---
title: Upcoming language features
framework: swift-compiler
role: collectionGroup
path: swift-compiler/documentation/diagnostics/upcoming-language-features
---

# Upcoming language features

Upcoming language features enable new (but potentially source breaking) functionality that be enabled by default in an upcoming language mode.

## Overview

Overview Upcoming language features allow the incremental adoption of language features that would otherwise only be available in a new language mode, without having to fully migrate to that mode. They can be enabled on the command line with -enable-upcoming-feature <feature>. Some upcoming features have an additional “migration” mode, where the compiler will emit warnings with fix-its to help migrate to that mode. This can be enabled with -enable-upcoming-feature <feature>:migrate.

## Topics

- [Existential any (ExistentialAny)](swift-compiler/documentation/diagnostics/existential-any.md)
- [Member import visibility (MemberImportVisibility)](swift-compiler/documentation/diagnostics/member-import-visibility.md)
- [nonisolated(nonsending) by Default (NonisolatedNonsendingByDefault)](swift-compiler/documentation/diagnostics/nonisolated-nonsending-by-default.md)

## See Also

- [Diagnostic groups](swift-compiler/documentation/diagnostics/diagnostic-groups.md)