From d102deaec90f6f5bfe38140b459a05215d3254f9 Mon Sep 17 00:00:00 2001
From: Balajiganapathi S <balajiganapathi.s@gmail.com>
Date: Fri, 17 Nov 2017 22:25:07 +0530
Subject: Detect cyclic constant definitions

---
 libsolidity/analysis/ConstantEvaluator.cpp | 16 ++++++++++------
 libsolidity/analysis/ConstantEvaluator.h   |  7 +++++--
 2 files changed, 15 insertions(+), 8 deletions(-)

(limited to 'libsolidity/analysis')

diff --git a/libsolidity/analysis/ConstantEvaluator.cpp b/libsolidity/analysis/ConstantEvaluator.cpp
index 50044eb6..cb8bbc05 100644
--- a/libsolidity/analysis/ConstantEvaluator.cpp
+++ b/libsolidity/analysis/ConstantEvaluator.cpp
@@ -77,18 +77,22 @@ void ConstantEvaluator::endVisit(Literal const& _literal)
 
 void ConstantEvaluator::endVisit(Identifier const& _identifier)
 {
-	VariableDeclaration const *variableDeclaration = dynamic_cast<VariableDeclaration const *>(_identifier.annotation().referencedDeclaration);
+	VariableDeclaration const* variableDeclaration = dynamic_cast<VariableDeclaration const*>(_identifier.annotation().referencedDeclaration);
 	if (!variableDeclaration)
 		return;
 	if (!variableDeclaration->isConstant())
 		m_errorReporter.fatalTypeError(_identifier.location(), "Identifier must be declared constant.");
 
 	ASTPointer<Expression> value = variableDeclaration->value();
-	if (value)
-	{
-		if (!value->annotation().type)
-			ConstantEvaluator e(*value, m_errorReporter);
+	if (!value)
+		m_errorReporter.fatalTypeError(_identifier.location(), "Constant identifier declaration must have a constant value.");
 
-		_identifier.annotation().type = value->annotation().type;
+	if (!value->annotation().type)
+	{
+		if (m_depth > 32)
+			m_errorReporter.fatalTypeError(_identifier.location(), "Cyclic constant definition.");
+		ConstantEvaluator e(*value, m_errorReporter, m_depth + 1);
 	}
+
+	_identifier.annotation().type = value->annotation().type;
 }
diff --git a/libsolidity/analysis/ConstantEvaluator.h b/libsolidity/analysis/ConstantEvaluator.h
index 42ccfe7e..6725d610 100644
--- a/libsolidity/analysis/ConstantEvaluator.h
+++ b/libsolidity/analysis/ConstantEvaluator.h
@@ -38,8 +38,9 @@ class TypeChecker;
 class ConstantEvaluator: private ASTConstVisitor
 {
 public:
-	ConstantEvaluator(Expression const& _expr, ErrorReporter& _errorReporter):
-		m_errorReporter(_errorReporter)
+	ConstantEvaluator(Expression const& _expr, ErrorReporter& _errorReporter, size_t _newDepth = 0):
+		m_errorReporter(_errorReporter),
+		m_depth(_newDepth)
 	{
 		_expr.accept(*this);
 	}
@@ -51,6 +52,8 @@ private:
 	virtual void endVisit(Identifier const& _identifier);
 
 	ErrorReporter& m_errorReporter;
+	/// Current recursion depth.
+	size_t m_depth;
 };
 
 }
-- 
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