rt: Make rust_task::ref_count private

src/rt/rust_internal.h

@@ -105,8 +105,9 @@ static size_t const BUF_BYTES = 2048;
   void deref() { if (--ref_count == 0) { dtor; } }
 
 #define RUST_ATOMIC_REFCOUNT()                                            \
-public:                                                                   \
+private:                                                                  \
    intptr_t ref_count;                                                    \
+public:                                                                   \
    void ref() {                                                           \
        intptr_t old = sync::increment(ref_count);                         \
        assert(old > 0);                                                   \

src/rt/rust_kernel.cpp

@@ -190,6 +190,7 @@ rust_kernel::get_task_by_id(rust_task_id id) {
     task_table.get(id, &task);
     if(task) {
         if(task->get_ref_count() == 0) {
+            // FIXME: I don't think this is possible.
             // this means the destructor is running, since the destructor
             // grabs the kernel lock to unregister the task. Pretend this
             // doesn't actually exist.

src/rt/rust_task_thread.cpp

@@ -149,7 +149,7 @@ rust_task_thread::reap_dead_tasks() {
 void
 rust_task_thread::release_task(rust_task *task) {
     // Nobody should have a ref to the task at this point
-    I(this, task->ref_count == 0);
+    I(this, task->get_ref_count() == 0);
     // Kernel should not know about the task any more
     I(this, kernel->get_task_by_id(task->id) == NULL);
     // Now delete the task, which will require using this thread's