Patch codegen ICE due to unneeded variable for functions that return no parameters

Author: cameel

Diff for: libsolidity/experimental/codegen/IRGeneratorForStatements.cpp

@@ -323,7 +323,9 @@ void IRGeneratorForStatements::endVisit(FunctionCall const& _functionCall)
 	functionType = m_context.env->resolveRecursive(functionType);
 	m_context.enqueueFunctionDefinition(functionDefinition, functionType);
 	// TODO: account for return stack size
-	m_code << "let " << IRNames::localVariable(_functionCall) << " := " << IRNames::function(*m_context.env, *functionDefinition, functionType) << "(";
+	if (functionDefinition->returnParameterList() && !functionDefinition->returnParameterList()->parameters().empty())
+		m_code << "let " << IRNames::localVariable(_functionCall) << " := ";
+	m_code << IRNames::function(*m_context.env, *functionDefinition, functionType) << "(";
 	auto const& arguments = _functionCall.arguments();
 	if (arguments.size() > 1)
 		for (auto arg: arguments | ranges::views::drop_last(1))