1 files changed, 177 insertions, 0 deletions
diff --git a/lib/rubygems/errors.rb b/lib/rubygems/errors.rb
new file mode 100644
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+++ b/lib/rubygems/errors.rb
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+# frozen_string_literal: true
+
+#--
+# This file contains all the various exceptions and other errors that are used
+# inside of RubyGems.
+#
+# DOC: Confirm _all_
+#++
+
+module Gem
+  ##
+  # Raised when RubyGems is unable to load or activate a gem.  Contains the
+  # name and version requirements of the gem that either conflicts with
+  # already activated gems or that RubyGems is otherwise unable to activate.
+
+  class LoadError < ::LoadError
+    # Name of gem
+    attr_accessor :name
+
+    # Version requirement of gem
+    attr_accessor :requirement
+  end
+
+  ##
+  # Raised when trying to activate a gem, and that gem does not exist on the
+  # system.  Instead of rescuing from this class, make sure to rescue from the
+  # superclass Gem::LoadError to catch all types of load errors.
+  class MissingSpecError < Gem::LoadError
+    def initialize(name, requirement, extra_message = nil)
+      @name        = name
+      @requirement = requirement
+      @extra_message = extra_message
+      super(message)
+    end
+
+    def message # :nodoc:
+      build_message +
+        "Checked in 'GEM_PATH=#{Gem.path.join(File::PATH_SEPARATOR)}' #{@extra_message}, execute `gem env` for more information"
+    end
+
+    private
+
+    def build_message
+      total = Gem::Specification.stubs.size
+      "Could not find '#{name}' (#{requirement}) among #{total} total gem(s)\n"
+    end
+  end
+
+  ##
+  # Raised when trying to activate a gem, and the gem exists on the system, but
+  # not the requested version. Instead of rescuing from this class, make sure to
+  # rescue from the superclass Gem::LoadError to catch all types of load errors.
+  class MissingSpecVersionError < MissingSpecError
+    attr_reader :specs
+
+    def initialize(name, requirement, specs)
+      @specs = specs
+      super(name, requirement)
+    end
+
+    private
+
+    def build_message
+      names = specs.map(&:full_name)
+      "Could not find '#{name}' (#{requirement}) - did find: [#{names.join ","}]\n"
+    end
+  end
+
+  # Raised when there are conflicting gem specs loaded
+
+  class ConflictError < LoadError
+    ##
+    # A Hash mapping conflicting specifications to the dependencies that
+    # caused the conflict
+
+    attr_reader :conflicts
+
+    ##
+    # The specification that had the conflict
+
+    attr_reader :target
+
+    def initialize(target, conflicts)
+      @target    = target
+      @conflicts = conflicts
+      @name      = target.name
+
+      reason = conflicts.map do |act, dependencies|
+        "#{act.full_name} conflicts with #{dependencies.join(", ")}"
+      end.join ", "
+
+      # TODO: improve message by saying who activated `con`
+
+      super("Unable to activate #{target.full_name}, because #{reason}")
+    end
+  end
+
+  class ErrorReason; end
+
+  # Generated when trying to lookup a gem to indicate that the gem
+  # was found, but that it isn't usable on the current platform.
+  #
+  # fetch and install read these and report them to the user to aid
+  # in figuring out why a gem couldn't be installed.
+  #
+  class PlatformMismatch < ErrorReason
+    ##
+    # the name of the gem
+    attr_reader :name
+
+    ##
+    # the version
+    attr_reader :version
+
+    ##
+    # The platforms that are mismatched
+    attr_reader :platforms
+
+    def initialize(name, version)
+      @name = name
+      @version = version
+      @platforms = []
+    end
+
+    ##
+    # append a platform to the list of mismatched platforms.
+    #
+    # Platforms are added via this instead of injected via the constructor
+    # so that we can loop over a list of mismatches and just add them rather
+    # than perform some kind of calculation mismatch summary before creation.
+    def add_platform(platform)
+      @platforms << platform
+    end
+
+    ##
+    # A wordy description of the error.
+    def wordy
+      format("Found %s (%s), but was for platform%s %s", @name, @version, @platforms.size == 1 ? "" : "s", @platforms.join(" ,"))
+    end
+  end
+
+  ##
+  # An error that indicates we weren't able to fetch some
+  # data from a source
+
+  class SourceFetchProblem < ErrorReason
+    ##
+    # Creates a new SourceFetchProblem for the given +source+ and +error+.
+
+    def initialize(source, error)
+      @source = source
+      @error = error
+    end
+
+    ##
+    # The source that had the fetch problem.
+
+    attr_reader :source
+
+    ##
+    # The fetch error which is an Exception subclass.
+
+    attr_reader :error
+
+    ##
+    # An English description of the error.
+
+    def wordy
+      "Unable to download data from #{Gem::Uri.redact(@source.uri)} - #{@error.message}"
+    end
+
+    ##
+    # The "exception" alias allows you to call raise on a SourceFetchProblem.
+
+    alias_method :exception, :error
+  end
+end