Improve "firstArgumentValue" and "argumentValue" extension functions

Using the argument value, which is of type "Any?", is more implicit and
thus difficult to read than using the ConstantValue instance and casting
it to the needed constant value implementation before taking the value

compiler/frontend/src/org/jetbrains/kotlin/resolve/AnnotationUtil.kt

@@ -21,6 +21,7 @@ import org.jetbrains.kotlin.descriptors.annotations.AnnotationDescriptor
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.resolve.DescriptorUtils
+import org.jetbrains.kotlin.resolve.constants.ConstantValue
 import org.jetbrains.kotlin.resolve.constants.ErrorValue
 
 val JVM_STATIC_ANNOTATION_FQ_NAME = FqName("kotlin.jvm.JvmStatic")
@@ -43,6 +44,6 @@ private val STRICTFP_ANNOTATION_FQ_NAME = FqName("kotlin.jvm.Strictfp")
 fun DeclarationDescriptor.findStrictfpAnnotation() =
     DescriptorUtils.getAnnotationByFqName(annotations, STRICTFP_ANNOTATION_FQ_NAME)
 
-fun AnnotationDescriptor.argumentValue(parameterName: String): Any? {
-    return allValueArguments[Name.identifier(parameterName)].takeUnless { it is ErrorValue }?.value
+fun AnnotationDescriptor.argumentValue(parameterName: String): ConstantValue<*>? {
+    return allValueArguments[Name.identifier(parameterName)].takeUnless { it is ErrorValue }
 }

compiler/frontend/src/org/jetbrains/kotlin/resolve/deprecationUtil.kt

@@ -33,6 +33,9 @@ import org.jetbrains.kotlin.resolve.DeprecationLevelValue.*
 import org.jetbrains.kotlin.resolve.annotations.argumentValue
 import org.jetbrains.kotlin.resolve.calls.checkers.isOperatorMod
 import org.jetbrains.kotlin.resolve.calls.checkers.shouldWarnAboutDeprecatedModFromBuiltIns
+import org.jetbrains.kotlin.resolve.constants.AnnotationValue
+import org.jetbrains.kotlin.resolve.constants.EnumValue
+import org.jetbrains.kotlin.resolve.constants.StringValue
 import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameSafe
 import org.jetbrains.kotlin.serialization.ProtoBuf
 import org.jetbrains.kotlin.serialization.deserialization.descriptors.DeserializedClassDescriptor
@@ -42,6 +45,7 @@ import org.jetbrains.kotlin.storage.StorageManager
 import org.jetbrains.kotlin.types.KotlinType
 import org.jetbrains.kotlin.types.TypeUtils
 import org.jetbrains.kotlin.utils.SmartList
+import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 
 private val JAVA_DEPRECATED = FqName("java.lang.Deprecated")
 
@@ -55,27 +59,22 @@ fun Deprecation.deprecatedByOverriddenMessage(): String? = (this as? DeprecatedB
 
 fun Deprecation.deprecatedByAnnotationReplaceWithExpression(): String? {
     val annotation = (this as? DeprecatedByAnnotation)?.annotation ?: return null
-    val replaceWithAnnotation = annotation.argumentValue(kotlin.Deprecated::replaceWith.name)
-            as? AnnotationDescriptor ?: return null
-
-    return replaceWithAnnotation.argumentValue(kotlin.ReplaceWith::expression.name) as String
+    val replaceWithAnnotation =
+        annotation.argumentValue(kotlin.Deprecated::replaceWith.name)?.safeAs<AnnotationValue>()?.value ?: return null
+    return replaceWithAnnotation.argumentValue(kotlin.ReplaceWith::expression.name)?.safeAs<StringValue>()?.value
 }
 
 private data class DeprecatedByAnnotation(val annotation: AnnotationDescriptor, override val target: DeclarationDescriptor) : Deprecation {
     override val deprecationLevel: DeprecationLevelValue
-        get() {
-            val level = annotation.argumentValue("level") as? ClassDescriptor
-
-            return when (level?.name?.asString()) {
-                "WARNING" -> WARNING
-                "ERROR" -> ERROR
-                "HIDDEN" -> HIDDEN
-                else -> WARNING
-            }
+        get() = when (annotation.argumentValue("level")?.safeAs<EnumValue>()?.enumEntryName?.asString()) {
+            "WARNING" -> WARNING
+            "ERROR" -> ERROR
+            "HIDDEN" -> HIDDEN
+            else -> WARNING
         }
 
     override val message: String?
-        get() = annotation.argumentValue("message") as? String
+        get() = annotation.argumentValue("message")?.safeAs<StringValue>()?.value
 }
 
 private data class DeprecatedByOverridden(private val deprecations: Collection<Deprecation>) : Deprecation {