Better blame assignment when a spec is erroneous

Applies to the specification of the return value of a function.

5 files changed, 68 insertions, 21 deletions

diff --git a/lib/dialyzer/src/dialyzer.erl b/lib/dialyzer/src/dialyzer.erl
index 3e7680f4bb..683b518831 100644
--- a/lib/dialyzer/src/dialyzer.erl
+++ b/lib/dialyzer/src/dialyzer.erl
@@ -394,6 +394,10 @@ message_to_string({contract_supertype, [M, F, _A, Contract, Sig]}) ->
   io_lib:format("Type specification ~w:~w~s"
 		" is a supertype of the success typing: ~w:~w~s\n",
 		[M, F, Contract, M, F, Sig]);
+message_to_string({contract_range, [Contract, M, F, ArgStrings, Line, CRet]}) ->
+  io_lib:format("The contract ~w:~w~s cannot be right because the inferred"
+		" return for ~w~s on line ~w is ~s\n",
+		[M, F, Contract, F, ArgStrings, Line, CRet]);
 message_to_string({invalid_contract, [M, F, A, Sig]}) ->
   io_lib:format("Invalid type specification for function ~w:~w/~w."
 		" The success typing is ~s\n", [M, F, A, Sig]);
diff --git a/lib/dialyzer/src/dialyzer.hrl b/lib/dialyzer/src/dialyzer.hrl
index aa3f703af2..9d2e554981 100644
--- a/lib/dialyzer/src/dialyzer.hrl
+++ b/lib/dialyzer/src/dialyzer.hrl
@@ -52,10 +52,11 @@
 -define(WARN_CONTRACT_NOT_EQUAL, warn_contract_not_equal).
 -define(WARN_CONTRACT_SUBTYPE, warn_contract_subtype).
 -define(WARN_CONTRACT_SUPERTYPE, warn_contract_supertype).
+-define(WARN_CONTRACT_RANGE, warn_contract_range).
 -define(WARN_CALLGRAPH, warn_callgraph).
 -define(WARN_UNMATCHED_RETURN, warn_umatched_return).
 -define(WARN_RACE_CONDITION, warn_race_condition).
--define(WARN_BEHAVIOUR,warn_behaviour).
+-define(WARN_BEHAVIOUR, warn_behaviour).
 
 %%
 %% The following type has double role:
@@ -70,7 +71,7 @@
                        | ?WARN_CONTRACT_NOT_EQUAL | ?WARN_CONTRACT_SUBTYPE
                        | ?WARN_CONTRACT_SUPERTYPE | ?WARN_CALLGRAPH
                        | ?WARN_UNMATCHED_RETURN | ?WARN_RACE_CONDITION
-                       | ?WARN_BEHAVIOUR.
+                       | ?WARN_BEHAVIOUR | ?WARN_CONTRACT_RANGE.
 
