From 64a6cdc80e2f3c33c3cb18b41721b2738337cb56 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20H=C3=B6gberg?= <john@erlang.org>
Date: Tue, 23 Apr 2019 07:40:48 +0200
Subject: beam_validator: Don't infer types for dead values

---
 lib/compiler/src/beam_validator.erl        | 22 ++++++++++++++++++----
 lib/compiler/test/beam_validator_SUITE.erl | 25 +++++++++++++++++++++++--
 2 files changed, 41 insertions(+), 6 deletions(-)

(limited to 'lib')

diff --git a/lib/compiler/src/beam_validator.erl b/lib/compiler/src/beam_validator.erl
index efd2be94cb..09a5a6c104 100644
--- a/lib/compiler/src/beam_validator.erl
+++ b/lib/compiler/src/beam_validator.erl
@@ -1604,8 +1604,13 @@ infer_types_1(#value{op={bif,'=:='},args=[LHS,RHS]}) ->
     end;
 infer_types_1(#value{op={bif,element},args=[{integer,Index}=Key,Tuple]}) ->
     fun(Val, S) ->
-            Type = get_term_type(Val, S),
-            update_type(fun meet/2,{tuple,[Index],#{ Key => Type }}, Tuple, S)
+            case is_value_alive(Tuple, S) of
+                true ->
+                    Type = {tuple,[Index], #{ Key => get_term_type(Val, S) }},
+                    update_type(fun meet/2, Type, Tuple, S);
+                false ->
+                    S
+            end
     end;
 infer_types_1(#value{op={bif,is_atom},args=[Src]}) ->
     infer_type_test_bif({atom,[]}, Src);
@@ -1629,7 +1634,10 @@ infer_types_1(#value{op={bif,is_tuple},args=[Src]}) ->
     infer_type_test_bif({tuple,[0],#{}}, Src);
 infer_types_1(#value{op={bif,tuple_size}, args=[Tuple]}) ->
     fun({integer,Arity}, S) ->
-            update_type(fun meet/2, {tuple,Arity,#{}}, Tuple, S);
+            case is_value_alive(Tuple, S) of
+                true -> update_type(fun meet/2, {tuple,Arity,#{}}, Tuple, S);
+                false -> S
+            end;
        (_, S) -> S
     end;
 infer_types_1(_) ->
@@ -1637,7 +1645,10 @@ infer_types_1(_) ->
 
 infer_type_test_bif(Type, Src) ->
     fun({atom,true}, S) ->
-            update_type(fun meet/2, Type, Src, S);
+            case is_value_alive(Src, S) of
+                true -> update_type(fun meet/2, Type, Src, S);
+                false -> S
+            end;
        (_, S) ->
             S
     end.
@@ -2274,6 +2285,9 @@ get_raw_type(#value_ref{}=Ref, #vst{current=#st{vs=Vs}}) ->
 get_raw_type(Src, #vst{}) ->
     get_literal_type(Src).
 
+is_value_alive(#value_ref{}=Ref, #vst{current=#st{vs=Vs}}) ->
+    is_map_key(Ref, Vs).
+
 get_literal_type(nil=T) -> T;
 get_literal_type({atom,A}=T) when is_atom(A) -> T;
 get_literal_type({float,F}=T) when is_float(F) -> T;
diff --git a/lib/compiler/test/beam_validator_SUITE.erl b/lib/compiler/test/beam_validator_SUITE.erl
index de5a3c2873..6b1438abdd 100644
--- a/lib/compiler/test/beam_validator_SUITE.erl
+++ b/lib/compiler/test/beam_validator_SUITE.erl
@@ -35,7 +35,7 @@
 	 map_field_lists/1,cover_bin_opt/1,
 	 val_dsetel/1,bad_tuples/1,bad_try_catch_nesting/1,
          receive_stacked/1,aliased_types/1,type_conflict/1,
-         infer_on_eq/1]).
+         infer_on_eq/1,infer_dead_value/1]).
 
 -include_lib("common_test/include/ct.hrl").
 
@@ -65,7 +65,7 @@ groups() ->
        map_field_lists,cover_bin_opt,val_dsetel,
        bad_tuples,bad_try_catch_nesting,
        receive_stacked,aliased_types,type_conflict,
-       infer_on_eq]}].
+       infer_on_eq,infer_dead_value]}].
 
 init_per_suite(Config) ->
     test_lib:recompile(?MODULE),
@@ -679,6 +679,27 @@ infer_on_eq_4(T) ->
     true = erlang:tuple_size(T) =:= 1,
     {ok, erlang:element(1, T)}.
 
+%% ERIERL-348; types were inferred for dead values, causing validation to fail.
+
+infer_dead_value(Config) when is_list(Config) ->
+    a = idv_1({a, b, c, d, e, f, g}, {0, 0, 0, 0, 0, 0, 0}),
+    b = idv_1({a, b, c, d, 0, 0, 0}, {a, b, c, d, 0, 0, 0}),
+    c = idv_1({0, 0, 0, 0, 0, f, g}, {0, 0, 0, 0, 0, f, g}),
+    error = idv_1(gurka, gaffel),
+    ok.
+
+idv_1({_A, _B, _C, _D, _E, _F, _G},
+      {0, 0, 0, 0, 0, 0, 0}) ->
+    a;
+idv_1({A, B, C, D,_E, _F, _G}=_Tuple1,
+      {A, B, C, D, 0, 0, 0}=_Tuple2) ->
+    b;
+idv_1({_A, _B, _C, _D, _E, F, G},
+      {0, 0, 0, 0, 0, F, G}) ->
+    c;
+idv_1(_A, _B) ->
+    error.
+
 %%%-------------------------------------------------------------------------
 
 transform_remove(Remove, Module) ->
-- 
cgit v1.2.3