedVar],State}.
diff --git a/lib/compiler/test/bs_match_SUITE.erl b/lib/compiler/test/bs_match_SUITE.erl
index 1e3c670fb8..9184e14cb2 100644
--- a/lib/compiler/test/bs_match_SUITE.erl
+++ b/lib/compiler/test/bs_match_SUITE.erl
@@ -142,7 +142,14 @@ otp_5269(Config) when is_list(Config) ->
[X || <<X:X>> <- [<<1:32>>,<<2:32>>,<<3:8>>]] end,
%% "binsize variable" ^
[1,2]),
-
+ ?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,
+ ok),
ok.
null_fields(Config) when is_list(Config) ->