Microsoft/TypeScript

Enum types are not checked in binary operators

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#3,845 opened on Jul 13, 2015

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 (5 comments) (0 reactions) (0 assignees)TypeScript (6,726 forks)batch import
Breaking ChangeBugDomain: enumHelp Wanted

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Description

I ran into this for real while trying to fix a bug in the compiler. We disallow assigning one enum to another if you use the = operator. But we do not disallow it for any of the compound assignment operators. Nor do we disallow for bitwise operators. I think we should disallow all of them.

enum E { }
enum F { }

var e: E;
var f: F;

e = f; // Error
e |= f; // No error
var g = e | f; // No error, g is number

Contributor guide

Research direction
Locate the type checking logic for binary operators in checker.ts and add enum type mismatch checks similar to the assignment operator.
Tech stack
typescript
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
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
TypeScriptGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50