Introduce conversions from signed pure constants to unsigned ones

#KT-24717 In Progress
 #KT-25996 Open
 #KT-25997 Open

core/descriptors/src/org/jetbrains/kotlin/builtins/UnsignedType.kt

@@ -10,7 +10,7 @@ import org.jetbrains.kotlin.descriptors.PackageFragmentDescriptor
 import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.types.KotlinType
-import kotlin.reflect.KClass
+import org.jetbrains.kotlin.types.TypeUtils
 
 
 enum class UnsignedType(val classId: ClassId) {
@@ -28,6 +28,8 @@ object UnsignedTypes {
     val unsignedTypeNames = enumValues<UnsignedType>().map { it.typeName }.toSet()
 
     fun isUnsignedType(type: KotlinType): Boolean {
+        if (TypeUtils.noExpectedType(type)) return false
+
         val descriptor = type.constructor.declarationDescriptor ?: return false
         return isUnsignedClass(descriptor)
     }

core/descriptors/src/org/jetbrains/kotlin/resolve/constants/CompileTimeConstant.kt

@@ -122,10 +122,28 @@ class UnsignedErrorValueTypeConstant(
 }
 
 class IntegerValueTypeConstant(
-        private val value: Number,
-        module: ModuleDescriptor,
-        override val parameters: CompileTimeConstant.Parameters
+    private val value: Number,
+    module: ModuleDescriptor,
+    override val parameters: CompileTimeConstant.Parameters,
+    val convertedFromSigned: Boolean = false
 ) : CompileTimeConstant<Number> {
+    companion object {
+        @JvmStatic
+        fun IntegerValueTypeConstant.convertToUnsignedConstant(module: ModuleDescriptor): IntegerValueTypeConstant {
+            val newParameters = CompileTimeConstant.Parameters(
+                parameters.canBeUsedInAnnotation,
+                parameters.isPure,
+                isUnsignedNumberLiteral = true,
+                isUnsignedLongNumberLiteral = parameters.isUnsignedLongNumberLiteral,
+                usesVariableAsConstant = parameters.usesVariableAsConstant,
+                usesNonConstValAsConstant = parameters.usesNonConstValAsConstant,
+                isConvertableConstVal = parameters.isConvertableConstVal
+            )
+
+            return IntegerValueTypeConstant(value, module, newParameters, convertedFromSigned = true)
+        }
+    }
+
     private val typeConstructor = IntegerValueTypeConstructor(value.toLong(), module, parameters)
 
     override fun toConstantValue(expectedType: KotlinType): ConstantValue<Number> {
@@ -146,8 +164,8 @@ class IntegerValueTypeConstant(
     }
 
     val unknownIntegerType = KotlinTypeFactory.simpleTypeWithNonTrivialMemberScope(
-            Annotations.EMPTY, typeConstructor, emptyList(), false,
-            ErrorUtils.createErrorScope("Scope for number value type ($typeConstructor)", true)
+        Annotations.EMPTY, typeConstructor, emptyList(), false,
+        ErrorUtils.createErrorScope("Scope for number value type ($typeConstructor)", true)
     )
 
     fun getType(expectedType: KotlinType): KotlinType = TypeUtils.getPrimitiveNumberType(typeConstructor, expectedType)