Apply hint never finishes -- no error in the log

[talldeveloper]

Your environment

Which OS do you use?
Windows 10 Home 22H2
Which version of GHC do you use and how did you install it?
9.2.4 via ghcup
How is your project built (alternative: link to the project)?
cabal build

Which LSP client (editor/plugin) do you use?
VSCode + Haskell plugin
Which version of HLS do you use and how did you install it?
1.8.0.0 via ghcup
Have you configured HLS in any way (especially: a hie.yaml file)?
no

Steps to reproduce

Apply a hlint suggestion (right-click, quick fix, apply hint)

Expected behaviour

The hint should be applied to the code

Actual behaviour

The "applying hint" notification keeps spinning, but nothing happens

Debug information

I set logging to verbose, but no error is shown in the log. When applying the hint:

`[Trace - 8:35:35 PM] Received response 'textDocument/codeAction - (32)' in 30ms.
Result: [
{
"command": {
"arguments": [
{
"file": "file:///c%3A/Users/Arno%20Prive/Projects/aoc2022/app/Day06.hs",
"hintTitle": "Redundant $",
"start_pos": {
"character": 31,
"line": 21
}
}
],
"command": "15004:hlint:applyOne",
"title": "Apply hint "Redundant $""
},
"diagnostics": [
{
"code": "refact:Redundant $",
"message": "Redundant $\nFound:\n (show . firstUnique) $ 4\nWhy not:\n (show . firstUnique) 4\n",
"range": {
"end": {
"character": 32,
"line": 21
},
"start": {
"character": 31,
"line": 21
}
},
"severity": 3,
"source": "hlint"
}
],
"isPreferred": true,
"kind": "quickfix",
"title": "Apply hint "Redundant $""
},
{
"diagnostics": [
{
"code": "refact:Redundant $",
"message": "Redundant $\nFound:\n (show . firstUnique) $ 4\nWhy not:\n (show . firstUnique) 4\n",
"range": {
"end": {
"character": 32,
"line": 21
},
"start": {
"character": 31,
"line": 21
}
},
"severity": 3,
"source": "hlint"
}
],
"edit": {
"changes": {
"file:///c%3A/Users/Arno%20Prive/Projects/aoc2022/app/Day06.hs": [
{
"newText": "{-# OPTIONS_GHC -Wno-unrecognised-pragmas #-}\n{-# HLINT ignore "Redundant $" #-}\n",
"range": {
"end": {
"character": 0,
"line": 0
},
"start": {
"character": 0,
"line": 0
}
}
}
]
}
},
"isPreferred": false,
"kind": "quickfix",
"title": "Ignore hint "Redundant $" in this module"
}
]

[Trace - 8:35:39 PM] Sending request 'workspace/executeCommand - (33)'.
Params: {
"command": "15004:hlint:applyOne",
"arguments": [
{
"file": "file:///c%3A/Users/Arno%20Prive/Projects/aoc2022/app/Day06.hs",
"hintTitle": "Redundant $",
"start_pos": {
"character": 31,
"line": 21
}
}
]
}

[Trace - 8:35:39 PM] Received request 'window/workDoneProgress/create - (10)'.
Params: {
"token": 1
}

[Trace - 8:35:39 PM] Sending response 'window/workDoneProgress/create - (10)'. Processing request took 0ms
No result returned.

[Trace - 8:35:39 PM] Received notification '$/progress'.
Params: {
"token": 1,
"value": {
"cancellable": true,
"kind": "begin",
"title": "Applying hint: Redundant $"
}
}

2022-12-06T19:36:23.170769Z | Info | Live bytes: 83.85MB Heap size: 377.49MB
[Trace - 8:36:23 PM] Received notification 'window/logMessage'.
Params: {
"message": "Live bytes: 83.85MB Heap size: 377.49MB",
"type": 3
}

[Info - 8:36:23 PM] Live bytes: 83.85MB Heap size: 377.49MB
`

[michaelpj]

What happens if you use hlint --refactor from the CLI, does it work?

[talldeveloper]

Running "hlint lint --refactor " showed that it could not find refactor. I installed apply-refact using cabal, and put cabal/bin on the path. The hlint command now produces the correct output, but when applying the hint using the Haskell plugin in VSCode, it still does not do anything. The progress indicator keeps spinning without an error in the log.

[michaelpj]

Ugh. Okay, I guess that's definitely a bug. I guess we need more logs in there, otherwise the only thing I can think you might try is to strace HLS and see whether anything suspicious is going on when it hangs.

[talldeveloper]

