Search each file of a multi-targeted F# project once in Go To All

[xperiandri]

Description

Go To All (Ctrl+T / Code Search) on a multi-targeted F# solution showed F# results late — often only on the second search — and the window stalled while it searched. Reproduced on a solution with 135 project instances (26 project files, five target frameworks each for the app projects).

How the search runs: Roslyn's NavigateToSearcher hands the F# service every project instance one after another (the ExternalAccess bridge loops SearchProjectAsync over the projects of a group), and only publishes a project's results when the whole project is done. The F# service then:

• parsed every file of every instance — one parse per file per target framework, since the parse cache is per DocumentId and the defines differ;
• read the text of every document before matching anything, which for a closed document is a file read — one per file per framework per keystroke;
• started all of a project's documents at once, unthrottled, so one project meant hundreds of concurrent parses and reads.

Change (NavigateToSearchService.fs):

• The first instance of a project file in the solution searches every file. The other instances search only the files they alone compile and the files whose parse depends on the defines (ParsedInput … Trivia.ConditionalDirectives), remembered per file path from whichever instance parsed the file first; an instance that meets a file before any parse of it searches it as before. Results for one file therefore come from one instance, except under conditional compilation.
• A document's text is read only after one of its declarations matched.
• A project's documents are searched at most ProcessorCount at a time (whenAllThrottled).

Not changed: Roslyn searches only its own persisted index while the solution is not fully loaded (SearchCachedDocumentsAsync is skipped for services without IAdvancedNavigateToSearchService), so F# results still appear only once the solution has loaded; that needs an ExternalAccess extension.

Tests: MultiTargetNavigateToSearchTests loads one project as two instances (one without FOO and without the fourth file, one with both) through RoslynTestHelpers.CreateMultiTargetSolution and searches both instances in solution order: a declaration in a file every instance compiles, one under #if FOO, and one in the instance-only file are each reported exactly once. The first commit (test helpers) is shared with #20462.

No timings are claimed: per search the work goes from one parse and one file read per file per framework to one parse per file (plus the files with conditional directives) and a read per matched file.

Checklist

• Test cases added

• Performance benchmarks added in case of performance changes

• Release notes entry updated:

  Please make sure to add an entry with short succinct description of the change as well as link to this pull request to the respective release notes file, if applicable.

  Release notes files:

  • If anything under src/Compiler has been changed, please make sure to make an entry in docs/release-notes/.FSharp.Compiler.Service/<version>.md, where <version> is usually "highest" one, e.g. 42.8.200
  • If language feature was added (i.e. LanguageFeatures.fsi was changed), please add it to docs/release-notes/.Language/preview.md
  • If a change to FSharp.Core was made, please make sure to edit docs/release-notes/.FSharp.Core/<version>.md where version is "highest" one, e.g. 8.0.200.

  Information about the release notes entries format can be found in the documentation.
  Example:

  • More inlines for Result module. (PR #16106)
  • Correctly handle assembly imports with public key token of 0 length. (Issue #16359, PR #16363)
    *while! (Language suggestion #1038, PR #14238)

  If you believe that release notes are not necessary for this PR, please add NO_RELEASE_NOTES label to the pull request.

🤖 Generated with Claude Code

[github-actions]

❗ Release notes required

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---

✅ Found changes and release notes in following paths:

Change path	Release notes path	Description
`vsintegration/src`	docs/release-notes/.VisualStudio/18.vNext.md

[xperiandri]

Suggested change

	syntheticProject.GetAllProjects()
	|> List.distinctBy _.Name
	|> List.map (fun project -> project, ProjectId.CreateNewId())
	syntheticProject.GetAllProjects()
	|> Seq.distinctBy _.Name
	|> Seq.map (fun project -> project, ProjectId.CreateNewId())
	|> Seq.toList

[xperiandri]

I suppose it will be more performant, no?

Suggested change

	let instances =
	project.Solution.Projects
	|> Seq.filter (fun p -> p.FilePath = projectPath)
	|> Seq.map _.Id
	|> List.ofSeq
	fun (document: Document) ->
	match document.FilePath with
	| null -> true
	| path ->
	let documentIds = project.Solution.GetDocumentIdsWithFilePath path
	let owner =
	instances
	|> List.find (fun id -> documentIds |> Seq.exists (fun documentId -> documentId.ProjectId = id))
	let instances =
	project.Solution.Projects
	|> Seq.filter (fun p -> p.FilePath = projectPath)
	|> Seq.map _.Id
	|> Seq.toArray
	fun (document: Document) ->
	match document.FilePath with
	| null -> true
	| path ->
	let documentIds = project.Solution.GetDocumentIdsWithFilePath path
	let owner =
	instances
	|> Array.find (fun id -> documentIds |> Seq.exists (fun documentId -> documentId.ProjectId = id))

[T-Gro]

🤖🕵️ Shared declarations disappear from Current Project searches on a non-owner target after the cache warms.

// Existing multi-target fixture; fresh service, second target active.
let p = solution.GetProject instances[1]
let run () =
    service.SearchProjectAsync(p, ImmutableArray.Empty, "plainUse",
        service.KindsProvided, CancellationToken.None).Result
run () // contains plainUse
run () // empty

Roslyn submits only the active project for this scope. Preserve project-local results; the solution-order owner is not searched.

[T-Gro]

🤖🕵️ Newly conditional declarations are missing from the first solution search after an edit. Warm the cache on a shared file without directives, then replace its text in both target instances with:

module ModuleSecond
#if FOO
let addedFoo = 1
#endif

Searching addedFoo in the FOO instance first, then the plain owner, returns no result; repeating finds it. Roslyn prioritizes the active project, so this order occurs in normal searches. Validate the cached flag against the current text version before skipping.