.gitlab-ci.yml

@@ -444,7 +444,7 @@ hadrian-multi:
     # workaround for docker permissions
     - sudo chown ghc:ghc -R .
   variables:
-    GHC_FLAGS: "-Werror=-Wno-error=incomplete-record-selectors -Wwarn=deprecations"
+    GHC_FLAGS: "-Werror=-Wno-error=incomplete-record-selectors -Wwarn=deprecations -Wwarn=unused-imports"
        # -Wno-error=incomplete-record-selectors is present because -Wall now
        # includes -Wincomplete-record-selectors, and hadrian-multi has many, many
        # warnings about incomplete record selectors.  A better fix would be to
@@ -1235,6 +1235,7 @@ ghcup-metadata-release:
   # No explicit needs for release pipeline as we assume we need everything and everything will pass.
   extends: .ghcup-metadata
   script:
+    - nix shell -f .gitlab/rel_eng -c ghcup-metadata --release-mode --metadata ghcup-0.0.7.yaml --date="$(date -d $CI_PIPELINE_CREATED_AT +%Y-%m-%d)" --pipeline-id="$CI_PIPELINE_ID" --version="$ProjectVersion" --fragment
     - nix shell -f .gitlab/rel_eng -c ghcup-metadata --release-mode --metadata ghcup-0.0.7.yaml --date="$(date -d $CI_PIPELINE_CREATED_AT +%Y-%m-%d)" --pipeline-id="$CI_PIPELINE_ID" --version="$ProjectVersion" > "metadata_test.yaml"
   rules:
     - if: '$RELEASE_JOB == "yes"'

.gitlab/rel_eng/fetch-gitlab-artifacts/fetch_gitlab.py

@@ -132,7 +132,7 @@ def fetch_artifacts(release: str, pipeline_id: int,
                 for f in doc_files:
                     subprocess.run(['tar', '-xf', f, '-C', dest])
                     logging.info(f'extracted docs {f} to {dest}')
-                index_path = destdir / 'index.html'
+                index_path = destdir / 'docs' / 'index.html'
                 index_path.replace(dest / 'index.html')
             elif job.name == 'hackage-doc-tarball':
                 dest = dest_dir / 'hackage_docs'

.gitlab/rel_eng/mk-ghcup-metadata/mk_ghcup_metadata.py

@@ -243,7 +243,9 @@ def mk_new_yaml(release_mode, version, date, pipeline_type, job_map):
                               , "unknown_versioning" : centos7  }
           , "Linux_Fedora"  : { ">= 33": fedora33
                               , "unknown_versioning": centos7 }
-          , "Linux_RedHat"  : { "unknown_versioning": centos7 }
+          , "Linux_RedHat"  : { "< 9": centos7
+                              , ">= 9": fedora33
+                              , "unknown_versioning": fedora33 }
           , "Linux_UnknownLinux" : { "unknown_versioning": rocky8 }
           , "Darwin" : { "unknown_versioning" : darwin_x86 }
           , "Windows" : { "unknown_versioning" :  windows }

.gitmodules

@@ -104,7 +104,7 @@
 	url = https://gitlab.haskell.org/ghc/libffi-tarballs.git
 	ignore = untracked
 [submodule "gmp-tarballs"]
-	path = libraries/ghc-bignum/gmp/gmp-tarballs
+	path = libraries/ghc-internal/gmp/gmp-tarballs
 	url = https://gitlab.haskell.org/ghc/gmp-tarballs.git
 [submodule "libraries/exceptions"]
 	path = libraries/exceptions

compiler/GHC/Builtin/Names.hs

@@ -574,9 +574,9 @@ gHC_INTERNAL_CONTROL_MONAD_ZIP :: Module
 gHC_INTERNAL_CONTROL_MONAD_ZIP  = mkGhcInternalModule (fsLit "GHC.Internal.Control.Monad.Zip")
 
 gHC_INTERNAL_NUM_INTEGER, gHC_INTERNAL_NUM_NATURAL, gHC_INTERNAL_NUM_BIGNAT :: Module
-gHC_INTERNAL_NUM_INTEGER            = mkBignumModule (fsLit "GHC.Num.Integer")
-gHC_INTERNAL_NUM_NATURAL            = mkBignumModule (fsLit "GHC.Num.Natural")
-gHC_INTERNAL_NUM_BIGNAT             = mkBignumModule (fsLit "GHC.Num.BigNat")
+gHC_INTERNAL_NUM_INTEGER            = mkGhcInternalModule (fsLit "GHC.Internal.Bignum.Integer")
+gHC_INTERNAL_NUM_NATURAL            = mkGhcInternalModule (fsLit "GHC.Internal.Bignum.Natural")
+gHC_INTERNAL_NUM_BIGNAT             = mkGhcInternalModule (fsLit "GHC.Internal.Bignum.BigNat")
 
