swiftlang/swift

Error says `@preconcurrency` only applies in inheritance clauses

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#88,338 创建于 2026年4月7日

 (2 条评论) (0 个反应) (0 位负责人)Swift (10,719 个派生)batch import
@preconcurrencyTypeResolverattributescompilerdiagnostics qualitygood first issueswift 6.3type checker

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描述

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

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