Revert "Revert "Add support of aliases for Method""

This reverts commit d7ca93c62c.

lib/pry/commands/stat.rb

@@ -16,10 +16,13 @@ class Pry
 
     def process
       meth = method_object
+      aliases = meth.aliases
+
       output.puts unindent <<-EOS
         Method Information:
         --
         Name: #{meth.name}
+        Alias#{ "es" if aliases.length > 1 }: #{ aliases.any? ? aliases.join(", ") : "None." }
         Owner: #{meth.owner ? meth.owner : "Unknown"}
         Visibility: #{meth.visibility}
         Type: #{meth.is_a?(::Method) ? "Bound" : "Unbound"}

lib/pry/method.rb

@@ -403,6 +403,24 @@ class Pry
       source_file == Pry.eval_path
     end
 
+    # @return [Array<String>] All known aliases for the method.
+    # @note On Ruby 1.8 this method always returns an empty Array for methods
+    #   implemented in C.
+    def aliases
+      owner = @method.owner
+      # Avoid using `to_sym` on {Method#name}, which returns a `String`, because
+      # it won't be garbage collected.
+      name = @method.name
+
+      alias_list = owner.instance_methods.combination(2).select do |pair|
+        owner.instance_method(pair.first) == owner.instance_method(pair.last) &&
+          pair.include?(name)
+      end.flatten
+      alias_list.delete(name)
+
+      alias_list.map(&:to_s)
+    end
+
     # @return [Boolean] Is the method definitely an alias?
     def alias?
       name != original_name

test/test_method.rb

@@ -1,4 +1,5 @@
 require 'helper'
+require 'set'
 
 describe Pry::Method do
   it "should use String names for compatibility" do
@@ -397,5 +398,48 @@ describe Pry::Method do
       meth.send(:method_name_from_first_line, "def obj_name.x").should == "x"
     end
   end
+
+  describe 'method aliases' do
+    before do
+      @class = Class.new {
+        def eat
+        end
+
+        alias fress eat
+        alias_method :omnomnom, :fress
+
+        def eruct
+        end
+      }
+    end
+
+    it 'should be able to find method aliases' do
+      meth = Pry::Method(@class.new.method(:eat))
+      aliases = Set.new(meth.aliases)
+
+      aliases.should == Set.new(["fress", "omnomnom"])
+    end
+
+    it 'should return an empty Array if cannot find aliases' do
+      meth = Pry::Method(@class.new.method(:eruct))
+      meth.aliases.should.be.empty
+    end
+
+    it 'should not include the own name in the list of aliases' do
+      meth = Pry::Method(@class.new.method(:eat))
+      meth.aliases.should.not.include "eat"
+    end
+
+    unless Pry::Helpers::BaseHelpers.mri_18?
+      # Ruby 1.8 doesn't support this feature.
+      it 'should be able to find aliases for methods implemented in C' do
+        meth = Pry::Method(Hash.new.method(:key?))
+        aliases = Set.new(meth.aliases)
+
+        aliases.should == Set.new(["include?", "member?", "has_key?"])
+      end
+    end
+
+  end
 end