Remove ErrDoc and MsgDoc

This commit boldly removes the ErrDoc and the MsgDoc from the codebase.
The former was introduced with the only purpose of classifying errors
according to their importance, but a similar result can be obtained just
by having a simple [SDoc], and placing bullets after each of them.

On top of that I have taken the perhaps controversial decision to also
banish MsgDoc, as it was merely a type alias over an SDoc and as such it wasn't
offering any extra type safety. Granted, it was perhaps making type
signatures slightly more "focused", but at the expense of cognitive
burden: if it's really just an SDoc, let's call it with its proper name.

1 files changed, 4 insertions, 5 deletions

diff --git a/compiler/GHC/Tc/Utils/Env.hs b/compiler/GHC/Tc/Utils/Env.hs
index 3267a24cd6..8dcb0b47f7 100644
--- a/compiler/GHC/Tc/Utils/Env.hs
+++ b/compiler/GHC/Tc/Utils/Env.hs
@@ -112,7 +112,6 @@ import GHC.Unit.External
 import GHC.Utils.Outputable
 import GHC.Utils.Panic
 import GHC.Utils.Encoding
-import GHC.Utils.Error
 import GHC.Utils.Misc ( HasDebugCallStack )
 
 import GHC.Data.FastString
@@ -155,7 +154,7 @@ lookupGlobal hsc_env name
             Failed msg      -> pprPanic "lookupGlobal" msg
         }
 
-lookupGlobal_maybe :: HscEnv -> Name -> IO (MaybeErr MsgDoc TyThing)
+lookupGlobal_maybe :: HscEnv -> Name -> IO (MaybeErr SDoc TyThing)
 -- This may look up an Id that one has previously looked up.
 -- If so, we are going to read its interface file, and add its bindings
 -- to the ExternalPackageTable.
@@ -174,7 +173,7 @@ lookupGlobal_maybe hsc_env name
           lookupImported_maybe hsc_env name
         }
 
-lookupImported_maybe :: HscEnv -> Name -> IO (MaybeErr MsgDoc TyThing)
+lookupImported_maybe :: HscEnv -> Name -> IO (MaybeErr SDoc TyThing)
 -- Returns (Failed err) if we can't find the interface file for the thing
 lookupImported_maybe hsc_env name
   = do  { mb_thing <- lookupType hsc_env name
@@ -183,7 +182,7 @@ lookupImported_maybe hsc_env name
             Nothing    -> importDecl_maybe hsc_env name
             }
 
-importDecl_maybe :: HscEnv -> Name -> IO (MaybeErr MsgDoc TyThing)
+importDecl_maybe :: HscEnv -> Name -> IO (MaybeErr SDoc TyThing)
 importDecl_maybe hsc_env name
   | Just thing <- wiredInNameTyThing_maybe name
   = do  { when (needWiredInHomeIface thing)
@@ -200,7 +199,7 @@ ioLookupDataCon hsc_env name = do
     Succeeded thing -> return thing
     Failed msg      -> pprPanic "lookupDataConIO" msg
 
-ioLookupDataCon_maybe :: HscEnv -> Name -> IO (MaybeErr MsgDoc DataCon)
+ioLookupDataCon_maybe :: HscEnv -> Name -> IO (MaybeErr SDoc DataCon)
 ioLookupDataCon_maybe hsc_env name = do
     thing <- lookupGlobal hsc_env name
     return $ case thing of