Package.swift: '.watchOS(.v4)' emits a deprecation warning in Xcode (watchOS 9.0 is the oldest supported version)

[yoropico]

Description

When BigInt is resolved as a dependency in a project built with a current Xcode / Swift toolchain, the package manifest produces a deprecation warning in the Issue navigator of every downstream project:

'v4' is deprecated: watchOS 9.0 is the oldest supported version

It comes from the platforms declaration in Package.swift:

platforms: [
    .macOS(.v10_13),
    .iOS(.v12),
    .tvOS(.v12),
    .watchOS(.v4),        // ← warns
    .macCatalyst(.v13),
    .visionOS(.v1),
],

Recent toolchains have dropped the SupportedPlatform.WatchOSVersion.v4 symbol to deprecated status (watchOS 9.0 is now the oldest deployable version), so every consumer of BigInt sees this warning on package resolution. master and the v6.0.0 tag still declare .watchOS(.v4), so upgrading doesn't avoid it.

Suggested fix

Bump the watchOS entry to .watchOS(.v9) (and possibly revisit the other minimums — e.g. .macOS(.v10_13) / .iOS(.v12) are also near or below current toolchain floors). Since a platform minimum bump only affects consumers deploying below watchOS 9 — which current toolchains can no longer build for anyway — this should be safe in practice, though strictly it's a requirement change that may warrant a minor release.

Happy to send a PR if that's welcome.

Environment

• BigInt 5.7.0 (via SwiftPM, transitive dependency of Citadel)
• Xcode 27 beta (macOS 26 SDK-era toolchain) — warning also reproduces on recent Xcode 26 toolchains