error messages: Don't display ghci specific hints for missing packageswip/t22884

Tickets like #22884 suggest that it is confusing that GHC used on the
command line can suggest options which only work in GHCi.

This ticket uses the error message infrastructure to override certain
error messages which displayed GHCi specific information so that this
information is only showed when using GHCi.

The main annoyance is that we mostly want to display errors in the same
way as before, but with some additional information. This means that the
error rendering code has to be exported from the Iface/Errors/Ppr.hs
module.

I am unsure about whether the approach taken here is the best or most
maintainable solution.

Fixes #22884

1 files changed, 14 insertions, 6 deletions

diff --git a/compiler/GHC/Tc/Errors/Ppr.hs b/compiler/GHC/Tc/Errors/Ppr.hs
index 454d179c4b..460301273f 100644
--- a/compiler/GHC/Tc/Errors/Ppr.hs
+++ b/compiler/GHC/Tc/Errors/Ppr.hs
@@ -21,6 +21,10 @@ module GHC.Tc.Errors.Ppr
   , inHsDocContext
   , TcRnMessageOpts(..)
   , pprTyThingUsedWrong
+
+  -- | Useful when overriding message printing.
+  , messageWithInfoDiagnosticMessage
+  , messageWithHsDocContext
   )
   where
 
@@ -126,12 +130,8 @@ instance Diagnostic TcRnMessage where
                   (tcOptsShowContext opts)
                   (diagnosticMessage opts msg)
     TcRnWithHsDocContext ctxt msg
-      -> if tcOptsShowContext opts
-         then main_msg `unionDecoratedSDoc` ctxt_msg
-         else main_msg
-      where
-        main_msg = diagnosticMessage opts msg
-        ctxt_msg = mkSimpleDecorated (inHsDocContext ctxt)
+      -> messageWithHsDocContext opts ctxt (diagnosticMessage opts msg)
+
     TcRnSolverReport msg _ _
       -> mkSimpleDecorated $ pprSolverReportWithCtxt msg
     TcRnRedundantConstraints redundants (info, show_info)
@@ -3259,6 +3259,14 @@ messageWithInfoDiagnosticMessage unit_state ErrInfo{..} show_ctxt important =
       in (mapDecoratedSDoc (pprWithUnitState unit_state) important) `unionDecoratedSDoc`
          mkDecorated err_info'
 
+messageWithHsDocContext :: TcRnMessageOpts -> HsDocContext -> DecoratedSDoc -> DecoratedSDoc
+messageWithHsDocContext opts ctxt main_msg = do
+      if tcOptsShowContext opts
+         then main_msg `unionDecoratedSDoc` ctxt_msg
+         else main_msg
+      where
+        ctxt_msg = mkSimpleDecorated (inHsDocContext ctxt)
+
 dodgy_msg :: Outputable ie => SDoc -> GlobalRdrElt -> ie -> SDoc
 dodgy_msg kind tc ie
   = vcat [ text "The" <+> kind <+> text "item" <+> quotes (ppr ie) <+> text "suggests that"