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is superceded by the IfaceMessage, which is now structured compared to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.

2 files changed, 20 insertions, 17 deletions

diff --git a/compiler/GHC/Tc/Errors/Ppr.hs b/compiler/GHC/Tc/Errors/Ppr.hs
index 0d253cbf6b..5cc8ab5f64 100644
--- a/compiler/GHC/Tc/Errors/Ppr.hs
+++ b/compiler/GHC/Tc/Errors/Ppr.hs
@@ -76,7 +76,7 @@ import GHC.Types.Var.Set
 import GHC.Types.Var.Env
 import GHC.Types.Fixity (defaultFixity)
 
-import GHC.Unit.State (pprWithUnitState, UnitState)
+import GHC.Unit.State
 import GHC.Unit.Module
 import GHC.Unit.Module.Warnings  ( warningTxtCategory, pprWarningTxtForMsg )
 
@@ -101,13 +101,16 @@ import Data.Ord ( comparing )
 import Data.Bifunctor
 import qualified Language.Haskell.TH as TH
 import {-# SOURCE #-} GHC.Tc.Types (pprTcTyThingCategory)
+import GHC.Iface.Errors.Types
+import GHC.Iface.Errors.Ppr
 
 data TcRnMessageOpts = TcRnMessageOpts { tcOptsShowContext :: !Bool -- ^ Whether we show the error context or not
+                                       , tcOptsIfaceOpts   :: !IfaceMessageOpts
                                        }
 
 defaultTcRnMessageOpts :: TcRnMessageOpts
-defaultTcRnMessageOpts = TcRnMessageOpts { tcOptsShowContext = True }
-
+defaultTcRnMessageOpts = TcRnMessageOpts { tcOptsShowContext = True
+                                         , tcOptsIfaceOpts = defaultDiagnosticOpts @IfaceMessage }
 
 instance Diagnostic TcRnMessage where
   type DiagnosticOpts TcRnMessage = TcRnMessageOpts
@@ -1245,7 +1248,6 @@ instance Diagnostic TcRnMessage where
                            True  -> text (show item)
                            False -> text (TH.pprint item))
     TcRnReportCustomQuasiError _ msg -> mkSimpleDecorated $ text msg
-    TcRnInterfaceLookupError _ sdoc -> mkSimpleDecorated sdoc
     TcRnUnsatisfiedMinimalDef mindef
       -> mkSimpleDecorated $
         vcat [text "No explicit implementation for"
@@ -1733,6 +1735,8 @@ instance Diagnostic TcRnMessage where
          ppr (frr_context frr) $$
          text "cannot be assigned a fixed runtime representation," <+>
          text "not even by defaulting."
+    TcRnInterfaceError reason
+      -> diagnosticMessage (tcOptsIfaceOpts opts) reason
 
   diagnosticReason = \case
     TcRnUnknownMessage m
@@ -2105,8 +2109,6 @@ instance Diagnostic TcRnMessage where
       -> ErrorWithoutFlag
     TcRnReportCustomQuasiError isError _
       -> if isError then ErrorWithoutFlag else WarningWithoutFlag
-    TcRnInterfaceLookupError{}
-      -> ErrorWithoutFlag
     TcRnUnsatisfiedMinimalDef{}
       -> WarningWithFlag (Opt_WarnMissingMethods)
     TcRnMisplacedInstSig{}
@@ -2307,6 +2309,9 @@ instance Diagnostic TcRnMessage where
       -> ErrorWithoutFlag
     TcRnCannotDefaultConcrete{}
       -> ErrorWithoutFlag
+    TcRnInterfaceError err
+      -> interfaceErrorReason err
+
 
   diagnosticHints = \case
     TcRnUnknownMessage m
@@ -2685,8 +2690,6 @@ instance Diagnostic TcRnMessage where
       -> noHints
     TcRnReportCustomQuasiError{}
       -> noHints
-    TcRnInterfaceLookupError{}
-      -> noHints
     TcRnUnsatisfiedMinimalDef{}
       -> noHints
     TcRnMisplacedInstSig{}
@@ -2908,6 +2911,8 @@ instance Diagnostic TcRnMessage where
       -> noHints
     TcRnCannotDefaultConcrete{}
       -> [SuggestAddTypeSignatures UnnamedBinding]
+    TcRnInterfaceError reason
+      -> interfaceErrorHints reason
 
   diagnosticCode = constructorCode
 
diff --git a/compiler/GHC/Tc/Errors/Types.hs b/compiler/GHC/Tc/Errors/Types.hs
index a8d7c30846..38615d0f0d 100644
--- a/compiler/GHC/Tc/Errors/Types.hs
+++ b/compiler/GHC/Tc/Errors/Types.hs
@@ -124,6 +124,7 @@ import GHC.Tc.Types.Origin ( CtOrigin (ProvCtxtOrigin), SkolemInfoAnon (SigSkol)
 import GHC.Tc.Types.Rank (Rank)
 import GHC.Tc.Utils.TcType (IllegalForeignTypeReason, TcType, TcSigmaType, TcPredType)
 import GHC.Types.Avail (AvailInfo)
+import GHC.Types.Basic
 import GHC.Types.Error
 import GHC.Types.Hint (UntickedPromotedThing(..))
 import GHC.Types.ForeignCall (CLabelString)
@@ -151,7 +152,6 @@ import GHC.Core.TyCon (TyCon, Role)
 import GHC.Core.Type (Kind, Type, ThetaType, PredType)
 import GHC.Driver.Backend (Backend)
 import GHC.Unit.State (UnitState)
-import GHC.Types.Basic
 import GHC.Utils.Misc (capitalise, filterOut)
 import qualified GHC.LanguageExtensions as LangExt
 import GHC.Data.FastString (FastString)
@@ -166,6 +166,7 @@ import qualified Language.Haskell.TH.Syntax as TH
 
 import GHC.Generics ( Generic )
 import GHC.Types.Name.Env (NameEnv)
+import GHC.Iface.Errors.Types
 
 {-
 Note [Migrating TcM Messages]
@@ -232,6 +233,11 @@ data TcRnMessage where
   -}
   TcRnUnknownMessage :: UnknownDiagnostic -> TcRnMessage
 
+  {-| Wrap an 'IfaceMessage' to a 'TcRnMessage' for when we attempt to load interface
+      files during typechecking but encounter an error. -}
+
+  TcRnInterfaceError :: !IfaceMessage -> TcRnMessage
+
   {-| TcRnMessageWithInfo is a constructor which is used when extra information is needed
       to be provided in order to qualify a diagnostic and where it was originated (and why).
       It carries an extra 'UnitState' which can be used to pretty-print some names
@@ -2723,14 +2729,6 @@ data TcRnMessage where
     -> !String -- Error body
     -> TcRnMessage
 
-  {-| TcRnInterfaceLookupError is an error resulting from looking up a name in an interface file.
-
-      Example(s):
-
-     Test cases:
-  -}
-  TcRnInterfaceLookupError :: !Name -> !SDoc -> TcRnMessage
-
   {- | TcRnUnsatisfiedMinimalDef is a warning that occurs when a class instance
        is missing methods that are required by the minimal definition.