 gHC_INTERNAL_BASE, gHC_INTERNAL_ENUM,
     gHC_INTERNAL_GHCI, gHC_INTERNAL_GHCI_HELPERS, gHC_CSTRING, gHC_INTERNAL_DATA_STRING,
@@ -686,9 +686,6 @@ mAIN_NAME      = mkModuleNameFS (fsLit "Main")
 mkPrimModule :: FastString -> Module
 mkPrimModule m = mkModule primUnit (mkModuleNameFS m)
 
-mkBignumModule :: FastString -> Module
-mkBignumModule m = mkModule bignumUnit (mkModuleNameFS m)
-
 mkGhcInternalModule :: FastString -> Module
 mkGhcInternalModule m = mkGhcInternalModule_ (mkModuleNameFS m)
 

compiler/GHC/Core.hs

@@ -14,9 +14,10 @@ module GHC.Core (
 
         -- * In/Out type synonyms
         InId, InBind, InExpr, InAlt, InArg, InType, InKind,
-               InBndr, InVar, InCoercion, InTyVar, InCoVar,
+               InBndr, InVar, InCoercion, InTyVar, InCoVar, InTyCoVar,
         OutId, OutBind, OutExpr, OutAlt, OutArg, OutType, OutKind,
-               OutBndr, OutVar, OutCoercion, OutTyVar, OutCoVar, MOutCoercion,
+               OutBndr, OutVar, OutCoercion, OutTyVar, OutCoVar,
+               OutTyCoVar, MOutCoercion,
 
         -- ** 'Expr' construction
         mkLet, mkLets, mkLetNonRec, mkLetRec, mkLams,

compiler/GHC/Core/Coercion.hs

@@ -2283,7 +2283,7 @@ liftCoSubstTyVarBndrUsing view_co fun lc@(LC subst cenv) old_var
     stuff    = fun lc old_kind
     eta      = view_co stuff
     k1       = coercionLKind eta
-    new_var  = uniqAway (getSubstInScope subst) (setVarType old_var k1)
+    new_var  = uniqAway (substInScopeSet subst) (setVarType old_var k1)
 
     lifted   = mkGReflRightCo Nominal (TyVarTy new_var) eta
                -- :: new_var ~ new_var |> eta
@@ -2303,7 +2303,7 @@ liftCoSubstCoVarBndrUsing view_co fun lc@(LC subst cenv) old_var
     stuff    = fun lc old_kind
     eta      = view_co stuff
     k1       = coercionLKind eta
-    new_var  = uniqAway (getSubstInScope subst) (setVarType old_var k1)
+    new_var  = uniqAway (substInScopeSet subst) (setVarType old_var k1)
 
     -- old_var :: s1  ~r s2
     -- eta     :: (s1' ~r s2') ~N (t1 ~r t2)
@@ -2387,7 +2387,7 @@ lcLookupCoVar (LC subst _) cv = lookupCoVar subst cv
 
 -- | Get the 'InScopeSet' from a 'LiftingContext'
 lcInScopeSet :: LiftingContext -> InScopeSet
-lcInScopeSet (LC subst _) = getSubstInScope subst
+lcInScopeSet (LC subst _) = substInScopeSet subst
 
 {-
 %************************************************************************

compiler/GHC/Core/Opt/Arity.hs

@@ -2304,7 +2304,7 @@ mkEtaWW orig_oss ppr_orig_expr in_scope orig_ty
 
     go _ [] subst _
        ----------- Done!  No more expansion needed
-       = (getSubstInScope subst, EI [] MRefl)
+       = (substInScopeSet subst, EI [] MRefl)
 
