Implement "find file references"

[Copilot]

Implements the "find file references" feature (right-click a JS/TS file in VS Code explorer → Find File References), which finds all files that import or triple-slash-reference a given file.

The core challenge: getReferencesForNonModule was a stub, and the multi-project search logic required a document position (which file-level queries don't have).

Changes

Core algorithm (internal/ls/findallreferences.go)

• Implement getReferencesForNonModule() using program.GetIncludeReasons() + FileIncludeReason.GetSpanInReferrer() to enumerate non-module references pointing to a file
• Add GetFileReferences(ctx, uri, orchestrator) to LanguageService — dispatches to getReferencedSymbolsForModule for module files (has exports), or getReferencesForNonModule for script files; when a CrossProjectOrchestrator is provided, searches all initial projects and expands via GetProjectsLoadingProjectTree to find additional projects in the dependency tree, deduplicating results

Compiler helper (internal/compiler/fileInclude.go)

• Add FileIncludeReason.GetSpanInReferrer(program) — exported method that returns the referring file name and text range for a file-include reason, with trivia-skipping matching TypeScript's behavior. The logic lives in ls via program.GetIncludeReasons() + this method.

LSP protocol (internal/lsp/lsproto/)

• Add custom/findFileReferences request: params = FindFileReferencesParams{textDocument} (no position), result = Location[] | null

LSP server (internal/lsp/server.go)

• Register handleFindFileReferences — uses getLanguageServiceAndCrossProjectOrchestrator (same pattern as registerMultiProjectReferenceRequestHandler) and delegates to GetFileReferences with the orchestrator, enabling full cross-project search including project dependency tree traversal

VS Code extension (_extension/)

• Add Client.findFileReferences(uri) calling custom/findFileReferences
• Register _typescript.findAllFileReferences command (the standard VS Code command hooked by the explorer context menu) that calls the above and shows results via editor.action.showReferences

Fourslash test infrastructure

• Add VerifyBaselineFindFileReferences to the fourslash framework
• Add manual tests TestFindFileReferences, TestFindFileReferencesNonModule, and TestGetFileReferences_deduplicate (cross-project deduplication)
• Update convertFourslash.mts to support verify.baselineGetFileReferences(...) and fix directory traversal so server-subdirectory tests are reachable when filtering by basename; port getFileReferences1, getFileReferences2, getFileReferences_server1, and getFileReferences_server2 from the TypeScript fourslash suite

Side effect

Implementing getReferencesForNonModule also fixes findAllReferences on triple-slash /// <reference path/types/lib> nodes — previously they returned no span and omitted transitive referencing files (e.g. require("./b") in a .js file). The findAllReferencesTripleSlash submodule baseline is updated to match TypeScript's expected output, and the stale diff file is removed.

Original prompt

Fix this issue #3250

Created from VS Code.

---

💬 Send tasks to Copilot coding agent from Slack and Teams to turn conversations into code. Copilot posts an update in your thread when it's finished.

[DanielRosenwasser]

@copilot go

[DanielRosenwasser]

Update convertfourslash.mts to add any existing tests that need to be ported.

[Copilot]

Done in 38e7195. Added baselineGetFileReferences support to convertFourslash.mts (parser + generator + interface + union type membership), and generated TestGetFileReferences1 and TestGetFileReferences2 from the existing TypeScript fourslash tests.

[DanielRosenwasser]

Can this just live in ls? Explain why if not.

[Copilot]

Moved to ls in 38e7195. Instead of putting the logic on Program, I added a single exported method FileIncludeReason.GetSpanInReferrer(program) to compiler/fileInclude.go that handles the isReferencedFile() check + location retrieval + synthetic filtering + trivia-skipping (matching TypeScript's skipTrivia(file.text, importLiteral.pos)). The ls code calls program.GetIncludeReasons() + ref.GetSpanInReferrer() directly. The GetNonModuleFileReferences/NonModuleFileReference types on Program are removed.

[jakebailey]

Does this need to be a cross-project aware call? Or did Strada really only do one project? I bet it does need to be cross-project a la registerMultiProjectReferenceRequestHandler.

[DanielRosenwasser]

It should be cross-project. That's the challenge I was talking about in the original issue. Fix it @copilot.

[Copilot]

Fixed in f9bedbc. GetFileReferences now accepts a CrossProjectOrchestrator and uses it to search all initial projects (GetAllProjectsForInitialRequest) plus any additional projects discovered via GetProjectsLoadingProjectTree, deduplicating results across all of them. handleFindFileReferences is simplified to call getLanguageServiceAndCrossProjectOrchestrator and delegate to the LS. Also ported getFileReferences_server1, _server2, and _deduplicate from TypeScript's fourslash suite to validate the cross-project behavior.