Microsoft/TypeScript

Middle operand in comma operator list not properly checked for side-effect-freeness

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#33,646 建立於 2019年9月27日

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BugDomain: Error MessagesHelp Wanted

描述

TypeScript Version: master at f304b81fa54285f Search Terms: comma side effects

Code

declare const obj: any;
console.log(`${JSON.stringify(obj), undefined, 2}`);

Expected behavior: error TS2695: Left side of comma operator is unused and has no side effects.

Actual behavior: No errors

Playground Link: http://www.typescriptlang.org/play/#code/CYUwxgNghgTiAEYD2A7AzgF3kgRgKwC54oUBPAbgChl0kIQA6CJAcwAoADAEgG8ApAMoB5AHINMMAJYoWkgGak2uPAEoANPACuKUHOkhgGgEwBfDiqpA

Related Issues: #10814

貢獻者指南

技術棧
typescript
領域
backend
議題類型
bug
難度面向新貢獻者的預計實作難度，1 表示很小改動，5 表示專家級工作。
3
預計時間有經驗貢獻者完成調查、實作、測試並準備 pull request 的粗略時間範圍。
1-3 hours
活動狀態議題目前的可參與程度：新鮮、活躍、陳舊、阻塞或等待維護者輸入。
fresh
清晰度議題是否清楚說明預期改動、驗收標準和下一步。
mostly clear
前置要求
Understanding of TypeScript compiler internalsFamiliarity with side effect analysis
新手友善度1-100 的估計分數，表示該議題對首次貢獻者的友善程度。
40
研究方向
Investigate the comma operator side effect checking in the TypeScript compiler. The related issue #10814 may provide context. Look at the checker file (likely checker.ts) where TS2695 is emitted to understand why the middle operand is not being checked. The fix may involve ensuring all operands in a comma expression are evaluated for side effect freeness.