K2: introduce unwrapFlexibleAndDefinitelyNotNull

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirCyclicTypeBoundsChecker.kt

@@ -77,5 +77,5 @@ object FirCyclicTypeBoundsChecker : FirBasicDeclarationChecker() {
         ref.unwrapBound().mapNotNull { extractTypeParamName(it.coneType) }.toSet()
 
     private fun extractTypeParamName(type: ConeKotlinType): Name? =
-        (type.lowerBoundIfFlexible().unwrapDefinitelyNotNull() as? ConeTypeParameterType)?.lookupTag?.name
+        (type.unwrapFlexibleAndDefinitelyNotNull() as? ConeTypeParameterType)?.lookupTag?.name
 }

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirTopLevelTypeAliasChecker.kt

@@ -24,7 +24,7 @@ object FirTopLevelTypeAliasChecker : FirTypeAliasChecker() {
         }
 
         fun containsTypeParameter(type: ConeKotlinType): Boolean {
-            val unwrapped = type.lowerBoundIfFlexible().unwrapDefinitelyNotNull()
+            val unwrapped = type.unwrapFlexibleAndDefinitelyNotNull()
 
             if (unwrapped is ConeTypeParameterType) {
                 return true

compiler/fir/cones/src/org/jetbrains/kotlin/fir/types/ConeTypes.kt

@@ -118,6 +118,10 @@ fun ConeSimpleKotlinType.unwrapDefinitelyNotNull(): ConeSimpleKotlinType {
     }
 }
 
+fun ConeKotlinType.unwrapFlexibleAndDefinitelyNotNull(): ConeKotlinType {
+    return lowerBoundIfFlexible().unwrapDefinitelyNotNull()
+}
+
 class ConeCapturedTypeConstructor(
     val projection: ConeTypeProjection,
     var supertypes: List<ConeKotlinType>? = null,