Merge pull request #1875 from jhogberg/john/compiler/fix-varsize-binary-comprehension/OTP-15186/ERL-665

Fix a crash when compiling variable-sized binary comprehensions

2 files changed, 34 insertions, 13 deletions

diff --git a/lib/compiler/src/v3_core.erl b/lib/compiler/src/v3_core.erl
index 0196e7fdfd..3b746ab5bf 100644
--- a/lib/compiler/src/v3_core.erl
+++ b/lib/compiler/src/v3_core.erl
@@ -1501,7 +1501,7 @@ bc_initial_size(E0, Q, St0) ->
     end.
 
 bc_elem_size({bin,_,El}, St0) ->
-    case bc_elem_size_1(El, 0, []) of
+    case bc_elem_size_1(El, ordsets:new(), 0, []) of
 	{Bits,[]} ->
 	    {#c_literal{val=Bits},[],[],St0};
 	{Bits,Vars0} ->
@@ -1515,19 +1515,33 @@ bc_elem_size(_, _) ->
     throw(impossible).
 
 bc_elem_size_1([{bin_element,_,{string,_,String},{integer,_,N},_}=El|Es],
-	       Bits, Vars) ->
+	       DefVars, Bits, SizeVars) ->
     U = get_unit(El),
-    bc_elem_size_1(Es, Bits+U*N*length(String), Vars);
-bc_elem_size_1([{bin_element,_,_,{integer,_,N},_}=El|Es], Bits, Vars) ->
+    bc_elem_size_1(Es, DefVars, Bits+U*N*length(String), SizeVars);
+bc_elem_size_1([{bin_element,_,Expr,{integer,_,N},_}=El|Es],
+               DefVars0, Bits, SizeVars) ->
     U = get_unit(El),
-    bc_elem_size_1(Es, Bits+U*N, Vars);
-bc_elem_size_1([{bin_element,_,_,{var,_,Var},_}=El|Es], Bits, Vars) ->
-    U = get_unit(El),
-    bc_elem_size_1(Es, Bits, [{U,#c_var{name=Var}}|Vars]);
-bc_elem_size_1([_|_], _, _) ->
+    DefVars = bc_elem_size_def_var(Expr, DefVars0),
+    bc_elem_size_1(Es, DefVars, Bits+U*N, SizeVars);
+bc_elem_size_1([{bin_element,_,Expr,{var,_,Src},_}=El|Es],
+               DefVars0, Bits, SizeVars) ->
+    case ordsets:is_element(Src, DefVars0) of
+        false ->
+            U = get_unit(El),
+            DefVars = bc_elem_size_def_var(Expr, DefVars0),
+            bc_elem_size_1(Es, DefVars, Bits, [{U,#c_var{name=Src}}|SizeVars]);
+        true ->
+            throw(impossible)
+    end;
+bc_elem_size_1([_|_], _, _, _) ->
     throw(impossible);
-bc_elem_size_1([], Bits, Vars) ->
-    {Bits,Vars}.
+bc_elem_size_1([], _DefVars, Bits, SizeVars) ->
+    {Bits,SizeVars}.
+
+bc_elem_size_def_var({var,_,Var}, DefVars) ->
+    ordsets:add_element(Var, DefVars);
+bc_elem_size_def_var(_Expr, DefVars) ->
+    DefVars.
 
 bc_elem_size_combine([{U,V}|T], U, UVars, Acc) ->
     bc_elem_size_combine(T, U, [V|UVars], Acc);
diff --git a/lib/compiler/test/bs_bincomp_SUITE.erl b/lib/compiler/test/bs_bincomp_SUITE.erl
index 42361ea546..a5d49020a9 100644
--- a/lib/compiler/test/bs_bincomp_SUITE.erl
+++ b/lib/compiler/test/bs_bincomp_SUITE.erl
@@ -26,7 +26,7 @@
 	 init_per_group/2,end_per_group/2,
 	 byte_aligned/1,bit_aligned/1,extended_byte_aligned/1,
 	 extended_bit_aligned/1,mixed/1,filters/1,trim_coverage/1,
-	 nomatch/1,sizes/1,general_expressions/1]).
+	 nomatch/1,sizes/1,general_expressions/1,matched_out_size/1]).
 
 -include_lib("common_test/include/ct.hrl").
 
@@ -35,7 +35,7 @@ suite() -> [{ct_hooks,[ts_install_cth]}].
 all() -> 
     [byte_aligned, bit_aligned, extended_byte_aligned,
      extended_bit_aligned, mixed, filters, trim_coverage,
-     nomatch, sizes, general_expressions].
+     nomatch, sizes, general_expressions, matched_out_size].
 
 groups() -> 
     [].
@@ -338,6 +338,13 @@ general_expressions(_) ->
 
 -undef(BAD).
 
+matched_out_size(Config) when is_list(Config) ->
+    <<1, 2>> = matched_out_size_1(<<4, 1:4, 4, 2:4>>),
+    ok.
+
+matched_out_size_1(Binary) ->
+    << <<X>> || <<S, X:S>> <= Binary>>.
+
 cs_init() ->
     erts_debug:set_internal_state(available_internal_state, true),
     ok.