Approximate definitely not-null types for type parameter's types if they are already not-null (has not-null upper bounds)

^KT-44440 Fixed
2021-01-21 14:57:28 +03:00
parent f2c1608c2b
commit f06a5321a6
12 changed files with 144 additions and 45 deletions
@@ -338,6 +338,12 @@ abstract class AbstractTypeApproximator(val ctx: TypeSystemInferenceExtensionCon
        val originalType = type.original()
        val approximatedOriginalType =
            if (toSuper) approximateToSuperType(originalType, conf, depth) else approximateToSubType(originalType, conf, depth)
+        val typeWithErasedNullability = originalType.withNullability(false)
+
+        // Approximate T!! into T if T is already not-null (has not-null upper bounds)
+        if (originalType.typeConstructor().isTypeParameterTypeConstructor() && !typeWithErasedNullability.isNullableType()) {
+            return typeWithErasedNullability
+        }

        return if (conf.definitelyNotNullType) {
            approximatedOriginalType?.makeDefinitelyNotNullOrNotNull()