Try to simplify zoo of functions in `Tc.Utils.Monad`

This commit tries to untangle the zoo of diagnostic-related functions
in `Tc.Utils.Monad` so that we can have the interfaces mentions only
`TcRnMessage`s while we push the creation of these messages upstream.

It also ports TcRnMessage diagnostics to use the new API, in particular
this commit switch to use TcRnMessage in the external interfaces
of the diagnostic functions, and port the old SDoc to be wrapped
into TcRnUnknownMessage.

1 files changed, 8 insertions, 5 deletions

diff --git a/compiler/GHC/Tc/Utils/Backpack.hs b/compiler/GHC/Tc/Utils/Backpack.hs
index a3b0068b3e..d433a46aed 100644
--- a/compiler/GHC/Tc/Utils/Backpack.hs
+++ b/compiler/GHC/Tc/Utils/Backpack.hs
@@ -47,6 +47,7 @@ import GHC.Unit.Module.ModDetails
 import GHC.Unit.Module.Imported
 import GHC.Unit.Module.Deps
 
+import GHC.Tc.Errors.Types
 import GHC.Tc.Gen.Export
 import GHC.Tc.Solver
 import GHC.Tc.TyCl.Utils
@@ -89,8 +90,9 @@ import Data.List (find)
 
 import {-# SOURCE #-} GHC.Tc.Module
 
-fixityMisMatch :: TyThing -> Fixity -> Fixity -> SDoc
+fixityMisMatch :: TyThing -> Fixity -> Fixity -> TcRnMessage
 fixityMisMatch real_thing real_fixity sig_fixity =
+  TcRnUnknownMessage $ mkPlainError noHints $
     vcat [ppr real_thing <+> text "has conflicting fixities in the module",
           text "and its hsig file",
           text "Main module:" <+> ppr_fix real_fixity,
@@ -167,7 +169,7 @@ checkHsigIface tcg_env gr sig_iface
         -- tcg_env (TODO: but maybe this isn't relevant anymore).
         r <- tcLookupImported_maybe name
         case r of
-          Failed err -> addErr err
+          Failed err -> addErr (TcRnUnknownMessage $ mkPlainError noHints err)
           Succeeded real_thing -> checkHsigDeclM sig_iface sig_thing real_thing
 
       -- The hsig did NOT define this function; that means it must
@@ -711,7 +713,7 @@ mergeSignatures
             -- 3(d). Extend the name substitution (performing shaping)
             mb_r <- extend_ns nsubst as2
             case mb_r of
-                Left err -> failWithTc err
+                Left err -> failWithTc (TcRnUnknownMessage $ mkPlainError noHints err)
                 Right nsubst' -> return (nsubst',oks',(imod, thinned_iface):ifaces)
         nsubst0 = mkNameShape (moduleName inner_mod) (mi_exports lcl_iface0)
         ok_to_use0 = mkOccSet (exportOccs (mi_exports lcl_iface0))
@@ -1021,7 +1023,7 @@ checkImplements impl_mod req_mod@(Module uid mod_name) = do
                                                isig_mod sig_mod NotBoot
     isig_iface <- case mb_isig_iface of
         Succeeded (iface, _) -> return iface
-        Failed err -> failWithTc $
+        Failed err -> failWithTc $ TcRnUnknownMessage $ mkPlainError noHints $
             hang (text "Could not find hi interface for signature" <+>
                   quotes (ppr isig_mod) <> colon) 4 err
 
@@ -1029,7 +1031,8 @@ checkImplements impl_mod req_mod@(Module uid mod_name) = do
     -- we need.  (Notice we IGNORE the Modules in the AvailInfos.)
     forM_ (exportOccs (mi_exports isig_iface)) $ \occ ->
         case lookupGlobalRdrEnv impl_gr occ of
-            [] -> addErr $ quotes (ppr occ)
+            [] -> addErr $ TcRnUnknownMessage $ mkPlainError noHints $
+                        quotes (ppr occ)
                     <+> text "is exported by the hsig file, but not exported by the implementing module"
                     <+> quotes (pprWithUnitState unit_state $ ppr impl_mod)
             _ -> return ()