 %%
 %% This is the representation of each warning as they will be returned
diff --git a/lib/dialyzer/src/dialyzer_dataflow.erl b/lib/dialyzer/src/dialyzer_dataflow.erl
index b01e7a4b05..215b4d67c1 100644
--- a/lib/dialyzer/src/dialyzer_dataflow.erl
+++ b/lib/dialyzer/src/dialyzer_dataflow.erl
@@ -657,7 +657,8 @@ handle_apply_or_call([{TypeOfApply, {Fun, Sig, Contr, LocalRet}}|Left],
       true  -> opaque;
       false -> structured
     end,
-  RetWithoutLocal = t_inf(t_inf(ContrRet, BifRet, RetMode), SigRange, RetMode),
+  RetWithoutContr = t_inf(SigRange, BifRet, RetMode),
+  RetWithoutLocal = t_inf(ContrRet, RetWithoutContr, RetMode),
   ?debug("--------------------------------------------------------\n", []),
   ?debug("Fun: ~p\n", [Fun]),
   ?debug("Args: ~s\n", [erl_types:t_to_string(t_product(ArgTypes))]),
@@ -666,6 +667,7 @@ handle_apply_or_call([{TypeOfApply, {Fun, Sig, Contr, LocalRet}}|Left],
 	 [erl_types:t_to_string(t_product(NewArgsContract))]),
   ?debug("NewArgsBif: ~s\n", [erl_types:t_to_string(t_product(NewArgsBif))]),
   ?debug("NewArgTypes: ~s\n", [erl_types:t_to_string(t_product(NewArgTypes))]),
+  ?debug("RetWithoutContr: ~s\n",[erl_types:t_to_string(RetWithoutContr)]),
   ?debug("RetWithoutLocal: ~s\n", [erl_types:t_to_string(RetWithoutLocal)]),
   ?debug("BifRet: ~s\n", [erl_types:t_to_string(BifRange(NewArgTypes))]),
   ?debug("ContrRet: ~s\n", [erl_types:t_to_string(CRange(TmpArgTypes))]),
@@ -700,22 +702,39 @@ handle_apply_or_call([{TypeOfApply, {Fun, Sig, Contr, LocalRet}}|Left],
   State2 =
     case FailedConj andalso not (IsFailBif orelse IsFailSig) of
       true ->
-	FailedSig = any_none(NewArgsSig),
-	FailedContract = any_none([CRange(TmpArgsContract)|NewArgsContract]),
-	FailedBif = any_none([BifRange(NewArgsBif)|NewArgsBif]),
-	InfSig = t_inf(t_fun(SigArgs, SigRange),
-		       t_fun(BifArgs, BifRange(BifArgs))),
-	FailReason = apply_fail_reason(FailedSig, FailedBif, FailedContract),
-        Msg = get_apply_fail_msg(Fun, Args, ArgTypes, NewArgTypes, InfSig,
-				 Contr, CArgs, State1, FailReason),
-	WarnType = case Msg of
-		     {call, _} -> ?WARN_FAILING_CALL;
-		     {apply, _} -> ?WARN_FAILING_CALL;
-		     {call_with_opaque, _} -> ?WARN_OPAQUE;
-		     {call_without_opaque, _} -> ?WARN_OPAQUE;
-		     {opaque_type_test, _} -> ?WARN_OPAQUE
-		   end,
-	state__add_warning(State1, WarnType, Tree, Msg);
+	case t_is_none(RetWithoutLocal) andalso
+	  not t_is_none(RetWithoutContr) andalso
+	  not any_none(NewArgTypes) of
+	  true ->
+	    {value, C1} = Contr,
+	    Contract = dialyzer_contracts:contract_to_string(C1),
+	    {M1, F1, A1} = state__lookup_name(Fun, State),
+	    ArgStrings = format_args(Args, ArgTypes, State),
+	    CRet = erl_types:t_to_string(RetWithoutContr),
+	    %% This Msg will be post_processed by dialyzer_succ_typings
+	    Msg =
+	      {contract_range, [Contract, M1, F1, A1, ArgStrings, CRet]},
+	    state__add_warning(State1, ?WARN_CONTRACT_RANGE, Tree, Msg);
+	  false ->
+	    FailedSig = any_none(NewArgsSig),
+	    FailedContract =
+	      any_none([CRange(TmpArgsContract)|NewArgsContract]),
+	    FailedBif = any_none([BifRange(NewArgsBif)|NewArgsBif]),
+	    InfSig = t_inf(t_fun(SigArgs, SigRange),
+			   t_fun(BifArgs, BifRange(BifArgs))),
+	    FailReason =
+	      apply_fail_reason(FailedSig, FailedBif, FailedContract),
+	    Msg = get_apply_fail_msg(Fun, Args, ArgTypes, NewArgTypes, InfSig,
+				     Contr, CArgs, State1, FailReason),
+	    WarnType = case Msg of
+			 {call, _} -> ?WARN_FAILING_CALL;
+			 {apply, _} -> ?WARN_FAILING_CALL;
+			 {call_with_opaque, _} -> ?WARN_OPAQUE;
+			 {call_without_opaque, _} -> ?WARN_OPAQUE;
+			 {opaque_type_test, _} -> ?WARN_OPAQUE
+		       end,
+	    state__add_warning(State1, WarnType, Tree, Msg)
+	end;
       false -> State1
     end,
   State3 =
diff --git a/lib/dialyzer/src/dialyzer_options.erl b/lib/dialyzer/src/dialyzer_options.erl
index 29e164628a..b2a67de8bd 100644
--- a/lib/dialyzer/src/dialyzer_options.erl
+++ b/lib/dialyzer/src/dialyzer_options.erl
@@ -47,6 +47,7 @@ build(Opts) ->
 		  ?WARN_FAILING_CALL,
 		  ?WARN_BIN_CONSTRUCTION,
 		  ?WARN_CALLGRAPH,
+		  ?WARN_CONTRACT_RANGE,
 		  ?WARN_CONTRACT_TYPES,
 		  ?WARN_CONTRACT_SYNTAX],
   DefaultWarns1 = ordsets:from_list(DefaultWarns),
diff --git a/lib/dialyzer/src/dialyzer_succ_typings.erl b/lib/dialyzer/src/dialyzer_succ_typings.erl
index 8bfc66fc39..daf68d24f0 100644
--- a/lib/dialyzer/src/dialyzer_succ_typings.erl
+++ b/lib/dialyzer/src/dialyzer_succ_typings.erl
@@ -131,8 +131,9 @@ get_warnings_from_modules([M|Ms], State, DocPlt,
   %% Check if there are contracts for functions that do not exist
   Warnings1 = 
     dialyzer_contracts:contracts_without_fun(Contracts, AllFuns, Callgraph),
-  {Warnings2, FunTypes, RaceCode, PublicTables, NamedTables} =
+  {RawWarnings2, FunTypes, RaceCode, PublicTables, NamedTables} =
     dialyzer_dataflow:get_warnings(ModCode, Plt, Callgraph, Records, NoWarnUnused),
+  {NewAcc, Warnings2} = postprocess_dataflow_warns(RawWarnings2, State, Acc),
   Attrs = cerl:module_attrs(ModCode),
   Warnings3 = if BehavioursChk ->
 		  dialyzer_behaviours:check_callbacks(M, Attrs,
@@ -145,10 +146,31 @@ get_warnings_from_modules([M|Ms], State, DocPlt,
                                        NamedTables),
   State1 = st__renew_state_calls(NewCallgraph, State),
   get_warnings_from_modules(Ms, State1, NewDocPlt, BehavioursChk,
-			    [Warnings1, Warnings2, Warnings3|Acc]);
+			    [Warnings1, Warnings2, Warnings3|NewAcc]);
 get_warnings_from_modules([], #st{plt = Plt}, DocPlt, _, Acc) ->
   {lists:flatten(Acc), Plt, DocPlt}.
 
