microsoft / microsoft/TypeScript
Confusing error on computed name class member
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Description
### 🔎 Search Terms
late bindable computed symbol class member
### 🕗 Version & Regression Information
- This is the behavior in every version I tried
### ⏯ Playground Link
https://www.typescriptlang.org/play/?target=99&lib=lib.esnext.d.ts&ts=5.9.0-dev.20250326#code/MYewdgzgLgBArmAlgRzgUwMoE8C2AjEAGwAYYBeGbfIgOgDMQAnACgCJWBKAbgCge6EwKInAwA5migBVJKky4CJZhwBcMKFgAOaEHXiz0VRaQDePGDEaS4jMPpSGFRYrwC+fYIQCGECDADChBAAzDBmFgDaEtIG8tRKHAC65DCsdIiM0KxuPEA
### 💻 Code
```ts
const uniqueSymbol0 = Symbol.for("");
function getUniqueSymbol0(): typeof uniqueSymbol0 {
return uniqueSymbol0;
}
class Cls3 {
[getUniqueSymbol0()] = "first"; // A computed property name in a class property declaration must have a simple literal type or a 'unique symbol' type.(1166)
}
```
### 🙁 Actual behavior
The error is confusing because this expression has a `unique symbol` type already
### 🙂 Expected behavior
This error should mention more accurate late-bindable requirements. From the source code:
```ts
/**
* Indicates whether a declaration name is definitely late-bindable.
* A declaration name is only late-bindable if:
* - It is a `ComputedPropertyName`.
* - Its expression is an `Identifier` or either a `PropertyAccessExpression` an
* `ElementAccessExpression` consisting only of these same three types of nodes.
* - The type of its expression is a string or numeric literal type, or is a `unique symbol` type.
*/
```
### Additional information about the issue
_No response_
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the linked TypeScript Playground example and the source comment describing definitely late-bindable declaration names. Trace the diagnostic for the computed class property and make its wording reflect the stated expression and type requirements; verify that the example reports the more accurate error.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- typescript
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100