Read cached registry distributions when --config-settings are present (#10578)

## Summary

Closes https://github.com/astral-sh/uv/issues/10577.

crates/uv-distribution/src/index/registry_wheel_index.rs

@@ -3,6 +3,8 @@ use std::collections::hash_map::Entry;
 use rustc_hash::{FxHashMap, FxHashSet};
 
 use uv_cache::{Cache, CacheBucket, WheelCache};
+use uv_cache_key::cache_digest;
+use uv_configuration::ConfigSettings;
 use uv_distribution_types::{CachedRegistryDist, Hashed, Index, IndexLocations, IndexUrl};
 use uv_fs::{directories, files, symlinks};
 use uv_normalize::PackageName;
@@ -31,6 +33,7 @@ pub struct RegistryWheelIndex<'a> {
     index_locations: &'a IndexLocations,
     hasher: &'a HashStrategy,
     index: FxHashMap<&'a PackageName, Vec<IndexEntry<'a>>>,
+    build_configuration: &'a ConfigSettings,
 }
 
 impl<'a> RegistryWheelIndex<'a> {
@@ -40,12 +43,14 @@ impl<'a> RegistryWheelIndex<'a> {
         tags: &'a Tags,
         index_locations: &'a IndexLocations,
         hasher: &'a HashStrategy,
+        build_configuration: &'a ConfigSettings,
     ) -> Self {
         Self {
             cache,
             tags,
             index_locations,
             hasher,
+            build_configuration,
             index: FxHashMap::default(),
         }
     }
@@ -67,6 +72,7 @@ impl<'a> RegistryWheelIndex<'a> {
                 self.tags,
                 self.index_locations,
                 self.hasher,
+                self.build_configuration,
             )),
         };
         versions
@@ -79,6 +85,7 @@ impl<'a> RegistryWheelIndex<'a> {
         tags: &Tags,
         index_locations: &'index IndexLocations,
         hasher: &HashStrategy,
+        build_configuration: &ConfigSettings,
     ) -> Vec<IndexEntry<'index>> {
         let mut entries = vec![];
 
@@ -162,9 +169,8 @@ impl<'a> RegistryWheelIndex<'a> {
                 WheelCache::Index(index.url()).wheel_dir(package.to_string()),
             );
 
-            // For registry wheels, the cache structure is: `<index>/<package-name>/<version>/`.
+            // For registry source distributions, the cache structure is: `<index>/<package-name>/<version>/`.
             for shard in directories(&cache_shard) {
-                // Read the existing metadata from the cache, if it exists.
                 let cache_shard = cache_shard.shard(shard);
 
                 // Read the revision from the cache.
@@ -190,7 +196,16 @@ impl<'a> RegistryWheelIndex<'a> {
                 };
 
                 if let Some(revision) = revision {
-                    for wheel_dir in symlinks(cache_shard.join(revision.id())) {
+                    let cache_shard = cache_shard.shard(revision.id());
+
+                    // If there are build settings, we need to scope to a cache shard.
+                    let cache_shard = if build_configuration.is_empty() {
+                        cache_shard
+                    } else {
+                        cache_shard.shard(cache_digest(build_configuration))
+                    };
+
+                    for wheel_dir in symlinks(cache_shard) {
                         if let Some(wheel) = CachedWheel::from_built_source(wheel_dir) {
                             if wheel.filename.compatibility(tags).is_compatible() {
                                 // Enforce hash-checking based on the source distribution.

crates/uv-installer/src/plan.rs

@@ -56,7 +56,8 @@ impl<'a> Planner<'a> {
         tags: &Tags,
     ) -> Result<Plan> {
         // Index all the already-downloaded wheels in the cache.
-        let mut registry_index = RegistryWheelIndex::new(cache, tags, index_locations, hasher);
+        let mut registry_index =
+            RegistryWheelIndex::new(cache, tags, index_locations, hasher, config_settings);
         let built_index = BuiltWheelIndex::new(cache, tags, hasher, config_settings);
 
         let mut cached = vec![];
@@ -248,7 +249,7 @@ impl<'a> Planner<'a> {
                         }
                         Some(&entry.dist)
                     }) {
-                        debug!("Requirement already cached: {distribution}");
+                        debug!("Registry requirement already cached: {distribution}");
                         cached.push(CachedDist::Registry(distribution.clone()));
                         continue;
                     }

crates/uv/tests/it/pip_install.rs

@@ -3251,7 +3251,89 @@ fn launcher_with_symlink() -> Result<()> {
 }
 
 #[test]
-fn config_settings() {
+fn config_settings_registry() {
+    let context = TestContext::new("3.12");
+
+    // Install with a `-C` flag. In this case, the flag has no impact on the build, but uv should
+    // respect it anyway.
+    uv_snapshot!(context.filters(), context.pip_install()
+        .arg("iniconfig")
+        .arg("--no-binary")
+        .arg("iniconfig")
+        .arg("-C=global-option=build_ext"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 1 package in [TIME]
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + iniconfig==2.0.0
+    "###
+    );
+
+    // Uninstall the package.
+    uv_snapshot!(context.filters(), context.pip_uninstall()
+        .arg("iniconfig"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Uninstalled 1 package in [TIME]
+     - iniconfig==2.0.0
+    "###);
+
+    // Re-install the package, with the same flag. We should read from the cache.
+    uv_snapshot!(context.filters(), context.pip_install()
+        .arg("iniconfig")
+        .arg("--no-binary")
+        .arg("iniconfig")
+        .arg("-C=global-option=build_ext"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + iniconfig==2.0.0
+    "###
+    );
+
+    // Uninstall the package.
+    uv_snapshot!(context.filters(), context.pip_uninstall()
+        .arg("iniconfig"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Uninstalled 1 package in [TIME]
+     - iniconfig==2.0.0
+    "###);
+
+    // Re-install the package, without the flag. We should build it from source.
+    uv_snapshot!(context.filters(), context.pip_install()
+        .arg("iniconfig")
+        .arg("--no-binary")
+        .arg("iniconfig"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 1 package in [TIME]
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + iniconfig==2.0.0
+    "###
+    );
+}
+
+#[test]
+fn config_settings_path() {
     let context = TestContext::new("3.12");
 
     // Install the editable package.