The actual problem was introduced in 4f1e85b468, note how `hashCode` is implemented:
```
var currentHashCode = cachedHashCode
if (currentHashCode == 0) return currentHashCode
...
```
It's a silly bug, there should be check `if (currentHashCode != 0) ...` because `0` is used a marker for "uncomputed value".
Now, in the commit 0219b86d06 I added map with `KotlinType` as a key and because of constant `hash` for `KotlinType`, we basically got `List` instead of `Map`, which caused this performance regression
#KT-34063 Fixed
After refinement is introduced it becomes possible to have a different
descriptors instances for effectively the same descriptors
Also, it accidentally fixes KT-25432 because is caused by a different
version of descriptors created for NewCapturedType
^KT-25432 Fixed
There is added a new service named `SubstitutingScopeProvider`, that
provides factory that creates captured types and approximator for them.
In OI they are the same as before commit, for NI they are empty, because
that approximation interferes with NI algorithm
That service is injected into function descriptors and property descriptors
and used for creating `SubstitutingScope` with correct services
Also there is changed time when we approximate captured types in NI
(after all call checkers)
#KT-25290 Fixed
Add `IntegerLiteralTypeConstructor` that holds types, that can take
integer literal with given value. It has two supertypes
(`Number` and `Comparable<IntegerLiteralType>`) and have
special rules for subtyping, `intersect` and `commonSuperType`
functions with primitive number:
Example (assuming that ILT holds Int type):
* ILT <: Int
* Int :> ILT
* ILT intersect Int = Int
* commonSuperType(ILT, Int) = Int
#KT-30293 Fixed
#KT-30446 Fixed
Consider following expression: 'call() is Foo'. Suppose that we know
something about the 'call()', e.g. 'returns(foo) -> <condition>'
Previously, we've tried to re-use knowledge about 'call()', constructing
some smart clause, like 'returns(true) -> foo is Foo && <condition>'.
The conceptual error here is that *we can't* argue that <condition>
holds. Imagine that 'call()' actually has unspecified 'returns(foo2) ->
<!condition>', and 'foo2 is Foo' also holds. Then we would get
'returns(true) -> foo2 is Foo && <condition>' <=> 'returns(true) ->
<condition>' for the whole call, which is not correct.
More concrete example would be something like:
'if (!x.isNullOrEmpty() is Boolean)'
^KT-27241 Fixed
Mikhail Zarechenskiy