Use Gem::CompactIndexClient in Bundler

Switch Bundler's compact index fetcher and the outdated-version check
from Bundler::CompactIndexClient to the RubyGems client, wiring
Bundler's filesystem access helper into the new hook. Bundler keeps its
orchestration layer (parallel workers, FIPS detection, mirrors) and only
swaps the client underneath. The RubyGems updater raises
Gem::CompactIndexClient::Error for an invalid gzip response where
Bundler's raised HTTPError, so rescue it in compact_index_request to
preserve the fallback to the dependency API.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: hsbt

lib/bundler.rb

@@ -41,7 +41,6 @@ module Bundler
   autoload :Checksum,               File.expand_path("bundler/checksum", __dir__)
   autoload :CLI,                    File.expand_path("bundler/cli", __dir__)
   autoload :CIDetector,             File.expand_path("bundler/ci_detector", __dir__)
-  autoload :CompactIndexClient,     File.expand_path("bundler/compact_index_client", __dir__)
   autoload :Definition,             File.expand_path("bundler/definition", __dir__)
   autoload :Dependency,             File.expand_path("bundler/dependency", __dir__)
   autoload :Deprecate,              File.expand_path("bundler/deprecate", __dir__)

lib/bundler/cli.rb

@@ -785,9 +785,13 @@ def warn_on_outdated_bundler
       return unless SharedHelpers.md5_available?
 
       require_relative "vendored_uri"
+      require "rubygems/compact_index_client"
+      if Gem::CompactIndexClient.respond_to?(:filesystem_access=)
+        Gem::CompactIndexClient.filesystem_access = SharedHelpers.method(:filesystem_access)
+      end
       remote = Source::Rubygems::Remote.new(Gem::URI("https://rubygems.org"))
       cache_path = Bundler.user_cache.join("compact_index", remote.cache_slug)
-      latest = Bundler::CompactIndexClient.new(cache_path).latest_version("bundler")
+      latest = Gem::CompactIndexClient.new(cache_path).latest_version("bundler")
       return unless latest
 
       current = Gem::Version.new(VERSION)

lib/bundler/fetcher/compact_index.rb

@@ -2,6 +2,15 @@
 
 require_relative "base"
 require_relative "../worker"
+require "rubygems/compact_index_client"
+
+# Route the client's filesystem access through Bundler's helper so
+# permission problems raise friendly Bundler errors. The respond_to?
+# check covers a host RubyGems that already loaded its own copy of the
+# client from before the hook existed.
+if Gem::CompactIndexClient.respond_to?(:filesystem_access=)
+  Gem::CompactIndexClient.filesystem_access = Bundler::SharedHelpers.method(:filesystem_access)
+end
 
 module Bundler
   class Fetcher
@@ -11,12 +20,12 @@ def self.compact_index_request(method_name)
         undef_method(method_name)
         define_method(method_name) do |*args, &blk|
           method.bind_call(self, *args, &blk)
-        rescue NetworkDownError, CompactIndexClient::Updater::MismatchedChecksumError => e
+        rescue NetworkDownError, Gem::CompactIndexClient::Updater::MismatchedChecksumError => e
           raise HTTPError, e.message
         rescue AuthenticationRequiredError, BadAuthenticationError
           # Fail since we got a 401 from the server.
           raise
-        rescue HTTPError => e
+        rescue HTTPError, Gem::CompactIndexClient::Error => e
           Bundler.ui.trace(e)
           nil
         end
@@ -35,7 +44,7 @@ def specs_for_names(gem_names)
         until remaining_gems.empty?
           log_specs { "Looking up gems #{remaining_gems.inspect}" }
           deps = fetch_gem_infos(remaining_gems).flatten(1)
-          next_gems = deps.flat_map {|d| d[CompactIndexClient::INFO_DEPS].flat_map(&:first) }.uniq
+          next_gems = deps.flat_map {|d| d[Gem::CompactIndexClient::INFO_DEPS].flat_map(&:first) }.uniq
           deps.each {|dep| gem_info << dep }
           complete_gems.concat(deps.map(&:first)).uniq!
           remaining_gems = next_gems - complete_gems
@@ -53,7 +62,7 @@ def available?
         end
         # Read info file checksums out of /versions, so we can know if gems are up to date
         compact_index_client.available?
-      rescue CompactIndexClient::Updater::MismatchedChecksumError => e
+      rescue Gem::CompactIndexClient::Updater::MismatchedChecksumError => e
         Bundler.ui.debug(e.message)
         nil
       end
@@ -75,7 +84,7 @@ def release_resolution_memory!
       def compact_index_client
         @compact_index_client ||=
           SharedHelpers.filesystem_access(cache_path) do
-            CompactIndexClient.new(cache_path, client_fetcher)
+            Gem::CompactIndexClient.new(cache_path, client_fetcher)
           end
       end
 

spec/install/gems/compact_index_spec.rb

@@ -23,10 +23,10 @@
 
     bundle :install, artifice: "compact_index", env: { "DEBUG_COMPACT_INDEX" => "true" }
     expect(out).to include("Fetching gem metadata from #{source_uri}")
-    expect(err).to include("[Bundler::CompactIndexClient] available?")
-    expect(err).to include("[Bundler::CompactIndexClient] fetching versions")
-    expect(err).to include("[Bundler::CompactIndexClient] info(myrack)")
-    expect(err).to include("[Bundler::CompactIndexClient] fetching info/myrack")
+    expect(err).to include("[Gem::CompactIndexClient] available?")
+    expect(err).to include("[Gem::CompactIndexClient] fetching versions")
+    expect(err).to include("[Gem::CompactIndexClient] info(myrack)")
+    expect(err).to include("[Gem::CompactIndexClient] fetching info/myrack")
     expect(the_bundle).to include_gems "myrack 1.0.0"
   end