Remove HasSrcSpan (#17494)

Metric Decrease:
    haddock.compiler

compiler/GHC/Hs/Expr.hs

@@ -920,7 +920,7 @@ ppr_expr (SectionR _ op expr)
 ppr_expr (ExplicitTuple _ exprs boxity)
     -- Special-case unary boxed tuples so that they are pretty-printed as
     -- `Unit x`, not `(x)`
-  | [dL -> L _ (Present _ expr)] <- exprs
+  | [L _ (Present _ expr)] <- exprs
   , Boxed <- boxity
   = hsep [text (mkTupleStr Boxed 1), ppr expr]
   | otherwise

compiler/GHC/Hs/Pat.hs

@@ -710,7 +710,7 @@ isIrrefutableHsPat
 
     go (ConPatIn {})       = False     -- Conservative
     go (ConPatOut
-        { pat_con  = (dL->L _ (RealDataCon con))
+        { pat_con  = L _ (RealDataCon con)
         , pat_args = details })
                            =
       isJust (tyConSingleDataCon_maybe (dataConTyCon con))
@@ -718,9 +718,8 @@ isIrrefutableHsPat
       -- the latter is false of existentials. See #4439
       && all goL (hsConPatArgs details)
     go (ConPatOut
-        { pat_con = (dL->L _ (PatSynCon _pat)) })
+        { pat_con = L _ (PatSynCon _pat) })
                            = False -- Conservative
-    go (ConPatOut{})       = panic "ConPatOut:Impossible Match" -- due to #15884
     go (LitPat {})         = False
     go (NPat {})           = False
     go (NPlusKPat {})      = False
@@ -790,8 +789,8 @@ conPatNeedsParens p = go
 -- | @'parenthesizePat' p pat@ checks if @'patNeedsParens' p pat@ is true, and
 -- if so, surrounds @pat@ with a 'ParPat'. Otherwise, it simply returns @pat@.
 parenthesizePat :: PprPrec -> LPat (GhcPass p) -> LPat (GhcPass p)
-parenthesizePat p lpat@(dL->L loc pat)
-  | patNeedsParens p pat = cL loc (ParPat noExtField lpat)
+parenthesizePat p lpat@(L loc pat)
+  | patNeedsParens p pat = L loc (ParPat noExtField lpat)
   | otherwise            = lpat
 
 {-

compiler/GHC/Hs/Types.hs

@@ -1063,14 +1063,14 @@ hsAllLTyVarNames (HsQTvs { hsq_ext = kvs
 hsAllLTyVarNames (XLHsQTyVars nec) = noExtCon nec
 
 hsLTyVarLocName :: LHsTyVarBndr (GhcPass p) -> Located (IdP (GhcPass p))
-hsLTyVarLocName = onHasSrcSpan hsTyVarName
+hsLTyVarLocName = mapLoc hsTyVarName
 
 hsLTyVarLocNames :: LHsQTyVars (GhcPass p) -> [Located (IdP (GhcPass p))]
 hsLTyVarLocNames qtvs = map hsLTyVarLocName (hsQTvExplicit qtvs)
 
 -- | Convert a LHsTyVarBndr to an equivalent LHsType.
 hsLTyVarBndrToType :: LHsTyVarBndr (GhcPass p) -> LHsType (GhcPass p)
-hsLTyVarBndrToType = onHasSrcSpan cvt
+hsLTyVarBndrToType = mapLoc cvt
   where cvt (UserTyVar _ n) = HsTyVar noExtField NotPromoted n
         cvt (KindedTyVar _ (L name_loc n) kind)
           = HsKindSig noExtField

compiler/GHC/HsToCore/PmCheck.hs

@@ -282,7 +282,7 @@ checkSingle' locn var p = do
     (Covered   , _          ) -> plain                              -- useful
     (NotCovered, NotDiverged) -> plain { pmresultRedundant = m    } -- redundant
     (NotCovered, Diverged   ) -> plain { pmresultInaccessible = m } -- inaccessible rhs
-  where m = [cL locn [cL locn p]]
+  where m = [L locn [L locn p]]
 
