Merge branch 'nox/fix-seq-opt/OTP-10818'

* nox/fix-seq-opt/OTP-10818:
  Add two tests for unused multiple values in effect context
  Forbid multiple values in Core Erlang sequence arguments

5 files changed, 61 insertions, 4 deletions

diff --git a/lib/compiler/src/core_lint.erl b/lib/compiler/src/core_lint.erl
index 8b688df830..1e8983f594 100644
--- a/lib/compiler/src/core_lint.erl
+++ b/lib/compiler/src/core_lint.erl
@@ -309,7 +309,7 @@ expr(#c_fun{vars=Vs,body=B}, Def, Rt, St0) ->
     {Vvs,St1} = variable_list(Vs, St0),
     return_match(Rt, 1, body(B, union(Vvs, Def), any, St1));
 expr(#c_seq{arg=Arg,body=B}, Def, Rt, St0) ->
-    St1 = expr(Arg, Def, any, St0),		%Ignore values
+    St1 = expr(Arg, Def, 1, St0),
     body(B, Def, Rt, St1);
 expr(#c_let{vars=Vs,arg=Arg,body=B}, Def, Rt, St0) ->
     St1 = body(Arg, Def, let_varcount(Vs), St0), %This is a body
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl
index 07b054c5d7..cda3f7d81e 100644
--- a/lib/compiler/src/sys_core_fold.erl
+++ b/lib/compiler/src/sys_core_fold.erl
@@ -132,7 +132,12 @@ body(Body, Sub) ->
 
 body(#c_values{anno=A,es=Es0}, Ctxt, Sub) ->
     Es1 = expr_list(Es0, Ctxt, Sub),
-    #c_values{anno=A,es=Es1};
+    case Ctxt of
+	value ->
+	    #c_values{anno=A,es=Es1};
+	effect ->
+	    make_effect_seq(Es1, Sub)
+    end;
 body(E, Ctxt, Sub) ->
     ?ASSERT(verify_scope(E, Sub)),
     expr(E, Ctxt, Sub).
diff --git a/lib/compiler/test/Makefile b/lib/compiler/test/Makefile
index b9c5be09ce..51b3064589 100644
--- a/lib/compiler/test/Makefile
+++ b/lib/compiler/test/Makefile
@@ -75,6 +75,7 @@ INLINE= \
 
 CORE_MODULES = \
 	bs_shadowed_size_var \
+	unused_multiple_values_error \
 	nested_call_in_case
 
 
diff --git a/lib/compiler/test/core_fold_SUITE.erl b/lib/compiler/test/core_fold_SUITE.erl
index c2a592f699..abc9ab6a72 100644
--- a/lib/compiler/test/core_fold_SUITE.erl
+++ b/lib/compiler/test/core_fold_SUITE.erl
@@ -21,7 +21,8 @@
 -export([all/0, suite/0,groups/0,init_per_suite/1, end_per_suite/1, 
 	 init_per_group/2,end_per_group/2,
 	 t_element/1,setelement/1,t_length/1,append/1,t_apply/1,bifs/1,
-	 eq/1,nested_call_in_case/1,guard_try_catch/1,coverage/1]).
+	 eq/1,nested_call_in_case/1,guard_try_catch/1,coverage/1,
+	 unused_multiple_values_error/1,unused_multiple_values/1]).
 
 -export([foo/0,foo/1,foo/2,foo/3]).
 
@@ -36,7 +37,8 @@ all() ->
 groups() -> 
     [{p,test_lib:parallel(),
       [t_element,setelement,t_length,append,t_apply,bifs,
-       eq,nested_call_in_case,guard_try_catch,coverage]}].
+       eq,nested_call_in_case,guard_try_catch,coverage,
+       unused_multiple_values_error,unused_multiple_values]}].
 
 
 init_per_suite(Config) ->
@@ -289,3 +291,41 @@ cover_is_safe_bool_expr(X) ->
     end.
 
 id(I) -> I.
+
+unused_multiple_values_error(Config) when is_list(Config) ->
+    PrivDir = ?config(priv_dir, Config),
+    Dir = filename:dirname(code:which(?MODULE)),
+    Core = filename:join(Dir, "unused_multiple_values_error"),
+    Opts = [no_copt,clint,return,from_core,{outdir,PrivDir}
+	   |test_lib:opt_opts(?MODULE)],
+    {error,[{unused_multiple_values_error,
+        [{core_lint,{return_mismatch,{hello,1}}}]}],
+     []} = c:c(Core, Opts),
+    ok.
+
+unused_multiple_values(Config) when is_list(Config) ->
+    put(unused_multiple_values, []),
+    [false] = test_unused_multiple_values(false),
+    [b,a,{a,b},false] = test_unused_multiple_values({a,b}),
+    ok.
+
+test_unused_multiple_values(X) ->
+    ok = do_unused_multiple_values(X),
+    get(unused_multiple_values).
+
+do_unused_multiple_values(X) ->
+    case do_something(X) of
+        false ->
+            A = false;
+        Res ->
+            {A,B} = Res,
+            do_something(A),
+            do_something(B)
+    end,
+    _ThisShouldNotFail = A,
+    ok.
+
+do_something(I) ->
+    put(unused_multiple_values,
+	[I|get(unused_multiple_values)]),
+    I.
diff --git a/lib/compiler/test/unused_multiple_values_error.core b/lib/compiler/test/unused_multiple_values_error.core
new file mode 100644
index 0000000000..e06587c936
--- /dev/null
+++ b/lib/compiler/test/unused_multiple_values_error.core
@@ -0,0 +1,11 @@
+module 'unused_multiple_values_error' ['hello'/1]
+    attributes []
+'hello'/1 =
+    fun (_cor0) ->
+	do
+	    case _cor0 of
+	      <_cor0> when 'true' ->
+		  <'ok','ok'>
+	    end
+	    'ok'
+end