perf(package): hand out link maps behind Rc

PackageInterface::getRequires() and friends return the array of Link objects;
in PHP that is a copy-on-write array of object references, so a caller pays
nothing to look at it. The port returned IndexMap<String, Link> by value, so
every call deep-cloned the whole map, keys and constraints included. Pool
building calls these accessors once per package per candidate, which put
IndexMap::clone at 13.5% of `require laravel/laravel`.

Store the maps as Rc<IndexMap<String, Link>> and return a handle. Callers that
mutate the map clone it explicitly at the point of mutation, matching where PHP
would separate the array.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

1 files changed, 5 insertions, 5 deletions

diff --git a/crates/shirabe/src/package/root_package.rs b/crates/shirabe/src/package/root_package.rs
index 0807d15b..e1c4b35e 100644
--- a/crates/shirabe/src/package/root_package.rs
+++ b/crates/shirabe/src/package/root_package.rs
@@ -338,19 +338,19 @@ impl PackageInterface for RootPackage {
     fn get_stability(&self) -> &str {
         self.inner.get_stability()
     }
-    fn get_requires(&self) -> IndexMap<String, Link> {
+    fn get_requires(&self) -> std::rc::Rc<IndexMap<String, Link>> {
         self.inner.get_requires()
     }
-    fn get_conflicts(&self) -> IndexMap<String, Link> {
+    fn get_conflicts(&self) -> std::rc::Rc<IndexMap<String, Link>> {
         self.inner.get_conflicts()
     }
-    fn get_provides(&self) -> IndexMap<String, Link> {
+    fn get_provides(&self) -> std::rc::Rc<IndexMap<String, Link>> {
         self.inner.get_provides()
     }
-    fn get_replaces(&self) -> IndexMap<String, Link> {
+    fn get_replaces(&self) -> std::rc::Rc<IndexMap<String, Link>> {
         self.inner.get_replaces()
     }
-    fn get_dev_requires(&self) -> IndexMap<String, Link> {
+    fn get_dev_requires(&self) -> std::rc::Rc<IndexMap<String, Link>> {
         self.inner.get_dev_requires()
     }
     fn get_suggests(&self) -> IndexMap<String, String> {