---
title: Useless availability check (UselessAvailabilityCheck)
framework: swift-compiler
role: article
role_heading: Article
path: swift-compiler/documentation/diagnostics/useless-availability-check
---

# Useless availability check (UselessAvailabilityCheck)

Warnings that identify if #available queries that are guaranteed to succeed because an enclosing scope already restricts availability.

## Overview

Overview When an if #available query checks for an availability that is already implied by the availability of an enclosing scope (such as a containing declaration’s @available attribute or another if #available block), the check is unnecessary and the guard will always succeed at runtime. @available(macOS 26.4, *) struct WeatherView: View {   var body: some View {     if #available(macOS 26.0, *) { // warning: unnecessary check for 'macOS'; enclosing scope ensures guard will always be true       // ...     }   } } The if #available check above can be removed because WeatherView is already restricted to macOS 26.4 or newer, which implies macOS 26.0 or newer.

## See Also

- [@dynamicCallable implementation requirements (DynamicCallable)](swift-compiler/documentation/diagnostics/dynamic-callable-requirements.md)
- [Add @preconcurrency import (AddPreconcurrencyImport)](swift-compiler/documentation/diagnostics/add-preconcurrency-import.md)
- [Always enabled availability domains (AlwaysAvailableDomain)](swift-compiler/documentation/diagnostics/always-available-domain.md)
- [Argument matching for trailing closures (TrailingClosureMatching)](swift-compiler/documentation/diagnostics/trailing-closure-matching.md)
- [Calling a mutating async actor-isolated method (ActorIsolatedMutatingAsync)](swift-compiler/documentation/diagnostics/actor-isolated-mutating-async.md)
- [Calling an actor-isolated method from a synchronous nonisolated context (ActorIsolatedCall)](swift-compiler/documentation/diagnostics/actor-isolated-call.md)
- [Captures in a `@Sendable` closure (SendableClosureCaptures)](swift-compiler/documentation/diagnostics/sendable-closure-captures.md)
- [Compilation caching (CompilationCaching)](swift-compiler/documentation/diagnostics/compilation-caching.md)
- [Conforming to `StringInterpolationProtocol` (StringInterpolationConformance)](swift-compiler/documentation/diagnostics/string-interpolation-conformance.md)
- [Conversion from `@isolated(any)` function type to synchronous function type (ConversionFromIsolatedAnyToSynchronous)](swift-compiler/documentation/diagnostics/conversion-from-isolated-any-to-synchronous.md)
- [Cross-isolation data race (RegionIsolationCrossIsolationDataRace)](swift-compiler/documentation/diagnostics/region-isolation-cross-isolation-data-race.md)
- [Deprecated declaration warnings (DeprecatedDeclaration)](swift-compiler/documentation/diagnostics/deprecated-declaration.md)
- [Deprecated implementation-only imports (ImplementationOnlyDeprecated)](swift-compiler/documentation/diagnostics/implementation-only-deprecated.md)
- [Dynamic exclusivity (DynamicExclusivity)](swift-compiler/documentation/diagnostics/dynamic-exclusivity.md)
- [Embedded Swift language restrictions (EmbeddedRestrictions)](swift-compiler/documentation/diagnostics/embedded-restrictions.md)