Remove some dead code

From the notes.ghc.drop list found using weeder in #17713

9 files changed, 5 insertions, 100 deletions

diff --git a/compiler/GHC/Cmm/Dataflow/Block.hs b/compiler/GHC/Cmm/Dataflow/Block.hs
index d2e52a8904..ac567ca605 100644
--- a/compiler/GHC/Cmm/Dataflow/Block.hs
+++ b/compiler/GHC/Cmm/Dataflow/Block.hs
@@ -66,13 +66,7 @@ data MaybeO ex t where
   JustO    :: t -> MaybeO O t
   NothingO ::      MaybeO C t
 
--- | Maybe type indexed by closed/open
-data MaybeC ex t where
-  JustC    :: t -> MaybeC C t
-  NothingC ::      MaybeC O t
-
 deriving instance Functor (MaybeO ex)
-deriving instance Functor (MaybeC ex)
 
 -- -----------------------------------------------------------------------------
 -- The Block type
diff --git a/compiler/GHC/Cmm/Parser.y b/compiler/GHC/Cmm/Parser.y
index d303e435d0..95edf0693a 100644
--- a/compiler/GHC/Cmm/Parser.y
+++ b/compiler/GHC/Cmm/Parser.y
@@ -873,17 +873,6 @@ section s           = OtherSection s
 mkString :: String -> CmmStatic
 mkString s = CmmString (BS8.pack s)
 
--- |
--- Given an info table, decide what the entry convention for the proc
--- is.  That is, for an INFO_TABLE_RET we want the return convention,
--- otherwise it is a NativeNodeCall.
---
-infoConv :: Maybe CmmInfoTable -> Convention
-infoConv Nothing = NativeNodeCall
-infoConv (Just info)
-  | isStackRep (cit_rep info) = NativeReturn
-  | otherwise                 = NativeNodeCall
-
 -- mkMachOp infers the type of the MachOp from the type of its first
 -- argument.  We assume that this is correct: for MachOps that don't have
 -- symmetrical args (e.g. shift ops), the first arg determines the type of
diff --git a/compiler/GHC/Core/Utils.hs b/compiler/GHC/Core/Utils.hs
index 82d920a58e..0a9d923a32 100644
--- a/compiler/GHC/Core/Utils.hs
+++ b/compiler/GHC/Core/Utils.hs
@@ -27,7 +27,7 @@ module GHC.Core.Utils (
         getIdFromTrivialExpr_maybe,
         exprIsCheap, exprIsExpandable, exprIsCheapX, CheapAppFun,
         exprIsHNF, exprOkForSpeculation, exprOkForSideEffects, exprIsWorkFree,
-        exprIsBig, exprIsConLike,
+        exprIsConLike,
         isCheapApp, isExpandableApp,
         exprIsTickedString, exprIsTickedString_maybe,
         exprIsTopLevelBindable,
@@ -2075,8 +2075,6 @@ c.f. add_evals in Simplify.simplAlt
 -- | A cheap equality test which bales out fast!
 --      If it returns @True@ the arguments are definitely equal,
 --      otherwise, they may or may not be equal.
---
--- See also 'exprIsBig'
 cheapEqExpr :: Expr b -> Expr b -> Bool
 cheapEqExpr = cheapEqExpr' (const False)
 
@@ -2100,17 +2098,6 @@ cheapEqExpr' ignoreTick e1 e2
     go _ _ = False
 
 
-exprIsBig :: Expr b -> Bool
--- ^ Returns @True@ of expressions that are too big to be compared by 'cheapEqExpr'
-exprIsBig (Lit _)      = False
-exprIsBig (Var _)      = False
-exprIsBig (Type _)     = False
-exprIsBig (Coercion _) = False
-exprIsBig (Lam _ e)    = exprIsBig e
-exprIsBig (App f a)    = exprIsBig f || exprIsBig a
-exprIsBig (Cast e _)   = exprIsBig e    -- Hopefully coercions are not too big!
-exprIsBig (Tick _ e)   = exprIsBig e
-exprIsBig _            = True
 
 eqExpr :: InScopeSet -> CoreExpr -> CoreExpr -> Bool
 -- Compares for equality, modulo alpha
diff --git a/compiler/GHC/HsToCore/Utils.hs b/compiler/GHC/HsToCore/Utils.hs
index d11e59a0c8..ce1096995a 100644
--- a/compiler/GHC/HsToCore/Utils.hs
+++ b/compiler/GHC/HsToCore/Utils.hs
@@ -38,7 +38,7 @@ module GHC.HsToCore.Utils (
         mkSelectorBinds,
 
         selectSimpleMatchVarL, selectMatchVars, selectMatchVar,
-        mkOptTickBox, mkBinaryTickBox, decideBangHood, addBang,
+        mkOptTickBox, mkBinaryTickBox, decideBangHood,
         isTrueLHsExpr
     ) where
 
