Disallow unary plus at the parsing stage

libsolidity/analysis/SyntaxChecker.cpp

@@ -332,9 +332,7 @@ bool SyntaxChecker::visit(Literal const& _literal)
 
 bool SyntaxChecker::visit(UnaryOperation const& _operation)
 {
-	if (_operation.getOperator() == Token::Add)
-		m_errorReporter.syntaxError(9636_error, _operation.location(), "Use of unary + is disallowed.");
-
+	solAssert(_operation.getOperator() != Token::Add);
 	return true;
 }
 

libsolidity/ast/Types.cpp

@@ -819,16 +819,17 @@ BoolResult FixedPointType::isExplicitlyConvertibleTo(Type const& _convertTo) con
 
 TypeResult FixedPointType::unaryOperatorResult(Token _operator) const
 {
+	solAssert(_operator != Token::Add);
+
 	switch (_operator)
 	{
 	case Token::Delete:
 		// "delete" is ok for all fixed types
 		return TypeResult{TypeProvider::emptyTuple()};
-	case Token::Add:
 	case Token::Sub:
 	case Token::Inc:
 	case Token::Dec:
-		// for fixed, we allow +, -, ++ and --
+		// for fixed, we allow -, ++ and --
 		return this;
 	default:
 		return nullptr;

libsolidity/codegen/ExpressionCompiler.cpp

@@ -511,8 +511,8 @@ bool ExpressionCompiler::visit(UnaryOperation const& _unaryOperation)
 		m_currentLValue.reset();
 		break;
 	case Token::Add: // +
-		// unary add, so basically no-op
-		break;
+		// According to SyntaxChecker...
+		solAssert(false, "Use of unary + is disallowed.");
 	case Token::Sub: // -
 		solUnimplementedAssert(
 			type.category() != Type::Category::FixedPoint,

libsolidity/parsing/Parser.cpp

@@ -1863,6 +1863,10 @@ ASTPointer<Expression> Parser::parseUnaryExpression(
 	ASTNodeFactory nodeFactory = _partiallyParsedExpression ?
 		ASTNodeFactory(*this, _partiallyParsedExpression) : ASTNodeFactory(*this);
 	Token token = m_scanner->currentToken();
+
+	if (token == Token::Add)
+		fatalParserError(9636_error, "Use of unary + is disallowed.");
+
 	if (!_partiallyParsedExpression && (TokenTraits::isUnaryOp(token) || TokenTraits::isCountOp(token)))
 	{
 		// prefix expression