 -- | Exhaustive for guard matches, is used for guards in pattern bindings and
 -- in @MultiIf@ expressions.
@@ -293,7 +293,7 @@ checkGuardMatches hs_ctx guards@(GRHSs _ grhss _) = do
     dflags <- getDynFlags
     let combinedLoc = foldl1 combineSrcSpans (map getLoc grhss)
         dsMatchContext = DsMatchContext hs_ctx combinedLoc
-        match = cL combinedLoc $
+        match = L combinedLoc $
                   Match { m_ext = noExtField
                         , m_ctxt = hs_ctx
                         , m_pats = []
@@ -360,8 +360,8 @@ checkMatches' vars matches = do
         (NotCovered, Diverged )   -> (rs, final_u, m:is, pc1 Semi.<> pc2)
 
     hsLMatchToLPats :: LMatch id body -> Located [LPat id]
-    hsLMatchToLPats (dL->L l (Match { m_pats = pats })) = cL l pats
-    hsLMatchToLPats _                                   = panic "checkMatches'"
+    hsLMatchToLPats (L l (Match { m_pats = pats })) = L l pats
+    hsLMatchToLPats _                               = panic "checkMatches'"
 
 getNFirstUncovered :: [Id] -> Int -> [Delta] -> DsM [Delta]
 getNFirstUncovered _    0 _              = pure []
@@ -465,7 +465,7 @@ translatePat fam_insts x pat = case pat of
 
   -- (x@pat)   ==>   Translate pat with x as match var and handle impedance
   --                 mismatch with incoming match var
-  AsPat _ (dL->L _ y) p -> (mkPmLetVar y x ++) <$> translateLPat fam_insts y p
+  AsPat _ (L _ y) p -> (mkPmLetVar y x ++) <$> translateLPat fam_insts y p
 
   SigPat _ p _ty -> translateLPat fam_insts x p
 
@@ -481,7 +481,7 @@ translatePat fam_insts x pat = case pat of
         pure (PmLet y (wrap_rhs_y (Var x)) : grds)
 
   -- (n + k)  ===>   let b = x >= k, True <- b, let n = x-k
-  NPlusKPat _pat_ty (dL->L _ n) k1 k2 ge minus -> do
+  NPlusKPat _pat_ty (L _ n) k1 k2 ge minus -> do
     b <- mkPmId boolTy
     let grd_b = vanillaConGrd b trueDataCon []
     [ke1, ke2] <- traverse dsOverLit [unLoc k1, k2]
@@ -527,14 +527,14 @@ translatePat fam_insts x pat = case pat of
     --
     -- See #14547, especially comment#9 and comment#10.
 
-  ConPatOut { pat_con     = (dL->L _ con)
+  ConPatOut { pat_con     = L _ con
             , pat_arg_tys = arg_tys
             , pat_tvs     = ex_tvs
             , pat_dicts   = dicts
             , pat_args    = ps } -> do
     translateConPatOut fam_insts x con arg_tys ex_tvs dicts ps
 
-  NPat ty (dL->L _ olit) mb_neg _ -> do
+  NPat ty (L _ olit) mb_neg _ -> do
     -- See Note [Literal short cut] in MatchLit.hs
     -- We inline the Literal short cut for @ty@ here, because @ty@ is more
     -- precise than the field of OverLitTc, which is all that dsOverLit (which
@@ -657,7 +657,7 @@ translateConPatOut fam_insts x con univ_tys ex_tvs dicts = \case
 -- Translate a single match
 translateMatch :: FamInstEnvs -> [Id] -> LMatch GhcTc (LHsExpr GhcTc)
                -> DsM (GrdVec, [GrdVec])
-translateMatch fam_insts vars (dL->L _ (Match { m_pats = pats, m_grhss = grhss }))
+translateMatch fam_insts vars (L _ (Match { m_pats = pats, m_grhss = grhss }))
   = do
       pats'   <- concat <$> zipWithM (translateLPat fam_insts) vars pats
       guards' <- mapM (translateGuards fam_insts) guards
@@ -665,8 +665,8 @@ translateMatch fam_insts vars (dL->L _ (Match { m_pats = pats, m_grhss = grhss }
       return (pats', guards')
       where
         extractGuards :: LGRHS GhcTc (LHsExpr GhcTc) -> [GuardStmt GhcTc]
-        extractGuards (dL->L _ (GRHS _ gs _)) = map unLoc gs
-        extractGuards _                       = panic "translateMatch"
+        extractGuards (L _ (GRHS _ gs _)) = map unLoc gs
+        extractGuards _                   = panic "translateMatch"
 
