Don‘t they ring fence the pension money from the other social fiscus?
From what I understand the issue is more around France having declining birth rates, and people living longer and using up more pension money.
Not having enough young workers to support the older ones with their contributions is the main issue they are trying to solve.
So one way to solve it is to raise the pension age. Another solution is to get more young migrants to make up for the low birth rates.
The migrants will obviously be a drain on other resources until they are hopefully able to contribute more than they cost.