Fix a null dereference when casting a value to a unit type.
ChangeLog
2018-04-28 Dan Robertson <danlrobertson89@gmail.com>
PR rust/23124
* gdb/rust-exp.y (convert_params_to_types): Ensure that the params
pointer is not null before dereferencing it.
testsuite/ChangeLog
2018-04-28 Dan Robertson <danlrobertson89@gmail.com>
PR rust/23124
* gdb.rust/expr.exp: Test that the unit type is correctly parsed
when casting.