use invariant for unique borrow in projection

[csmoe]

Closes #112056
r? @lcnr

Clashed with lcnr's fix almost at the same time, and their patch seems more reasonable.

[rust-log-analyzer]

The job x86_64-gnu-llvm-14 failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

normalized stderr:
error[E0521]: borrowed data escapes outside of closure
  --> $DIR/issue-112056.rs:11:17
   |
LL |     fn create_self_reference<'a>(&'a mut self) {
   |                                  ------------ `self` declared here, outside of the closure body
...
LL |                 self.borrowed = borrow;

error[E0597]: `self` does not live long enough
  --> $DIR/issue-112056.rs:11:17
   |
   |
LL | impl<'b> Spooky<'b> {
   |      -- lifetime `'b` defined here
LL |     fn create_self_reference<'a>(&'a mut self) {
LL |         let mut closure = || {
   |                           -- value captured here
...
LL |                 self.borrowed = borrow;
   |                 |
   |                 borrowed value does not live long enough
   |                 borrowed value does not live long enough
   |                 assignment requires that `self` is borrowed for `'b`
LL |     }
LL |     }
   |      - `self` dropped here while still borrowed
error: lifetime may not live long enough
  --> $DIR/issue-112056.rs:11:17
   |
   |
LL | impl<'b> Spooky<'b> {
   |      -- lifetime `'b` defined here
LL |     fn create_self_reference<'a>(&'a mut self) {
   |                              -- lifetime `'a` defined here
...
LL |                 self.borrowed = borrow;
   |                 ^^^^^^^^^^^^^^^^^^^^^^ assignment requires that `'a` must outlive `'b`
   |
   = help: consider adding the following bound: `'a: 'b`
error: aborting due to 3 previous errors

Some errors have detailed explanations: E0521, E0597.
For more information about an error, try `rustc --explain E0521`.
---
To only update this specific test, also pass `--test-args mir/issue-112056.rs`

error: 1 errors occurred comparing output.
status: exit status: 1
command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/ui/mir/issue-112056.rs" "-Zthreads=1" "--sysroot" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2" "--target=x86_64-unknown-linux-gnu" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Zdeduplicate-diagnostics=no" "-Cstrip=debuginfo" "--remap-path-prefix=/checkout/tests/ui=fake-test-src-base" "--emit" "metadata" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/mir/issue-112056" "-A" "unused" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/mir/issue-112056/auxiliary"
stdout: none
error[E0521]: borrowed data escapes outside of closure
  --> fake-test-src-base/mir/issue-112056.rs:11:17
   |
   |
LL |     fn create_self_reference<'a>(&'a mut self) {
   |                                  ------------ `self` declared here, outside of the closure body
...
LL |                 self.borrowed = borrow;

error[E0597]: `self` does not live long enough
  --> fake-test-src-base/mir/issue-112056.rs:11:17
   |
   |
LL | impl<'b> Spooky<'b> {
   |      -- lifetime `'b` defined here
LL |     fn create_self_reference<'a>(&'a mut self) {
LL |         let mut closure = || {
   |                           -- value captured here
...
LL |                 self.borrowed = borrow;
   |                 |
   |                 borrowed value does not live long enough
   |                 borrowed value does not live long enough
   |                 assignment requires that `self` is borrowed for `'b`
LL |     }
LL |     }
   |      - `self` dropped here while still borrowed
error: lifetime may not live long enough
  --> fake-test-src-base/mir/issue-112056.rs:11:17
   |
   |
LL | impl<'b> Spooky<'b> {
   |      -- lifetime `'b` defined here
LL |     fn create_self_reference<'a>(&'a mut self) {
   |                              -- lifetime `'a` defined here
...
LL |                 self.borrowed = borrow;
   |                 ^^^^^^^^^^^^^^^^^^^^^^ assignment requires that `'a` must outlive `'b`
   |
   = help: consider adding the following bound: `'a: 'b`
error: aborting due to 3 previous errors

Some errors have detailed explanations: E0521, E0597.
For more information about an error, try `rustc --explain E0521`.