Why is IQS not building after April 2021 release? Add "iqs" namespace.

[giangiac]

Hi all, I opened this issue as a way to communicate with all users.
In April 2021 we released IQS 2.1.0
This version includes new features and examples (see CHANGELOG for a short list), but also some code cleaning.
As part of adopting good coding practices, we collect all IQS class and methods in namespace "iqs".
If you have problems re-building previous projects, this may be the reason.

The fix is simple. In C++, when declaring a new QubitRegister object just use:
QubitRegister(...) ---> iqs::QubitRegister(...)

[mbuchberger1967]

I used the name 'iqs' myself as a sub-namespace in my project's namespace structure.
This can be fixed by using the ::iqs::QubitRegister to access the new top-level namespace 'iqs'.

[giangiac]

Is it enough to use ::iqs::QubitRegister in your project's code, or should the leading "::" be used in this repository's (i.e. intel-qs) code too?

[mbuchberger1967]

It is enough to use ::iqs::QubitRegister in my code. Just as a hint for others, if they run into a similar problem.