Microsoft/TypeScript

Redundant "has or is using private name" diagnostic when name not found

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#52,033 opened on Dec 27, 2022

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BugDomain: Declaration EmitHelp Wanted

Description

Bug Report

🔎 Search Terms

multiple not found declaration redundant using private cannot find name not found

🕗 Version & Regression Information

⏯ Playground Link

Playground link with relevant code

💻 Code

export let value: NotFound = 0;

Note that the declaration compiler option must be enabled.

🙁 Actual behavior

Cannot find name 'NotFound'.
Exported variable 'value' has or is using private name 'NotFound'.

🙂 Expected behavior

Just one of the two errors. "private name" implies the name exists, which is incorrect, so I'd expect just the one that appears when you don't have declaration: true:

Cannot find name 'NotFound'.

Found while working on #52032.

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.
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.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
basic TypeScriptcompiler diagnostics concept
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
35
Research direction
The issue is in the TypeScript compiler's diagnostic emission when a name is not found and declaration mode is enabled. Likely relevant files are in the checker (src/checker.ts) or binder (src/binder.ts) where the 'has or is using private name' error is emitted. Look for conditional logic that checks for the 'cannot find name' error before emitting the private name error. The linked issue #52032 may provide additional context. Investigate the exact location where both diagnostics are produced and determine how to suppress the redundant one when the name is not found.