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Visual Studio : When defining names in pattern matching auto completion should not be triggered. #5594

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Visual Studio : When defining names in pattern matching auto completion should not be triggered.#5594
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Area-LangService-AutoCompleteautocomplete/intellisenseBugImpact-Low(Internal MS Team use only) Describes an issue with limited impact on existing code.
Milestone
Backlog

Description

@goswinr
goswinr
opened on Sep 6, 2018

When binding values to names in pattern matching autocompletion gets triggered but should not.

•in this case autocompletion is not desired:
2018-09-06_143700
(update: DU and Enums are an exception to that as mentioned by @rojepp below)

•nor is autocompletion desired in this case:
2018-09-06_143738

•however when matching on types autocompletion might be desired:
2018-09-06_143718

As expected, autocompletion is not triggerd when binding a values to name with let or fun .

Microsoft Visual Studio Community 2017
Version 15.8.2
VisualStudio.15.Release/15.8.2+28010.2016
Microsoft .NET Framework
Version 4.7.03062

Visual F# Tools 10.2 for F# 4.5 15.8.0.0. Commit Hash: c55dd2c.
Microsoft Visual F# Tools 10.2 for F# 4.5

Activity

  1. cartermp
    added
    Bug
    Area-LangService-API
    on Sep 7, 2018
  2. cartermp
    added this to the 16.0 milestone on Sep 7, 2018

  3. rojepp commented on Sep 7, 2018

    @rojepp
    rojepp
    on Sep 7, 2018
    Contributor

    In your first example, I'd expect a filtered list showing only types. You often match for a DU and assign names inside.

         match smth with
     | Call(None, methInfo, args) ->
     ...

  4. goswinr commented on Sep 7, 2018

    @goswinr
    goswinr
    on Sep 7, 2018
    ContributorAuthor

    @rojepp a distinction between typing a DU/Enum or a new name could be made when the first letter is typed in upper or lower case.

  5. dsyme
    added
    Impact-Medium(Internal MS Team use only) Describes an issue with moderate impact on existing code.
    on Sep 13, 2018

  6. dsyme commented on Sep 13, 2018

    @dsyme
    dsyme
    on Sep 13, 2018
    Contributor

    It would be great to have this fixed (I notice it quite often but just mentally ignore it after too long)

  7. goswinr commented on Oct 1, 2018

    @goswinr
    goswinr
    on Oct 1, 2018
    ContributorAuthor

    similarly the x in for x in xs do should probably not trigger autocompletion`.
    At least if it is lower case ( not a DU)
    image

  8. cartermp
    modified the milestones: 16.0, 16.1 on Feb 21, 2019

  9. cartermp commented on Apr 6, 2019

    @cartermp
    cartermp
    on Apr 6, 2019
    Contributor

    This is significantly less annoying in VS 2019 GA for thefor x in ... case:

    image

    The match case issue remains, though we reduced the noise in completion in general so you should see a lot less useless stuff there.

  10. cartermp
    removed
    Impact-Medium(Internal MS Team use only) Describes an issue with moderate impact on existing code.
    on Apr 6, 2019
  11. cartermp
    modified the milestones: 16.1, 16.2 on Apr 23, 2019
  12. cartermp
    removed this from the 16.2 milestone on Apr 30, 2019

  13. 3 remaining items

  14. cartermp
    added this to the Backlog - Lower Priority milestone on Aug 26, 2020
  15. cartermp
    modified the milestones: Backlog - Lower Priority, Backlog on Oct 28, 2020
  16. dsyme
    added
    Area-LangService-AutoCompleteautocomplete/intellisense
    and removed
    Area-LangService-API
    on Apr 5, 2022

  17. kerams commented on Apr 13, 2022

    @kerams
    kerams
    on Apr 13, 2022
    Contributor

    The right side of as is also a pattern, so completions could be desirable.

  18. vzarytovskii
    added this to F# Compiler and Toolingon Jun 17, 2022
  19. vzarytovskii
    moved this to Not Planned in F# Compiler and Toolingon Jun 17, 2022
  20. github-actions
    added
    AI-thinks-windows-only
    on Mar 16, 2026
  21. github-actions
    removed
    AI-thinks-windows-only
    on Sep 29, 2026

  22. github-actions commented on Sep 29, 2026

    @github-actions
    github-actionsBot
    on Sep 29, 2026 – with GitHub Actions
    Contributor

    🤖 This is an automated response from Repo Assist.

    This issue is testable cross-platform through FSharp.Compiler.Service: completion is produced by GetDeclarationListInfo, and the repository test helper Checker.getCompletionInfo exercises that API directly. I have therefore removed the AI-thinks-windows-only label.

    The issue still reproduces at current HEAD 9b0b8a44015743b1c6a05fc0a739dfcddcf353ba (committed 2026-09-29, less than one day old). A focused FCS test run used these caret positions and expected zero completion items:

    • match A 1 with | A value{caret} -> (): 205 items
    • for value{caret} in [ 1 ] do (): 202 items
    • match box 1 with | :? int as value{caret} -> () | _ -> (): 202 items

    The exact command was dotnet test tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.Tests.fsproj --filter-method '*Issue 5594*' -c Release. The temporary probe failed as expected and was removed, so no regression-test PR was opened.

    Current compiler proof from built fsi and #version;;:

    F# Interactive version 15.2.200.0 for F# 11.2
FSharp.Core version 11.0.0.0
.NET Runtime version 11.0.0-rc.1.26420.103
Linux x64

    This remains an open FCS completion bug rather than Visual Studio-specific behavior.

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  23. goswinr commented on Sep 29, 2026

    @goswinr
    goswinr
    on Sep 29, 2026
    ContributorAuthor

    closing old issue. using VS code now. not VS anymore

  24. goswinr
    closed this as completedon Sep 29, 2026

  25. goswinr commented on Sep 29, 2026

    @goswinr
    goswinr
    on Sep 29, 2026
    ContributorAuthor

    actually, if it is in FCS , keep it open

  26. goswinr
    reopened this on Sep 29, 2026
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