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, 11 insertions, 11 deletions

diff --git a/compiler/GHC/Iface/Load.hs b/compiler/GHC/Iface/Load.hs
index 8e5bcf9f4b..01b4f4906f 100644
--- a/compiler/GHC/Iface/Load.hs
+++ b/compiler/GHC/Iface/Load.hs
@@ -140,7 +140,7 @@ where the code that e1 expands to might import some defns that
 also turn out to be needed by the code that e2 expands to.
 -}
 
-tcLookupImported_maybe :: Name -> TcM (MaybeErr MsgDoc TyThing)
+tcLookupImported_maybe :: Name -> TcM (MaybeErr SDoc TyThing)
 -- Returns (Failed err) if we can't find the interface file for the thing
 tcLookupImported_maybe name
   = do  { hsc_env <- getTopEnv
@@ -149,7 +149,7 @@ tcLookupImported_maybe name
             Just thing -> return (Succeeded thing)
             Nothing    -> tcImportDecl_maybe name }
 
-tcImportDecl_maybe :: Name -> TcM (MaybeErr MsgDoc TyThing)
+tcImportDecl_maybe :: Name -> TcM (MaybeErr SDoc TyThing)
 -- Entry point for *source-code* uses of importDecl
 tcImportDecl_maybe name
   | Just thing <- wiredInNameTyThing_maybe name
@@ -160,7 +160,7 @@ tcImportDecl_maybe name
   | otherwise
   = initIfaceTcRn (importDecl name)
 
-importDecl :: Name -> IfM lcl (MaybeErr MsgDoc TyThing)
+importDecl :: Name -> IfM lcl (MaybeErr SDoc TyThing)
 -- Get the TyThing for this Name from an interface file
 -- It's not a wired-in thing -- the caller caught that
 importDecl name
@@ -302,7 +302,7 @@ loadSrcInterface_maybe :: SDoc
                        -> ModuleName
                        -> IsBootInterface     -- {-# SOURCE #-} ?
                        -> Maybe FastString    -- "package", if any
-                       -> RnM (MaybeErr MsgDoc ModIface)
+                       -> RnM (MaybeErr SDoc ModIface)
 
 loadSrcInterface_maybe doc mod want_boot maybe_pkg
   -- We must first find which Module this import refers to.  This involves
@@ -408,7 +408,7 @@ loadInterfaceWithException doc mod_name where_from
 
 ------------------
 loadInterface :: SDoc -> Module -> WhereFrom
-              -> IfM lcl (MaybeErr MsgDoc ModIface)
+              -> IfM lcl (MaybeErr SDoc ModIface)
 
 -- loadInterface looks in both the HPT and PIT for the required interface
 -- If not found, it loads it, and puts it in the PIT (always).
@@ -663,7 +663,7 @@ is_external_sig home_unit iface =
 -- we are actually typechecking p.)
 computeInterface ::
        SDoc -> IsBootInterface -> Module
-    -> TcRnIf gbl lcl (MaybeErr MsgDoc (ModIface, FilePath))
+    -> TcRnIf gbl lcl (MaybeErr SDoc (ModIface, FilePath))
 computeInterface doc_str hi_boot_file mod0 = do
     MASSERT( not (isHoleModule mod0) )
     hsc_env <- getTopEnv
@@ -695,7 +695,7 @@ computeInterface doc_str hi_boot_file mod0 = do
 -- @p[A=\<A>,B=\<B>]:B@ never includes B.
 moduleFreeHolesPrecise
     :: SDoc -> Module
-    -> TcRnIf gbl lcl (MaybeErr MsgDoc (UniqDSet ModuleName))
+    -> TcRnIf gbl lcl (MaybeErr SDoc (UniqDSet ModuleName))
 moduleFreeHolesPrecise doc_str mod
  | moduleIsDefinite mod = return (Succeeded emptyUniqDSet)
  | otherwise =
@@ -728,7 +728,7 @@ moduleFreeHolesPrecise doc_str mod
             Failed err -> return (Failed err)
 
 wantHiBootFile :: HomeUnit -> ExternalPackageState -> Module -> WhereFrom
-               -> MaybeErr MsgDoc IsBootInterface
+               -> MaybeErr SDoc IsBootInterface
 -- Figure out whether we want Foo.hi or Foo.hi-boot
 wantHiBootFile home_unit eps mod from
   = case from of
@@ -816,7 +816,7 @@ findAndReadIface :: SDoc
                  -> Module
                  -> IsBootInterface     -- True  <=> Look for a .hi-boot file
                                         -- False <=> Look for .hi file
-                 -> TcRnIf gbl lcl (MaybeErr MsgDoc (ModIface, FilePath))
+                 -> TcRnIf gbl lcl (MaybeErr SDoc (ModIface, FilePath))
         -- Nothing <=> file not found, or unreadable, or illegible
         -- Just x  <=> successfully found and parsed
 
@@ -926,7 +926,7 @@ writeIface dflags hi_file_path new_iface
 
 -- @readIface@ tries just the one file.
 readIface :: Module -> FilePath
-          -> TcRnIf gbl lcl (MaybeErr MsgDoc ModIface)
+          -> TcRnIf gbl lcl (MaybeErr SDoc ModIface)
         -- Failed err    <=> file not found, or unreadable, or illegible
         -- Succeeded iface <=> successfully found and parsed
 
@@ -1229,7 +1229,7 @@ badIfaceFile file err
   = vcat [text "Bad interface file:" <+> text file,
           nest 4 err]
 
-hiModuleNameMismatchWarn :: Module -> Module -> MsgDoc
+hiModuleNameMismatchWarn :: Module -> Module -> SDoc
 hiModuleNameMismatchWarn requested_mod read_mod
  | moduleUnit requested_mod == moduleUnit read_mod =
     sep [text "Interface file contains module" <+> quotes (ppr read_mod) <> comma,