When compiler error occurs, the extension stops working

When i open a new window of vscode, the extension works well. And while i am typing some codes, linter reports that the codes, which i've written, have an error(e.g. [ghcmod] parse error (possibly incorrect indentation or mismatched brackets), of course. Since then vscode-hie-server extension stops working. For example, when i hover mouse on a symbol, the popup message only shows Loading....

So, i looked into the log of vscode for this situation:

# For this time, the extension works well.

$ cat /Users/foo/Library/Application\ Support/Code/logs/20181230T175051/exthost1/output_logging_20181230T175052/4-Haskell\ HIE\ \(study\).log
2018-12-30 17:50:54.699438 [ThreadId 4] - run entered for hie-wrapper(hie-wrapper) Version 0.4.0.1, Git revision 337fd9bf6254b50820bfe73046353ae2c4f86b34 (2315 commits) x86_64 ghc-8.2.1
2018-12-30 17:50:54.701665 [ThreadId 4] - Current directory:/Users/foo/dev/study
2018-12-30 17:50:54.707812 [ThreadId 4] - Cradle directory:/Users/foo/dev/study
2018-12-30 17:50:54.708637 [ThreadId 4] - Using plain GHC version
2018-12-30 17:50:54.781151 [ThreadId 4] - Project GHC version:8.6.3
2018-12-30 17:50:54.781611 [ThreadId 4] - hie exe candidates :["hie-8.6.3","hie-8.6","hie"]
2018-12-30 17:50:54.782368 [ThreadId 4] - found hie exe at:/Users/foo/.local/bin/hie-8.6.3
2018-12-30 17:50:54.783003 [ThreadId 4] - args:["--lsp"]
2018-12-30 17:50:54.783339 [ThreadId 4] - launching ....



2018-12-30 17:50:54.802044 [ThreadId 4] - Using plain GHC version
2018-12-30 17:50:54.874546 [ThreadId 4] - Run entered for HIE(hie-8.6.3) Version 0.4.0.1, Git revision 337fd9bf6254b50820bfe73046353ae2c4f86b34 (2315 commits) x86_64 ghc-8.6.3
2018-12-30 17:50:54.875851 [ThreadId 4] - Current directory:/Users/foo/dev/study
2018-12-30 17:50:54.929107 [ThreadId 13] - UUsing hie version: Version 0.4.0.1, Git revision 337fd9bf6254b50820bfe73046353ae2c4f86b34 (2315 commits) x86_64 ghc-8.6.3
sing plain GHC version
Using hoogle db at: /Users/foo/.hoogle/default-haskell-5.0.17.hoo

# For this time, the extension doesn't work anymore. Take note of last line of log.

$ cat /Users/foo/Library/Application\ Support/Code/logs/20181230T175051/exthost1/output_logging_20181230T175052/4-Haskell\ HIE\ \(study\).log
2018-12-30 17:50:54.699438 [ThreadId 4] - run entered for hie-wrapper(hie-wrapper) Version 0.4.0.1, Git revision 337fd9bf6254b50820bfe73046353ae2c4f86b34 (2315 commits) x86_64 ghc-8.2.1
2018-12-30 17:50:54.701665 [ThreadId 4] - Current directory:/Users/foo/dev/study
2018-12-30 17:50:54.707812 [ThreadId 4] - Cradle directory:/Users/foo/dev/study
2018-12-30 17:50:54.708637 [ThreadId 4] - Using plain GHC version
2018-12-30 17:50:54.781151 [ThreadId 4] - Project GHC version:8.6.3
2018-12-30 17:50:54.781611 [ThreadId 4] - hie exe candidates :["hie-8.6.3","hie-8.6","hie"]
2018-12-30 17:50:54.782368 [ThreadId 4] - found hie exe at:/Users/foo/.local/bin/hie-8.6.3
2018-12-30 17:50:54.783003 [ThreadId 4] - args:["--lsp"]
2018-12-30 17:50:54.783339 [ThreadId 4] - launching ....



2018-12-30 17:50:54.802044 [ThreadId 4] - Using plain GHC version
2018-12-30 17:50:54.874546 [ThreadId 4] - Run entered for HIE(hie-8.6.3) Version 0.4.0.1, Git revision 337fd9bf6254b50820bfe73046353ae2c4f86b34 (2315 commits) x86_64 ghc-8.6.3
2018-12-30 17:50:54.875851 [ThreadId 4] - Current directory:/Users/foo/dev/study
2018-12-30 17:50:54.929107 [ThreadId 13] - UUsing hie version: Version 0.4.0.1, Git revision 337fd9bf6254b50820bfe73046353ae2c4f86b34 (2315 commits) x86_64 ghc-8.6.3
sing plain GHC version
Using hoogle db at: /Users/foo/.hoogle/default-haskell-5.0.17.hoo
hie-8.6.3: Prelude.head: empty list # <-------------------- This line is newly generated log.

To fix this situation, i have to restart vscode over again. Reopening the file doesn't work without restarting vscode...

---

Mac OS : 10.14.2(18C54)
vscode : 1.30.1(1.30.1)

$ stack --version | head -1
1.9.3 x86_64

$ stack ghc -- --version
The Glorious Glasgow Haskell Compilation System, version 8.6.3

[alanz]

Can you provide the contents of the directory you are working in here? Or the file you are opening?

