Cannot drop a lock in `throw_exception_internal` (#55) · Issues · mu / mu-impl-fast

Cannot drop a lock in `throw_exception_internal`

In my latest commit, I have modified the structure of the exception table (so that it dosn't use unsafe pointers, and in order to fix Issue #53 (closed) ). In throw_exception_internal I acquire a read lock the compiled_callsite_table, we wan't this lock to be realesed before calling exception_restore, however the borrow checker won't let me:

error[E0505]: cannot move out of `compiled_callsite_table` because it is borrowed
  --> src/runtime/exception.rs:89:18
   |
65 |             let table_entry = compiled_callsite_table.get(&callsite);
   |                               ----------------------- borrow of `compiled_callsite_table` occurs here
...
89 |             drop(compiled_callsite_table); // drop the lock first
   |                  ^^^^^^^^^^^^^^^^^^^^^^^ move out of `compiled_callsite_table` occurs here

So I have commented out line 89, and things seam to work. The function exception_restore is marked as non-returning, so perhaps the rust compiler is smart enough to do the drop for us, if it isn't, we will get a deadlock if someone tries to acquire a write lock once an exception has been thrown (however currently we only modify the table once at startup, before any exceptions are thrown, so this won't occur).

In my latest commit, I have modified the structure of the exception table (so that it dosn't use unsafe pointers, and in order to fix Issue #53 ).
In `throw_exception_internal` I acquire a read lock the `compiled_callsite_table`, we wan't this lock to be realesed before calling `exception_restore`, however the borrow checker won't let me:

```
error[E0505]: cannot move out of `compiled_callsite_table` because it is borrowed
  --> src/runtime/exception.rs:89:18
   |
65 |             let table_entry = compiled_callsite_table.get(&callsite);
   |                               ----------------------- borrow of `compiled_callsite_table` occurs here
...
89 |             drop(compiled_callsite_table); // drop the lock first
   |                  ^^^^^^^^^^^^^^^^^^^^^^^ move out of `compiled_callsite_table` occurs here

```

So I have commented out line 89, and things seam to work.
The function `exception_restore` is marked as non-returning, so perhaps the rust compiler is smart enough to do the drop for us, if it isn't, we will get a deadlock if  someone tries to acquire a write lock once an exception has been thrown (however currently we only modify the table once at startup, before any exceptions are thrown, so this won't occur).