RFE: debug pretty printers for Rc/Arc

[cuviper]

It would be nice if rust-gdb/etc. could pretty-print the inner value of Rc and Arc. Right now you only get the raw details, like:

(gdb) p foo
$1 = Rc<i32> = {ptr = NonNull<alloc::rc::RcBox<i32>> = {
    pointer = NonZero<*const alloc::rc::RcBox<i32>> = {0x555555783a40}},
  phantom = PhantomData<i32>}

Getting the actual value requires manual field access, foo.ptr.pointer.0.value, which could also change if Rc internals change.

Maybe this could be approached as more general Deref support, so you could p *foo here, but right now that just says "Attempt to take contents of a non-pointer value."

[tromey]

this could be approached as more general Deref support

This is a good idea but first it requires that traits be emitted into the DWARF. There's another bug open for this.

[mcclure]

Time traveller from 2024 here: Is this still a live issue? I'm currently able to pretty print ArcRefCell and AtomicRefCell, at least.