Wingman: TODO(sandy) error pops up after the first tactic

[lsmor]

Your environment

Which OS do you use:
Ubuntu 20.04.3 LTS

Which lsp-client do you use:
VS Code

Describe your project (alternative: link to the project):
It is a regular stack project which can be found here. Nothing really wierd, just a normal advent of code project with one executable per day.

stack snapshot: 18.6 -> GHC 8.10.7
HLS version: 1.5.1

Steps to reproduce

write the following file and positionate the cursor on the underscore, then trigger the code action "Wingman: case split on d"

module Main where

data Input = Input

example :: Input -> Input
example d = _


main :: IO ()
main = print "hello hls"

Expected behaviour

It should complete the line example d = _ introducing Input constructor like example Input = _d. Some times, It works fine when I re-start hls but 8 out of 10 times it keeps failing.

Actual behaviour

And error pops up TODO(sandy)

Include debug information

This is the output when I set VS code extension setting to debug. (I've been unable to run haskell-language-server-wrapper)

Debug output:

2021-12-07 12:01:51.274203053 [ThreadId 4442] INFO hls:	finish: Wingman.getIdeDynflags.GetModSummaryWithoutTimestamps (took 0.00s)
2021-12-07 12:01:51.274730682 [ThreadId 4443] INFO hls:	finish: Wingman.judgementForHole.GetHieAst (took 0.00s)
2021-12-07 12:01:51.275544442 [ThreadId 4444] INFO hls:	finish: Wingman.judgementForHole.GetBindings (took 0.00s)
2021-12-07 12:01:51.275816949 [ThreadId 4445] INFO hls:	finish: Wingman.judgementForHole.TypeCheck (took 0.00s)
[Error - 12:01:51] Request workspace/executeCommand failed.
  Message: TODO(sandy)
  Code: -32603 
2021-12-07 12:01:51.276098968 [ThreadId 4446] INFO hls:	finish: Wingman.judgementForHole.GhcSessionDeps (took 0.00s)
2021-12-07 12:01:51.350012789 [ThreadId 4464] INFO hls:	finish: Pragmas.GetParsedModule (took 0.00s)
2021-12-07 12:01:51.350191098 [ThreadId 4467] INFO hls:	finish: retrie (took 0.00s)
2021-12-07 12:01:51.350225369 [ThreadId 4465] INFO hls:	finish: Wingman.getIdeDynflags.GetModSummaryWithoutTimestamps (took 0.00s)

[jneira]

thanks for the bug report, pinging @isovector due to the explicit mention 😉

[wenkokke]

I'm having the same issue with VSCode on macOS (11.6) with HLS 1.5.1.

[isovector]

Which version of GHC, @wenkokke ? I'll see if I can repro this on the weekend.

[wenkokke]

I got these errors with GHC 8.10.7, using any of the case splitting primitives except for introduce-and-destruct, so my experience is consistent with the errors shown above.

I can do a bit more thorough testing if that’d help?

[isovector]

That would be extremely helpful, thanks. The block that pushes out the error message is a MaybeT over mostly HLS functionality. I haven't touched Wingman for a few releases, so my guess is that something in the infrastructure has changed --- likely one of the data sources that used to be blocking is no longer.

Do you notice more successes if you wait for 30 seconds after making the last change? Do you see this problem less often on smaller projects?

[wenkokke]

Do you notice more successes if you wait for 30 seconds after making the last change? Do you see this problem less often on smaller projects?

I see this error on every single attempt that I make to pattern match regardless of project size (though I have only tested it on small projects).

I'm guessing that the amount of time that I wait doesn't really affect things, and I think that I haven't been calling these functions immediately... but I'm not sure. I will report back.

[wenkokke]

I started a cabal project with only a single file with only the following lines:

module Test where

nope :: Bool -> Bool
nope b = _wc

Now running "Case split on b" raises "TODO(sandy)" as a popup. However, "introduce lambda" works just fine, e.g., to obtain the above code from:

nope :: Bool -> Bool
nope = _

Similarly, "introduce and destruct term" works just fine.

The amount of time waited has no effect on any of these behaviors.

[isovector]

My guess is that something broke the datacon lookup stuff. The most recent change to this function was #2128. I'm traveling right now, but will try to find some time to dig in over the weekend.

[lsmor]

Hi @isovector . I've tried different approaches and found that Wingman is able to perfom one action, but not two. the error is not so related with the action but with number of actions you want to perform. Let me explain via example.

1 . Start with this file.

data Dummy a = Dummy a

f :: Dummy Int -> Int
f = _ 

2. If I launch "Introduce lambda", It doesn't fail

data Dummy a = Dummy a

f :: Dummy Int -> Int
f du = _wa

3. If after (2) I launch "case split on du" It fails with TODO(sandy).

data Dummy a = Dummy a

f :: Dummy Int -> Int
f du = _wa -- Fails when triying "case split" action

3.1 If now, I come back to (1) and hit again "Introduce lambda" it fails with the same error

data Dummy a = Dummy a

f :: Dummy Int -> Int
f = _  -- Now this fails after first fail at (2)

3.2 If after (3) I re-start HLS and rehit "case split on du"... It does work fine!!

data Dummy a = Dummy a

f :: Dummy Int -> Int
f (Dummy n) = _wa   -- now it is working 

4. If "attempt to fill hole" is launched it fails with same error.

data Dummy a = Dummy a

f :: Dummy Int -> Int
f (Dummy n) = _wa   -- Fails after attempt to fill hole.

4.1 If at (4) I restart HLS andt rehit "attempt to fill hole" now it works fine.

data Dummy a = Dummy a

f :: Dummy Int -> Int
f (Dummy n) = n   -- it works.

FYI: @wenkokke

[wenkokke]

I can confirm that this is indeed the case!