swiftlang/swift

[SR-6207] Misleading error for unqualified use of static variable in method

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#48,759 opened on 2017年10月24日

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 (8 comments) (0 reactions) (0 assignees)Swift (69,989 stars) (10,719 forks)batch import
bugcompilerdiagnostics qualityexpressionsgood first issuestatic declarationsswift 6.0type checker

説明
Previous ID SR-6207
Radar rdar://problem/24291352
Original Reporter @huonw
Type Bug
Status In Progress
Resolution

Swift 4
Votes 0
Component/s Compiler
Labels Bug, DiagnosticsQoI, StarterBug
Assignee None
Priority Medium

md5: 47c00d1618aecdca414e977e2fbf19c9

Issue Description:

struct HasStatic {
    func foo() {
        print(cvar)
    }
    static let cvar = 123
}

hasstatic.swift:3:11: error: static member 'cvar' cannot be used on instance of type 'HasStatic'
    print(cvar)
          ^~~~
          HasStatic.

The fixit helps, but it still isn't obvious what's going wrong. The compiler is acting like the use of cvar was written self.cvar, and hints at this with "an instance of", but it's easy to gloss over the subtlety. The text could be tweaked, maybe like

static member 'cvar' can only be used on the type 'HasStatic', not the instance 'X'

where the X is the relevant parent value. (e.g. self for this case, or foo.bar for foo.bar.cvar).

コントリビューターガイド

技術スタック
swift
領域
tooling
Issue 種別
bug
難度新しい貢献者にとっての実装難度です。1 は非常に小さな変更、5 は専門的な作業です。
2
推定時間経験ある貢献者が調査、実装、テスト、pull request 準備にかけるおおよその時間範囲です。
1-3 hours
活動状況Issue が今どれだけ取り組みやすいかを示します。新しい、活発、古い、ブロック中、またはメンテナー入力待ちなどです。
stale
明確さ期待される変更、受け入れ条件、次の手順がどれだけ明確かを示します。
clear
前提条件
なし
初心者向け度初回貢献者にどれだけ取り組みやすいかを 1-100 で推定したスコアです。
80
調査方針
The issue is about improving a diagnostic message in the Swift compiler. The error occurs when a static member is used unqualified in an instance context. The diagnostic is emitted by the compiler's semantic analysis (Sema). Look at the file lib/Sema/CSSimplify.cpp or similar files where static member access is resolved. The fix involves changing the error message string to be more explicit, e.g., 'static member 'cvar' can only be used on the type 'HasStatic', not the instance 'X'. Since the issue is labeled StarterBug and is in the swift repository, a good starting point is to search for the exact error message in the codebase and modify it accordingly.