FIR: Refine makesSenseToBeDefinitelyNotNull

Make it work just the same as the analogue from FE 1.0
This change is necessary since many tests start failing after
we began reporting diagnostics after call completion

compiler/fir/tree/src/org/jetbrains/kotlin/fir/types/FirTypeUtils.kt

@@ -10,9 +10,11 @@ import org.jetbrains.kotlin.fir.expressions.FirAnnotationCall
 import org.jetbrains.kotlin.fir.expressions.FirConstExpression
 import org.jetbrains.kotlin.fir.expressions.FirExpression
 import org.jetbrains.kotlin.fir.render
-import org.jetbrains.kotlin.name.StandardClassIds
 import org.jetbrains.kotlin.fir.types.impl.FirImplicitBuiltinTypeRef
 import org.jetbrains.kotlin.name.ClassId
+import org.jetbrains.kotlin.name.StandardClassIds
+import org.jetbrains.kotlin.types.AbstractNullabilityChecker
+import org.jetbrains.kotlin.types.AbstractTypeCheckerContext
 import org.jetbrains.kotlin.types.ConstantValueKind
 import kotlin.contracts.ExperimentalContracts
 import kotlin.contracts.contract
@@ -137,15 +139,37 @@ fun FirTypeProjection.toConeTypeProjection(): ConeTypeProjection =
         else -> error("!")
     }
 
-fun makesSenseToBeDefinitelyNotNull(type: ConeKotlinType): Boolean =
-    type.canHaveUndefinedNullability() // TODO: also check nullability
+fun AbstractTypeCheckerContext.makesSenseToBeDefinitelyNotNull(
+    type: ConeKotlinType,
+    useCorrectedNullabilityForFlexibleTypeParameters: Boolean
+): Boolean {
+    if (!type.canHaveUndefinedNullability()) return false
+
+    // Replacing `useCorrectedNullabilityForFlexibleTypeParameters` with true for all call-sites seems to be correct
+    // But it seems that it should be a new feature: KT-28785 would be automatically fixed then
+    // (see the tests org.jetbrains.kotlin.spec.checkers.DiagnosticsTestSpecGenerated.NotLinked.Dfa.Pos.test12/13)
+    // So it should be a language feature, but it's hard correctly identify language version settings for all call sites
+    // Thus, we have non-trivial value at org.jetbrains.kotlin.load.java.typeEnhancement.JavaTypeEnhancement.notNullTypeParameter
+    // that run under related language-feature only
+    if (useCorrectedNullabilityForFlexibleTypeParameters && type is ConeTypeParameterType) {
+        // Effectively checks if the type is flexible or has nullable bound
+        return with(typeSystemContext) {
+            type.isNullableType()
+        }
+    }
+
+    // Actually, this code should work for type parameters as well, but it breaks some cases
+    // See KT-40114
+
+    return !AbstractNullabilityChecker.isSubtypeOfAny(this, type)
+}
 
 fun ConeKotlinType.canHaveUndefinedNullability(): Boolean {
     return when (this) {
         is ConeTypeVariableType,
-        is ConeCapturedType
+        is ConeCapturedType,
+        is ConeTypeParameterType
         -> true
-        is ConeTypeParameterType -> type.isMarkedNullable || !hasNotNullUpperBound()
         else -> false
     }
 }