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author | Björn Gustavsson <bjorn@erlang.org> | 2011-03-14 15:15:09 +0100 |
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committer | Björn Gustavsson <bjorn@erlang.org> | 2011-03-23 11:07:52 +0100 |
commit | c7188f410f5d2688783dfbb850e1e55718885f87 (patch) | |
tree | fb4eec23ff53a0ec9b1c4ff5e4d25d1718194745 /lib | |
parent | b412280c8591300b22386c21fb109da3a697c0c9 (diff) | |
download | otp-c7188f410f5d2688783dfbb850e1e55718885f87.tar.gz otp-c7188f410f5d2688783dfbb850e1e55718885f87.tar.bz2 otp-c7188f410f5d2688783dfbb850e1e55718885f87.zip |
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
Diffstat (limited to 'lib')
-rw-r--r-- | lib/compiler/src/v3_core.erl | 16 | ||||
-rw-r--r-- | lib/compiler/test/bs_match_SUITE.erl | 9 | ||||
-rw-r--r-- | lib/stdlib/test/erl_eval_SUITE.erl | 11 |
3 files changed, 34 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) -> 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) -> |