Convert interface file loading errors into proper diagnosticswip/interface-loading-errs

This patch converts all the errors to do with loading interface files
into proper structured diagnostics.

* DriverMessage: Sometimes in the driver we attempt to load an interface
  file so we embed the IfaceMessage into the DriverMessage.
* TcRnMessage: Most the time we are loading interface files during
  typechecking, so we embed the IfaceMessage

This patch also removes the TcRnInterfaceLookupError constructor which
is superceded by the IfaceMessage, which is now structured compared to
just storing an SDoc before.

1 files changed, 14 insertions, 1 deletions

diff --git a/compiler/GHC/Tc/Utils/Monad.hs b/compiler/GHC/Tc/Utils/Monad.hs
index d713fce376..75b74cbb35 100644
--- a/compiler/GHC/Tc/Utils/Monad.hs
+++ b/compiler/GHC/Tc/Utils/Monad.hs
@@ -2,6 +2,7 @@
 {-# LANGUAGE ExplicitForAll    #-}
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE RecordWildCards   #-}
+{-# LANGUAGE TypeApplications  #-}
 
 {-# OPTIONS_GHC -fno-warn-orphans #-}
 
@@ -138,7 +139,7 @@ module GHC.Tc.Utils.Monad(
   forkM,
   setImplicitEnvM,
 
-  withException,
+  withException, withIfaceErr,
 
   -- * Stuff for cost centres.
   getCCIndexM, getCCIndexTcM,
@@ -222,6 +223,8 @@ import qualified Data.Map as Map
 import GHC.Driver.Env.KnotVars
 import GHC.Linker.Types
 import GHC.Types.Unique.DFM
+import GHC.Iface.Errors.Types
+import GHC.Iface.Errors.Ppr
 
 {-
 ************************************************************************
@@ -661,6 +664,16 @@ withException ctx do_this = do
         Failed err -> liftIO $ throwGhcExceptionIO (ProgramError (renderWithContext ctx err))
         Succeeded result -> return result
 
+withIfaceErr :: MonadIO m => SDocContext -> m (MaybeErr MissingInterfaceError a) -> m a
+withIfaceErr ctx do_this = do
+    r <- do_this
+    case r of
+        Failed err -> do
+          let opts = defaultDiagnosticOpts @IfaceMessage
+              msg   = missingInterfaceErrorDiagnostic opts err
+          liftIO $ throwGhcExceptionIO (ProgramError (renderWithContext ctx msg))
+        Succeeded result -> return result
+
 {-
 ************************************************************************
 *                                                                      *