Microsoft/TypeScript

TypeChecker#getConstantValue(node) doesn't properly resolve values

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#4,217 opened on Aug 7, 2015

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 (5 comments) (0 reactions) (0 assignees)TypeScript (48,455 stars) (6,726 forks)batch import
BugDomain: APIHelp Wanted

Description

Courtesy of @ivogabe from here.

I'm working with the compiler api and I noticed that TypeChecker#getConstantValue(node) only returns a value if I first call TypeChecker#getSymbolAtLocation(node). node is an ElementAccessExpression or a PropertyAccessExpression. Is that a bug or by design?

Contributor guide

Tech stack
typescript
Domain
tooling
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
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.
mostly clear
Prerequisites
Understanding TypeScript compiler APIAccess to TypeScript source code
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20
Research direction
Investigate the implementation of getConstantValue and getSymbolAtLocation in checker.ts. Check if getConstantValue depends on a pre computed value that getSymbolAtLocation sets. Look at the call chain and see if there is a missing internal state update. Also review the Gitter conversation linked for more context.