See
https://youtrack.jetbrains.com/issue/KT-19251https://github.com/puniverse/quasar/issues/280https://bugs.openjdk.java.net/browse/JDK-8046233
Inline function calls (as well as try/catch expressions) in constructor
arguments produce bytecode that spills stack, and stores uninitialized
objects (created by 'NEW C', but not initialized by 'C.<init>') to
local variables. Such bytecode is valid according to the JVM spec, but
confuses Quasar (and other bytecode postprocessing tools),
and fails to verify under some (buggy) versions of JDK 8.
In order to avoid that, we apply 'processUnitializedStores' already
implemented for coroutines. It moves 'NEW' instructions after the
constructor arguments evaluation, producing code like
<initialize class C using Class.forName>
<evaluate constructor arguments>
<store constructor arguments to variables>
NEW C
DUP
<load constructor arguments from variables>
INVOKESPECIAL C.<init>(...)
NB some other expressions, such as break/continue in the constructor
arguments, also can produce "weird" bytecode: object is created by a
'NEW C' instruction, but later (conditionally) POPped from stack and
left uninitialized. This, as we know, also can screw bytecode
postprocessing. However, it looks like we can get away with it ATM.
Otherwise it looks like we'd have to analyze constructor arguments, see
if the evaluation can "jump out", and perform argument linearization in
codegen.
Similar to enum entry initialization, when we have a companion object
in an interface, its constructor (or clinit) initializes its state
before the instance field in corresponding interface is initialized.
So, interface companion object must be accessed via a captured object
reference (#0, or #0.this$0 for inner anonymous objects).
This annotation is currently internal because we only commit to its
support for our own libraries. It will be used to change JVM package
names of declarations in JDK-specific stdlib additions (now called
kotlin-stdlib-jre7/8), both to preserve source compatibility of the old
Kotlin code and to solve the split package problem (KT-19258)
Before this change, we were computing the visibility of an inherited
private property setter, and ISE at AsmUtil.getVisibilityAccessFlag
happened ("invisible_fake is not a valid visibility in backend")
Enum entries are "special" kind of singletons that should be
referenced as a captured 'this' instance inside during entry
initialization, because corresponding static fields in enum class
are not initialized yet.
#KT-7257 Fixed
Use it for char boxing/unboxing and unit materialization.
Possible to use for other purposes, for example, to add type checks
to dynamics.
See KT-18793, KT-17915, KT-19081, KT-18216, KT-12970, KT-17014,
KT-13932, KT-13930
In an inner class of the enum entry class, enum entry reference should
be generated as an outer 'this', not as a enum entry access, because
enum entry itself may be not initialized yet.
Alexey Andreev