     go n oss@(one_shot:oss1) subst ty
        ----------- Forall types  (forall a. ty)
@@ -2351,7 +2351,7 @@ mkEtaWW orig_oss ppr_orig_expr in_scope orig_ty
                          -- but its type isn't a function, or a binder
                          -- does not have a fixed runtime representation
        = warnPprTrace True "mkEtaWW" ((ppr orig_oss <+> ppr orig_ty) $$ ppr_orig_expr)
-         (getSubstInScope subst, EI [] MRefl)
+         (substInScopeSet subst, EI [] MRefl)
         -- This *can* legitimately happen:
         -- e.g.  coerce Int (\x. x) Essentially the programmer is
         -- playing fast and loose with types (Happy does this a lot).
@@ -3246,7 +3246,7 @@ freshEtaId n subst ty
       = (subst', eta_id')
       where
         Scaled mult' ty' = Type.substScaledTyUnchecked subst ty
-        eta_id' = uniqAway (getSubstInScope subst) $
+        eta_id' = uniqAway (substInScopeSet subst) $
                   mkSysLocalOrCoVar (fsLit "eta") (mkBuiltinUnique n) mult' ty'
                   -- "OrCoVar" since this can be used to eta-expand
                   -- coercion abstractions

compiler/GHC/Core/Opt/Simplify/Utils.hs

@@ -872,7 +872,7 @@ wrappers created by CPR, exactly case (4) above.  Without this limitation I
 got too much fruitless inlining, which led to regressions (#22317 is an example).
 
 A good example of a function where this 'small incentive' is important is
-GHC.Num.Integer where we ended up with calls like this:
+GHC.Internal.Bignum.Integer where we ended up with calls like this:
      case (integerSignum a b) of r -> ...
 but were failing to inline integerSignum, even though it always returns
 a single constructor, so it is very helpful to inline it. There is also an
@@ -1068,7 +1068,7 @@ interstingArg returns
    (a) NonTrivArg for an arg with an OtherCon [] unfolding
    (b) ValueArg for an arg with an OtherCon [c1,c2..] unfolding.
 
-Reason for (a): I found (in the GHC.Num.Integer library) that I was
+Reason for (a): I found (in the GHC.Internal.Bignum.Integer module) that I was
 inlining a pretty big function when all we knew was that its arguments
 were evaluated, nothing more.  That in turn make the enclosing function
 too big to inline elsewhere.

compiler/GHC/Core/Opt/SpecConstr.hs

@@ -2453,7 +2453,7 @@ callsToNewPats env fn spec_info@(SI { si_specs = done_specs }) bndr_occs calls
               good_pats :: [CallPat]
               good_pats = catMaybes mb_pats
 
-              in_scope = getSubstInScope (sc_subst env)
+              in_scope = substInScopeSet (sc_subst env)
 
               -- Remove patterns we have already done
               new_pats = filterOut is_done good_pats
@@ -2571,7 +2571,7 @@ callToPat :: ScEnv -> [ArgOcc] -> Call -> UniqSM (Maybe CallPat)
         --      over the following term variables
         -- The [CoreExpr] are the argument patterns for the rule
 callToPat env bndr_occs call@(Call fn args con_env)
-  = do  { let in_scope = getSubstInScope (sc_subst env)
+  = do  { let in_scope = substInScopeSet (sc_subst env)
 
         ; arg_triples <- zipWith3M (argToPat env in_scope con_env) args bndr_occs (map (const NotMarkedStrict) args)
                    -- This zip trims the args to be no longer than

compiler/GHC/Core/Opt/Specialise.hs

@@ -1824,7 +1824,7 @@ specLookupRule env fn args phase rules
   = lookupRule ropts in_scope_env is_active fn args rules
   where
     dflags       = se_dflags env
-    in_scope     = getSubstInScope (se_subst env)
+    in_scope     = substInScopeSet (se_subst env)
     in_scope_env = ISE in_scope (whenActiveUnfoldingFun is_active)
     ropts        = initRuleOpts dflags
     is_active    = isActive phase
@@ -2573,7 +2573,7 @@ specHeader env (bndr : bndrs) (SpecType ty : args)
   = do { -- Find qvars, the type variables to add to the binders for the rule
          -- Namely those free in `ty` that aren't in scope
          -- See (MP2) in Note [Specialising polymorphic dictionaries]
-         let in_scope = Core.getSubstInScope (se_subst env)
+         let in_scope = Core.substInScopeSet (se_subst env)
              qvars    = scopedSort $
                         filterOut (`elemInScopeSet` in_scope) $
                         tyCoVarsOfTypeList ty
@@ -2635,7 +2635,7 @@ specHeader env (bndr : bndrs) (SpecDict d : args)
               )
        }
    where
-     in_scope = Core.getSubstInScope (se_subst env)
+     in_scope = Core.substInScopeSet (se_subst env)
 
