Merge branch 'hl/fix-ms_transform-scope-warn'

* hl/fix-ms_transform-scope-warn:
  ms_transform: Fix incorrect `variable shadowed' warnings

OTP-9646

2 files changed, 53 insertions, 9 deletions

diff --git a/lib/stdlib/src/ms_transform.erl b/lib/stdlib/src/ms_transform.erl
index 48e22e53fa..63b397f3a5 100644
--- a/lib/stdlib/src/ms_transform.erl
+++ b/lib/stdlib/src/ms_transform.erl
@@ -333,17 +333,18 @@ form({function,Line,Name0,Arity0,Clauses0}) ->
 form(AnyOther) ->
     AnyOther.
 function(Name, Arity, Clauses0) ->
-    {Clauses1,_} = clauses(Clauses0,gb_sets:new()),
+    Clauses1 = clauses(Clauses0),
     {Name,Arity,Clauses1}.
-clauses([C0|Cs],Bound) ->
-    {C1,Bound1} = clause(C0,Bound),
-    {C2,Bound2} = clauses(Cs,Bound1),
-    {[C1|C2],Bound2};
-clauses([],Bound) -> {[],Bound}.
+clauses([C0|Cs]) ->
+    C1 = clause(C0,gb_sets:new()),
+    C2 = clauses(Cs),
+    [C1|C2];
+clauses([]) -> [].
+
 clause({clause,Line,H0,G0,B0},Bound) ->
     {H1,Bound1} = copy(H0,Bound),
-    {B1,Bound2} = copy(B0,Bound1),
-    {{clause,Line,H1,G0,B1},Bound2}.
+    {B1,_Bound2} = copy(B0,Bound1),
+    {clause,Line,H1,G0,B1}.
 
 copy({call,Line,{remote,_Line2,{atom,_Line3,ets},{atom,_Line4,fun2ms}},
       As0},Bound) ->
diff --git a/lib/stdlib/test/ms_transform_SUITE.erl b/lib/stdlib/test/ms_transform_SUITE.erl
index 4e5df12798..c9688354b1 100644
--- a/lib/stdlib/test/ms_transform_SUITE.erl
+++ b/lib/stdlib/test/ms_transform_SUITE.erl
@@ -39,6 +39,7 @@
 -export([float_1_function/1]).
 -export([action_function/1]).
 -export([warnings/1]).
+-export([no_warnings/1]).
 -export([init_per_testcase/2, end_per_testcase/2]).
 
 init_per_testcase(_Func, Config) ->
@@ -55,7 +56,7 @@ all() ->
     [from_shell, basic_ets, basic_dbg, records,
      record_index, multipass, bitsyntax, record_defaults,
      andalso_orelse, float_1_function, action_function,
-     warnings, top_match, old_guards, autoimported,
+     warnings, no_warnings, top_match, old_guards, autoimported,
      semicolon].
 
 groups() -> 
@@ -155,6 +156,34 @@ warnings(Config) when is_list(Config) ->
 	compile_ww(Prog7),
     ok.
 
+no_warnings(suite) ->
+    [];
+no_warnings(doc) ->
+    ["Check that variables bound in other function clauses don't generate "
+     "warning"];
+no_warnings(Config) when is_list(Config) ->
+    ?line setup(Config),
+    Prog = <<"tmp(X) when X > 100 ->\n",
+	     "   Y=X,\n"
+	     "   Y;\n"
+	     "tmp(X) ->\n"
+	     "   ets:fun2ms(fun(Y) ->\n"
+	     "                  {X, 3*Y}\n"
+	     "              end)">>,
+    ?line [] = compile_no_ww(Prog),
+
+    Prog2 = <<"tmp(X) when X > 100 ->\n",
+	     "   Y=X,\n"
+	     "   Y;\n"
+	     "tmp(X) when X < 200 ->\n"
+	     "   ok;\n"
+	     "tmp(X) ->\n"
+	     "   ets:fun2ms(fun(Y) ->\n"
+	     "                  {X, 3*Y}\n"
+	     "              end)">>,
+    ?line [] = compile_no_ww(Prog2),
+    ok.
+
 andalso_orelse(suite) ->
     [];
 andalso_orelse(doc) ->
@@ -842,6 +871,20 @@ compile_ww(Records,Expr) ->
 					       nowarn_unused_record]),
     Wlist.
 
+compile_no_ww(Expr) ->
+    Prog = <<
+	"-module(tmp).\n",
+    "-include_lib(\"stdlib/include/ms_transform.hrl\").\n",
+    "-export([tmp/1]).\n\n",
+    Expr/binary,".\n">>,
+    FN=temp_name(),
+    file:write_file(FN,Prog),
+    {ok,Forms} = epp:parse_file(FN,"",""),
+    {ok,tmp,_Bin,Wlist} = compile:forms(Forms,[return_warnings,
+					       nowarn_unused_vars,
+					       nowarn_unused_record]),
+    Wlist.
+
 do_eval(String) ->
     {done,{ok,T,_},[]} = erl_scan:tokens(
 			   [],