chakra-core/ChakraCore

No syntax error for let redeclaring var in a block

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#849 opened on Apr 21, 2016

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 (3 comments) (0 reactions) (0 assignees)JavaScript (1,374 forks)batch import
BugSeverity: 3help wanted

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Description

{ var x; let x; }

Expected: SyntaxError, duplicate delcarations. Actual: No error, var is hoisted out.

Contributor guide

Research direction
Investigate the parser in ChakraCore where var and let declarations are handled. Look for the block scope processing and ensure that redeclaration of var by let within the same block triggers a SyntaxError.
Tech stack
javascript
Domain
compilers
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
JavaScriptC++
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40