@@ -957,19 +957,6 @@ decideBangHood dflags lpat
            BangPat _ _   -> lp
            _             -> L l (BangPat noExtField lp)
 
--- | Unconditionally make a 'Pat' strict.
-addBang :: LPat GhcTc -- ^ Original pattern
-        -> LPat GhcTc -- ^ Banged pattern
-addBang = go
-  where
-    go lp@(L l p)
-      = case p of
-           ParPat x p    -> L l (ParPat x (go p))
-           LazyPat _ lp' -> L l (BangPat noExtField lp')
-                                  -- Should we bring the extension value over?
-           BangPat _ _   -> lp
-           _             -> L l (BangPat noExtField lp)
-
 isTrueLHsExpr :: LHsExpr GhcTc -> Maybe (CoreExpr -> DsM CoreExpr)
 
 -- Returns Just {..} if we're sure that the expression is True
diff --git a/compiler/main/Annotations.hs b/compiler/main/Annotations.hs
index c282217d33..3c4340e900 100644
--- a/compiler/main/Annotations.hs
+++ b/compiler/main/Annotations.hs
@@ -9,7 +9,6 @@ module Annotations (
         -- * Main Annotation data types
         Annotation(..), AnnPayload,
         AnnTarget(..), CoreAnnTarget,
-        getAnnTargetName_maybe,
 
         -- * AnnEnv for collecting and querying Annotations
         AnnEnv,
@@ -57,11 +56,6 @@ data AnnTarget name
 -- | The kind of annotation target found in the middle end of the compiler
 type CoreAnnTarget = AnnTarget Name
 
--- | Get the 'name' of an annotation target if it exists.
-getAnnTargetName_maybe :: AnnTarget name -> Maybe name
-getAnnTargetName_maybe (NamedTarget nm) = Just nm
-getAnnTargetName_maybe _                = Nothing
-
 instance Outputable name => Outputable (AnnTarget name) where
     ppr (NamedTarget nm) = text "Named target" <+> ppr nm
     ppr (ModuleTarget mod) = text "Module target" <+> ppr mod
diff --git a/compiler/simplCore/CoreMonad.hs b/compiler/simplCore/CoreMonad.hs
index 2dcafcdbcb..cb17f33b88 100644
--- a/compiler/simplCore/CoreMonad.hs
+++ b/compiler/simplCore/CoreMonad.hs
@@ -29,7 +29,7 @@ module CoreMonad (
 
     -- ** Reading from the monad
     getHscEnv, getRuleBase, getModule,
-    getDynFlags, getOrigNameCache, getPackageFamInstEnv,
+    getDynFlags, getPackageFamInstEnv,
     getVisibleOrphanMods, getUniqMask,
     getPrintUnqualified, getSrcSpanM,
 
@@ -66,7 +66,6 @@ import FastString
 import ErrUtils( Severity(..), DumpFormat (..), dumpOptionsFromFlag )
 import UniqSupply
 import MonadUtils
-import NameCache
 import NameEnv
 import SrcLoc
 import Data.Bifunctor ( bimap )
@@ -74,7 +73,6 @@ import ErrUtils (dumpAction)
 import Data.List (intersperse, groupBy, sortBy)
 import Data.Ord
 import Data.Dynamic
-import Data.IORef
 import Data.Map (Map)
 import qualified Data.Map as Map
 import qualified Data.Map.Strict as MapStrict
@@ -709,13 +707,6 @@ instance HasDynFlags CoreM where
 instance HasModule CoreM where
     getModule = read cr_module
 
--- | The original name cache is the current mapping from 'Module' and
--- 'OccName' to a compiler-wide unique 'Name'
-getOrigNameCache :: CoreM OrigNameCache
-getOrigNameCache = do
-    nameCacheRef <- fmap hsc_NC getHscEnv
-    liftIO $ fmap nsNames $ readIORef nameCacheRef
-
 getPackageFamInstEnv :: CoreM PackageFamInstEnv
 getPackageFamInstEnv = do
     hsc_env <- getHscEnv
diff --git a/compiler/typecheck/Constraint.hs b/compiler/typecheck/Constraint.hs
index 40fc8fdedb..c0eefe72b2 100644
--- a/compiler/typecheck/Constraint.hs
+++ b/compiler/typecheck/Constraint.hs
@@ -55,7 +55,7 @@ module Constraint (
         isWanted, isGiven, isDerived, isGivenOrWDeriv,
         ctEvRole,
 
