Add Yarn PnP support by GGomez99 · Pull Request #1966 · microsoft/typescript-go

Guyllian Gomez (GGomez99) · 2025-10-28T09:46:26Z

⚠️ [20th Aug 2026] PR Update ⚠️

Due to the migration of typescript-go repo to the original Typescript repo, this PR has been recreated here:
microsoft/TypeScript#63919

Closes microsoft/TypeScript#63769

Co-authored with gun-yu (@gun-yu) as a result of their changes (#1876) being merged in this PR

Motivation

This PR adds Plug'n'Play support natively to Typescript Go, following this issue: microsoft/TypeScript#63769
It has been reviewed and supported by Maël Nison (@arcanis), the lead maintainer of Yarn, and the original author of Yarn PnP.

Datadog has a frontend monorepo using yarn with over 6k packages, and seeing how TS Strada struggles with our current scaling, we decided to invest time in adding a native Yarn PnP support for Typescript Go.
This PnP implementation has been actively used in the IDE of more than 230 engineers at Datadog, and we're committed to fixing all issues reported to us.

Challenges

We did not integrate it in our CI yet as we still have several packages failing on build mode (most errors seem to be reported in the issues section of TS Corsa). Because the TS Corsa API is not available yet, we also couldn't integrate it properly with a fast lage setup unlike with the TS Strada API.

Changes

It's based on the main changes from the original yarn patch (microsoft/TypeScript@99f3e13) that the community has been maintaining for years throughout Typescript Strada updates, except that we implemented the official PnP specification so it doesn't depend on third-party code.

Implemented features:

PnP VFS that handles virtual folders and zip files seamlessly, with caching and fallback to the original vfs if pnp is not available
Add PnP API and manifest handling, following the yarn PnP specification
Initialize the PnP API every time a Host is initialized for both build and LSP modes
Add PnP support when resolving modules in internal/module/resolver.go
Add PnP support for auto-imports and completion at internal/modulespecifiers/specifiers.go
Add PnP support for root types at internal/core/compileroptions.go
Handle zip paths when going to implementation with the LSP
Update the baseline testing framework to handle PnP when needed
PnP manifest auto-refresh by watching .pnp.cjs changes

Tests

Basic PnP setup
Types from transitive dependencies
Root types loading from PnP dependencies
Completion and autoimports

Guyllian Gomez (GGomez99) · 2025-10-28T13:36:36Z

@microsoft-github-policy-service agree company="Datadog"

Guyllian Gomez (GGomez99) · 2025-10-28T15:26:39Z

I see my tests are not passing in CI, looking into it 🙇

Jake Bailey (jakebailey) · 2025-10-28T16:07:59Z

+var (
+	isPnpApiInitialized atomic.Uint32
+	cachedPnpApi        *PnpApi
+	pnpMu               sync.Mutex
+	// testPnpCache stores per-goroutine PnP APIs for test isolation
+	// Key is goroutine ID (as int)
+	testPnpCache sync.Map // map[int]*PnpApi
+)
+
+// getGoroutineID returns the current goroutine ID
+// It is usually not recommended to work with goroutine IDs, but it is the most non-intrusive way to setup a parallel testing environment for PnP API
+func getGoroutineID() int {
+	var buf [64]byte
+	n := runtime.Stack(buf[:], false)
+	idField := strings.Fields(strings.TrimPrefix(string(buf[:n]), "goroutine "))[0]
+	id, _ := strconv.Atoi(idField)
+	return id
+}
+


All of this global / goroutine local storage is something that won't work. If we are storing something, it needs to be attached to a Program, Project, a Host, etc, not global. Parsing out the goroutine ID is definitely a bad idea, especially given our LSP can handle multiple requests at the same time from multiple goroutines and so on.

Jake Bailey (@jakebailey) Thank you for having a first look at this PR!
Since your comments, we changed how we initialize the PnpApi by attaching it to the Host directly on initialization. The host can then provide it through host.PnpApi() which will return nil or the pnpapi instance if in a yarn project

Jake Bailey (jakebailey) · 2025-10-28T16:09:04Z

+
+	pnpApi := &PnpApi{fs: fs, url: filePath}
+
+	manifestData, err := pnpApi.findClosestPnpManifest()


I don't really understand this init. Surely one needs to be able to load multiple projects with differing pnp info at the same time? All of this info really does need to be handled differently.

With the last changes mentioned in this comment, we initialize the PnP api with the Host. This means we assume that we have one yarn PnP project per host

I don't think we could initialize it on a smaller scope (like Project or Program) from looking at the changes we had to do to support PnP, but let me know what you think!

