Auto merge of #11081 - WaffleLapkin:no_for_in_option, r=epage

Don't use `for` loop on an `Option`

This PR removes a single `for` loop over `Option`, replacing it with an `if let` to improve code clarity. This currently blocks rust-lang/rust#99696 that adds a lint against this pattern.

src/cargo/ops/resolve.rs

@@ -386,21 +386,19 @@ pub fn resolve_with_previous<'cfg>(
  let keep = |p: &PackageId| pre_patch_keep(p) && !avoid_patch_ids.contains(p);
 
  let dev_deps = ws.require_optional_deps() || has_dev_units == HasDevUnits::Yes;
- // In the case where a previous instance of resolve is available, we
- // want to lock as many packages as possible to the previous version
- // without disturbing the graph structure.
+
  if let Some(r) = previous {
  trace!("previous: {:?}", r);
+
+ // In the case where a previous instance of resolve is available, we
+ // want to lock as many packages as possible to the previous version
+ // without disturbing the graph structure.
  register_previous_locks(ws, registry, r, &keep, dev_deps);
- }
 
- // Prefer to use anything in the previous lock file, aka we want to have conservative updates.
- for r in previous {
- for id in r.iter() {
- if keep(&id) {
- debug!("attempting to prefer {}", id);
- version_prefs.prefer_package_id(id);
- }
+ // Prefer to use anything in the previous lock file, aka we want to have conservative updates.
+ for id in r.iter().filter(keep) {
+ debug!("attempting to prefer {}", id);
+ version_prefs.prefer_package_id(id);
  }
  }