perf(tcw3): convert RcBorrow → Weak without strong clone

This was made possible by a recent addition to `rc-borrow`:
<CAD97/pointer-utils#59>

Author: yvt

Cargo.lock

@@ -31,7 +31,7 @@ ndarray = "0.13.0"
 neo_linked_list = { path = "../support/neo_linked_list" }
 owning_ref = "0.4.0"
 packed_simd = "0.3.0"
-rc-borrow = "1.0.0"
+rc-borrow = "1.3.0"
 rob = "0.1"
 rope = { path = "../support/rope" }
 sorted_diff = { path = "../support/sorted_diff" }

tcw3/Cargo.toml

@@ -1558,8 +1558,7 @@ fn pend_raise_change(inner: RcBorrow<'_, Inner>) {
         return;
     }
 
-    // FIXME: Remove this extra `upgrade`-ing
-    let inner_weak = Rc::downgrade(&RcBorrow::upgrade(inner));
+    let inner_weak = RcBorrow::to_weak(inner);
 
     inner.wm.invoke_on_update(move |wm| {
         if let Some(inner) = inner_weak.upgrade() {

tcw3/src/ui/views/entry.rs

@@ -9,7 +9,7 @@ use std::{
     cell::RefCell,
     cmp::{max, min},
     pin::Pin,
-    rc::{Rc, Weak},
+    rc::Weak,
 };
 
 use super::{
@@ -82,7 +82,7 @@ impl HWndRef<'_> {
             pal_wnd_cell.as_ref().unwrap(),
             pal::WndAttrs {
                 listener: Some(Box::new(PalWndListener {
-                    wnd: Rc::downgrade(&RcBorrow::upgrade(self.wnd)),
+                    wnd: RcBorrow::to_weak(self.wnd),
                 })),
                 ..Default::default()
             },