"Remove constraint" refactoring gets spacing wrong

[andreasabel]

Code action for remove constraint gets sometimes spacing wrong.

isInteractionMetaB
  :: forall m. (ReadTCState m, MonadReduce m, MonadPretty m)
  => MetaId
  -> Args
  -> m (Maybe (MetaId, InteractionId, Args))

is turned into

isInteractionMetaB
  :: forall m. ( MonadPretty m)
  =>MetaId
  -> Args
  -> m (Maybe (MetaId, InteractionId, Args))

but correct would be

isInteractionMetaB
  :: forall m. (MonadPretty m)
  => MetaId
  -> Args
  -> m (Maybe (MetaId, InteractionId, Args))

So the space from behind the => is shifted to behind the first (.

Movie

Refactorbug.mov

Your environment

• MacOS
• GHC 9.12.2
• HLS 2.12
• VSCode

Related:

• Fix remove constraint #1578
• Code action to remove redundant constraints can't deal with type operators properly #1300

[vidit-od]

I also tried to inspect this issue. I can reproduce the suggested bug, but I tried a lot of examples from linked issue #1300 as well. Here is what I have:

Example 1: No change after code action

f :: (**) a b => a -> b -> a
f = const

Example 2: No change after code action

g :: ((**) a b) => a -> b -> a
g = const

Example 3:

h :: ((**) a b, Eq a) => a -> b -> a
h = const

This turns into the following after the code action, which is still not the expected outcome:

h :: ((**) a b) => a -> b -> a
h = const

[andreasabel]

My OP reports this for a multi-line type signature, but I often get the same wrong space behavior for a single line signature, so it is likely not connected to line-breaks. It smells like a one-off-error somewhere in the refactorer.