Haskell-language-server: "Conflicting family instance declarations" false positive

[jneira]

From https://github.com/haskell/haskell-language-server/issues/175#issuecomment-660865914:

Small progress: my remaining issue seems to be exactly the same as digital-asset/ghcide#641

Should we keep this issue open?

[istathar]

I think I just ran into this. It wasn't a problem with 0.4.0 but when the vscode extension downloaded 0.5.0 suddenly I'm getting dozens of errors that look like:

Conflicting family instance declarations:
  Token Label = TechniqueToken
    -- Defined at /home/andrew/src/technique-lang/technique/lib/Technique/Formatter.hs:242:8
  Token Label = TechniqueToken
    -- Defined in module Technique.Formatter typecheck

which is clearly spurious. The build outside from the command-line works fine. Is there a way to work around this perchance?

AfC

[aviaviavi]

I'm also seeing this in 0.5.0, but was seeing it in the previous version too. Our app compiles just fine, but haskell-language-server is failing on files, complaining of this "conflicting family instance declaration"