Merge pull request #5195 from ethereum/unsigned-array-index

Do not crash on non-unsigned array index

2 files changed, 6 insertions, 3 deletions

diff --git a/libsolidity/analysis/TypeChecker.cpp b/libsolidity/analysis/TypeChecker.cpp
index 5ffdda57..069be156 100644
--- a/libsolidity/analysis/TypeChecker.cpp
+++ b/libsolidity/analysis/TypeChecker.cpp
@@ -2316,7 +2316,8 @@ bool TypeChecker::visit(IndexAccess const& _access)
 			m_errorReporter.typeError(_access.location(), "Index expression cannot be omitted.");
 		else
 		{
-			expectType(*index, IntegerType(256));
+			if (!expectType(*index, IntegerType(256)))
+				m_errorReporter.fatalTypeError(_access.location(), "Index expression cannot be represented as an unsigned integer.");
 			if (auto integerType = dynamic_cast<RationalNumberType const*>(type(*index).get()))
 				if (bytesType.numBytes() <= integerType->literalValue(nullptr))
 					m_errorReporter.typeError(_access.location(), "Out of bounds array access.");
@@ -2487,7 +2488,7 @@ Declaration const& TypeChecker::dereference(UserDefinedTypeName const& _typeName
 	return *_typeName.annotation().referencedDeclaration;
 }
 
-void TypeChecker::expectType(Expression const& _expression, Type const& _expectedType)
+bool TypeChecker::expectType(Expression const& _expression, Type const& _expectedType)
 {
 	_expression.accept(*this);
 	if (!type(_expression)->isImplicitlyConvertibleTo(_expectedType))
@@ -2516,7 +2517,9 @@ void TypeChecker::expectType(Expression const& _expression, Type const& _expecte
 				_expectedType.toString() +
 				"."
 			);
+		return false;
 	}
+	return true;
 }
 
 void TypeChecker::requireLValue(Expression const& _expression)
diff --git a/libsolidity/analysis/TypeChecker.h b/libsolidity/analysis/TypeChecker.h
index 8d25a88e..6ea99ca2 100644
--- a/libsolidity/analysis/TypeChecker.h
+++ b/libsolidity/analysis/TypeChecker.h
@@ -143,7 +143,7 @@ private:
 
 	/// Runs type checks on @a _expression to infer its type and then checks that it is implicitly
 	/// convertible to @a _expectedType.
-	void expectType(Expression const& _expression, Type const& _expectedType);
+	bool expectType(Expression const& _expression, Type const& _expectedType);
 	/// Runs type checks on @a _expression to infer its type and then checks that it is an LValue.
 	void requireLValue(Expression const& _expression);