[rubygems/rubygems] Backwards compatibility for 2.5.17-2.5.23 caches

https://github.com/rubygems/rubygems/commit/9dbfce76cf

lib/bundler/runtime.rb

@@ -136,7 +136,11 @@ module Bundler
       specs_to_cache.each do |spec|
         next if spec.name == "bundler"
         next if spec.source.is_a?(Source::Gemspec)
-        spec.source.cache(spec, custom_path) if spec.source.respond_to?(:cache)
+        if spec.source.respond_to?(:migrate_cache)
+          spec.source.migrate_cache(custom_path, local: local)
+        elsif spec.source.respond_to?(:cache)
+          spec.source.cache(spec, custom_path)
+        end
       end
 
       Dir[cache_path.join("*/.git")].each do |git_dir|

lib/bundler/source/git.rb

@@ -214,16 +214,16 @@ module Bundler
         requires_checkout? ? spec.post_install_message : nil
       end
 
+      def migrate_cache(custom_path = nil, local: false)
+        if local
+          cache_to(custom_path, try_migrate: false)
+        else
+          cache_to(custom_path, try_migrate: true)
+        end
+      end
+
       def cache(spec, custom_path = nil)
-        return unless Bundler.feature_flag.cache_all?
-
-        app_cache_path = app_cache_path(custom_path)
-        return if cache_path == app_cache_path
-
-        cached!
-        FileUtils.rm_rf(app_cache_path)
-        git_proxy.checkout if requires_checkout?
-        git_proxy.copy_to(app_cache_path, @submodules)
+        cache_to(custom_path, try_migrate: false)
       end
 
       def load_spec_files
@@ -267,14 +267,36 @@ module Bundler
 
       private
 
+      def cache_to(custom_path, try_migrate: false)
+        return unless Bundler.feature_flag.cache_all?
+
+        app_cache_path = app_cache_path(custom_path)
+
+        migrate = try_migrate ? bare_repo?(app_cache_path) : false
+
+        set_cache_path!(nil) if migrate
+
+        return if cache_path == app_cache_path
+
+        cached!
+        FileUtils.rm_rf(app_cache_path)
+        git_proxy.checkout if migrate || requires_checkout?
+        git_proxy.copy_to(app_cache_path, @submodules)
+      end
+
       def checkout
         Bundler.ui.debug "  * Checking out revision: #{ref}"
-        if use_app_cache?
+        if use_app_cache? && !bare_repo?(app_cache_path)
           SharedHelpers.filesystem_access(install_path.dirname) do |p|
             FileUtils.mkdir_p(p)
           end
           FileUtils.cp_r("#{app_cache_path}/.", install_path)
         else
+          if use_app_cache? && bare_repo?(app_cache_path)
+            Bundler.ui.warn "Installing from cache in old \"bare repository\" format for compatibility. " \
+                            "Please run `bundle cache` and commit the updated cache to migrate to the new format and get rid of this warning."
+          end
+
           git_proxy.copy_to(install_path, submodules)
         end
         serialize_gemspecs_in(install_path)
@@ -416,6 +438,10 @@ module Bundler
       def override_for(path)
         Bundler.settings.local_overrides.key(path)
       end
+
+      def bare_repo?(path)
+        File.exist?(path.join("objects")) && File.exist?(path.join("HEAD"))
+      end
     end
   end
 end

spec/bundler/cache/git_spec.rb

@@ -239,6 +239,96 @@ RSpec.describe "bundle cache with git" do
     expect(the_bundle).to include_gem "foo 1.0"
   end
 
+  it "installs properly a bundler 2.5.17-2.5.23 cache as a bare repository without cloning remote repositories" do
+    git = build_git "foo"
+
+    short_ref = git.ref_for("main", 11)
+    cache_dir = bundled_app("vendor/cache/foo-1.0-#{short_ref}")
+
+    gemfile <<-G
+      source "https://gem.repo1"
+      gem "foo", :git => '#{lib_path("foo-1.0")}'
+    G
+    bundle "config set global_gem_cache false"
+    bundle "config set cache_all true"
+    bundle "config path vendor/bundle"
+    bundle :install
+
+    # Simulate old cache by copying the real cache folder to vendor/cache
+    FileUtils.mkdir_p bundled_app("vendor/cache")
+    FileUtils.cp_r "#{Dir.glob(vendored_gems("cache/bundler/git/foo-1.0-*")).first}/.", cache_dir
+    FileUtils.rm_rf bundled_app("vendor/bundle")
+
+    bundle "install --local --verbose"
+    expect(err).to include("Installing from cache in old \"bare repository\" format for compatibility")
+
+    expect(out).to_not include("Fetching")
+
+    # leaves old cache alone
+    expect(cache_dir.join("lib/foo.rb")).not_to exist
+    expect(cache_dir.join("HEAD")).to exist
+
+    expect(the_bundle).to include_gem "foo 1.0"
+  end
+
+  it "migrates a bundler 2.5.17-2.5.23 cache as a bare repository when not running with --local" do
+    git = build_git "foo"
+
+    short_ref = git.ref_for("main", 11)
+    cache_dir = bundled_app("vendor/cache/foo-1.0-#{short_ref}")
+
+    gemfile <<-G
+      source "https://gem.repo1"
+      gem "foo", :git => '#{lib_path("foo-1.0")}'
+    G
+    bundle "config set global_gem_cache false"
+    bundle "config set cache_all true"
+    bundle "config path vendor/bundle"
+    bundle :install
+
+    # Simulate old cache by copying the real cache folder to vendor/cache
+    FileUtils.mkdir_p bundled_app("vendor/cache")
+    FileUtils.cp_r "#{Dir.glob(vendored_gems("cache/bundler/git/foo-1.0-*")).first}/.", cache_dir
+    FileUtils.rm_rf bundled_app("vendor/bundle")
+
+    bundle "install --verbose"
+    expect(out).to include("Fetching")
+
+    # migrates old cache alone
+    expect(cache_dir.join("lib/foo.rb")).to exist
+    expect(cache_dir.join("HEAD")).not_to exist
+
+    expect(the_bundle).to include_gem "foo 1.0"
+  end
+
+  it "migrates a bundler 2.5.17-2.5.23 cache as a bare repository when running `bundle cache`, even if gems already installed" do
+    git = build_git "foo"
+
+    short_ref = git.ref_for("main", 11)
+    cache_dir = bundled_app("vendor/cache/foo-1.0-#{short_ref}")
+
+    gemfile <<-G
+      source "https://gem.repo1"
+      gem "foo", :git => '#{lib_path("foo-1.0")}'
+    G
+    bundle "config set global_gem_cache false"
+    bundle "config set cache_all true"
+    bundle "config path vendor/bundle"
+    bundle :install
+
+    # Simulate old cache by copying the real cache folder to vendor/cache
+    FileUtils.mkdir_p bundled_app("vendor/cache")
+    FileUtils.cp_r "#{Dir.glob(vendored_gems("cache/bundler/git/foo-1.0-*")).first}/.", cache_dir
+
+    bundle "cache"
+
+    # migrates old cache alone
+    expect(cache_dir.join("lib/foo.rb")).to exist
+    expect(cache_dir.join("HEAD")).not_to exist
+
+    expect(the_bundle).to include_gem "foo 1.0"
+  end
+
   it "copies repository to vendor cache, including submodules" do
     # CVE-2022-39253: https://lore.kernel.org/lkml/xmqq4jw1uku5.fsf@gitster.g/
     system(*%W[git config --global protocol.file.allow always])