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kotlin-fork/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt1778.fir.kt
T
Nikolay Lunyak f0720c1d12 [FIR] Fix K2 behavior according to RULES1
The compiler should only report diagnostics for
comparisons over builtins and identity-less types,
other incompatibilities should be reported
via inspections.

It's ok that in `equalityChecksOnIntegerTypes`
instead of `EQUALITY_NOT_APPLICABLE_WARNING` we get
`EQUALITY_NOT_APPLICABLE`, because
`ProperEqualityChecksInBuilderInferenceCalls`
is already active by default.

This change also replaces the notion of a representative superclass
with the least upper bound.
This makes complex types like
intersection/flexible transparent to
RULES1-based compatibility checks.
One way to look at it is to think
that this is an automatic way of handling
type parameters: automatic picking of
"interesting" bounds, and checking them against one another.

Note that `TypeIntersector.intersectTypes`
for `Int` and `T` where `T` is a type parameter
may return both `{Int & T}` or `null`
depending on `T`-s bounds. At the same time,
for type parameters `T` and `K` it will
always return `{T & K}`.

`ConeTypeIntersector.intersectTypes`, on the
other hand, will always return `{Int & T}`
irrespectively of the bounds. Meaning, the two
intersectors differ in corner cases.

`lowerBoundIfFlexible` call in `isLiterallyTypeParameter` is backed by
the `equalityOfFlexibleTypeParameters` test.

^KT-35134 #fixed-in-k2
^KT-22499 #fixed-in-k2
^KT-46383 #fixed-in-k2
2023-03-31 15:01:50 +00:00

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// !CHECK_TYPE
// WITH_EXTENDED_CHECKERS
//KT-1778 Automatically cast error
package kt1778
import checkSubtype
fun main(args : Array<String>) {
val x = checkSubtype<Any>(args[0])
if(x is <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>java.lang.CharSequence<!>) {
if (<!EQUALITY_NOT_APPLICABLE_WARNING!>"a" == x<!>) x.<!FUNCTION_CALL_EXPECTED!>length<!> else x.length() // OK
if (<!EQUALITY_NOT_APPLICABLE_WARNING!>"a" == x<!> || <!EQUALITY_NOT_APPLICABLE_WARNING!>"b" == x<!>) x.<!FUNCTION_CALL_EXPECTED!>length<!> else x.length() // < THEN ERROR
if (<!EQUALITY_NOT_APPLICABLE_WARNING!>"a" == x<!> && <!EQUALITY_NOT_APPLICABLE_WARNING!>"a" == x<!>) x.<!FUNCTION_CALL_EXPECTED!>length<!> else x.length() // < ELSE ERROR
}
}