Replace Molinillo with PubGrub for dependency resolution

Manifest.txt

@@ -471,9 +471,9 @@ lib/rubygems/resolver/api_set/gem_parser.rb
 lib/rubygems/resolver/api_specification.rb
 lib/rubygems/resolver/best_set.rb
 lib/rubygems/resolver/composed_set.rb
-lib/rubygems/resolver/conflict.rb
 lib/rubygems/resolver/current_set.rb
 lib/rubygems/resolver/dependency_request.rb
+lib/rubygems/resolver/incompatibility.rb
 lib/rubygems/resolver/git_set.rb
 lib/rubygems/resolver/git_specification.rb
 lib/rubygems/resolver/index_set.rb
@@ -487,8 +487,8 @@ lib/rubygems/resolver/requirement_list.rb
 lib/rubygems/resolver/set.rb
 lib/rubygems/resolver/source_set.rb
 lib/rubygems/resolver/spec_specification.rb
+lib/rubygems/resolver/strategy.rb
 lib/rubygems/resolver/specification.rb
-lib/rubygems/resolver/stats.rb
 lib/rubygems/resolver/vendor_set.rb
 lib/rubygems/resolver/vendor_specification.rb
 lib/rubygems/s3_uri_signer.rb
@@ -533,27 +533,6 @@ lib/rubygems/util/atomic_file_writer.rb
 lib/rubygems/util/licenses.rb
 lib/rubygems/validator.rb
 lib/rubygems/vendor/.document
-lib/rubygems/vendor/molinillo/LICENSE
-lib/rubygems/vendor/molinillo/lib/molinillo.rb
-lib/rubygems/vendor/molinillo/lib/molinillo/delegates/resolution_state.rb
-lib/rubygems/vendor/molinillo/lib/molinillo/delegates/specification_provider.rb
-lib/rubygems/vendor/molinillo/lib/molinillo/dependency_graph.rb
-lib/rubygems/vendor/molinillo/lib/molinillo/dependency_graph/action.rb
-lib/rubygems/vendor/molinillo/lib/molinillo/dependency_graph/add_edge_no_circular.rb
-lib/rubygems/vendor/molinillo/lib/molinillo/dependency_graph/add_vertex.rb
-lib/rubygems/vendor/molinillo/lib/molinillo/dependency_graph/delete_edge.rb
-lib/rubygems/vendor/molinillo/lib/molinillo/dependency_graph/detach_vertex_named.rb
-lib/rubygems/vendor/molinillo/lib/molinillo/dependency_graph/log.rb
-lib/rubygems/vendor/molinillo/lib/molinillo/dependency_graph/set_payload.rb
-lib/rubygems/vendor/molinillo/lib/molinillo/dependency_graph/tag.rb
-lib/rubygems/vendor/molinillo/lib/molinillo/dependency_graph/vertex.rb
-lib/rubygems/vendor/molinillo/lib/molinillo/errors.rb
-lib/rubygems/vendor/molinillo/lib/molinillo/gem_metadata.rb
-lib/rubygems/vendor/molinillo/lib/molinillo/modules/specification_provider.rb
-lib/rubygems/vendor/molinillo/lib/molinillo/modules/ui.rb
-lib/rubygems/vendor/molinillo/lib/molinillo/resolution.rb
-lib/rubygems/vendor/molinillo/lib/molinillo/resolver.rb
-lib/rubygems/vendor/molinillo/lib/molinillo/state.rb
 lib/rubygems/vendor/net-http/COPYING
 lib/rubygems/vendor/net-http/lib/net/http.rb
 lib/rubygems/vendor/net-http/lib/net/http/exceptions.rb
@@ -578,6 +557,24 @@ lib/rubygems/vendor/optparse/lib/optparse/shellwords.rb
 lib/rubygems/vendor/optparse/lib/optparse/time.rb
 lib/rubygems/vendor/optparse/lib/optparse/uri.rb
 lib/rubygems/vendor/optparse/lib/optparse/version.rb
+lib/rubygems/vendor/pub_grub/LICENSE.txt
+lib/rubygems/vendor/pub_grub/lib/pub_grub.rb
+lib/rubygems/vendor/pub_grub/lib/pub_grub/assignment.rb
+lib/rubygems/vendor/pub_grub/lib/pub_grub/basic_package_source.rb
+lib/rubygems/vendor/pub_grub/lib/pub_grub/failure_writer.rb
+lib/rubygems/vendor/pub_grub/lib/pub_grub/incompatibility.rb
+lib/rubygems/vendor/pub_grub/lib/pub_grub/package.rb
+lib/rubygems/vendor/pub_grub/lib/pub_grub/partial_solution.rb
+lib/rubygems/vendor/pub_grub/lib/pub_grub/rubygems.rb
+lib/rubygems/vendor/pub_grub/lib/pub_grub/solve_failure.rb
+lib/rubygems/vendor/pub_grub/lib/pub_grub/static_package_source.rb
+lib/rubygems/vendor/pub_grub/lib/pub_grub/strategy.rb
+lib/rubygems/vendor/pub_grub/lib/pub_grub/term.rb
+lib/rubygems/vendor/pub_grub/lib/pub_grub/version.rb
+lib/rubygems/vendor/pub_grub/lib/pub_grub/version_constraint.rb
+lib/rubygems/vendor/pub_grub/lib/pub_grub/version_range.rb
+lib/rubygems/vendor/pub_grub/lib/pub_grub/version_solver.rb
+lib/rubygems/vendor/pub_grub/lib/pub_grub/version_union.rb
 lib/rubygems/vendor/resolv/COPYING
 lib/rubygems/vendor/resolv/lib/resolv.rb
 lib/rubygems/vendor/securerandom/COPYING
@@ -602,9 +599,9 @@ lib/rubygems/vendor/uri/lib/uri/rfc3986_parser.rb
 lib/rubygems/vendor/uri/lib/uri/version.rb
 lib/rubygems/vendor/uri/lib/uri/ws.rb
 lib/rubygems/vendor/uri/lib/uri/wss.rb
-lib/rubygems/vendored_molinillo.rb
 lib/rubygems/vendored_net_http.rb
 lib/rubygems/vendored_optparse.rb
+lib/rubygems/vendored_pub_grub.rb
 lib/rubygems/vendored_securerandom.rb
 lib/rubygems/vendored_timeout.rb
 lib/rubygems/vendored_tsort.rb

