add code fix for wildcard _ in pattern match for fs43 on |->

[jkone27]

Suggest | _ -> for match mistaken with infix operator |->

add code fix for wildcard operator suggestion in pattern match for fs43, targets:
dotnet/fsharp#15748

as worked in amplifying fsharp session:
https://amplifying-fsharp.github.io/sessions/2023/09/01/

WHY

the operator |-> is not defined, so this is usually just a user forgetting to complete the match

HOW

🤖 Generated by Copilot at df83900

• Add a new code fix for adding a missing wildcard operator to a match expression (link, link)
  • Define a new module FsAutoComplete.CodeFix.AddMissingWildcardOperator in src/FsAutoComplete/CodeFixes/AddMissingWildcardOperator.fs and its signature file in src/FsAutoComplete/CodeFixes/AddMissingWildcardOperator.fsi (link, link)
  • Export a title, a function to try to find the pattern that needs the fix, and a function to apply the fix using the CodeFix type and the SyntaxVisitorBase and SyntaxTraversal utilities (link, link)
• Register the new code fix function in the language server implementations (link, link)
  • Add the function to the list of code fixes supported by the AdaptiveFSharpLspServer type in src/FsAutoComplete/LspServers/AdaptiveFSharpLspServer.fs (link)
  • Add the function to the list of code fixes supported by the FSharpLspServer type in src/FsAutoComplete/LspServers/FsAutoComplete.Lsp.fs (link)
• Add a test case for the new code fix using the test helpers (link, link)
  • Define a new test module FsAutoComplete.Tests.CodeFixTests.AddMissingWildcardOperatorTests in test/FsAutoComplete.Tests.Lsp/CodeFixTests/AddMissingWildcardOperatorTests.fs (link)
  • Check that the code fix can suggest a wildcard pattern for a missing match case in a simple example using the CodeFix and Diagnostics utilities (link)
  • Add the new test module to the list of test modules in the tests function in test/FsAutoComplete.Tests.Lsp/CodeFixTests/Tests.fs (link)

[TheAngryByrd]

@dawedawe mentioned some good fixes

[baronfel]

Needs a format but otherwise LGTM.

[jkone27]

fixed the suggestions, not clear how i run format, can it be added as a git hook at commit phase on master? i am not very familiar with fantomas, would be good if it could be hooked onto dotnet format or .editorconfig i guess most .net devs are familiar with those concepts. formatted the changed files individually with
dotnet fantomas filename.fs

[nojaf]

Hi,

Running this target sets up the git hook:
https://github.com/fsharp/FsAutoComplete/blob/e3353360771969be51ab3c84a57a432cf41816cf/build/Program.fs#L107-L110

dotnet run --project ./build/build.fsproj -- -t EnsureRepoConfig

And I think it would be nice to see a message when
https://github.com/fsharp/FsAutoComplete/blob/e3353360771969be51ab3c84a57a432cf41816cf/Directory.Solution.targets#L10-L12

fails.

Something like Please run "dotnet fantomas src" to format your files.
I'm not sure how to do that one with msbuild trickery.

[edgarfgp]

@jkone27 Could you have a look at the conflicts. Seems that this almost ready :)

[Krzysztof-Cieslak]

/repo-assist can you rebase this PR

[github-actions]

🤖 This is an automated response from Repo Assist.

Hi @jkone27! I've completed the rebase analysis for this PR. Unfortunately I'm unable to force-push the rebased branch directly (rebasing rewrites commit history which requires a force push), but I've worked through all the conflicts and can share exactly what needs to change.

Rebase Summary

The PR has 5 commits that cherry-pick cleanly onto current main with the following conflict resolutions:

Key changes needed to bring this PR up to date:

1. src/FsAutoComplete/LspServers/FsAutoComplete.Lsp.fs — deleted
This file was removed from the codebase. The change to this file in the original PR should be dropped.

2. src/FsAutoComplete/LspServers/AdaptiveFSharpLspServer.fs — no change needed
The forceGetProjectOptions/forceGetFSharpProjectOptions helper functions that conflicted are already in the current file (added by a later commit). No action needed.

3. src/FsAutoComplete/LspServers/AdaptiveServerState.fs — add registration
Code fixes are now registered here instead of AdaptiveFSharpLspServer.fs. Add one line:

         AddMissingFunKeyword.fix forceFindSourceText getLineText
+        AddMissingWildcardOperator.fix tryGetParseAndCheckResultsForFile
         MakeOuterBindingRecursive.fix tryGetParseAndCheckResultsForFile getLineText

4. test/FsAutoComplete.Tests.Lsp/CodeFixTests/Tests.fs — add test entry

-      ExprTypeMismatchTests.tests state ]
+      ExprTypeMismatchTests.tests state
+      AddMissingWildcardOperatorTests.tests state ]

5. test/FsAutoComplete.Tests.Lsp/CodeFixTests/AddMissingWildcardOperatorTests.fs — fix focused test
Change ftestCaseAsync → testCaseAsync (focused test markers cause CI failures).

Quick rebase commands

git fetch upstream main
git rebase upstream/main
# Resolve conflicts as described above, then:
git push --force-with-lease origin fix-dotnet-fsharp-15748-amplifying-fsharp

The new files (AddMissingWildcardOperator.fs, AddMissingWildcardOperator.fsi, AddMissingWildcardOperatorTests.fs) should apply cleanly — the only manual work is the 3 small changes above.

Let me know if you'd like any help! 🙂

Generated by Repo Assist for issue #1157

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[Krzysztof-Cieslak]

/repo-assist rebase changes from this PR and push them as new PR

[github-actions]

Pull request created: #1472

Generated by Repo Assist

[github-actions]

🤖 This is an automated response from Repo Assist.

Done! I've rebased the changes from this PR onto current main and created a new PR with the rebased changes.

The following adaptations were made:

• FsAutoComplete.Lsp.fs was removed from the codebase — that change was dropped
• Code fix registration moved from AdaptiveFSharpLspServer.fs to AdaptiveServerState.fs
• ftestCaseAsync → testCaseAsync (focused test markers cause CI failures)
• Fixed unused variable lineStr → _lineStr

The build succeeds ✅. The new PR is ready for review.

Generated by Repo Assist for issue #1157

To install this workflow, run gh aw add githubnext/agentics/workflows/repo-assist.md@f2c5cf1e4af58e09a93ba0703c6bf084711b265f. View source at https://github.com/githubnext/agentics/tree/f2c5cf1e4af58e09a93ba0703c6bf084711b265f/workflows/repo-assist.md.

[Krzysztof-Cieslak]

Thanks a lot for this, and sorry it took us so long to merge it