... w.r.t the variance of their type arguments.
Because `Object[]` is represented as `Array<Any>..Array<out Any>?`,
when we substitute, we can't just take the upper bound because it
changes the variance of the type agument.
Instead, we construct a flexible type and use both bounds, like with
collections with flexible mutability.
#KT-65246 Fixed
The main reason of this commit is the fact that it makes no sense
to create type checker forks in case of two or more types which equal
each other.
Also, this commit fixes the test taken from KT-59514
(see interconnectedGenerics.kt test changed in this commit).
In this particular case we have a subType of C.WithL<Pr!, En<Pr>!>,
and a superType of R<T> with a superType constructor R.
In findCorrespondingSupertypes we get *two* similar supertypes here,
both have a string representation of:
R<Il<@EnhancedNullability En<Pr>!>!>.
If we create two forks because of it, we get NEW_INFERENCE_ERROR
with the following subtyping violation:
Il<@EnhancedNullability En<Pr>!>! <: En<Pr>!.
NEW_INFERENCE_ERROR happens because we make a redundant fork in that case,
but the forks should still work despite it (see KT-62333).
These two types appear due to the content of FirCorrespondingSupertypeCache.
For a key C.WithL and a superType R it stores the following pair of supertypes:
- R<Il<@EnhancedNullability S>!>
- R<Il<(@EnhancedNullability S & Any, @EnhancedNullability S?)>!>
After substitution of S to En<Pr>! they become similar.
NB: if we change jspecify severity level from strict to warn,
then 'R<Il<(S & Any, S?)>!>' is the only remaining supertype,
and @EnhancedNullability annotation is no more in use.
The type hierarchy in this example looks like:
WithL<T, S> <: CanWithB<T, S>, R.F<S, Il<S>>
CanWithB<T, S> <: R.F<S, Il<S>>
R.F<S, Il<S>> <: R<Il<S>>
So R is reachable by two different ways, via CanWithB and directly via R.F.
#KT-59514 Fixed
That issue might be fixed via changing
TypeVariableMarker.shouldBeFlexible at ConeConstraintSystemUtilContext
but this and some other tricks have been added because of incorrect
handling of constraints where type variable has a flexible bound
^KT-51168 Fixed
* Change 1.6 to 1.7 constants
* Fix SAFE_CALL_WILL_CHANGE_NULLABILITY for testData
* Change EXPOSED_PROPERTY_TYPE_IN_CONSTRUCTOR_WARNING to EXPOSED_PROPERTY_TYPE_IN_CONSTRUCTOR_ERROR
* Change NON_EXHAUSTIVE_WHEN_STATEMENT to NO_ELSE_IN_WHEN
* Fix testData for SafeCallsAreAlwaysNullable
* Change T -> T & Any in test dumps
* Change INVALID_CHARACTERS_NATIVE_WARNING -> INVALID_CHARACTERS_NATIVE_ERROR
* TYPECHECKER_HAS_RUN_INTO_RECURSIVE_PROBLEM_WARNING -> TYPECHECKER_HAS_RUN_INTO_RECURSIVE_PROBLEM_ERROR
We are going to deprecate `WITH_RUNTIME` directive. The main reason
behind this change is that `WITH_STDLIB` directive better describes
its meaning, specifically it will add kotlin stdlib to test's classpath.
Kirill Rakhman