From 96cf13613c53b641cf7e8a45f83fb71809d6b336 Mon Sep 17 00:00:00 2001
From: Hans Bolinder <hasse@erlang.org>
Date: Fri, 8 Sep 2017 13:16:16 +0200
Subject: dialyzer: Improve check of unknown types

The implementation of OTP-14218 (commit 6d3b38a) has a weakness: only
a very limited part of the type form is checked. This is now fixed:
types not used by specs are checked equally well as types used by
specs.

The new function erl_types:t_from_form_check_remote() checks usage of
remote types. It does not expand used local types, and has (almost) no
limits on depth and size.
---
 lib/dialyzer/src/dialyzer_contracts.erl |  5 ++++-
 lib/dialyzer/src/dialyzer_utils.erl     | 22 +++++++++++-----------
 2 files changed, 15 insertions(+), 12 deletions(-)

(limited to 'lib/dialyzer/src')

diff --git a/lib/dialyzer/src/dialyzer_contracts.erl b/lib/dialyzer/src/dialyzer_contracts.erl
index b554ebc2cc..e72c1aecfc 100644
--- a/lib/dialyzer/src/dialyzer_contracts.erl
+++ b/lib/dialyzer/src/dialyzer_contracts.erl
@@ -555,6 +555,9 @@ from_form_with_check(Form, ExpTypes, MFA, RecordTable, VarTable, Cache) ->
   Site = {spec, MFA},
   C1 = erl_types:t_check_record_fields(Form, ExpTypes, Site, RecordTable,
                                        VarTable, Cache),
+  %% The check costs some time, and with the assumption that contracts
+  %% are not very deep, it does not add anything.
+  %% erl_types:t_from_form_check_remote(Form, ExpTypes, MFA, RecordTable),
   erl_types:t_from_form(Form, ExpTypes, Site, RecordTable, VarTable, C1).
 
 constraints_to_dict(Constrs, MFA, RecDict, ExpTypes, RecordTable,
@@ -840,7 +843,7 @@ is_remote_types_related(Contract, CSig, Sig, MFA, RecDict) ->
 
 t_from_forms_without_remote([{FType, []}], MFA, RecDict) ->
   Site = {spec, MFA},
-  {Type1, _} = erl_types:t_from_form_without_remote(FType, Site, RecDict),
+  Type1 = erl_types:t_from_form_without_remote(FType, Site, RecDict),
   {ok, erl_types:subst_all_vars_to_any(Type1)};
 t_from_forms_without_remote([{_FType, _Constrs}], _MFA, _RecDict) ->
   %% 'When' constraints
diff --git a/lib/dialyzer/src/dialyzer_utils.erl b/lib/dialyzer/src/dialyzer_utils.erl
index 511a6d66bf..9b8fbc67eb 100644
--- a/lib/dialyzer/src/dialyzer_utils.erl
+++ b/lib/dialyzer/src/dialyzer_utils.erl
@@ -326,9 +326,12 @@ process_record_remote_types(CServer) ->
                 {record, Name} ->
                   FieldFun =
                     fun({Arity, Fields}, C4) ->
-                        Site = {record, {Module, Name, Arity}},
+                        MRA = {Module, Name, Arity},
+                        Site = {record, MRA},
                         {Fields1, C7} =
                           lists:mapfoldl(fun({FieldName, Field, _}, C5) ->
+                                             check_remote(Field, ExpTypes,
+                                                          MRA, RecordTable),
                                              {FieldT, C6} =
                                                erl_types:t_from_form
                                                  (Field, ExpTypes, Site,
@@ -342,18 +345,12 @@ process_record_remote_types(CServer) ->
                   {FieldsList, C3} =
                     lists:mapfoldl(FieldFun, C2, orddict:to_list(Fields)),
                   {{Key, {FileLine, orddict:from_list(FieldsList)}}, C3};
-                {type, Name, NArgs} ->
+                {_TypeOrOpaque, Name, NArgs} ->
                   %% Make sure warnings about unknown types are output
                   %% also for types unused by specs.
-                  Site = {type, {Module, Name, NArgs}},
-                  L = erl_anno:new(0),
-                  Args = lists:duplicate(NArgs, {var, L, '_'}),
-                  UserType = {user_type, L, Name, Args},
-                  {_NewType, C3} =
-                    erl_types:t_from_form(UserType, ExpTypes, Site,
-                                          RecordTable, VarTable, C2),
-                  {{Key, Value}, C3};
-                {opaque, _Name, _NArgs} ->
+                  MTA = {Module, Name, NArgs},
+                  {{_Module, _FileLine, Form, _ArgNames}, _Type} = Value,
+                  check_remote(Form, ExpTypes, MTA, RecordTable),
                   {{Key, Value}, C2}
               end
           end,
@@ -454,6 +451,9 @@ msg_with_position(Fun, FileLine) ->
       throw({error, NewMsg})
   end.
 
+check_remote(Form, ExpTypes, What, RecordTable) ->
+  erl_types:t_from_form_check_remote(Form, ExpTypes, What, RecordTable).
+
 -spec merge_types(codeserver(), dialyzer_plt:plt()) -> codeserver().
 
 merge_types(CServer, Plt) ->
-- 
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