Import code action imports inside of CPP

[isovector]

Your environment

Output of haskell-language-server --probe-tools or haskell-language-server-wrapper --probe-tools:

haskell-language-server version: 1.0.0.0 (GHC: 8.8.4) (PATH: /home/sandy/.local/bin/haskell-language-server) (GIT hash: 25252164db6b2a01ccb0a7436009478ce2939f0a)
Tool versions found on the $PATH
cabal:      3.2.0.0
stack:      2.3.3
ghc:        8.10.4

Which lsp-client do you use: vim/coc

Steps to reproduce

{-# LANGUAGE CPP #-} 

import Prelude
#ifdef __GLASGOW_HASKELL__
import Data.Maybe
#endif

foo :: All
foo = All True

Use the "ImportAll from Data.Monoid" code action.

Expected behaviour

import Prelude
import Data.Monoid
#ifdef __GLASGOW_HASKELL__
import Data.Maybe
#endif

Actual behaviour

import Prelude
#ifdef __GLASGOW_HASKELL__
import Data.Maybe
import Data.Monoid
#endif

Why this is frustrating

Rather than using ifdef, consider if the CPP is #if __GLASGOW_HASKELL__ == 808, then your imports only get added for your current compiler version.

[michaelpj]

I'm pretty sure that all our file edits are potentially incorrect in the presence of CPP. I don't know of any reasonable way to fix that.