         guards = map extractGuards (grhssGRHSs grhss)
 translateMatch _ _ _ = panic "translateMatch"
@@ -1247,10 +1247,10 @@ dsPmWarn dflags ctx@(DsMatchContext kind loc) vars pm_result
       when (approx && (exists_u || exists_i)) $
         putSrcSpanDs loc (warnDs NoReason approx_msg)
 
-      when exists_r $ forM_ redundant $ \(dL->L l q) -> do
+      when exists_r $ forM_ redundant $ \(L l q) -> do
         putSrcSpanDs l (warnDs (Reason Opt_WarnOverlappingPatterns)
                                (pprEqn q "is redundant"))
-      when exists_i $ forM_ inaccessible $ \(dL->L l q) -> do
+      when exists_i $ forM_ inaccessible $ \(L l q) -> do
         putSrcSpanDs l (warnDs (Reason Opt_WarnOverlappingPatterns)
                                (pprEqn q "has inaccessible right hand side"))
       when exists_u $ putSrcSpanDs loc $ warnDs flag_u_reason $
@@ -1366,7 +1366,7 @@ pprContext singular (DsMatchContext kind _loc) msg rest_of_msg_fun
 
     (ppr_match, pref)
         = case kind of
-             FunRhs { mc_fun = (dL->L _ fun) }
+             FunRhs { mc_fun = L _ fun }
                   -> (pprMatchContext kind, \ pp -> ppr fun <+> pp)
              _    -> (pprMatchContext kind, \ pp -> pp)
 

compiler/basicTypes/Name.hs

@@ -205,12 +205,6 @@ nameOccName name = n_occ  name
 nameSrcLoc  name = srcSpanStart (n_loc name)
 nameSrcSpan name = n_loc  name
 
-type instance SrcSpanLess Name = Name
-instance HasSrcSpan Name where
-  composeSrcSpan   (L sp  n) = n {n_loc = sp}
-  decomposeSrcSpan n         = L (n_loc n) n
-
-
 {-
 ************************************************************************
 *                                                                      *

compiler/basicTypes/SrcLoc.hs

@@ -85,9 +85,7 @@ module SrcLoc (
         leftmost_smallest, leftmost_largest, rightmost,
         spans, isSubspanOf, sortLocated,
 
-        -- ** HasSrcSpan
-        HasSrcSpan(..), SrcSpanLess, dL, cL,
-        pattern LL, onHasSrcSpan, liftL
+        liftL
     ) where
 
 import GhcPrelude
@@ -182,7 +180,7 @@ advanceSrcLoc (SrcLoc f l c) _    = SrcLoc f  l (c + 1)
 ************************************************************************
 -}
 
-sortLocated :: HasSrcSpan a => [a] -> [a]
+sortLocated :: [Located a] -> [Located a]
 sortLocated things = sortBy (comparing getLoc) things
 
 instance Outputable RealSrcLoc where
@@ -533,36 +531,35 @@ type RealLocated = GenLocated RealSrcSpan
 mapLoc :: (a -> b) -> GenLocated l a -> GenLocated l b
 mapLoc = fmap
 
-unLoc :: HasSrcSpan a => a -> SrcSpanLess a
-unLoc (dL->L _ e) = e
+unLoc :: GenLocated l e -> e
+unLoc (L _ e) = e
 
-getLoc :: HasSrcSpan a => a -> SrcSpan
-getLoc (dL->L l _) = l
+getLoc :: GenLocated l e -> l
+getLoc (L l _) = l
 
