From 21dee1c8ba42d392d3f39dffdcffa9ee87c20a79 Mon Sep 17 00:00:00 2001
From: chriseth <chris@ethereum.org>
Date: Tue, 29 Sep 2020 16:23:45 +0200
Subject: [PATCH] Check for circular constants across contracts.

---
 libsolidity/analysis/PostTypeChecker.cpp | 37 +++++++++++++++++-------
 libsolidity/analysis/PostTypeChecker.h   |  7 +++++
 libsolidity/interface/CompilerStack.cpp  |  2 ++
 3 files changed, 36 insertions(+), 10 deletions(-)

diff --git a/libsolidity/analysis/PostTypeChecker.cpp b/libsolidity/analysis/PostTypeChecker.cpp
index 47be22810..4699a0b14 100644
--- a/libsolidity/analysis/PostTypeChecker.cpp
+++ b/libsolidity/analysis/PostTypeChecker.cpp
@@ -38,6 +38,13 @@ bool PostTypeChecker::check(ASTNode const& _astRoot)
 	return Error::containsOnlyWarnings(m_errorReporter.errors());
 }
 
+bool PostTypeChecker::finalize()
+{
+	for (auto& checker: m_checkers)
+		checker->finalize();
+	return Error::containsOnlyWarnings(m_errorReporter.errors());
+}
+
 bool PostTypeChecker::visit(ContractDefinition const& _contractDefinition)
 {
 	return callVisit(_contractDefinition);
@@ -83,6 +90,11 @@ bool PostTypeChecker::visit(Identifier const& _identifier)
 	return callVisit(_identifier);
 }
 
+bool PostTypeChecker::visit(MemberAccess const& _memberAccess)
+{
+	return callVisit(_memberAccess);
+}
+
 bool PostTypeChecker::visit(StructDefinition const& _struct)
 {
 	return callVisit(_struct);
@@ -110,14 +122,7 @@ struct ConstStateVarCircularReferenceChecker: public PostTypeChecker::Checker
 	ConstStateVarCircularReferenceChecker(ErrorReporter& _errorReporter):
 		Checker(_errorReporter) {}
 
-	bool visit(ContractDefinition const&) override
-	{
-		solAssert(!m_currentConstVariable, "");
-		solAssert(m_constVariableDependencies.empty(), "");
-		return true;
-	}
-
-	void endVisit(ContractDefinition const&) override
+	void finalize() override
 	{
 		solAssert(!m_currentConstVariable, "");
 		for (auto declaration: m_constVariables)
@@ -128,9 +133,12 @@ struct ConstStateVarCircularReferenceChecker: public PostTypeChecker::Checker
 					"The value of the constant " + declaration->name() +
 					" has a cyclic dependency via " + identifier->name() + "."
 				);
+	}
 
-		m_constVariables.clear();
-		m_constVariableDependencies.clear();
+	bool visit(ContractDefinition const&) override
+	{
+		solAssert(!m_currentConstVariable, "");
+		return true;
 	}
 
 	bool visit(VariableDeclaration const& _variable) override
@@ -162,6 +170,15 @@ struct ConstStateVarCircularReferenceChecker: public PostTypeChecker::Checker
 		return true;
 	}
 
+	bool visit(MemberAccess const& _memberAccess) override
+	{
+		if (m_currentConstVariable)
+			if (auto var = dynamic_cast<VariableDeclaration const*>(_memberAccess.annotation().referencedDeclaration))
+				if (var->isConstant())
+					m_constVariableDependencies[m_currentConstVariable].insert(var);
+		return true;
+	}
+
 	VariableDeclaration const* findCycle(VariableDeclaration const& _startingFrom)
 	{
 		auto visitor = [&](VariableDeclaration const& _variable, util::CycleDetector<VariableDeclaration>& _cycleDetector, size_t _depth)
diff --git a/libsolidity/analysis/PostTypeChecker.h b/libsolidity/analysis/PostTypeChecker.h
index d3f23918c..c4745d279 100644
--- a/libsolidity/analysis/PostTypeChecker.h
+++ b/libsolidity/analysis/PostTypeChecker.h
@@ -54,6 +54,9 @@ public:
 	{
 		Checker(langutil::ErrorReporter& _errorReporter):
 			m_errorReporter(_errorReporter) {}
+
+		/// Called after all source units have been visited.
+		virtual void finalize() {}
 	protected:
 		langutil::ErrorReporter& m_errorReporter;
 	};
@@ -63,6 +66,9 @@ public:
 
 	bool check(ASTNode const& _astRoot);
 
+	/// Called after all source units have been visited.
+	bool finalize();
+
 private:
 	bool visit(ContractDefinition const& _contract) override;
 	void endVisit(ContractDefinition const& _contract) override;
@@ -77,6 +83,7 @@ private:
 	bool visit(FunctionCall const& _functionCall) override;
 
 	bool visit(Identifier const& _identifier) override;
+	bool visit(MemberAccess const& _identifier) override;
 
 	bool visit(StructDefinition const& _struct) override;
 	void endVisit(StructDefinition const& _struct) override;
diff --git a/libsolidity/interface/CompilerStack.cpp b/libsolidity/interface/CompilerStack.cpp
index 58ac8abec..1dae2b00e 100644
--- a/libsolidity/interface/CompilerStack.cpp
+++ b/libsolidity/interface/CompilerStack.cpp
@@ -387,6 +387,8 @@ bool CompilerStack::analyze()
 			for (Source const* source: m_sourceOrder)
 				if (source->ast && !postTypeChecker.check(*source->ast))
 					noErrors = false;
+			if (!postTypeChecker.finalize())
+				noErrors = false;
 		}
 
 		// Check that immutable variables are never read in c'tors and assigned