scala/scala — pull request #1360 by xeno-by (2012-09-20 09:14:11+00:00)
Title: don't try to create tags w/o scala-reflect.jar

Since recently type tags have relocated to scala-reflect.jar,
meaning that they are no longer always on library classpath.

In the compiler we do have code that generates type tags, and this code
is bound to fail if scala-reflect.jar isn't there.

I though this wouldn't be a problem, because type tag materialization
is only going to be triggered by users explicitly requesting a type tag.

That's generally true, but I overlooked a corner case. Since we provide
manifest <-> type tag compatibility, manifest lookup can sometimes trigger
tag lookup, which might result in tag synthesis, which blows up like this:
http://groups.google.com/group/scala-internals/browse_thread/thread/166ce4b71b7c46bb