Microsoft/TypeScript

Cannot get symbol inside class decorator (Cannot read property 'members' of un...)

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#8,136 opened on Apr 17, 2016

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BugDomain: APIDomain: DecoratorsHelp Wanted

Description

TypeScript Version:

1.8.10

Code

@Component({
  selector: SELECTOR
})
class SampleComponent {}
const SELECTOR = 'ng-demo';

Expected behavior:

With sample SyntaxWalker based on tslint, once I visit the PropertyAssignment - selector: SELECTOR and invoke typeChecker.getSymbolAtLocation(prop.initializer); I should get the SELECTOR symbol.

Actual behavior:

     TypeError: Cannot read property 'members' of undefined
      at resolveName (node_modules/typescript/lib/typescript.js:15307:73)
      at resolveEntityName (node_modules/typescript/lib/typescript.js:15725:26)
      at getSymbolOfEntityNameOrPropertyAccessExpression (node_modules/typescript/lib/typescript.js:28708:28)
      at Object.getSymbolAtLocation (node_modules/typescript/lib/typescript.js:28770:28)

Contributor guide

Tech stack
typescript
Domain
backendtooling
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
TypeScript decoratorsTypeScript compiler APISymbol resolutionTSLint syntax walker
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
15
Research direction
Investigate the symbol resolution in the TypeScript compiler when called within a decorator. Look at the function `resolveName` in `typescript.js` (line 15307) and trace how it handles property assignments in decorators. Check if the issue is related to decorators not being fully processed when symbol resolution occurs. Review the implementation of `getSymbolAtLocation` and understand why the 'members' property is undefined. Consider whether the issue persists in the latest TypeScript version.