 -- Finally, we don't want to specialise on this argument 'i':
 --   - It's an UnSpecArg, or

compiler/GHC/Core/SimpleOpt.hs

@@ -219,7 +219,7 @@ soeZapSubst env@(SOE { soe_subst = subst })
   = env { soe_inl = emptyVarEnv, soe_subst = zapSubst subst }
 
 soeInScope :: SimpleOptEnv -> InScopeSet
-soeInScope (SOE { soe_subst = subst }) = getSubstInScope subst
+soeInScope (SOE { soe_subst = subst }) = substInScopeSet subst
 
 soeSetInScope :: InScopeSet -> SimpleOptEnv -> SimpleOptEnv
 soeSetInScope in_scope env2@(SOE { soe_subst = subst2 })
@@ -246,7 +246,7 @@ simple_opt_expr env expr
   where
     rec_ids      = soe_rec_ids env
     subst        = soe_subst env
-    in_scope     = getSubstInScope subst
+    in_scope     = substInScopeSet subst
     in_scope_env = ISE in_scope alwaysActiveUnfoldingFun
 
     ---------------
@@ -481,7 +481,7 @@ simple_bind_pair env@(SOE { soe_inl = inl_env, soe_subst = subst })
     stable_unf = isStableUnfolding (idUnfolding in_bndr)
     active     = isAlwaysActive (idInlineActivation in_bndr)
     occ        = idOccInfo in_bndr
-    in_scope   = getSubstInScope subst
+    in_scope   = substInScopeSet subst
 
     out_rhs | JoinPoint join_arity <- idJoinPointHood in_bndr
             = simple_join_rhs join_arity
@@ -1321,7 +1321,7 @@ exprIsConApp_maybe ise@(ISE in_scope id_unf) expr
           scrut'           = subst_expr subst scrut
 
     go (Right sub) floats (Var v) cont
-       = go (Left (getSubstInScope sub))
+       = go (Left (substInScopeSet sub))
             floats
             (lookupIdSubst sub v)
             cont
@@ -1394,7 +1394,7 @@ exprIsConApp_maybe ise@(ISE in_scope id_unf) expr
     -- The Left case is wildly dominant
 
     subst_in_scope (Left in_scope) = in_scope
-    subst_in_scope (Right s) = getSubstInScope s
+    subst_in_scope (Right s) = substInScopeSet s
 
     subst_extend_in_scope (Left in_scope) v = Left (in_scope `extendInScopeSet` v)
     subst_extend_in_scope (Right s) v = Right (s `extendSubstInScope` v)

compiler/GHC/Core/Subst.hs

@@ -24,7 +24,7 @@ module GHC.Core.Subst (
         extendIdSubstWithClone,
         extendSubst, extendSubstList, extendSubstWithVar,
         extendSubstInScope, extendSubstInScopeList, extendSubstInScopeSet,
-        isInScope, setInScope, getSubstInScope,
+        isInScope, setInScope, substInScopeSet,
         extendTvSubst, extendCvSubst,
         delBndr, delBndrs, zapSubst,
 

compiler/GHC/Core/TyCo/Rep.hs

@@ -1218,14 +1218,15 @@ because the kinds of the bound tyvars can be different.
 
 The typing rule is:
 
-  kind_co : k1 ~N k2
-  tv1:k1 |- co : t1 ~r t2
+  G |- kind_co : k1 ~N k2
+  tv1 \not\in fv(typeKind(t1),typeKind(t2))  -- Skolem escape
+  G, tv1:k1 |- co : t1 ~r t2
   if r=N, then vis1=vis2
   ------------------------------------
-  ForAllCo (tv1:k1) vis1 vis2 kind_co co
-     : forall (tv1:k1) <vis1>. t1
+  G |- ForAllCo (tv1:k1) vis1 vis2 kind_co co
+         : forall (tv1:k1) <vis1>. t1
               ~r
-       forall (tv1:k2) <vis2>. (t2[tv1 |-> (tv1:k2) |> sym kind_co])
+           forall (tv1:k2) <vis2>. (t2[tv1 |-> (tv1:k2) |> sym kind_co])
 
