it's a very valid warning, and in 99 out of 100 times it would be unsafe. but this is the 1 time when it's not. - Joel

```
clang++ -Wall -Werror -I/home/ghorn/casadi/symbolic -c cbits/gen/test.cpp -o cbits/gen/test.o
cbits/gen/test.cpp:11:5: error: delete called on 'CasADi::FX' that has virtual functions but non-virtual
      destructor [-Werror,-Wdelete-non-virtual-dtor]
```