More detailed errors for invalid array lengths (such as division by zero).

3 files changed, 27 insertions, 3 deletions

diff --git a/Changelog.md b/Changelog.md
index 68b9973f..e691711b 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -2,6 +2,7 @@
 
 Features:
  * Syntax Checker: Turn the usage of ``callcode`` into an error as experimental 0.5.0 feature.
+ * Type Checker: More detailed errors for invalid array lengths (such as division by zero).
 
 Bugfixes:
 
diff --git a/libsolidity/analysis/ConstantEvaluator.cpp b/libsolidity/analysis/ConstantEvaluator.cpp
index 6636ad97..bc3b7cf1 100644
--- a/libsolidity/analysis/ConstantEvaluator.cpp
+++ b/libsolidity/analysis/ConstantEvaluator.cpp
@@ -28,6 +28,7 @@ using namespace std;
 using namespace dev;
 using namespace dev::solidity;
 
+/// FIXME: this is pretty much a copy of TypeChecker::endVisit(BinaryOperation)
 void ConstantEvaluator::endVisit(UnaryOperation const& _operation)
 {
 	TypePointer const& subType = _operation.subExpression().annotation().type;
@@ -37,6 +38,7 @@ void ConstantEvaluator::endVisit(UnaryOperation const& _operation)
 	_operation.annotation().type = t;
 }
 
+/// FIXME: this is pretty much a copy of TypeChecker::endVisit(BinaryOperation)
 void ConstantEvaluator::endVisit(BinaryOperation const& _operation)
 {
 	TypePointer const& leftType = _operation.leftExpression().annotation().type;
@@ -46,9 +48,24 @@ void ConstantEvaluator::endVisit(BinaryOperation const& _operation)
 	if (!dynamic_cast<RationalNumberType const*>(rightType.get()))
 		m_errorReporter.fatalTypeError(_operation.rightExpression().location(), "Invalid constant expression.");
 	TypePointer commonType = leftType->binaryOperatorResult(_operation.getOperator(), rightType);
-	if (Token::isCompareOp(_operation.getOperator()))
-		commonType = make_shared<BoolType>();
-	_operation.annotation().type = commonType;
+	if (!commonType)
+	{
+		m_errorReporter.typeError(
+			_operation.location(),
+			"Operator " +
+			string(Token::toString(_operation.getOperator())) +
+			" not compatible with types " +
+			leftType->toString() +
+			" and " +
+			rightType->toString()
+		);
+		commonType = leftType;
+	}
+	_operation.annotation().commonType = commonType;
+	_operation.annotation().type =
+		Token::isCompareOp(_operation.getOperator()) ?
+		make_shared<BoolType>() :
+		commonType;
 }
 
 void ConstantEvaluator::endVisit(Literal const& _literal)
diff --git a/test/libsolidity/SolidityNameAndTypeResolution.cpp b/test/libsolidity/SolidityNameAndTypeResolution.cpp
index 9b5ea349..e5990e9b 100644
--- a/test/libsolidity/SolidityNameAndTypeResolution.cpp
+++ b/test/libsolidity/SolidityNameAndTypeResolution.cpp
@@ -7247,6 +7247,12 @@ BOOST_AUTO_TEST_CASE(array_length_invalid_expression)
 		}
 	)";
 	CHECK_ERROR(text, TypeError, "Invalid literal value.");
+	text = R"(
+		contract C {
+			uint[3/0] ids;
+		}
+	)";
+	CHECK_ERROR(text, TypeError, "Operator / not compatible with types int_const 3 and int_const 0");
 }
 
 BOOST_AUTO_TEST_CASE(no_address_members_on_contract)