1 files changed, 64 insertions, 0 deletions
diff --git a/lib/bundler/source/rubygems_aggregate.rb b/lib/bundler/source/rubygems_aggregate.rb
new file mode 100644
index 0000000000..685bf7e90a
--- /dev/null
+++ b/lib/bundler/source/rubygems_aggregate.rb
@@ -0,0 +1,64 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Source
+    class RubygemsAggregate
+      attr_reader :source_map, :sources
+
+      def initialize(sources, source_map)
+        @sources = sources
+        @source_map = source_map
+
+        @index = build_index
+      end
+
+      def specs
+        @index
+      end
+
+      def to_s
+        "any of the sources"
+      end
+
+      private
+
+      def build_index
+        Index.build do |idx|
+          dependency_names = source_map.pinned_spec_names
+
+          sources.all_sources.each do |source|
+            source.dependency_names = dependency_names - source_map.pinned_spec_names(source)
+            idx.add_source source.specs
+            dependency_names.concat(source.unmet_deps).uniq!
+          end
+
+          double_check_for_index(idx, dependency_names)
+        end
+      end
+
+      # Suppose the gem Foo depends on the gem Bar.  Foo exists in Source A.  Bar has some versions that exist in both
+      # sources A and B.  At this point, the API request will have found all the versions of Bar in source A,
+      # but will not have found any versions of Bar from source B, which is a problem if the requested version
+      # of Foo specifically depends on a version of Bar that is only found in source B. This ensures that for
+      # each spec we found, we add all possible versions from all sources to the index.
+      def double_check_for_index(idx, dependency_names)
+        pinned_names = source_map.pinned_spec_names
+
+        names = :names # do this so we only have to traverse to get dependency_names from the index once
+        unmet_dependency_names = lambda do
+          return names unless names == :names
+          new_names = sources.all_sources.map(&:dependency_names_to_double_check)
+          return names = nil if new_names.compact!
+          names = new_names.flatten(1).concat(dependency_names)
+          names.uniq!
+          names -= pinned_names
+          names
+        end
+
+        sources.all_sources.each do |source|
+          source.double_check_for(unmet_dependency_names)
+        end
+      end
+    end
+  end
+end