How do I do that? I changed the log level for the client logging to trace, but that did not reveal anything:
2022-12-08T19:38:27.196086Z | Debug | Getting hlint ideas for NormalizedFilePath "C:\Users\Arno Prive\Projects\aoc2022\app\Day08.hs"
2022-12-08T19:38:27.196086Z | Debug | Using extensions for NormalizedFilePath "C:\Users\Arno Prive\Projects\aoc2022\app\Day08.hs": [ MonomorphismRestriction
, DeepSubsumption
, RelaxedPolyRec
, ForeignFunctionInterface
, ImplicitPrelude
, DoAndIfThenElse
, EmptyDataDecls
, PatternGuards
, DatatypeContexts
, TraditionalRecordSyntax
, StarIsType
, CUSKs
, FieldSelectors ]
2022-12-08T19:38:27.204083Z | Debug | Finished: applyHint Took: 0.01s
[Trace - 8:38:27 PM] Received request 'window/workDoneProgress/create - (8)'.
[Trace - 8:38:27 PM] Sending response 'window/workDoneProgress/create - (8)'. Processing request took 0ms
[Trace - 8:38:27 PM] Received notification '$/progress'.
[Trace - 8:38:27 PM] Received notification 'window/logMessage'.
Getting hlint ideas for NormalizedFilePath "C:\Users\Arno Prive\Projects\aoc2022\app\Day08.hs"
[Trace - 8:38:27 PM] Received notification 'window/logMessage'.
Using extensions for NormalizedFilePath "C:\Users\Arno Prive\Projects\aoc2022\app\Day08.hs": [ MonomorphismRestriction
, DeepSubsumption
, RelaxedPolyRec
, ForeignFunctionInterface
, ImplicitPrelude
, DoAndIfThenElse
, EmptyDataDecls
, PatternGuards
, DatatypeContexts
, TraditionalRecordSyntax
, StarIsType
, CUSKs
, FieldSelectors ]
[Trace - 8:38:27 PM] Received notification 'window/logMessage'.
Finished: applyHint Took: 0.01s
2022-12-08T19:38:27.204083Z | Debug | Generated hlint ideas for for NormalizedFilePath "C:\Users\Arno Prive\Projects\aoc2022\app\Day08.hs": [[Replace {rtype = Decl, pos = SrcSpan {startLine = 43, startCol = 1, endLine = 43, endCol = 69}, subts = [("body",SrcSpan {startLine = 43, startCol = 15, endLine = 43, endCol = 63})], orig = "day08_1 = body"}]]
[Trace - 8:38:27 PM] Received notification 'window/logMessage'.
Generated hlint ideas for for NormalizedFilePath "C:\Users\Arno Prive\Projects\aoc2022\app\Day08.hs": [[Replace {rtype = Decl, pos = SrcSpan {startLine = 43, startCol = 1, endLine = 43, endCol = 69}, subts = [("body",SrcSpan {startLine = 43, startCol = 15, endLine = 43, endCol = 63})], orig = "day08_1 = body"}]]
2022-12-08T19:38:27.649435Z | Debug | Finished: applyHint Took: 0.00s
2022-12-08T19:38:27.649435Z | Debug | Finished: applyHint Took: 0.00s

It all seems to work fine.

Let me know if there are any log files that I can generate or dig up that will shed some light on this issue.

[Cmdv]

This seems to be happening on emacs/doom too as per this issue emacs-lsp/lsp-haskell#158

I'm on macOS 12.6 (Monterey), and via ghcup installed GHC 9.4.2 + HLS 1.8.0.0. Also tried on GHC 9.2.4 and same issue.

I got a little more information from logs between the client/server but it's not really a lot tbh.

1. It seems to recommend -Wdeferred-out-of-scope-variables for missing import of fromMaybe which is odd

Click to expand

Params: {
  "textDocument": {
    "uri": "file:///Users/cmdv/Code/Fun/AOC2022/src/Day5SupplyStack.hs"
  },
  "range": {
    "start": {
      "line": 92,
      "character": 19
    },
    "end": {
      "line": 92,
      "character": 19
    }
  },
  "context": {
    "diagnostics": [
      {
        "code": "-Wdeferred-out-of-scope-variables",
        "message": "Variable not in scope: fromMaybe :: [a0] -> Maybe [Char] -> t",
        "range": {
          "end": {
            "character": 28,
            "line": 92
          },
          "start": {
            "character": 19,
            "line": 92
          }
        },
        "severity": 1,
        "source": "typecheck"
      }
    ]
  }
}

2. Then further in the log it calling textDocument/cadeAction return [] and not sure if this is related but the heap seems quite big at 786.43MB?

Click to expand

[Trace - 12:19:27 pm] Received notification 'window/logMessage'.
Params: {
  "message": "Live bytes: 58.27MB Heap size: 786.43MB",
  "type": 3
}

[Trace - 12:20:41 pm] Sending request 'textDocument/codeAction - (372)'.
Params: {
  "textDocument": {
    "uri": "file:///Users/cmdv/Code/Fun/AOC2022/src/Day5SupplyStack.hs"
  },
  "range": {
    "start": {
      "line": 93,
      "character": 19
    },
    "end": {
      "line": 93,
      "character": 19
    }
  },
  "context": {
    "diagnostics": []
  }
}

3. Lastly everything else seems to work like code completion would rightly give Data.Maybe when starting to type fromMaybe then in the logs you see it picking up the errors and recommendations. 🤔

Gotten so used to using HLS to import my functions for me that I dearly miss it now, I can't quite iron out when this started happening for me but I'd say 3-4 weeks.

[0rphee]

This also seems to be happening when using hlswith helix, with these settings:

macOS 13.0.1 (M1 Mac)
GHC 9.2.5 
HLS 1.9.0.0

The funny thing here is that the problem doesn't seem to be caused by HLS directly, but by the ghc version. With HLS 1.7.0.0 (the version I used previously), and testing with ghc-9.2.5 gave the same result, namely, apply hint didn't work, but if I tried using ghc-9.0.2, it worked as expected.