lib/rubygems/commands/exec_command.rb

@@ -173,6 +173,9 @@ def install
   rescue Gem::InstallError => e
     alert_error "Error installing #{gem_name}:\n\t#{e.message}"
     terminate_interaction 1
+  rescue Gem::DependencyResolutionError => e
+    alert_error "Error installing #{gem_name}:\n\t#{e.message}"
+    terminate_interaction 2
   rescue Gem::GemNotFoundException => e
     show_lookup_failure e.name, e.version, e.errors, false
 

lib/rubygems/commands/install_command.rb

@@ -224,6 +224,9 @@ def install_gems # :nodoc:
       rescue Gem::InstallError => e
         alert_error "Error installing #{gem_name}:\n\t#{e.message}"
         exit_code |= 1
+      rescue Gem::DependencyResolutionError => e
+        alert_error "Error installing #{gem_name}:\n\t#{e.message}"
+        exit_code |= 2
       rescue Gem::UnsatisfiableDependencyError => e
         show_lookup_failure e.name, e.version, e.errors, suppress_suggestions,
                             "'#{gem_name}' (#{gem_version})"

lib/rubygems/exceptions.rb

@@ -33,22 +33,24 @@ class Gem::DependencyError < Gem::Exception; end
 class Gem::DependencyRemovalException < Gem::Exception; end
 
 ##
-# Raised by Gem::Resolver when a Gem::Dependency::Conflict reaches the
-# toplevel.  Indicates which dependencies were incompatible through #conflict
-# and #conflicting_dependencies
+# Raised by Gem::Resolver when dependency resolution fails.
 
 class Gem::DependencyResolutionError < Gem::DependencyError
-  attr_reader :conflict
-
   def initialize(conflict)
-    @conflict = conflict
-    a, b = conflicting_dependencies
+    @explanation = conflict.explanation
+    super @explanation
+  end
 
-    super "conflicting dependencies #{a} and #{b}\n#{@conflict.explanation}"
+  def explanation
+    @explanation
+  end
+
+  def conflict
+    nil
   end
 
   def conflicting_dependencies
-    @conflict.conflicting_dependencies
+    []
   end
 end
 
@@ -126,40 +128,6 @@ def initialize(name, version, errors = nil)
 
 Gem.deprecate_constant :SpecificGemNotFoundException
 
-##
-# Raised by Gem::Resolver when dependencies conflict and create the
-# inability to find a valid possible spec for a request.
-
-class Gem::ImpossibleDependenciesError < Gem::Exception
-  attr_reader :conflicts
-  attr_reader :request
-
-  def initialize(request, conflicts)
-    @request   = request
-    @conflicts = conflicts
-
-    super build_message
-  end
-
-  def build_message # :nodoc:
-    requester  = @request.requester
-    requester  = requester ? requester.spec.full_name : "The user"
-    dependency = @request.dependency
-
-    message = "#{requester} requires #{dependency} but it conflicted:\n".dup
-
-    @conflicts.each do |_, conflict|
-      message << conflict.explanation
-    end
-
-    message
-  end
-
-  def dependency
-    @request.dependency
-  end
-end
-
 class Gem::InstallError < Gem::Exception; end
 
 class Gem::RuntimeRequirementNotMetError < Gem::InstallError