load.c: real path to load

* load.c (rb_construct_expanded_load_path): expand load paths to
  real paths to get rid of duplicate loading from symbolic-linked
  directories.  [Feature #10222]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59984 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

load.c

@@ -85,7 +85,8 @@ rb_construct_expanded_load_path(enum expand_type type, int *has_relative, int *h
 	if (is_string)
 	    rb_str_freeze(path);
 	as_str = rb_get_path_check_convert(path, as_str, level);
-	expanded_path = rb_file_expand_path_fast(as_str, Qnil);
+	expanded_path = rb_check_realpath(Qnil, as_str);
+	if (NIL_P(expanded_path)) expanded_path = as_str;
 	rb_ary_push(ary, rb_fstring(expanded_path));
     }
     rb_obj_freeze(ary);

test/ruby/test_exception.rb

@@ -1019,7 +1019,7 @@ $stderr = $stdout; raise "\x82\xa0"') do |outs, errs, status|
     warning = nil
     path = nil
     Tempfile.create(%w[circular .rb]) do |t|
-      path = t.path
+      path = File.realpath(t.path)
       basename = File.basename(path)
       t.puts "require '#{basename}'"
       t.close

test/ruby/test_require.rb

@@ -881,4 +881,18 @@ class TestRequire < Test::Unit::TestCase
       end;
     end
   end
+
+  def test_symlink_load_path
+    Dir.mktmpdir {|tmp|
+      Dir.mkdir(File.join(tmp, "real"))
+      begin
+        File.symlink "real", File.join(tmp, "symlink")
+      rescue NotImplementedError, Errno::EACCES
+        skip "File.symlink is not implemented"
+      end
+      File.write(File.join(tmp, "real/a.rb"), "print __FILE__")
+      result = IO.popen([EnvUtil.rubybin, "-I#{tmp}/symlink", "-e", "require 'a.rb'"], &:read)
+      assert_operator(result, :end_with?, "/real/a.rb")
+    }
+  end
 end