[Git][ghc/ghc][wip/T22717] Accept an orphan declaration (sadly)

[sheaf (@sheaf)]

sheaf pushed to branch wip/T22717 at Glasgow Haskell Compiler / GHC


Commits:
81f69897 by Simon Peyton Jones at 2023-01-26T15:03:37+01:00
Accept an orphan declaration (sadly)

This accepts the orphan type family instance

  type instance DsForeignHook = ...

in GHC.HsToCore.Types.

See Note [The Decoupling Abstract Data Hack] in GHC.Driver.Hooks

- - - - -


7 changed files:

- compiler/GHC/Driver/Hooks.hs
- compiler/GHC/HsToCore/Types.hs
- compiler/GHC/Tc/Errors/Ppr.hs
- compiler/GHC/Tc/Errors/Types.hs
- compiler/GHC/Tc/Utils/Instantiate.hs
- compiler/GHC/Types/Error/Codes.hs
- compiler/GHC/Types/Hint.hs


Changes:

=====================================
compiler/GHC/Driver/Hooks.hs
=====================================
@@ -121,6 +121,9 @@ In doing so, the Hooks module (which is an hs-boot dependency of DynFlags) can
 be decoupled from its use of the DsM definition in GHC.HsToCore.Types. Since
 both DsM and the definition of @ForeignsHook@ live in the same module, there is
 virtually no difference for plugin authors that want to write a foreign hook.
+
+An awkward consequences is that the `type instance DsForeignsHook`, in
+GHC.HsToCore.Types is an orphan instance.
 -}
 
 -- See Note [The Decoupling Abstract Data Hack]


=====================================
compiler/GHC/HsToCore/Types.hs
=====================================
@@ -1,5 +1,10 @@
 {-# LANGUAGE TypeFamilies, UndecidableInstances #-}
 
+{-# OPTIONS_GHC -Wno-orphans #-}
+  -- Don't warn that `type instance DsForeignsHooks = ...`
+  -- is an orphan; see Note [The Decoupling Abstract Data Hack]
+  -- in GHC.Driver.Hooks
+
 -- | Various types used during desugaring.
 module GHC.HsToCore.Types (
         DsM, DsLclEnv(..), DsGblEnv(..),


=====================================
compiler/GHC/Tc/Errors/Ppr.hs
=====================================
@@ -418,11 +418,11 @@ instance Diagnostic TcRnMessage where
               sep [ text "The Monomorphism Restriction applies to the binding"
                   <> plural bindings
                   , text "for" <+> pp_bndrs ]
-    TcRnOrphanInst (Left cls_inst)
+    TcRnOrphanInstance (Left cls_inst)
       -> mkSimpleDecorated $
            hang (text "Orphan class instance:")
               2 (pprInstanceHdr cls_inst)
-    TcRnOrphanInst (Right fam_inst)
+    TcRnOrphanInstance (Right fam_inst)
       -> mkSimpleDecorated $
            hang (text "Orphan family instance:")
               2 (pprFamInst fam_inst)
@@ -1370,7 +1370,7 @@ instance Diagnostic TcRnMessage where
       -> ErrorWithoutFlag
     TcRnMonomorphicBindings{}
       -> WarningWithFlag Opt_WarnMonomorphism
-    TcRnOrphanInst{}
+    TcRnOrphanInstance{}
       -> WarningWithFlag Opt_WarnOrphans
     TcRnFunDepConflict{}
       -> ErrorWithoutFlag
@@ -1786,7 +1786,7 @@ instance Diagnostic TcRnMessage where
       -> case bindings of
           []     -> noHints
           (x:xs) -> [SuggestAddTypeSignatures $ NamedBindings (x NE.:| xs)]
-    TcRnOrphanInst clsOrFamInst
+    TcRnOrphanInstance clsOrFamInst
       -> [SuggestFixOrphanInst { isFamilyInstance = isFam }]
         where
           isFam = case clsOrFamInst :: Either ClsInst FamInst of


=====================================
compiler/GHC/Tc/Errors/Types.hs
=====================================
@@ -1079,7 +1079,7 @@ data TcRnMessage where
   -}
   TcRnMonomorphicBindings :: [Name] -> TcRnMessage
 
-  {-| TcRnOrphanInst is a warning (controlled by -Worphans) that arises when
+  {-| TcRnOrphanInstance is a warning (controlled by -Worphans) that arises when
       a typeclass instance or family instance is an \"orphan\", i.e. if it
       appears in a module in which neither the class/family nor the type being
       instanced are declared in the same module.
@@ -1089,7 +1089,7 @@ data TcRnMessage where
       Test cases: warnings/should_compile/T9178
                   typecheck/should_compile/T4912
   -}
-  TcRnOrphanInst :: Either ClsInst FamInst -> TcRnMessage
+  TcRnOrphanInstance :: Either ClsInst FamInst -> TcRnMessage
 
   {-| TcRnFunDepConflict is an error that occurs when there are functional dependencies
       conflicts between instance declarations.


=====================================
compiler/GHC/Tc/Utils/Instantiate.hs
=====================================
@@ -854,7 +854,7 @@ newClsInst overlap_mode dfun_name tvs theta clas tys
        ; let cls_inst = mkLocalClsInst dfun oflag tvs' clas tys'
 
        ; when (isOrphan (is_orphan cls_inst)) $
-         addDiagnostic (TcRnOrphanInst $ Left cls_inst)
+         addDiagnostic (TcRnOrphanInstance $ Left cls_inst)
 
        ; return cls_inst }
 
@@ -992,7 +992,7 @@ newFamInst flavor axiom
 
        ; let fam_inst = mkLocalFamInst flavor axiom tvs' cvs' lhs' rhs'
        ; when (isOrphan (fi_orphan fam_inst)) $
-         addDiagnostic (TcRnOrphanInst $ Right fam_inst)
+         addDiagnostic (TcRnOrphanInstance $ Right fam_inst)
 
        ; return fam_inst }
 


=====================================
compiler/GHC/Types/Error/Codes.hs
=====================================
@@ -381,7 +381,7 @@ type family GhcDiagnosticCode c = n | n -> c where
   GhcDiagnosticCode "TcRnBadAssociatedType"                         = 38351
   GhcDiagnosticCode "TcRnForAllRankErr"                             = 91510
   GhcDiagnosticCode "TcRnMonomorphicBindings"                       = 55524
-  GhcDiagnosticCode "TcRnOrphanInst"                                = 90177
+  GhcDiagnosticCode "TcRnOrphanInstance"                                = 90177
   GhcDiagnosticCode "TcRnFunDepConflict"                            = 46208
   GhcDiagnosticCode "TcRnDupInstanceDecls"                          = 59692
   GhcDiagnosticCode "TcRnConflictingFamInstDecls"                   = 34447


=====================================
compiler/GHC/Types/Hint.hs
=====================================
@@ -306,7 +306,7 @@ data GhcHint
     {-| Suggests to move an orphan instance (for a typeclass or a type or data
         family), or to newtype-wrap it.
 
-        Triggered by: 'GHC.Tc.Errors.Types.TcRnOrphanInst'
+        Triggered by: 'GHC.Tc.Errors.Types.TcRnOrphanInstance'
         Test cases(s): warnings/should_compile/T9178
                        typecheck/should_compile/T4912
                        indexed-types/should_compile/T22717_fam_orph



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/81f69897c7ac70d072782c1a4d9890838969f835

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/81f69897c7ac70d072782c1a4d9890838969f835
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