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is superceded by the IfaceMessage, which is now structured compared to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, 12 insertions, 9 deletions

diff --git a/compiler/GHC/IfaceToCore.hs b/compiler/GHC/IfaceToCore.hs
index aaacb86b7f..2a81b9c2a0 100644
--- a/compiler/GHC/IfaceToCore.hs
+++ b/compiler/GHC/IfaceToCore.hs
@@ -132,6 +132,7 @@ import GHC.Unit.Module.WholeCoreBindings
 import Data.IORef
 import Data.Foldable
 import GHC.Builtin.Names (ioTyConName, rOOT_MAIN)
+import GHC.Iface.Errors.Types
 
 {-
 This module takes
@@ -576,13 +577,14 @@ tcHiBootIface hsc_src mod
         -- to check consistency against, rather than just when we notice
         -- that an hi-boot is necessary due to a circular import.
         { hsc_env <- getTopEnv
-        ; read_result <- liftIO $ findAndReadIface hsc_env
-                                need (fst (getModuleInstantiation mod)) mod
-                                IsBoot  -- Hi-boot file
+        ; read_result <- liftIO $ findAndReadIface hsc_env need
+                                  (fst (getModuleInstantiation mod)) mod
+                                  IsBoot  -- Hi-boot file
 
         ; case read_result of {
-            Succeeded (iface, _path) -> do { tc_iface <- initIfaceTcRn $ typecheckIface iface
-                                           ; mkSelfBootInfo iface tc_iface } ;
+            Succeeded (iface, _path) ->
+              do { tc_iface <- initIfaceTcRn $ typecheckIface iface
+                 ; mkSelfBootInfo iface tc_iface } ;
             Failed err               ->
 
         -- There was no hi-boot file. But if there is circularity in
@@ -598,7 +600,10 @@ tcHiBootIface hsc_src mod
             Nothing -> return NoSelfBoot
             -- error cases
             Just (GWIB { gwib_isBoot = is_boot }) -> case is_boot of
-              IsBoot -> failWithTc (mkTcRnUnknownMessage $ mkPlainError noHints (elaborate err))
+              IsBoot ->
+                let diag = Can'tFindInterface err
+                             (LookingForHiBoot mod)
+                in failWithTc (TcRnInterfaceError diag)
               -- The hi-boot file has mysteriously disappeared.
               NotBoot -> failWithTc (mkTcRnUnknownMessage $ mkPlainError noHints moduleLoop)
               -- Someone below us imported us!
@@ -611,8 +616,6 @@ tcHiBootIface hsc_src mod
     moduleLoop = text "Circular imports: module" <+> quotes (ppr mod)
                      <+> text "depends on itself"
 
-    elaborate err = hang (text "Could not find hi-boot interface for" <+>
-                          quotes (ppr mod) <> colon) 4 err
 
 
 mkSelfBootInfo :: ModIface -> ModDetails -> TcRn SelfBootInfo
@@ -1968,7 +1971,7 @@ tcIfaceGlobal name
 
         { mb_thing <- importDecl name   -- It's imported; go get it
         ; case mb_thing of
-            Failed err      -> failIfM (ppr name <+> err)
+            Failed err      -> failIfM (ppr name <+> pprDiagnostic err)
             Succeeded thing -> return thing
         }}}