List comprehensions are treated as quasiquotes

[TheBFL]

Your environment

Which OS do you use?

• WSL 2 (Ubuntu)

Which version of GHC do you use and how did you install it?

• 9.0.2 ghcup

Which LSP client (editor/plugin) do you use?

• VSCode/Haskell

Which version of HLS do you use and how did you install it?

• 1.7.0.0 from ghcup.

Have you configured HLS in any way (especially: a hie.yaml file)?

• No.

Steps to reproduce

Create a haskell file in vscode, with the contents:

main = print [x| x <- [1..10]]

the same behavior occurs even when {-#LANGUAGE NoQuasiQuotes#-} is added.

Expected behaviour

HLS treats this as a list comprehension, and displays the appropriate suggestions (such as "redundant list comprehension"), when quasiquotes are disabled.

Actual behaviour

HLS gives an error when there is no space before the | in the list comprehension, claiming that it is an unterminated quasiquotation at end of input when QuasiQuotes are not enabled.

[drsooch]

Interesting... Appears to be 9.0.2 specific. Can't reproduce on 8.10.7 nor 9.2.4 using master branch.

[arademaker]

Same here in MacOS 12.15.1

[michaelpj]

Hmm, this seems like it could be us somehow enabling QuasiQuotes unconditionally, but I can't see how that would happen.

[TheBFL]

I tried this, and the exceptionally weird thing is that if the appropriate end of the quasiquotation is added, like so:

main = print [x| x <- [1..10]|]

then HLS gives a Quasi-quotes are not permitted without QuasiQuotes error. So it's not like they're just automatically enabled from what I can tell

[pepeiborra]

HLS parses in a slightly unconventional mode since it enables -haddock. Can you repro just with ghc -haddock Foo.hs?

[TheBFL]

ghc -haddock BugTest.hs compiles properly, and doesn't give any error about quasiquotes. Seems the issue is specific to HLS.

[wz1000]

I think this is triggered by hlint. I can't reproduce this with just ghcide.

[michaelpj]

Is this still a problem?