global UGen in class pre-ctor does not behave correctly

[gewang]

this results in an internal error with UGen.add() -- bar appears uninitialized

class Foo
{
    Gain boo => global Gain bar => dac;
}
Foo foo;

FYI this works

global Gain bar;
class Foo
{
    Gain boo => bar => dac;
}
Foo foo;