Allow creation of public symbols using MirrorSystem.getSymbol when passing a null library.

Allow creation of public symbols using MirrorSystem.getSymbol when passing a null library.

R=asiva@google.com, gbracha@google.com

Committed: https://code.google.com/p/dart/source/detail?r=30435

[gbracha, 2013-11-19 01:52:06]

tests lgtm

[rmacnak, 2013-11-20 00:27:46]

https://codereview.chromium.org/61753019/diff/50001/runtime/lib/mirrors_patch...
File runtime/lib/mirrors_patch.dart (left):

https://codereview.chromium.org/61753019/diff/50001/runtime/lib/mirrors_patch...
runtime/lib/mirrors_patch.dart:5: import "dart:nativewrappers";
We haven't needed this since the introduction of MirrorReference...

[siva, 2013-11-20 01:17:54]

lgtm

[rmacnak, 2013-11-20 01:33:29]

Committed patchset #2 manually as r30435 (presubmit successful).

[ahe, 2013-11-21 09:07:02]

https://codereview.chromium.org/61753019/diff/50001/runtime/lib/mirrors_patch...
File runtime/lib/mirrors_patch.dart (right):

https://codereview.chromium.org/61753019/diff/50001/runtime/lib/mirrors_patch...
runtime/lib/mirrors_patch.dart:80: if ((library != null && library is!
_LocalLibraryMirror) ||
Why are you checking for is! _LocalLibraryMirror?

My understanding is that it is too protect _mangleName from being called with
anything that isn't a _MirrorReference.

Using reflection, I can instantiate _LocalLibraryMirror and ensure it has a
bogus value for the field _reflectee. I believe I can provoke a crash that way
if Mirrors_mangleName makes too many assumptions. I'd argue that you should
remove the type test here and replace line 84 with:

if (library != null) {
  name = _mangleName(name, library._reflectee as _MirrorReference);
}

However, if _mangleName is so brittle, then you probably also need to write:

if (library != null) {
  name = _mangleName(name as String, library._reflectee as _MirrorReference);
}

If _mangleName is an instance method on _MirrorReference, you can reduce this
to:

if (library != null) {
  name = library._reflectee._mangleName(name as String);
}

Regardless, _mangleName can be invoked reflectively, so it should probably be
checking for String in C++, so really the first lines of this method should just
be:

if (library != null) {
  name = library._reflectee._mangleName(name);
} else if (name.startsWith('_')) {
  throw new ArgumentError("'$name' is private so this method needs a library");
}