v3_kernel: Handle sequences in guards

A guard with a sequence will cause a crash in v3_codegen. Currently,
it seems that a sequence in a guard will never happen when compiling
from Erlang code, but there are several reasons to fix this problem
anyway:

* There are other compilers that generate Core Erlang code.

* Changes to sys_core_fold (perhaps additional optimizations) may
  cause sequences to be generated in guards.

* A previously uncovered line in sys_core_fold:opt_guard_try/1 will
  now be covered.

3 files changed, 73 insertions, 5 deletions

diff --git a/lib/compiler/src/v3_kernel.erl b/lib/compiler/src/v3_kernel.erl
index 67e22a5662..8bbaf183c8 100644
--- a/lib/compiler/src/v3_kernel.erl
+++ b/lib/compiler/src/v3_kernel.erl
@@ -1537,10 +1537,11 @@ uguard_expr(#k_test{anno=A,op=Op,args=As}=Test, Rs, St) ->
     Used = union(op_vars(Op), lit_list_vars(As)),
     {Test#k_test{anno=#k{us=Used,ns=lit_list_vars(Rs),a=A}},
      Used,St};
-uguard_expr(#k_bif{anno=A,op=Op,args=As}=Bif, Rs, St) ->
+uguard_expr(#k_bif{anno=A,op=Op,args=As}=Bif, Rs, St0) ->
     Used = union(op_vars(Op), lit_list_vars(As)),
-    {Bif#k_bif{anno=#k{us=Used,ns=lit_list_vars(Rs),a=A},ret=Rs},
-     Used,St};
+    {Brs,St1} = bif_returns(Op, Rs, St0),
+    {Bif#k_bif{anno=#k{us=Used,ns=lit_list_vars(Brs),a=A},ret=Brs},
+     Used,St1};
 uguard_expr(#ivalues{anno=A,args=As}, Rs, St) ->
     Sets = foldr2(fun (V, Arg, Rhs) ->
 			  #iset{anno=A,vars=[V],arg=Arg,body=Rhs}
diff --git a/lib/compiler/test/core_SUITE.erl b/lib/compiler/test/core_SUITE.erl
index 874e02803d..fd1539e7fd 100644
--- a/lib/compiler/test/core_SUITE.erl
+++ b/lib/compiler/test/core_SUITE.erl
@@ -22,7 +22,7 @@
 	 init_per_group/2,end_per_group/2,
 	 init_per_testcase/2,end_per_testcase/2,
 	 dehydrated_itracer/1,nested_tries/1,
-	 make_effect_seq/1,eval_is_boolean/1,
+	 seq_in_guard/1,make_effect_seq/1,eval_is_boolean/1,
 	 unsafe_case/1,nomatch_shadow/1,reversed_annos/1]).
 
 -include_lib("test_server/include/test_server.hrl").
@@ -43,7 +43,7 @@ suite() -> [{ct_hooks,[ts_install_cth]}].
 
 all() -> 
     test_lib:recompile(?MODULE),
-    [dehydrated_itracer,nested_tries,make_effect_seq,
+    [dehydrated_itracer,nested_tries,seq_in_guard,make_effect_seq,
      eval_is_boolean,unsafe_case,nomatch_shadow,reversed_annos].
 
 groups() -> 
@@ -64,6 +64,7 @@ end_per_group(_GroupName, Config) ->
 
 ?comp(dehydrated_itracer).
 ?comp(nested_tries).
+?comp(seq_in_guard).
 ?comp(make_effect_seq).
 ?comp(eval_is_boolean).
 ?comp(unsafe_case).
diff --git a/lib/compiler/test/core_SUITE_data/seq_in_guard.core b/lib/compiler/test/core_SUITE_data/seq_in_guard.core
new file mode 100644
index 0000000000..44686a7187
--- /dev/null
+++ b/lib/compiler/test/core_SUITE_data/seq_in_guard.core
@@ -0,0 +1,66 @@
+module 'seq_in_guard' ['seq_in_guard'/0,
+		       't'/1]
+    attributes []
+'seq_in_guard'/0 =
+    %% Line 4
+    fun () ->
+	case <> of
+	  <> when 'true' ->
+	      let <_cor0> =
+		  catch
+		      %% Line 5
+		      apply 't'/1
+			  ({})
+	      in  %% Line 5
+		  case _cor0 of
+		    <{'EXIT',{'function_clause',_cor4}}> when 'true' ->
+			let <_cor2> =
+			    catch
+				%% Line 6
+				apply 't'/1
+				    ('atom')
+			in  %% Line 6
+			    case _cor2 of
+			      <{'EXIT',{'function_clause',_cor5}}> when 'true' ->
+				  %% Line 7
+				  apply 't'/1
+				      ({'a','b'})
+			      ( <_cor3> when 'true' ->
+				    primop 'match_fail'
+					({'badmatch',_cor3})
+				-| ['compiler_generated'] )
+			    end
+		    ( <_cor1> when 'true' ->
+			  primop 'match_fail'
+			      ({'badmatch',_cor1})
+		      -| ['compiler_generated'] )
+		  end
+	  ( <> when 'true' ->
+		( primop 'match_fail'
+		      ({'function_clause'})
+		  -| [{'function_name',{'seq_in_guard',0}}] )
+	    -| ['compiler_generated'] )
+	end
+'t'/1 =
+    %% Line 9
+    fun (_cor0) ->
+	case _cor0 of
+	  <X>
+	      when try
+		    do
+			call 'erlang':'element'
+			    (2, X)
+			'true'
+		of <Try> ->
+		    Try
+		catch <T,R> ->
+		    'false' ->
+	      %% Line 10
+	      'ok'
+	  ( <_cor3> when 'true' ->
+		( primop 'match_fail'
+		      ({'function_clause',_cor3})
+		  -| [{'function_name',{'t',1}}] )
+	    -| ['compiler_generated'] )
+	end
+end