Having multiple `using namespace` statements in one Jupyter cell doesn't work properly

[Ian Holst]

To Reproduce

I'm using the Jupyter kernel included in Cling, not xeus-cling. For example, run in the first cell:

#include <iostream>
#include <chrono>

using namespace std;
using namespace std::chrono;

Then in the second cell, I access something from the second namespace, std::chrono:

system_clock c;

I would expect this to successfully declare the variable and give no output, but instead Cling gives an error indicating that the std::chrono namespace has not been made available:

input_line_4:2:2: error: unknown type name 'system_clock'; did you mean 'std::chrono::system_clock'?
 system_clock c;
 ^~~~~~~~~~~~
 std::chrono::system_clock
/usr/include/c++/11/chrono:1125:12: note: 'std::chrono::system_clock' declared here
    struct system_clock
           ^
ename: evalue

This same code works fine in the Cling command line interpreter, where things are not split up into cells.

I know that the first using namespace worked, since I can use just cout << "test"; with no problem in later cells. Doing more tests (with code other than the C++ standard library), it looks like only the first using namespace is processed correctly by Cling, and all later ones in the same cell are ignored.

Setup

1. Cling version 0.9
2. Operating system: Ubuntu 22.04
3. I built Cling myself from source.

[Ian Holst]

I've confirmed that this is also an issue for the xeus-cling kernel. Here is a screenshot: