Remove the use of GPL lbraries (readline, gsl)

[isuruf]

I didn't see this at the code review, but ZIB and GPL don't go together. So, please remove GPL dependencies. This issue is mentioned in https://www.scipopt.org/index.php#license.

cc @conda-forge/core

[AntoinePrv]

Thanks for pointing this out @isuruf. Does it change anything if the libraries are linked dynamically?

[AntoinePrv]

@isuruf actually, gsl is used only in for the gcg subpackage, which is licensed under LGPL
https://gcg.or.rwth-aachen.de/#license

But it is not possible to have licenses for outputs in conda-build. We can add again gsl and package the LGPL license for gcg.

[isuruf]

gsl is used only in for the gcg subpackage, which is licensed under LGPL

But gcg has scip as a dependency right?

[AntoinePrv]

Yes. Would that prevent it from from using LGPL dependencies?

Python itself seems to be using readline, would that mean it's forbidden to distribute proprietary native Python packages?
I argree we should not link SCIP with readline, but in the case of gcg with gsl it does not seem so clear to me.

[AntoinePrv]

Or perhaps, looking at it the other way, we could ask the ZIB team the licensing more details about the implications to dynamically link against scip.

[isuruf]

Yes. Would that prevent it from from using LGPL dependencies?

IANAL, so can't say it does or not. To be on the safe side we could remove GSL.

cc @conda-forge/core