[PATCH] D92480: [llvm] Unify interface of (ThreadSafe)?RefCountedBase

[Nathan James via Phabricator via cfe-commits]

njames93 added a comment.

I've added test cases which demonstrate what these copies/moves are about.
The move constructor probably would never get used. I can't see of a reason to move the contents of a ref counted pointer. In which case there could be an argument to delete it.
The copy constructor OTOH is very likely to be used (which i think is the reason its currently defined in RefCountedBase).
Adding the CopyAssignment and MoveAssignment operators are there to make sure the compiler wont define them implicitly, copying the ref count.



================
Comment at: llvm/include/llvm/ADT/IntrusiveRefCntPtr.h:75-76
   RefCountedBase() = default;
+  // Copy and move constructors/assignments are no-ops as the RefCount isn't
+  // dictated by the class directly.
   RefCountedBase(const RefCountedBase &) {}
----------------
njames93 wrote:
> dexonsmith wrote:
> > dblaikie wrote:
> > > I can't quite understand this comment - perhaps you could try rephrasing it?
> > I'm not quite following why you needed to add these special members; it seems like just the destructor would be enough for the assertion; but if you do need them, can/should they be `= default`?
> They can't be defaulted as we don't want to copy the RefCount.
I understand it in my head, just can't think of the best way to write it down.


================
Comment at: llvm/include/llvm/ADT/IntrusiveRefCntPtr.h:75-80
+  // Copy and move constructors/assignments are no-ops as the RefCount isn't
+  // dictated by the class directly.
   RefCountedBase(const RefCountedBase &) {}
+  RefCountedBase(RefCountedBase &&) {}
+  RefCountedBase &operator=(const RefCountedBase &) { return *this; }
+  RefCountedBase &operator=(RefCountedBase &&) { return *this; }
----------------
dexonsmith wrote:
> dblaikie wrote:
> > I can't quite understand this comment - perhaps you could try rephrasing it?
> I'm not quite following why you needed to add these special members; it seems like just the destructor would be enough for the assertion; but if you do need them, can/should they be `= default`?
They can't be defaulted as we don't want to copy the RefCount.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D92480/new/

https://reviews.llvm.org/D92480