From 804df7a55aa2ec49c2001f03aa5f0af1e5f7e18f Mon Sep 17 00:00:00 2001
From: Stavros Aronis <aronisstav@gmail.com>
Date: Wed, 23 Nov 2011 17:28:57 +0100
Subject: No warnings for underspecs with remote types

---
 lib/dialyzer/src/dialyzer_contracts.erl | 110 +++++++++++++++++++++++++++-----
 1 file changed, 95 insertions(+), 15 deletions(-)

(limited to 'lib/dialyzer/src/dialyzer_contracts.erl')

diff --git a/lib/dialyzer/src/dialyzer_contracts.erl b/lib/dialyzer/src/dialyzer_contracts.erl
index 3469d70a4d..6f83e29a57 100644
--- a/lib/dialyzer/src/dialyzer_contracts.erl
+++ b/lib/dialyzer/src/dialyzer_contracts.erl
@@ -256,7 +256,7 @@ check_extraneous([C|Cs], SuccType) ->
 check_extraneous_1(Contract, SuccType) ->
   CRngs = erl_types:t_elements(erl_types:t_fun_range(Contract)),
   STRng = erl_types:t_fun_range(SuccType),
-  %% io:format("CR = ~p\nSR = ~p\n", [CRngs, STRng]),
+  ?debug("CR = ~p\nSR = ~p\n", [CRngs, STRng]),
   case [CR || CR <- CRngs, erl_types:t_is_none(erl_types:t_inf(CR, STRng, opaque))] of
     [] -> ok;
     CRs -> {error, {extra_range, erl_types:t_sup(CRs), STRng}}
@@ -444,7 +444,21 @@ get_invalid_contract_warnings_funs([{MFA, {FileLine, Contract}}|Left],
 	  {error, invalid_contract} ->
 	    [invalid_contract_warning(MFA, FileLine, Sig, RecDict)|Acc];
 	  {error, {extra_range, ExtraRanges, STRange}} ->
-	    [extra_range_warning(MFA, FileLine, ExtraRanges, STRange)|Acc];
+	    Warn =
+	      case t_from_forms_without_remote(Contract#contract.forms,
+					       RecDict) of
+		{ok, NoRemoteType} ->
+		  CRet = erl_types:t_fun_range(NoRemoteType),
+		  erl_types:t_is_subtype(ExtraRanges, CRet);
+		unsupported ->
+		  true
+	      end,
+	    case Warn of
+	      true ->
+		[extra_range_warning(MFA, FileLine, ExtraRanges, STRange)|Acc];
+	      false ->
+		Acc
+	    end;
 	  {error, Msg} ->
 	    [{?WARN_CONTRACT_SYNTAX, FileLine, Msg}|Acc];
 	  ok ->
@@ -507,26 +521,92 @@ picky_contract_check(CSig0, Sig0, MFA, FileLine, Contract, RecDict, Acc) ->
 extra_contract_warning({M, F, A}, FileLine, Contract, CSig, Sig, RecDict) ->
   SigString = lists:flatten(dialyzer_utils:format_sig(Sig, RecDict)),
   ContractString0 = lists:flatten(dialyzer_utils:format_sig(CSig, RecDict)),
-  case SigString =:= ContractString0 of
+  %% The only difference is in record fields containing 'undefined' or not.
+  IsUndefRecordFieldsRelated = SigString =:= ContractString0,
+  {IsRemoteTypesRelated, SubtypeRelation} =
+    is_remote_types_related(Contract, CSig, Sig, RecDict),
+  case IsUndefRecordFieldsRelated orelse IsRemoteTypesRelated of
     true ->
-      %% The only difference is in record fields containing 'undefined' or not.
       no_warning;
     false ->
       ContractString = contract_to_string(Contract),
       {Tag, Msg} =
-	case erl_types:t_is_subtype(CSig, Sig) of
-	  true ->
+	case SubtypeRelation of
+	  contract_is_subtype ->
 	    {?WARN_CONTRACT_SUBTYPE,
 	     {contract_subtype, [M, F, A, ContractString, SigString]}};
-	  false ->
-	    case erl_types:t_is_subtype(Sig, CSig) of
-	      true ->
-		{?WARN_CONTRACT_SUPERTYPE,
-		 {contract_supertype, [M, F, A, ContractString, SigString]}};
-	      false ->
-		{?WARN_CONTRACT_NOT_EQUAL,
-		 {contract_diff, [M, F, A, ContractString, SigString]}}
-	    end
+	  contract_is_supertype ->
+	    {?WARN_CONTRACT_SUPERTYPE,
+	     {contract_supertype, [M, F, A, ContractString, SigString]}};
+	  neither ->
+	    {?WARN_CONTRACT_NOT_EQUAL,
+	     {contract_diff, [M, F, A, ContractString, SigString]}}
 	end,
       {warning, {Tag, FileLine, Msg}}
   end.
+
+is_remote_types_related(Contract, CSig, Sig, RecDict) ->
+  case erl_types:t_is_subtype(CSig, Sig) of
+    true ->
+      {false, contract_is_subtype};
+    false ->
+      case erl_types:t_is_subtype(Sig, CSig) of
+	true ->
+	  case t_from_forms_without_remote(Contract#contract.forms, RecDict) of
+	    {ok, NoRemoteTypeSig} ->
+	      case blame_remote(CSig, NoRemoteTypeSig, Sig) of
+		true ->
+		  {true, neither};
+		false ->
+		  {false, contract_is_supertype}
+	      end;
+	    unsupported ->
+	      {false, contract_is_supertype}
+	  end;
+	false ->
+	  {false, neither}
+      end
+  end.
+
+t_from_forms_without_remote([{FType, []}], RecDict) ->
+  Type0 = erl_types:t_from_form(FType, RecDict),
+  Map =
+    fun(Type) ->
+	case erl_types:t_is_remote(Type) of
+	  true -> erl_types:t_none();
+	  false -> Type
+	end
+    end,
+  {ok, erl_types:t_map(Map, Type0)};
+t_from_forms_without_remote([{_FType, _Constrs}], _RecDict) ->
+  %% 'When' constraints
+  unsupported;
+t_from_forms_without_remote(_Forms, _RecDict) ->
+  %% Lots of forms
+  unsupported.
+
+blame_remote(ContractSig, NoRemoteContractSig, Sig) ->
+  CArgs  = erl_types:t_fun_args(ContractSig),
+  CRange = erl_types:t_fun_range(ContractSig),
+  NRArgs = erl_types:t_fun_args(NoRemoteContractSig),
+  NRRange = erl_types:t_fun_range(NoRemoteContractSig),
+  SArgs = erl_types:t_fun_args(Sig),
+  SRange = erl_types:t_fun_range(Sig),
+  blame_remote_list([CRange|CArgs], [NRRange|NRArgs], [SRange|SArgs]).
+
+blame_remote_list([], [], []) ->
+  true;
+blame_remote_list([CArg|CArgs], [NRArg|NRArgs], [SArg|SArgs]) ->
+  case erl_types:t_is_equal(CArg, NRArg) of
+    true ->
+      case not erl_types:t_is_equal(CArg, SArg) of
+	true  -> false;
+	false -> blame_remote_list(CArgs, NRArgs, SArgs)
+      end;
+    false ->
+      case erl_types:t_is_subtype(SArg, NRArg)
+	andalso not erl_types:t_is_subtype(NRArg, SArg) of
+	true  -> false;
+	false -> blame_remote_list(CArgs, NRArgs, SArgs)
+      end
+  end.
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