-        wrapType, wrapTypeWithImplication,
+        wrapType,
 
         CtFlavour(..), ShadowInfo(..), ctEvFlavour,
         CtFlavourRole, ctEvFlavourRole, ctFlavourRole,
@@ -86,7 +86,6 @@ import Coercion
 import Class
 import TyCon
 import Var
-import Id
 
 import TcType
 import TcEvidence
@@ -1292,17 +1291,6 @@ pprEvVarWithType v = ppr v <+> dcolon <+> pprType (evVarPred v)
 
 
 
--- | Wraps the given type with the constraints (via ic_given) in the given
--- implication, according to the variables mentioned (via ic_skols)
--- in the implication, but taking care to only wrap those variables
--- that are mentioned in the type or the implication.
-wrapTypeWithImplication :: Type -> Implication -> Type
-wrapTypeWithImplication ty impl = wrapType ty mentioned_skols givens
-    where givens = map idType $ ic_given impl
-          skols = ic_skols impl
-          freeVars = fvVarSet $ tyCoFVsOfTypes (ty:givens)
-          mentioned_skols = filter (`elemVarSet` freeVars) skols
-
 wrapType :: Type -> [TyVar] -> [PredType] -> Type
 wrapType ty skols givens = mkSpecForAllTys skols $ mkPhiTy givens ty
 
diff --git a/compiler/types/CoAxiom.hs b/compiler/types/CoAxiom.hs
index 066daefaed..49fc5e07a5 100644
--- a/compiler/types/CoAxiom.hs
+++ b/compiler/types/CoAxiom.hs
@@ -26,7 +26,7 @@ module CoAxiom (
        Role(..), fsFromRole,
 
        CoAxiomRule(..), TypeEqn,
-       BuiltInSynFamily(..), trivialBuiltInFamily
+       BuiltInSynFamily(..)
        ) where
 
 import GhcPrelude
@@ -563,11 +563,3 @@ data BuiltInSynFamily = BuiltInSynFamily
   , sfInteractInert :: [Type] -> Type ->
                        [Type] -> Type -> [TypeEqn]
   }
-
--- Provides default implementations that do nothing.
-trivialBuiltInFamily :: BuiltInSynFamily
-trivialBuiltInFamily = BuiltInSynFamily
-  { sfMatchFam      = \_ -> Nothing
-  , sfInteractTop   = \_ _ -> []
-  , sfInteractInert = \_ _ _ _ -> []
-  }
diff --git a/compiler/utils/Binary.hs b/compiler/utils/Binary.hs
index 1c52cb56fb..16d7ccf37d 100644
--- a/compiler/utils/Binary.hs
+++ b/compiler/utils/Binary.hs
@@ -31,10 +31,8 @@ module Binary
 --   closeBin,
 
    seekBin,
-   seekBy,
    tellBin,
    castBin,
-   isEOFBin,
    withBinBuffer,
 
    writeBinMem,
@@ -184,21 +182,6 @@ seekBin h@(BinMem _ ix_r sz_r _) (BinPtr !p) = do
         then do expandBin h p; writeFastMutInt ix_r p
         else writeFastMutInt ix_r p
 
-seekBy :: BinHandle -> Int -> IO ()
-seekBy h@(BinMem _ ix_r sz_r _) !off = do
-  sz <- readFastMutInt sz_r
-  ix <- readFastMutInt ix_r
-  let ix' = ix + off
-  if (ix' >= sz)
-        then do expandBin h ix'; writeFastMutInt ix_r ix'
-        else writeFastMutInt ix_r ix'
-
-isEOFBin :: BinHandle -> IO Bool
-isEOFBin (BinMem _ ix_r sz_r _) = do
-  ix <- readFastMutInt ix_r
-  sz <- readFastMutInt sz_r
-  return (ix >= sz)
-
 writeBinMem :: BinHandle -> FilePath -> IO ()
 writeBinMem (BinMem _ ix_r _ arr_r) fn = do
   h <- openBinaryFile fn WriteMode