Incorrect code-generation when using CartesianProduct together with NoConstraint in a certain way for bound constraints

[itsmathtime]

Describe the bug When I combine CartesianProduct with NoConstraint in a certain way I am able to generate code that triggers the assert at src/constraints/cartesian_product.rs:139. Even though all inputs and constraints are well formed. To me it looks like there is an assumption that NoConstraint is not used with CartesianProduct, which is a bug.

To Reproduce

Steps to reproduce the behavior:

1. Run the attached code trigger_opengen_error.txt

Expected behavior

As far as I understand, the problem is well posed, and the code-generation should not generate code that triggers the assertion at src/constraints/cartesian_product.rs:139

System information:

• System/Platform: Laptop

• OS: [e.g. Ubuntu, iOS, Windows, Raspbian, etc] Ubuntu 19.04

• What is the output of rustup show?

  
  Default host: x86_64-unknown-linux-gnu
  rustup home:  /home/myuser/.rustup

nightly-x86_64-unknown-linux-gnu (default) rustc 1.43.0-nightly (7cdbc87a4 2020-03-14)

 - What is the output of `rustc -V`?
`rustc 1.43.0-nightly (7cdbc87a4 2020-03-14)`

 - Python/MATLAB version if relevant
Using python 3.7

[alphaville]

Apologies for the delay. I've confirmed the issue and will try to fix it soon.

[alphaville]

After a closer look, I found the problem. In you code you should write:

cstrs = [og.constraints.NoConstraints(),
         og.constraints.NoConstraints(),
         og.constraints.Ball2(None, 1.5),
         og.constraints.NoConstraints(),
         og.constraints.NoConstraints()]

You had omitted the parentheses. The difference is that og.constraints.NoConstraints() is an object of type og.constraints.NoConstraints, whereas og.constraints.NoConstraints is the corresponding class.

In your example you might want to rethink your segment ids. You can also combine the sets of type NoConstraints into a single instance of NoConstraints if you like. You may find more information about it here.

I will update the documentation with some additional examples.