Library methods such as 'listOf' are resolved
to have the package fragments as their parents,
but JVM expects their containing file classes as parents.
This fix generates those file classes and
uses them as parent replacements for such library methods.
Singleton instance is "initialized" by delegating constructor call,
which is superclass constructor call in case of singletons (because
singletons can't have more than one constructor).
Singleton constructor is effectively split into two stages:
- before a super constructor call;
- after a super constructor call.
Before super constructor call, singleton instance can't be used directly
(see KT-20662), because neither 'this' nor static instance is
initialized yet. However, it can be used in closures, in which case a
static instance should be used (escaping uninitialized this is
prohibited by JVM). Actually using this static instance before it is
initialized (e.g., invoking a method that uses this singleton) will
cause a correct ExceptionInInitializerError.
After a super constructor call, static instance of a singleton may be
not initialized yet (in case of enum entries and interface companion
objects). However, we already have an initialized 'this', which we
should use for singleton references.
#KT-20651 Fixed
Mikhail Glukhikh