`final actor` declaration not coverered by the grammar

[jansorg]

Location

https://docs.swift.org/swift-book/documentation/the-swift-programming-language/summaryofthegrammar

Description

The grammar does not specify the supported syntax public final actor ....

Correction

No response

[amartini51]

Checking this, I'm not sure final is meant to work on actors. SE-0306 says:

They are reference types like classes, but do not support inheritance, and therefore do not have (or need) features such as required and convenience initializers, overriding, or class members, open and final.

However, final actor does appear in one proposal, SE-0392 as @globalActor public final actor MainActor: GlobalActor.

Emailed several of the authors of the above SE proposals, to confirm whether final actor is meant to be supported.

[jansorg]

Thanks!
I saw public final actor in https://github.com/swiftlang/swift-subprocess, checked with the Swift 6.2.1 compiler and figured it should be in the grammar if the compiler doesn't complain. But please close if you think that it's not supposed to be supported.

[amartini51]

@jansorg Thanks for bringing attention to this issue! Here’s the PR tracking adding a warning to the compiler for this sytax: swiftlang/swift#85893