Otherwise, exception from org.jetbrains.kotlin.resolve.calls.inference.components.ConstraintInjector.TypeCheckerStateForConstraintInjector.fixedTypeVariable
might happen during forks resolution
The test data is extracted from intelliJ FP test
^KT-43296 Fixed
Otherwise, OVERLOAD_RESOLUTION_AMBIGUITY is reported for the calls to
the functions annotated as @OverloadResolutionByLambdaReturnType
^KT-43296 In Progress
The idea is that we should not fix (i.e. choose any of the fork branches)
on the stage of candidate processing before completion, but it's enough
just to check that current state can be converged to success.
And when completion starts, and we add expected type to the system,
we've got more information to choose the correct fork branch.
NB: The old `processForkConstraints` is being called just
at the beginning of the completion phase.
^KT-43296 In Progress
It's anyway safe to use avoidComprehensiveCheck = true because
during deserialization we're sure that we need DNN type because
it's been serialized as such.
AllOpen plugin makes the properties all-open, but the annotation class
is left closed, because allopen for k2 literally checks
`classKind == CLASS`.
Since the properties are open, a
`NON_FINAL_MEMBER_IN_FINAL_CLASS` diagnostic is reported for them. It's
positioning strategy seeks for the explicit `open` modifier which is
not present.
The added test should not crash the compiler.
^KT-54260 Fixed
This is needed not only as optimization, but also for cases, when
inferred type of function may differ from type of single expression.
Such situation may occur after next commit, which adds approximation
of return type of all declarations:
```
interface A
interface B
interface C : A, B
interface D : A, B
class Inv<T>(val x: T, val y: T)
fun foo(c: C, d: D) /* : Inv<Any> */ = Inv(c, d) /*: Inv<A & B> */
// Inv<A & B> /<: Inv<Any>
// but there should be no error
```
Also remove incorrect subtype check checkers
Test unsafeVarianceInAliasedFunctionalType.kt started to fail because
of KT-54894. This bug existed before, changes from this commit just
unhided it (previously it was hidden because incorrect subtype check
in `isSubtypeForTypeMismatch` which is used by FirFunctionReturnTypeMismatchChecker
`x?.y != null` does not imply that `x != null` if e.g. an argument to
`y` has reassigned `x` in the meantime.
The same is true for `x == y` and `functionWithContract(x, y)`, but
those are somewhat harder to implement since there is no easy way to
find the last node of a certain argument.
^KT-55096
Thinking of monomorphizing `Flow` (= `PersistentFlow`) and instead
adding a completely separate `MutableFlow` version; then `joinFlow`
would produce a mutable one, data flow analysis would add some
statements, convert to a persistent `Flow` and proceed to the next
node.
The code was already duplicated between FirDataFlowAnalyzer and
FirReturnsImpliesAnalyzer, so might as well use the latter to slightly
speed up the former.
This makes the `returns() implies` checker slightly cleaner, and also
fixes the case that I've missed where in RHS of `x ?:` type of `x` was
not set to `Nothing?`.
Dmitrii Gridin