From b2b45cc97bd02de1461cd14fe867aa3e03749c29 Mon Sep 17 00:00:00 2001
From: Mathias Baumann <git@supradigital.org>
Date: Mon, 2 Mar 2020 16:21:03 +0100
Subject: [PATCH] Ensure contract order in suggestion is equal to inheritance
 order

---
 libsolidity/analysis/OverrideChecker.cpp      | 21 +++++++++++++------
 libsolidity/analysis/OverrideChecker.h        |  2 +-
 .../interface/overrides_multiple.sol          |  7 ++++---
 3 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/libsolidity/analysis/OverrideChecker.cpp b/libsolidity/analysis/OverrideChecker.cpp
index 67862f7cd..f5c247afb 100644
--- a/libsolidity/analysis/OverrideChecker.cpp
+++ b/libsolidity/analysis/OverrideChecker.cpp
@@ -565,18 +565,17 @@ void OverrideChecker::checkOverride(OverrideProxy const& _overriding, OverridePr
 
 void OverrideChecker::overrideListError(
 	OverrideProxy const& _item,
-	set<ContractDefinition const*, CompareByID> _secondary,
+	vector<ContractDefinition const*> _secondary,
 	string const& _message1,
 	string const& _message2
 )
 {
-	// Using a set rather than a vector so the order is always the same
-	set<string> names;
+	vector<string> names;
 	SecondarySourceLocation ssl;
 	for (Declaration const* c: _secondary)
 	{
 		ssl.append("This contract: ", c->location());
-		names.insert("\"" + c->name() + "\"");
+		names.emplace_back("\"" + c->name() + "\"");
 	}
 	string contractSingularPlural = "contract ";
 	if (_secondary.size() > 1)
@@ -823,18 +822,28 @@ void OverrideChecker::checkOverrideList(OverrideProxy _item, OverrideProxyBySign
 		missingContracts = expectedContracts - specifiedContracts;
 
 	if (!missingContracts.empty())
+	{
+		vector<ContractDefinition const*> sortedMissingContracts;
+		for (size_t i = _item.contract().annotation().linearizedBaseContracts.size() - 1; i > 0; i--)
+		{
+			auto contract = _item.contract().annotation().linearizedBaseContracts[i];
+			if (missingContracts.count(contract))
+				sortedMissingContracts.emplace_back(contract);
+		}
+
 		overrideListError(
 			_item,
-			missingContracts,
+			sortedMissingContracts,
 			_item.astNodeNameCapitalized() + " needs to specify overridden ",
 			""
 		);
+	}
 
 	auto surplusContracts = specifiedContracts - expectedContracts;
 	if (!surplusContracts.empty())
 		overrideListError(
 			_item,
-			surplusContracts,
+			util::convertContainer<vector<ContractDefinition const*>>(surplusContracts),
 			"Invalid ",
 			"specified in override list: "
 		);
diff --git a/libsolidity/analysis/OverrideChecker.h b/libsolidity/analysis/OverrideChecker.h
index 0c57ccd65..b78aa3c84 100644
--- a/libsolidity/analysis/OverrideChecker.h
+++ b/libsolidity/analysis/OverrideChecker.h
@@ -157,7 +157,7 @@ private:
 	void checkOverride(OverrideProxy const& _overriding, OverrideProxy const& _super);
 	void overrideListError(
 		OverrideProxy const& _item,
-		std::set<ContractDefinition const*, CompareByID> _secondary,
+		std::vector<ContractDefinition const*> _secondary,
 		std::string const& _message1,
 		std::string const& _message2
 	);
diff --git a/test/libsolidity/syntaxTests/inheritance/interface/overrides_multiple.sol b/test/libsolidity/syntaxTests/inheritance/interface/overrides_multiple.sol
index 36d76f3a8..c037eb54d 100644
--- a/test/libsolidity/syntaxTests/inheritance/interface/overrides_multiple.sol
+++ b/test/libsolidity/syntaxTests/inheritance/interface/overrides_multiple.sol
@@ -14,7 +14,7 @@ interface SuperB {
     function test5() external returns (uint256);
 }
 
-interface Sub is SuperA, SuperB {
+interface Sub is SuperB, SuperA {
     function test1() external returns (uint256);
     function test2() external override returns (uint256);
     function test3() external override(SuperA) returns (uint256);
@@ -25,7 +25,8 @@ interface Sub is SuperA, SuperB {
 // ----
 // TypeError: (572-616): Overriding function is missing "override" specifier.
 // TypeError: (572-616): Overriding function is missing "override" specifier.
-// TypeError: (572-616): Function needs to specify overridden contracts "SuperA" and "SuperB".
-// TypeError: (647-655): Function needs to specify overridden contracts "SuperA" and "SuperB".
+// TypeError: (572-616): Function needs to specify overridden contracts "SuperB" and "SuperA".
+// TypeError: (647-655): Function needs to specify overridden contracts "SuperB" and "SuperA".
 // TypeError: (705-721): Function needs to specify overridden contract "SuperB".
 // TypeError: (771-787): Function needs to specify overridden contract "SuperA".
+// Warning: (837-861): Override specifier list order differs from inheritance order.