yarnpkg/yarn

yarn why does not tell if the package is a peer dependency

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#3301 opened on May 2, 2017

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 (2 comments) (2 reactions) (0 assignees)JavaScript (41,514 stars) (2,731 forks)batch import
good first issuetriaged

Description

Do you want to request a feature or report a bug? Bug

What is the current behavior? yarn why does not tell if the reason behind dependency is actually peer-dependency

If the current behavior is a bug, please provide the steps to reproduce. have a dependency with peer-dependency (ie. sass-loader with node-sass) ask yarn why node-sass the result is following:

yarn why node-sass
yarn why v0.23.3
[1/4] 🤔  Why do we have the module "node-sass"...?
[2/4] 🚚  Initialising dependency graph...
[3/4] 🔍  Finding dependency...
[4/4] 🚡  Calculating file sizes...
info Has been hoisted to "node-sass"
info This module exists because it's specified in "dependencies".
info Disk size without dependencies: "7.71MB"
info Disk size with unique dependencies: "12.09MB"
info Disk size with transitive dependencies: "37.87MB"
info Amount of shared dependencies: 109

What is the expected behavior? I'd like to know that node-sass exists also because it's a peer dependency of sass-loader

Please mention your node.js, yarn and operating system version. yarn: v0.23.3 node.js: v6.5.0 os: Latest osx

Contributor guide

Tech stack
javascriptnodejs
Domain
clideveloper experience
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.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Understanding of Yarn's dependency resolution
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
The issue requests that `yarn why` output includes peer dependency information. The current behavior prints 'This module exists because it's specified in dependencies' but does not mention peer dependencies. Since the repository is frozen (1.x line), any fix would likely apply to the classic Yarn codebase. Look at the source code that generates the output in `src/reporters/` or similar files. Specifically, find where the dependency relationship string is assembled, likely around logic that iterates over dependency types. There are no linked PRs or detailed comments, so the contributor should investigate the Yarn resolution algorithm and how it categorizes peer dependencies. Note that the issue is from 2017 and the repo is in maintenance mode, so verify if contributions are still accepted.