 Several things to note here
 

compiler/GHC/Core/TyCo/Subst.hs

@@ -15,7 +15,7 @@ module GHC.Core.TyCo.Subst
         emptySubst, mkEmptySubst, isEmptyTCvSubst, isEmptySubst,
         mkTCvSubst, mkTvSubst, mkCvSubst, mkIdSubst,
         getTvSubstEnv, getIdSubstEnv,
-        getCvSubstEnv, getSubstInScope, setInScope, getSubstRangeTyCoFVs,
+        getCvSubstEnv, substInScopeSet, setInScope, getSubstRangeTyCoFVs,
         isInScope, elemSubst, notElemSubst, zapSubst,
         extendSubstInScope, extendSubstInScopeList, extendSubstInScopeSet,
         extendTCvSubst, extendTCvSubstWithClone,
@@ -104,9 +104,9 @@ import Data.List (mapAccumL)
 data Subst
   = Subst InScopeSet  -- Variables in scope (both Ids and TyVars) /after/
                       -- applying the substitution
-          IdSubstEnv  -- Substitution from NcIds to CoreExprs
-          TvSubstEnv  -- Substitution from TyVars to Types
-          CvSubstEnv  -- Substitution from CoVars to Coercions
+          IdSubstEnv  -- Substitution from InId    to OutExpr
+          TvSubstEnv  -- Substitution from InTyVar to OutType
+          CvSubstEnv  -- Substitution from InCoVar to OutCoercion
 
         -- INVARIANT 1: See Note [The substitution invariant]
         -- This is what lets us deal with name capture properly
@@ -115,7 +115,7 @@ data Subst
         --              see Note [Substitutions apply only once]
         --
         -- INVARIANT 3: See Note [Extending the IdSubstEnv] in "GHC.Core.Subst"
-        -- and Note [Extending the TvSubstEnv and CvSubstEnv]
+        -- and              Note [Extending the TvSubstEnv and CvSubstEnv]
         --
         -- INVARIANT 4: See Note [Substituting types, coercions, and expressions]
 
@@ -183,8 +183,10 @@ A TCvSubst is not idempotent, but, unlike the non-idempotent substitution
 we use during unifications, it must not be repeatedly applied.
 
 Note [Extending the TvSubstEnv and CvSubstEnv]
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-See #tcvsubst_invariant# for the invariants that must hold.
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The TvSubstEnv and CvSubstEnv have a binding for each TyCoVar
+  - whose unique has changed, OR
+  - whose kind has changed
 
 This invariant allows a short-cut when the subst envs are empty:
 if the TvSubstEnv and CvSubstEnv are empty --- i.e. (isEmptyTCvSubst subst)
@@ -207,7 +209,7 @@ This invariant has several crucial consequences:
 * In substTy, substTheta, we can short-circuit when the TvSubstEnv is empty
 
 Note [Substituting types, coercions, and expressions]
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Types and coercions are mutually recursive, and either may have variables
 "belonging" to the other. Thus, every time we wish to substitute in a
 type, we may also need to substitute in a coercion, and vice versa.
@@ -295,8 +297,8 @@ getCvSubstEnv :: Subst -> CvSubstEnv
 getCvSubstEnv (Subst _ _ _ cenv) = cenv
 
 -- | Find the in-scope set: see Note [The substitution invariant]
-getSubstInScope :: Subst -> InScopeSet
-getSubstInScope (Subst in_scope _ _ _) = in_scope
+substInScopeSet :: Subst -> InScopeSet
+substInScopeSet (Subst in_scope _ _ _) = in_scope
 
 setInScope :: Subst -> InScopeSet -> Subst
 setInScope (Subst _ ids tvs cvs) in_scope = Subst in_scope ids tvs cvs

compiler/GHC/Core/Type.hs

@@ -121,7 +121,7 @@ module GHC.Core.Type (
         mkTYPEapp, mkTYPEapp_maybe,
         mkCONSTRAINTapp, mkCONSTRAINTapp_maybe,
         mkBoxedRepApp_maybe, mkTupleRepApp_maybe,
-        typeOrConstraintKind,
+        typeOrConstraintKind, liftedTypeOrConstraintKind,
 
