Note that `FlexibleNullability` doesn't
exist anymore: it was removed at
`65ea4e18`.
`preserveEnhancedNullability = true`
was needed because if we have an
`@EnhancedNullability DNN`, and we
substitute something into it, then
`withNullability` is called there becase
that's how DNNs work, not becase we want
to obtain some new type with a
different nullability.
This is backed by
the `compiler/testData/diagnostics/tests/j+k/integerNotNullable.kt` test
where we first have
`@EnhancedNullability T & Any`, then
we substitute `{T -> kotlin/Int!}` and
then inside
`org.jetbrains.kotlin.fir.resolve.substitution.AbstractConeSubstitutor#substituteOriginal`
(this is a DNN-specific function) we
call `withNullability(NOT_NULL)`,
and expect the attribute to be preserved. Otherwise this test would
fail with
`OVERLOAD_RESOLUTION_AMBIGUITY` for
`IntBox().put(1)`.
^KT-50221 Fixed
Merge-request: KT-MR-11272
Merged-by: Nikolay Lunyak <Nikolay.Lunyak@jetbrains.com>
Nikolay Lunyak
ed493c99e3