swiftlang/swift
GitHub で見るError says `@preconcurrency` only applies in inheritance clauses
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#88,338 opened on 2026年4月7日
@preconcurrencyTypeResolverattributescompilergood first issueswift 6.3type checker
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説明
Description
This is not true. The attribute can also be used on declarations such as types, functions, and imports.
Reproduction
let _: @preconcurrency @MainActor() -> Void = {}
error: '@preconcurrency' only applies in inheritance clauses
83 |
84 | let _: @preconcurrency @MainActor() -> Void = {}
| `- error: '@preconcurrency' only applies in inheritance clauses
85 |
Expected behavior
An accurate error message. It might be better to say that @preconcurrency cannot be used on a type attribute instead of enumerating all the valid positions.
Environment
Swift version 6.3-dev (fefcb257b5b5d32)
Additional information
No response