-noLoc :: HasSrcSpan a => SrcSpanLess a -> a
-noLoc e = cL noSrcSpan e
+noLoc :: e -> Located e
+noLoc e = L noSrcSpan e
 
-mkGeneralLocated :: HasSrcSpan e => String -> SrcSpanLess e -> e
-mkGeneralLocated s e = cL (mkGeneralSrcSpan (fsLit s)) e
+mkGeneralLocated :: String -> e -> Located e
+mkGeneralLocated s e = L (mkGeneralSrcSpan (fsLit s)) e
 
-combineLocs :: (HasSrcSpan a , HasSrcSpan b) => a -> b -> SrcSpan
+combineLocs :: Located a -> Located b -> SrcSpan
 combineLocs a b = combineSrcSpans (getLoc a) (getLoc b)
 
 -- | Combine locations from two 'Located' things and add them to a third thing
-addCLoc :: (HasSrcSpan a , HasSrcSpan b , HasSrcSpan c) =>
-           a -> b -> SrcSpanLess c -> c
-addCLoc a b c = cL (combineSrcSpans (getLoc a) (getLoc b)) c
+addCLoc :: Located a -> Located b -> c -> Located c
+addCLoc a b c = L (combineSrcSpans (getLoc a) (getLoc b)) c
 
 -- not clear whether to add a general Eq instance, but this is useful sometimes:
 
 -- | Tests whether the two located things are equal
-eqLocated :: (HasSrcSpan a , Eq (SrcSpanLess a)) => a -> a -> Bool
+eqLocated :: Eq a => GenLocated l a -> GenLocated l a -> Bool
 eqLocated a b = unLoc a == unLoc b
 
 -- not clear whether to add a general Ord instance, but this is useful sometimes:
 
 -- | Tests the ordering of the two located things
-cmpLocated :: (HasSrcSpan a , Ord (SrcSpanLess a)) => a -> a -> Ordering
+cmpLocated :: Ord a => GenLocated l a -> GenLocated l a -> Ordering
 cmpLocated a b = unLoc a `compare` unLoc b
 
 instance (Outputable l, Outputable e) => Outputable (GenLocated l e) where
@@ -604,90 +601,10 @@ isSubspanOf src parent
     | otherwise = srcSpanStart parent <= srcSpanStart src &&
                   srcSpanEnd parent   >= srcSpanEnd src
 
