Error on anon wildcards in tcAnonWildCardOcc

  The code in tcAnonWildCardOcc assumed that it could never encounter
  anonymous wildcards in illegal positions, because the renamer would
  have ruled them out. However, it's possible to sneak past the checks
  in the renamer by using Template Haskell. It isn't possible to simply
  pass on additional information when renaming Template Haskell
  brackets, because we don't know in advance in what context the bracket
  will be spliced in (see test case T15433b). So we accept that we might
  encounter these bogus wildcards in the typechecker and throw the
  appropriate error.

  This patch also migrates the error messages for illegal wildcards in
  types to use the diagnostic infrastructure.

  Fixes #15433

1 files changed, 1 insertions, 71 deletions

diff --git a/compiler/GHC/Rename/Utils.hs b/compiler/GHC/Rename/Utils.hs
index 1647c19e32..597af3d778 100644
--- a/compiler/GHC/Rename/Utils.hs
+++ b/compiler/GHC/Rename/Utils.hs
@@ -21,8 +21,6 @@ module GHC.Rename.Utils (
         badQualBndrErr, typeAppErr, badFieldConErr,
         wrapGenSpan, genHsVar, genLHsVar, genHsApp, genHsApps, genAppType,
         genHsIntegralLit, genHsTyLit,
-        HsDocContext(..), pprHsDocContext,
-        inHsDocContext, withHsDocContext,
 
         newLocalBndrRn, newLocalBndrsRn,
 
@@ -43,6 +41,7 @@ import GHC.Core.Type
 import GHC.Hs
 import GHC.Types.Name.Reader
 import GHC.Tc.Errors.Types
+import GHC.Tc.Errors.Ppr (withHsDocContext)
 import GHC.Tc.Utils.Env
 import GHC.Tc.Utils.Monad
 import GHC.Types.Error
@@ -677,72 +676,3 @@ genHsIntegralLit lit = wrapGenSpan $ HsLit noAnn (HsInt noExtField lit)
 
 genHsTyLit :: FastString -> HsType GhcRn
 genHsTyLit = HsTyLit noExtField . HsStrTy NoSourceText
-
-{-
-************************************************************************
-*                                                                      *
-\subsection{Contexts for renaming errors}
-*                                                                      *
-************************************************************************
--}
-
--- AZ:TODO: Change these all to be Name instead of RdrName.
---          Merge TcType.UserTypeContext in to it.
-data HsDocContext
-  = TypeSigCtx SDoc
-  | StandaloneKindSigCtx SDoc
-  | PatCtx
-  | SpecInstSigCtx
-  | DefaultDeclCtx
-  | ForeignDeclCtx (LocatedN RdrName)
-  | DerivDeclCtx
-  | RuleCtx FastString
-  | TyDataCtx (LocatedN RdrName)
-  | TySynCtx (LocatedN RdrName)
-  | TyFamilyCtx (LocatedN RdrName)
-  | FamPatCtx (LocatedN RdrName)    -- The patterns of a type/data family instance
-  | ConDeclCtx [LocatedN Name]
-  | ClassDeclCtx (LocatedN RdrName)
-  | ExprWithTySigCtx
-  | TypBrCtx
-  | HsTypeCtx
-  | HsTypePatCtx
-  | GHCiCtx
-  | SpliceTypeCtx (LHsType GhcPs)
-  | ClassInstanceCtx
-  | GenericCtx SDoc   -- Maybe we want to use this more!
-
-withHsDocContext :: HsDocContext -> SDoc -> SDoc
-withHsDocContext ctxt doc = doc $$ inHsDocContext ctxt
-
-inHsDocContext :: HsDocContext -> SDoc
-inHsDocContext ctxt = text "In" <+> pprHsDocContext ctxt
-
-pprHsDocContext :: HsDocContext -> SDoc
-pprHsDocContext (GenericCtx doc)      = doc
-pprHsDocContext (TypeSigCtx doc)      = text "the type signature for" <+> doc
-pprHsDocContext (StandaloneKindSigCtx doc) = text "the standalone kind signature for" <+> doc
-pprHsDocContext PatCtx                = text "a pattern type-signature"
-pprHsDocContext SpecInstSigCtx        = text "a SPECIALISE instance pragma"
-pprHsDocContext DefaultDeclCtx        = text "a `default' declaration"
-pprHsDocContext DerivDeclCtx          = text "a deriving declaration"
-pprHsDocContext (RuleCtx name)        = text "the rewrite rule" <+> doubleQuotes (ftext name)
-pprHsDocContext (TyDataCtx tycon)     = text "the data type declaration for" <+> quotes (ppr tycon)
-pprHsDocContext (FamPatCtx tycon)     = text "a type pattern of family instance for" <+> quotes (ppr tycon)
-pprHsDocContext (TySynCtx name)       = text "the declaration for type synonym" <+> quotes (ppr name)
-pprHsDocContext (TyFamilyCtx name)    = text "the declaration for type family" <+> quotes (ppr name)
-pprHsDocContext (ClassDeclCtx name)   = text "the declaration for class" <+> quotes (ppr name)
-pprHsDocContext ExprWithTySigCtx      = text "an expression type signature"
-pprHsDocContext TypBrCtx              = text "a Template-Haskell quoted type"
-pprHsDocContext HsTypeCtx             = text "a type argument"
-pprHsDocContext HsTypePatCtx          = text "a type argument in a pattern"
-pprHsDocContext GHCiCtx               = text "GHCi input"
-pprHsDocContext (SpliceTypeCtx hs_ty) = text "the spliced type" <+> quotes (ppr hs_ty)
-pprHsDocContext ClassInstanceCtx      = text "GHC.Tc.Gen.Splice.reifyInstances"
-
-pprHsDocContext (ForeignDeclCtx name)
-   = text "the foreign declaration for" <+> quotes (ppr name)
-pprHsDocContext (ConDeclCtx [name])
-   = text "the definition of data constructor" <+> quotes (ppr name)
-pprHsDocContext (ConDeclCtx names)
-   = text "the definition of data constructors" <+> interpp'SP names