* add pnpapi test * remove cycle dependency * add error handling * add error message * apply error message * add error bubbling * code clean up * remove useless test * add empty findBrokenPeerDependencies * early return * change function name * apply code review * merge duplicate logic * apply collect usage * apply codereview * apply fromConfig

See: - https://devblogs.microsoft.com/typescript/announcing-typescript-7-0-rc/ Ok, so this is a bit fiddly, so let me explain what's going on: - We used to have `tsc` from `typescript` (v6), written in JS, and `tsgo` from `@typescript/native-preview`, so they could both be installed at the same time. - With v7, the RC package takes over the `tsc` executable; it's now the Go implementation and there is no separate `tsgo`; so... - We change our global install to `7.0-rc`, and ditto for the in-project install. We no longer have a v6 install on disk. - Rename (the project-local) `bin/tsgo` to `bin/tsc`, and make it run `tsc` instead of `tsgo`. - We update our Neovim config to assume `tsc` is now the Go version instead of the JS version; but note that we still have to use the "tsgo" config from nvim-lspconfig, because that hasn't been renamed yet, it's just that we configure it to use the `tsc` executable now instead of `tsgo`. - The Go implementation still doesn't support Yarn PnP and the corresponding PR (microsoft/typescript-go#1966) is still open, so we maintain our hack wherein we use the `ts_ls` config from nvim-lspconfig to use typescript-language-server with a wired-in path to a Yarn-managed shim. This looks fragile, and it probably is, but it has been working for me ever since I added it a couple of months ago (in 011cee5, "feat(nvim): point ts_ls at Yarn PnP tsserver shim when available", 2026-05-12). - The Neovim config will use a repo-local `tsc` if one exists, but note that it assumes `tsc` is the Go implementation. So if you use it in a repo with v6 or older, it won't work, because v6 doesn't support `--lsp --stdio`. I'm not worried about this; I have only a few such repos, and I will update them next time I have to work in them. - Update references to `tsgo` in docs to reference `tsc` instead. - Note: the `_tsc` completions in the third-party zsh-completions repo still match the JS implementation instead of the Go one; presumably they will eventually update. I am not sure exactly where the command line options diverge, other than having seen that while v7 supports LSP via `tsc --lsp --stdio`, v6 does not. Finally, and most importantly, merely updating my dotfiles on other machines won't make all this magically start working: I will need to manually uninstall the old `typescript` package and install the new one: ``` npm uninstall -g typescript @typescript/native-preview npm install -g typescript@rc --min-release-age=0 ``` Change-Id: rmoqwxkqwoywkxrlwspqqmwwmktwqrvz

## Summary - Bound the generated TypeScript compatibility patch to TypeScript versions before 7.0.0, and committed the matching generated patch artifact so the compat patch generator stays reproducible. - Fixed optional patch handling so `optional!` patches fall back when a package no longer ships a target file (for example `lib/_tsc.js` in TypeScript 7 / TypeScript compatibility shims), instead of failing the install with `ENOENT`. - Added regression coverage for both direct `typescript@7.0.1-rc` installs and the TypeScript 7 side-by-side recommendation where the `typescript` ident aliases to `npm:@typescript/typescript6@^6.0.0`. - Stabilized the scoped `plugin-typescript` acceptance test by moving it from `@babel/traverse` (now reported by npm search metadata as having included types) to a fixture package that still exercises DefinitelyTyped scoped package insertion. - Added deferred version metadata for the changed workspaces. ## Test plan - `yarn workspace @yarnpkg/plugin-compat test:plugin-compat` - `yarn test:unit packages/plugin-patch` - `node ./scripts/run-yarn.js test:integration packages/acceptance-tests/pkg-tests-specs/sources/plugins/plugin-typescript.test.ts` - `yarn version check` ## Notes TypeScript 7 ships a native compiler package layout and no longer has the legacy JS compiler files patched by the existing PnP compatibility diff, such as `lib/_tsc.js`. Bounding the TypeScript compat patch makes this intent explicit, while the optional patch fallback fixes the broader bug that `optional!` patch failures caused by missing target files were still fatal. TypeScript 7 support should ship with microsoft/typescript-go#1966. Made with Cursor --------- Co-authored-by: Cursor <cursoragent@cursor.com> Co-authored-by: John Doe <you@example.com> Co-authored-by: Maël Nison <mael.nison@mistral.ai>

Jose Ramirez Fuentes (proyectoramirez) · 2026-07-07T15:42:25Z

What is a good way to try this PR in a yarn project?

