Make show_source resolve top-level constant names (#831)

Author: st0012

lib/irb/source_finder.rb

@@ -19,7 +19,7 @@ def initialize(irb_context)
  def find_source(signature, super_level = 0)
  context_binding = @irb_context.workspace.binding
  case signature
- when /\A[A-Z]\w*(::[A-Z]\w*)*\z/ # Const::Name
+ when /\A(::)?[A-Z]\w*(::[A-Z]\w*)*\z/ # Const::Name
  eval(signature, context_binding) # trigger autoload
  base = context_binding.receiver.yield_self { |r| r.is_a?(Module) ? r : Object }
  file, line = base.const_source_location(signature)

test/irb/cmd/test_show_source.rb

@@ -272,5 +272,33 @@ def foo
 
  assert_match(%r[#{@ruby_file.to_path}:2\s+def foo\r\n end], out)
  end
+
+ def test_show_source_with_double_colons
+ write_ruby <<~RUBY
+ class Foo
+ end
+
+ class Foo
+ class Bar
+ end
+ end
+
+ binding.irb
+ RUBY
+
+ out = run_ruby_file do
+ type "show_source ::Foo"
+ type "exit"
+ end
+
+ assert_match(%r[#{@ruby_file.to_path}:1\s+class Foo\r\nend], out)
+
+ out = run_ruby_file do
+ type "show_source ::Foo::Bar"
+ type "exit"
+ end
+
+ assert_match(%r[#{@ruby_file.to_path}:5\s+class Bar\r\n end], out)
+ end
  end
 end