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, 25 insertions, 20 deletions

diff --git a/crates/shirabe/src/package/root_alias_package.rs b/crates/shirabe/src/package/root_alias_package.rs
index 4a4115d7..d5ea720e 100644
--- a/crates/shirabe/src/package/root_alias_package.rs
+++ b/crates/shirabe/src/package/root_alias_package.rs
@@ -78,44 +78,49 @@ impl RootPackageInterface for RootAliasPackage {
     }
 
     fn set_requires(&mut self, requires: IndexMap<String, Link>) {
-        self.inner.inner.requires = self
-            .inner
-            .inner
-            .replace_self_version_dependencies(requires.clone(), Link::TYPE_REQUIRE);
+        self.inner.inner.requires = std::rc::Rc::new(
+            self.inner
+                .inner
+                .replace_self_version_dependencies(requires.clone(), Link::TYPE_REQUIRE),
+        );
 
         self.alias_of.set_requires(requires);
     }
 
     fn set_dev_requires(&mut self, dev_requires: IndexMap<String, Link>) {
-        self.inner.inner.dev_requires = self
-            .inner
-            .inner
-            .replace_self_version_dependencies(dev_requires.clone(), Link::TYPE_DEV_REQUIRE);
+        self.inner.inner.dev_requires = std::rc::Rc::new(
+            self.inner
+                .inner
+                .replace_self_version_dependencies(dev_requires.clone(), Link::TYPE_DEV_REQUIRE),
+        );
 
         self.alias_of.set_dev_requires(dev_requires);
     }
 
     fn set_conflicts(&mut self, conflicts: IndexMap<String, Link>) {
-        self.inner.inner.conflicts = self
-            .inner
-            .inner
-            .replace_self_version_dependencies(conflicts.clone(), Link::TYPE_CONFLICT);
+        self.inner.inner.conflicts = std::rc::Rc::new(
+            self.inner
+                .inner
+                .replace_self_version_dependencies(conflicts.clone(), Link::TYPE_CONFLICT),
+        );
         self.alias_of.set_conflicts(conflicts);
     }
 
     fn set_provides(&mut self, provides: IndexMap<String, Link>) {
-        self.inner.inner.provides = self
-            .inner
-            .inner
-            .replace_self_version_dependencies(provides.clone(), Link::TYPE_PROVIDE);
+        self.inner.inner.provides = std::rc::Rc::new(
+            self.inner
+                .inner
+                .replace_self_version_dependencies(provides.clone(), Link::TYPE_PROVIDE),
+        );
         self.alias_of.set_provides(provides);
     }
 
     fn set_replaces(&mut self, replaces: IndexMap<String, Link>) {
-        self.inner.inner.replaces = self
-            .inner
-            .inner
-            .replace_self_version_dependencies(replaces.clone(), Link::TYPE_REPLACE);
+        self.inner.inner.replaces = std::rc::Rc::new(
+            self.inner
+                .inner
+                .replace_self_version_dependencies(replaces.clone(), Link::TYPE_REPLACE),
+        );
         self.alias_of.set_replaces(replaces);
     }