This is a working directory:

$ ls -l ~/dev/study
.rw-r--r--      1  293 foo staff 2018-12-30 22:34 test2.hs

This is test2.hs file:

module Test2 where

ifEven myFunction x = if even x
                      then myFunction x
                      else x

inc n = n + 1
double n = n*2
square n = n^2

ifEvenInc n = ifEven inc n
ifEvenDouble n = ifEven double n
ifEvenSquare n = ifEven square n

genIfEven f = (\x -> ifEven f x)

You may reproduce this situation following:

1. Delete ifEvenSquare n = ifEven square n line, though, I think the file contents doesn't matter concerning this issue.
2. Type slowly that line was deleted just now again.
3. You may see error like below(If you copy and paste that error) in vscode problems tab.
4. Since then, the extension doesn't work(get freeze) anymore. If you mouse hover on any symbol, you can see just popup message showing Loading.... Also, If you edit the file contents, autocompletion, linter also doesn't work.

{
	"resource": "/Users/foo/dev/study/test2.hs",
	"owner": "Haskell HIE (study)",
	"severity": 8,
	"message": "parse error on input ‘=’\nPerhaps you need a 'let' in a 'do' block?\ne.g. 'let x = 5' instead of 'x = 5'",
	"source": "ghcmod",
	"startLineNumber": 15,
	"startColumn": 13,
	"endLineNumber": 15,
	"endColumn": 14
}

I showed the vscode log above(before this situation occurs, and after).

[alanz]

My reproduction of this problem shows up in the logs as

2018-12-30 20:58:53.995929109 [ThreadId 4] - ---> {"jsonrpc":"2.0","id":63,"method":"textDocument/codeAction","params":{"textDocument":{"uri":"file:///tmp/fff/test2.hs"},"range":{"start":{"line":0,"character":0},"end":{"line":14,"character":0}},"context":{"diagnostics":[{"range":{"start":{"line":0,"character":0},"end":{"line":1,"character":0}},"message":"","severity":1,"source":"ghcmod"},{"range":{"start":{"line":13,"character":12},"end":{"line":13,"character":13}},"message":"parse error on input ‘=’\nPerhaps you need a 'let' in a 'do' block?\ne.g. 'let x = 5' instead of 'x = 5'","severity":1,"source":"ghcmod"}]}}}
2018-12-30 20:58:53.996207007 [ThreadId 13] - ****** reactor: got message number:68
2018-12-30 20:58:53.996245936 [ThreadId 13] - reactor:got CodeActionRequest:RequestMessage {_jsonrpc = "2.0", _id = IdInt 63, _method = TextDocumentCodeAction, _params = CodeActionParams {_textDocument = TextDocumentIdentifier {_uri = Uri {getUri = "file:///tmp/fff/test2.hs"}}, _range = Range {_start = Position {_line = 0, _character = 0}, _end = Position {_line = 14, _character = 0}}, _context = CodeActionContext {_diagnostics = List [Diagnostic {_range = Range {_start = Position {_line = 0, _character = 0}, _end = Position {_line = 1, _character = 0}}, _severity = Just DsError, _code = Nothing, _source = Just "ghcmod", _message = "", _relatedInformation = Nothing},Diagnostic {_range = Range {_start = Position {_line = 13, _character = 12}, _end = Position {_line = 13, _character = 13}}, _severity = Just DsError, _code = Nothing, _source = Just "ghcmod", _message = "parse error on input \8216=\8217\nPerhaps you need a 'let' in a 'do' block?\ne.g. 'let x = 5' instead of 'x = 5'", _relatedInformation = Nothing}], only = Nothing}}}
2018-12-30 20:58:53.99647098 [ThreadId 15] - ideDispatcher: got request 68 with id: IdInt 63
2018-12-30 20:58:53.996504462 [ThreadId 15] - ideDispatcher: top of loop
2018-12-30 20:58:53.996526303 [ThreadId 15] - ideDispatcher: got request 68 with id: IdInt 63
2018-12-30 20:58:53.996548192 [ThreadId 15] - ideDispatcher: top of loop
2018-12-30 20:58:53.996566929 [ThreadId 15] - ideDispatcher: got request 68 with id: IdInt 63
2018-12-30 20:58:53.996595281 [ThreadId 15] - ideDispatcher: top of loop
2018-12-30 20:58:53.996615554 [ThreadId 15] - ideDispatcher: got request 68 with id: IdInt 63
2018-12-30 20:58:53.996685422 [ThreadId 15] - ideDispatcher: top of loop
2018-12-30 20:58:53.996709778 [ThreadId 15] - ideDispatcher: got request 68 with id: IdInt 63
2018-12-30 20:58:53.99674188 [ThreadId 15] - ideDispatcher: top of loop
2018-12-30 20:58:53.996762266 [ThreadId 15] - ideDispatcher: got request 68 with id: IdInt 63
2018-12-30 20:58:53.996785092 [ThreadId 15] - ideDispatcher: top of loop
2018-12-30 20:58:53.996803474 [ThreadId 15] - ideDispatcher: got request 68 with id: IdInt 63

Which means the ideDispatcher is endlessly processing the same request.