Microsoft/TypeScript

[CLI] "@" character removed when it's first path character with --build

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#62,373 opened on Sep 1, 2025

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BugDomain: tsc -bHelp Wanted

Description

🔎 Search Terms

"cli", "tsc", "build mode", "path"

🕗 Version & Regression Information

  • This changed between versions 3.0 and 3.1 (LOL) and continue to 5.9.2

⏯ Playground Link

https://github.com/GongT/issues/tree/typescript-path-at-char

💻 Code

# all this is ok
tsc -p @scoped/package/src
tsc -b xxx@yyy/package/src
cd @scoped ; tsc -p package/src

# this is not
tsc -b @scoped/package/src

🙁 Actual behavior

error TS5083: Cannot read file 'scoped/package/src'.

🙂 Expected behavior

It should read @scoped/package/src(/tsconfig.json)

Additional information about the issue

No response

Contributor guide

Tech stack
typescript
Domain
cli
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
Familiarity with TypeScript compiler CLIKnowledge of path parsing in Node.js
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70
Research direction
Investigate the path normalization logic in the TypeScript compiler's CLI argument parser. Look for where '@' characters are stripped from the beginning of paths when the build (or b) flag is used. Check files like src/compiler/commandLineParser.ts or related utilities. Consider how the '@' symbol is interpreted for paths vs. response files. The fix should ensure that '@' at the start of a path argument is preserved, especially when used with build.