types_escaping_snapshot is unused

[est31]

I'm not familiar enough with the code to know what the purpose of types_escaping_snapshot is, but it seems unused.

rust/compiler/rustc_infer/src/infer/type_variable.rs

Lines 349 to 397 in d245464

	/// Finds the set of type variables that existed *before* `s`
	/// but which have only been unified since `s` started, and
	/// return the types with which they were unified. So if we had
	/// a type variable `V0`, then we started the snapshot, then we
	/// created a type variable `V1`, unified `V0` with `T0`, and
	/// unified `V1` with `T1`, this function would return `{T0}`.
	pub fn types_escaping_snapshot(&mut self, s: &super::Snapshot<'tcx>) -> Vec<Ty<'tcx>> {
	let mut new_elem_threshold = u32::MAX;
	let mut escaping_types = Vec::new();
	let actions_since_snapshot = self.undo_log.actions_since_snapshot(s);
	debug!("actions_since_snapshot.len() = {}", actions_since_snapshot.len());
	for i in 0..actions_since_snapshot.len() {
	let actions_since_snapshot = self.undo_log.actions_since_snapshot(s);
	match actions_since_snapshot[i] {
	super::UndoLog::TypeVariables(UndoLog::Values(sv::UndoLog::NewElem(index))) => {
	// if any new variables were created during the
	// snapshot, remember the lower index (which will
	// always be the first one we see). Note that this
	// action must precede those variables being
	// specified.
	new_elem_threshold = cmp::min(new_elem_threshold, index as u32);
	debug!("NewElem({}) new_elem_threshold={}", index, new_elem_threshold);
	}
	super::UndoLog::TypeVariables(UndoLog::Values(sv::UndoLog::Other(
	Instantiate { vid, .. },
	))) => {
	if vid.index < new_elem_threshold {
	// quick check to see if this variable was
	// created since the snapshot started or not.
	let mut eq_relations = ut::UnificationTable::with_log(
	&mut self.storage.eq_relations,
	&mut *self.undo_log,
	);
	let escaping_type = match eq_relations.probe_value(vid) {
	TypeVariableValue::Unknown { .. } => bug!(),
	TypeVariableValue::Known { value } => value,
	};
	escaping_types.push(escaping_type);
	}
	debug!("SpecifyVar({:?}) new_elem_threshold={}", vid, new_elem_threshold);
	}
	_ => {}
	}
	}
	escaping_types
	}

I'd just have removed it in #77739 but there are two comments mentioning it in the file and I'm not sure what to do about those.

[JohnTitor]

#83185 removed it and #84570 tracks remaining tasks, closing.