Guyllian Gomez (GGomez99) · 2026-07-09T15:49:56Z

What is a good way to try this PR in a yarn project?

Jose Ramirez Fuentes (@proyectoramirez) You can clone the repo and follow the How to build and run section of the contributing doc

## Summary - Bound the generated TypeScript compatibility patch to TypeScript versions before 7.0.0, and committed the matching generated patch artifact so the compat patch generator stays reproducible. - Fixed optional patch handling so `optional!` patches fall back when a package no longer ships a target file (for example `lib/_tsc.js` in TypeScript 7 / TypeScript compatibility shims), instead of failing the install with `ENOENT`. - Added regression coverage for both direct `typescript@7.0.1-rc` installs and the TypeScript 7 side-by-side recommendation where the `typescript` ident aliases to `npm:@typescript/typescript6@^6.0.0`. - Stabilized the scoped `plugin-typescript` acceptance test by moving it from `@babel/traverse` (now reported by npm search metadata as having included types) to a fixture package that still exercises DefinitelyTyped scoped package insertion. - Added deferred version metadata for the changed workspaces. ## Test plan - `yarn workspace @yarnpkg/plugin-compat test:plugin-compat` - `yarn test:unit packages/plugin-patch` - `node ./scripts/run-yarn.js test:integration packages/acceptance-tests/pkg-tests-specs/sources/plugins/plugin-typescript.test.ts` - `yarn version check` ## Notes TypeScript 7 ships a native compiler package layout and no longer has the legacy JS compiler files patched by the existing PnP compatibility diff, such as `lib/_tsc.js`. Bounding the TypeScript compat patch makes this intent explicit, while the optional patch fallback fixes the broader bug that `optional!` patch failures caused by missing target files were still fatal. TypeScript 7 support should ship with microsoft/typescript-go#1966. Made with Cursor --------- Co-authored-by: Cursor <cursoragent@cursor.com> Co-authored-by: John Doe <you@example.com> Co-authored-by: Maël Nison <mael.nison@mistral.ai>

Fix alias resolution and fallbackPool entry parsing

…np (up to 9977d6d)

Ryan Cavanaugh (RyanCavanaugh) · 2026-08-20T05:02:22Z

Thank you for contributing to the TypeScript native port!

Development has moved from this repository back to the main microsoft/TypeScript repository. GitHub does not have PR transfer functionality, so we're closing this PR here.

If this change is still relevant, please reopen it as a new pull request in microsoft/TypeScript. We'd appreciate your help carrying the contribution over, and we apologize for the extra work.

See microsoft/typescript-go#4918 for more information about the move.

Guyllian Gomez (GGomez99) · 2026-08-20T16:01:35Z

PR has been moved to: microsoft/TypeScript#63919 🙇

Jake Bailey (jakebailey) reviewed Oct 28, 2025

View reviewed changes

gun-yu (gun-yu) mentioned this pull request Oct 29, 2025

support pnp resolver #1876

Closed

Guyllian Gomez (GGomez99) force-pushed the guyllian.gomez/yarn-pnp branch from d70cc8a to 854be04 Compare October 29, 2025 14:07

Guyllian Gomez (GGomez99) added 5 commits October 30, 2025 11:27

Implement yarn pnp api

2ae52e9

Add pnpVFS + tests

134f3dc

Insert pnpApi in Host for LSP and CLI usages

fad87fa

Handle zip paths for LSP

f086507

Add pnp tests

e4a3c4b

Guyllian Gomez (GGomez99) force-pushed the guyllian.gomez/yarn-pnp branch 2 times, most recently from e92efeb to e4a3c4b Compare October 31, 2025 12:23

Fix pnpvfs test in windows

9aa7f3e

Guyllian Gomez (GGomez99) force-pushed the guyllian.gomez/yarn-pnp branch from 36c114c to 9aa7f3e Compare October 31, 2025 12:57

Guyllian Gomez (GGomez99) force-pushed the guyllian.gomez/yarn-pnp branch from 440f2f8 to 478d4d9 Compare November 3, 2025 10:50

Merge branch 'main' into guyllian.gomez/yarn-pnp

f3c6477

Guyllian Gomez (GGomez99) force-pushed the guyllian.gomez/yarn-pnp branch from 478d4d9 to f3c6477 Compare November 3, 2025 10:52

