tl;dr the current design of klibs does not allow to properly deserialize
the list of sealed subclasses in a sound way. It is possible that
a subclass of a sealed class is declared in a different file, AND is
private in that file.
A more detailed explanation:
Right now we don't serialize file signatures at all.
However, a private declaration's signature must necessarily include
the file signature.
How do we serialize a private declaration's signature into a klib
and deserialize it later?
**Serialization** is simple: we just serialize the file signature as
an empty protobuf message.
When we are **deserializing** a private declaration, we look at the file
that is being deserialized right now, and construct the file signature
based on that.
This logic, however, doesn't always work. An example is KT-54028.
Basically, if we have a sealed interface with a private implementor
declared in a different file, this breaks:
1. We are deserializing the sealed interface. The deserializer knows
that we are now in the file in which the sealed interface is declared.
2. As part of deserializing the interface, we deserialize its sealed
subclasses.
3. Naturally, we come to deserializing the private implementor that is
declared in another file, but the deserializer still thinks that we are
in the file in which the interface is declared. A wrong signature is
created, which leads to linkage failure.
We *could* fix this by properly serializing the file signature,
i.e. instead of an empty protobuf message we could write the file path
and its package to the klib. However, there a problems with this
approach:
- The current design of signatures allows a situation where two
different files can have the same relative path
(for example, with the help of the `-Xklib-relative-path-base` compiler
flag) *and* the same package, which would introduce ambiguity during
linkage.
- Most importantly, this appoach won't work well with incremental
compilation of klibs. Currently we rely on the assumption that all
cross-file references are handled with public signatures, and private
signatures are only used inside a single file. This allows to move
declarations across files without recompiling it's use sites.
It has been decided to apply the following hacky solution: we just don't
deserialize the list of sealed subclasses from klibs.
The list of sealed subclasses is not used in lowerings, so it should be
safe.
#KT-54028 Fixed
Overriding equals, hashCode, toString and any other member that is not
expect does not require satisfying the rules of expect-actual matching.
#KT-57381 Fixed
Fake overrides are needed at least for static fields inherited from Java
interfaces. Not static methods though, because they are not inherited.
#KT-57302 Fixed
with dedicated opt-in language feature and special
annotation or module capability.
Not intended for a general use, solves specific K/N
scenario with interop libs.
#KT-55902 fixed
When building the original for a substitution override for a synthetic
property, use the initial setter as fallback when unsubstituting it
returns null. This can happen when a generic class overrides the getter
of a synthetic property of a non-generic class. Then the setter is never
substituted, therefore there is nothing to unsubstitute.
^KT-57168 Fixed
A::foo is preferably resolved as an unbound reference to A.foo, however
if A.Companion is a subtype of A and the expected type has one fewer
parameter than the type of the unbound reference, generate a bound
reference with the companion as receiver.
^KT-56519 Fixed
The expression needs to be resolved first to determine if there is a
receiver that needs to be extracted to a temporary variable. Also, the
special case for prefix increment/decrement on local variable without
delegates requires resolution to check if the variable is local.
^KT-56771 Fixed
^KT-56659 Fixed
during tail-call optimization.
There can be code, where all next instructions are non-meaningful and
there is a back-edge, for example, while(true){}. Previously, analyzer
incorrectly assumed, that this cannot happen. Now, it keeps track of
visited instructions and says, that there is no meaningful instruction
in such case.
#KT-56815 Fixed
Previously, containingDeclarationSymbol for V was set to the outer class
BaseRoot, so its upper bounds was computed to the ones from TNested
at org.jetbrains.kotlin.fir.resolve.calls.CreateFreshTypeVariableSubstitutorStageKt.getTypeParameterFromExpandedClass
^KT-56706 Fixed
It would be more consistently to prohibit the behavior from the unmuted
test (see KT-52428), but it was decided to postpone the breaking change.
Unfortunately, it didn't work to make a test where for computing
star projections we would need to substitute other type parameters
because effectively, it's not allowed to have SAM conversion when
star projections/wildcard is based on a type parameter which bounds
use other type parameters.
^KT-53552 In progress
If a synthetic prop clashes with a real property (e.g. @JvmField
property from parent Kotlin class), don't generate fake override for the
synthetic property. This fixes a CONFLICTING_INHERITED_JVM_DECLARATIONS
error in a mixed hierarchy.
^KT-56538 Fixed
- The fix for KT-55570 caused some backend tests to fail, because errors
are now correctly reported for simple classes and actual/expect in
the same module is not supported in FIR. See KT-55177.
- The commit also adds separate tests for K2. Unfortunately, these have
to be disabled for K1 because K1 then reports "expect without actual"
errors.
Igor Yakovlev