microsoft / microsoft/TypeScript

Misleading error message for duplicate CLI flags

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Description

Bug Report

🔎 Search Terms

tsc multiple flag options cli

🕗 Version & Regression Information
  • This is the behavior in every version I tried, and I reviewed the FAQ for entries about CLI option parsing
⏯ Playground Link

N/A

💻 Code

Any of:

tsc -b -b
tsc -b --build
tsc -b --clean --build
🙁 Actual behavior
tsc -b -b      
error TS5072: Unknown build option '-b'.
🙂 Expected behavior

Something indicating the flag was provided twice, not that it's unknown?

tsc -b -b      
error TS5072: Duplicate build option '-b' provided.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by tracing TypeScript's CLI option parsing using the reported commands: tsc -b -b, tsc -b --build, and tsc -b --clean --build. Compare the current diagnostic with the expected duplicate-option wording; done means duplicate build flags are reported as duplicates rather than unknown options.

Written by the indexing model from the issue text.

Assessment

Tech stack
typescript
Domain
cli
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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