Guyllian Gomez (GGomez99) added 6 commits November 3, 2025 13:38

Apply lint on last pnp changes

b382639

Add pnp import completion

f8dd02f

Apply new lint fixes

2f17744

Mark any external pnp dependency as isExternalLibraryImport=true

993103b

Handle empty strings for FindLocator

0665cd8

Merge branch 'main' into guyllian.gomez/yarn-pnp

c343dca

Guyllian Gomez (GGomez99) force-pushed the guyllian.gomez/yarn-pnp branch from a98f2f6 to c343dca Compare November 20, 2025 13:49

Guyllian Gomez (GGomez99) added 2 commits November 20, 2025 14:57

Use strings.Cut instead of string.Index for pnp

781b5de

Fix completion issue for pnp packages

68db04a

Maël Nison (arcanis) mentioned this pull request Nov 24, 2025

Native support for PnP microsoft/TypeScript#35206

Closed

4 tasks

Guyllian Gomez (GGomez99) force-pushed the guyllian.gomez/yarn-pnp branch from e8885f5 to 4f9181b Compare November 28, 2025 11:39

Jake Bailey (jakebailey) mentioned this pull request Jun 18, 2026

@typescript/typescript6 compat package fails to install under Yarn (builtin TypeScript patch hard-errors on missing 'lib/_tsc.js') #4368

Closed

Guyllian Gomez (GGomez99) added 2 commits June 19, 2026 10:39

Merge branch 'main' into guyllian.gomez/yarn-pnp

088c3f1

Fix missing pnpapi method in aliasresolver test

74e9dee

Guyllian Gomez (GGomez99) added 3 commits July 2, 2026 13:11

Merge branch 'main' into guyllian.gomez/yarn-pnp

3954f78

Fix test fixtures for pnp

f3fa6ef

Invalidate all projects if .pnp.cjs changes

ff6ade7

Jake Bailey (jakebailey) mentioned this pull request Jul 8, 2026

Native Yarn Plug'n'Play module resolution #4568

Closed

EJ (ejc3) mentioned this pull request Jul 8, 2026

pnp: run all resolution test suites; fix the two bugs they surface GGomez99/typescript-go#8

Closed

Dobes Vandermeer (dobesv) mentioned this pull request Jul 9, 2026

Rebase luchta-tsc-worker onto TypeScript 7.0 GA (typescript/v7.0.2) dobesv/luchta#199

Closed

7 tasks

HansMaritzAtlassian and others added 5 commits July 13, 2026 22:29

Address PnP test review feedback

a5c6efe

Merge pull request #6 from Freakazo/pnp-alias-fallback

a6fd1e3

Fix alias resolution and fallbackPool entry parsing

Merge remote-tracking branch 'origin/main' into guyllian.gomez/yarn-p…

e82c2c4

…np (up to 9977d6d)

Merge remote-tracking branch 'origin/main' into guyllian.gomez/yarn-pnp

e2327fd

Merge remote-tracking branch 'origin/main' into guyllian.gomez/yarn-pnp

033081b

Maël Nison (arcanis) mentioned this pull request Jul 20, 2026

[Bug?]: Yarn 4.17.1 in pnp mode does not work with TypeScript 7.x yarnpkg/berry#7226

Closed

1 task

Valentin MELUSSON (valentinmelusson) mentioned this pull request Jul 29, 2026

disableSourceOfProjectReferenceRedirect causes lodash per-method submodule import to resolve to the wrong function #4758

Closed

Valentin MELUSSON (valentinmelusson) added 2 commits July 29, 2026 10:07

Merge branch 'main' into guyllian.gomez/yarn-pnp

32b6890

Fix package IDs for Yarn PnP submodule imports

4a3dad6

EJ (ejc3) mentioned this pull request Jul 30, 2026

Flow on the fleet shape + yarn 4 at fleet scale ejc3/node-monorepo-perf#47

Merged

Ryan Cavanaugh (RyanCavanaugh) added the Unmigrated PR This PR was open at the time of the repo move back to TypeScript label Aug 14, 2026

Dobes Vandermeer (dobesv) mentioned this pull request Jul 9, 2026

Rebase luchta-tsc-worker onto TypeScript 7.0 GA (typescript/v7.0.2) dobesv/luchta#200

Merged

Ryan Cavanaugh (RyanCavanaugh) closed this Aug 20, 2026

Guyllian Gomez (GGomez99) mentioned this pull request Aug 20, 2026

Add Yarn PnP module resolution support microsoft/TypeScript#63919

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Add Yarn PnP support - #1966

Add Yarn PnP support#1966
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		pnpApi := &PnpApi{fs: fs, url: filePath}

		manifestData, err := pnpApi.findClosestPnpManifest()

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⚠️ [20th Aug 2026] PR Update ⚠️

Motivation

Challenges

Changes

Implemented features:

Tests

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