Microsoft/vscode

[engineering] sourcemap issues

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#251233 opened on Jun 11, 2025

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 (4 comments) (0 reactions) (1 assignee)TypeScript (74,848 stars) (10,221 forks)batch import
debtengineeringhelp wanted

Description

  1. source files are duplicated inside sourcemap
❯ npm run gulp compile-build-without-mangling

❯ cat out-build/main.js.map | jq .sourceRoot
"file:///Users/tmm1/code/vscode/src"

❯ cat out-build/main.js.map | jq .sources
[
  "file:///Users/tmm1/code/vscode/src/main.ts",
  "main.ts"
]
  1. duplicated paths are further corrupted during minification
❯ npm run gulp minify-vscode

❯ cat out-vscode/main.js.map | jq '.sources[0,1]'
"../file:/Users/tmm1/code/vscode/src/vs/base/common/performance.ts"
"../vs/base/common/performance.ts"

❯ cat out-vscode-min/main.js.map | jq '.sources[0,1]'
"./file:/Users/tmm1/code/vscode/src/vs/base/common/performance.ts"
"vs/base/common/performance.ts"

Contributor guide

Tech stack
typescriptnodejs
Domain
build systemdeveloper experience
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
blocked
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
understanding of sourcemapsfamiliarity with gulp build systemknowledge of TypeScript compilation
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20
Research direction
The issue reports two problems: duplicate source file entries in generated sourcemaps and path corruption during minification. The reproduction steps are clearly given using gulp commands and jq queries. To investigate, start by examining the gulpfile build scripts, especially the 'compile build without mangling' and 'minify vscode' tasks. Look at the source map generation configuration, possibly in the TypeScript compiler options or a dedicated sourcemap plugin. The assignee may have insights; check the comments for any progress or hints. Consider proposing a fix that deduplicates source paths in the map generation step or normalizes paths before minification.