Look for source of dts file only if dts is not from node_modules unless we have project references in node_modules

[sheetalkamat]

Time to updategraph went from 276173.6424ms to 33199.64829999999ms

[Copilot]

Pull Request Overview

This PR adjusts how .d.ts files in node_modules are handled by only resolving their source when at least one project reference from node_modules has been encountered.

• Introduces a hasResolvedReferencencesInNodeModules flag to gate lookups of .d.ts sources in node_modules
• Adds a guard in getSourceOfProjectReferenceRedirect to skip node_modules paths until the flag is set
• Sets the flag to true once a project reference in node_modules is actually redirected

Comments suppressed due to low confidence (1)

src/compiler/program.ts:3827

• Consider adding unit tests to verify that .d.ts source resolution is skipped for node_modules paths until a project reference in node_modules is encountered, and then allowed afterwards.

if (!hasResolvedReferencencesInNodeModules && pathContainsNodeModules(path)) return undefined;

[Copilot]

There's a typo in the variable name hasResolvedReferencencesInNodeModules. Consider renaming it to hasResolvedReferencesInNodeModules for clarity and consistency.

Suggested change

	let hasResolvedReferencencesInNodeModules = false;
	let hasResolvedReferencesInNodeModules = false;

[Copilot]

[nitpick] This flag controls when to start resolving .d.ts sources from node_modules. Adding a brief comment above its declaration would improve maintainability and help future readers understand its purpose.

Suggested change

	let hasResolvedReferencencesInNodeModules = false;
	// Tracks whether `.d.ts` sources from `node_modules` have been resolved.
	let hasResolvedReferencencesInNodeModules = false;

[Copilot]

[nitpick] The pathContainsNodeModules check appears in multiple places. Extracting it into a well-named helper (e.g., isInNodeModules(path)) could reduce duplication and improve readability.

Suggested change

	function getSourceOfProjectReferenceRedirect(path: Path) {
	if (!isDeclarationFileName(path)) return undefined;
	if (!hasResolvedReferencencesInNodeModules && pathContainsNodeModules(path)) return undefined;
	if (mapFromToProjectReferenceRedirectSource === undefined) {
	function isInNodeModules(path: Path): boolean {
	return pathContainsNodeModules(path);
	}
	function getSourceOfProjectReferenceRedirect(path: Path) {
	if (!isDeclarationFileName(path)) return undefined;
	if (!hasResolvedReferencencesInNodeModules && isInNodeModules(path)) return undefined;
	if (mapFromToProjectReferenceRedirectSource === undefined) {

[sheetalkamat]

@typescript-bot pack this

[typescript-bot]

Starting jobs; this comment will be updated as builds start and complete.

Command	Status	Results
pack this	✅ Started	✅ Results

[typescript-bot]

Hey @sheetalkamat, I've packed this into an installable tgz. You can install it for testing by referencing it in your package.json like so:

{
    "devDependencies": {
        "typescript": "https://typescript.visualstudio.com/cf7ac146-d525-443c-b23c-0d58337efebc/_apis/build/builds/165141/artifacts?artifactName=tgz&fileId=B7ACC15D2E3B3FDEB41D55A6E5EAD826AFF18FBDD70B466821AD6189B9893DA502&fileName=/typescript-5.9.0-insiders.20250520.tgz"
    }
}

and then running npm install.

---

There is also a playground for this build and an npm module you can use via "typescript": "npm:@typescript-deploys/pr-build@5.9.0-pr-61739-2".;