chakra-core/ChakraCore

Redeclaration of a function* inside a block definition

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#6,459 opened on Jun 8, 2020

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Bughelp wanted

Description

Hi everyone, I found a case of redeclaration of a generator function inside a block definition.

version: 1.11.19 OS: Linux Ubuntu 19.10 x64

steps to reproduce:

{ function* f() { yield 1 } function f() { print(2) } } f() Actual results: 2

Expected results: SyntaxError: Identifier 'f' has already been declared

V8, SpiderMonkey works as expected.

cinfuzz

Contributor guide

Tech stack
javascript
Domain
backend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
5
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
over 1 week
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
JavaScript scoping rulesfunction declarations in blocksChakraCore parser internalsgenerator functions
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
10
Research direction
Investigate ChakraCore's parser handling of function declarations inside block scopes, specifically for generator functions. The issue indicates a redeclaration error is missing. Look at the parser's validation of duplicate identifiers in block scoped function declarations, likely in the ByteCodeGenerator or Parser files. Check the ECMAScript specification for block level function declarations.
Redeclaration of a function* inside a block definition · chakra-core/ChakraCore#6459 | Good First Issue