         -- *** Levity and boxity
         sORTKind_maybe, typeTypeOrConstraint,
@@ -201,7 +201,7 @@ module GHC.Core.Type (
         zipTCvSubst,
         notElemSubst,
         getTvSubstEnv,
-        zapSubst, getSubstInScope, setInScope, getSubstRangeTyCoFVs,
+        zapSubst, substInScopeSet, setInScope, getSubstRangeTyCoFVs,
         extendSubstInScope, extendSubstInScopeList, extendSubstInScopeSet,
         extendTCvSubst, extendCvSubst,
         extendTvSubst, extendTvSubstList, extendTvSubstAndInScope,
@@ -2685,9 +2685,7 @@ typeKind :: HasDebugCallStack => Type -> Kind
 -- No need to expand synonyms
 typeKind (TyConApp tc tys)      = piResultTys (tyConKind tc) tys
 typeKind (LitTy l)              = typeLiteralKind l
-typeKind (FunTy { ft_af = af }) = case funTyFlagResultTypeOrConstraint af of
-                                     TypeLike       -> liftedTypeKind
-                                     ConstraintLike -> constraintKind
+typeKind (FunTy { ft_af = af }) = liftedTypeOrConstraintKind (funTyFlagResultTypeOrConstraint af)
 typeKind (TyVarTy tyvar)        = tyVarKind tyvar
 typeKind (CastTy _ty co)        = coercionRKind co
 typeKind (CoercionTy co)        = coercionType co
@@ -2719,9 +2717,9 @@ typeKind ty@(ForAllTy {})
 
     lifted_kind_from_body  -- Implements (FORALL2)
       = case sORTKind_maybe body_kind of
-          Just (ConstraintLike, _) -> constraintKind
-          Just (TypeLike,       _) -> liftedTypeKind
-          Nothing -> pprPanic "typeKind" (ppr body_kind)
+          Just (torc, _) -> liftedTypeOrConstraintKind torc
+          Nothing        -> pprPanic "typeKind" (ppr body_kind)
+
 
 ---------------------------------------------
 
@@ -3450,3 +3448,7 @@ mkTupleRepApp_maybe _ = Nothing
 typeOrConstraintKind :: TypeOrConstraint -> RuntimeRepType -> Kind
 typeOrConstraintKind TypeLike       rep = mkTYPEapp       rep
 typeOrConstraintKind ConstraintLike rep = mkCONSTRAINTapp rep
+
+liftedTypeOrConstraintKind :: TypeOrConstraint -> Kind
+liftedTypeOrConstraintKind TypeLike       = liftedTypeKind
+liftedTypeOrConstraintKind ConstraintLike = constraintKind

compiler/GHC/CoreToStg/Prep.hs

@@ -2741,7 +2741,7 @@ cpeBigNatLit env i = assert (i >= 0) $ do
   let
     platform = cp_platform (cpe_config env)
 
-    -- Per the documentation in GHC.Num.BigNat, a BigNat# is:
+    -- Per the documentation in GHC.Internal.Bignum.BigNat, a BigNat# is:
     --   "Represented as an array of limbs (Word#) stored in
     --   little-endian order (Word# themselves use machine order)."
     --

compiler/GHC/Data/Unboxed.hs

@@ -4,6 +4,13 @@
 {-# LANGUAGE PatternSynonyms #-}
 {-# LANGUAGE UnliftedNewtypes #-}
 
+{-# OPTIONS_GHC -fno-omit-interface-pragmas #-}
+  -- If you use -fomit-interface-pragmas for your build, we won't
+  -- inline the matcher for JustUB, and that turns out to have a
+  -- catastropic effect on Lint, which uses unboxed Maybes.
+  -- Simple fix: switch off -fomit-interface-pragmas for this tiny
+  -- and very stable module.
+
 module GHC.Data.Unboxed (
   MaybeUB(JustUB, NothingUB),
   fmapMaybeUB, fromMaybeUB, apMaybeUB, maybeUB

compiler/GHC/Driver/Config/Core/Rules.hs

@@ -9,7 +9,7 @@ import GHC.Driver.DynFlags ( DynFlags, gopt, targetPlatform, homeUnitId_ )
 
 import GHC.Core.Rules.Config
 
-import GHC.Unit.Types     ( primUnitId, bignumUnitId )
+import GHC.Unit.Types     ( primUnitId )
 
 -- | Initialize RuleOpts from DynFlags
 initRuleOpts :: DynFlags -> RuleOpts
@@ -17,7 +17,6 @@ initRuleOpts dflags = RuleOpts
   { roPlatform                = targetPlatform dflags
   , roNumConstantFolding      = gopt Opt_NumConstantFolding dflags
   , roExcessRationalPrecision = gopt Opt_ExcessPrecision dflags
-    -- disable bignum rules in ghc-prim and ghc-bignum itself
+    -- disable bignum rules in ghc-prim
   , roBignumRules             = homeUnitId_ dflags /= primUnitId
-                                && homeUnitId_ dflags /= bignumUnitId
   }