+postprocess_dataflow_warns(RawWarnings, State, WarnAcc) ->
+  postprocess_dataflow_warns(RawWarnings, State, WarnAcc, []).
+
+postprocess_dataflow_warns([], _State, WAcc, Acc) ->
+  {WAcc, lists:reverse(Acc)};
+postprocess_dataflow_warns([{?WARN_CONTRACT_RANGE, {File, CallL}, Msg}|Rest],
+			   #st{codeserver = Codeserver} = State, WAcc, Acc) ->
+  {contract_range, [Contract, M, F, A, ArgStrings, CRet]} = Msg,
+  {ok, {{File, _ContrL} = FileLine, _C}} =
+    dialyzer_codeserver:lookup_mfa_contract({M,F,A}, Codeserver),
+  NewMsg =
+    {contract_range, [Contract, M, F, ArgStrings, CallL, CRet]},
+  W = {?WARN_CONTRACT_RANGE, FileLine, NewMsg},
+  Filter =
+    fun({?WARN_CONTRACT_TYPES, FL, _}) when FL =:= FileLine -> false;
+       (_) -> true
+    end,
+  postprocess_dataflow_warns(Rest, State, lists:filter(Filter, WAcc), [W|Acc]);
+postprocess_dataflow_warns([W|Rest], State, Wacc, Acc) ->
+  postprocess_dataflow_warns(Rest, State, Wacc, [W|Acc]).
+  
 refine_succ_typings(ModulePostorder, State) ->
   ?debug("Module postorder: ~p\n", [ModulePostorder]),
   refine_succ_typings(ModulePostorder, State, []).