-
-{-
-************************************************************************
-*                                                                      *
-\subsection{HasSrcSpan Typeclass to Set/Get Source Location Spans}
-*                                                                      *
-************************************************************************
--}
-
-{-
-Note [HasSrcSpan Typeclass]
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-To be able to uniformly set/get source location spans (of `SrcSpan`) in
-syntactic entities (`HsSyn`), we use the typeclass `HasSrcSpan`.
-More details can be found at the following wiki page
-  ImplementingTreesThatGrow/HandlingSourceLocations
-
-For most syntactic entities, the source location spans are stored in
-a syntactic entity by a wapper constuctor (introduced by TTG's
-new constructor extension), e.g., by `NewPat (WrapperPat sp pat)`
-for a source location span `sp` and a pattern `pat`.
--}
-
--- | Determines the type of undecorated syntactic entities
--- For most syntactic entities `E`, where source location spans are
--- introduced by a wrapper construtor of the same syntactic entity,
--- we have `SrcSpanLess E = E`.
--- However, some syntactic entities have a different type compared to
--- a syntactic entity `e :: E` may have the type `Located E` when
--- decorated by wrapping it with `L sp e` for a source span `sp`.
-type family SrcSpanLess a
-
--- | A typeclass to set/get SrcSpans
-class HasSrcSpan a where
-  -- | Composes a `SrcSpan` decoration with an undecorated syntactic
-  --   entity to form its decorated variant
-  composeSrcSpan   :: Located (SrcSpanLess a) -> a
-
-  -- | Decomposes a decorated syntactic entity into its `SrcSpan`
-  --   decoration and its undecorated variant
-  decomposeSrcSpan :: a -> Located (SrcSpanLess a)
-  {- laws:
-       composeSrcSpan . decomposeSrcSpan = id
-       decomposeSrcSpan . composeSrcSpan = id
-
-     in other words, `HasSrcSpan` defines an iso relation between
-     a `SrcSpan`-decorated syntactic entity and its undecorated variant
-     (together with the `SrcSpan`).
-  -}
-
-type instance SrcSpanLess (GenLocated l e) = e
-instance HasSrcSpan (Located a) where
-  composeSrcSpan   = id
-  decomposeSrcSpan = id
-
-
--- | An abbreviated form of decomposeSrcSpan,
---   mainly to be used in ViewPatterns
-dL :: HasSrcSpan a => a -> Located (SrcSpanLess a)
-dL = decomposeSrcSpan
-
--- | An abbreviated form of composeSrcSpan,
---   mainly to replace the hardcoded `L`
-cL :: HasSrcSpan a => SrcSpan -> SrcSpanLess a -> a
-cL sp e = composeSrcSpan (L sp e)
-
--- | A Pattern Synonym to Set/Get SrcSpans
-pattern LL :: HasSrcSpan a => SrcSpan -> SrcSpanLess a -> a
-pattern LL sp e <- (dL->L sp e)
-  where
-        LL sp e = cL sp e
-
--- | Lifts a function of undecorated entities to one of decorated ones
-onHasSrcSpan :: (HasSrcSpan a , HasSrcSpan b) =>
-                (SrcSpanLess a -> SrcSpanLess b) -> a -> b
-onHasSrcSpan f (dL->L l e) = cL l (f e)
-
-liftL :: (HasSrcSpan a, HasSrcSpan b, Monad m) =>
-         (SrcSpanLess a -> m (SrcSpanLess b)) -> a -> m b
-liftL f (dL->L loc a) = do
+liftL :: Monad m => (a -> m b) -> GenLocated l a -> m (GenLocated l b)
+liftL f (L loc a) = do
   a' <- f a
-  return $ cL loc a'
-
+  return $ L loc a'
 
 getRealSrcSpan :: RealLocated a -> RealSrcSpan
 getRealSrcSpan (L l _) = l

compiler/deSugar/Desugar.hs

@@ -369,13 +369,13 @@ Reason
 -}
 
 dsRule :: LRuleDecl GhcTc -> DsM (Maybe CoreRule)
-dsRule (dL->L loc (HsRule { rd_name = name
-                          , rd_act  = rule_act
-                          , rd_tmvs = vars
-                          , rd_lhs  = lhs
-                          , rd_rhs  = rhs }))
+dsRule (L loc (HsRule { rd_name = name
+                      , rd_act  = rule_act
+                      , rd_tmvs = vars
+                      , rd_lhs  = lhs
+                      , rd_rhs  = rhs }))
   = putSrcSpanDs loc $
-    do  { let bndrs' = [var | (dL->L _ (RuleBndr _ (dL->L _ var))) <- vars]
+    do  { let bndrs' = [var | L _ (RuleBndr _ (L _ var)) <- vars]
 
         ; lhs' <- unsetGOptM Opt_EnableRewriteRules $
                   unsetWOptM Opt_WarnIdentities $
@@ -412,8 +412,7 @@ dsRule (dL->L loc (HsRule { rd_name = name
 
         ; return (Just rule)
         } } }
-dsRule (dL->L _ (XRuleDecl nec)) = noExtCon nec
-dsRule _ = panic "dsRule: Impossible Match" -- due to #15884
+dsRule (L _ (XRuleDecl nec)) = noExtCon nec
 
 warnRuleShadowing :: RuleName -> Activation -> Id -> [Id] -> DsM ()
 -- See Note [Rules and inlining/other rules]

compiler/deSugar/DsArrows.hs

@@ -316,7 +316,7 @@ dsProcExpr
         :: LPat GhcTc
         -> LHsCmdTop GhcTc
         -> DsM CoreExpr
-dsProcExpr pat (dL->L _ (HsCmdTop (CmdTopTc _unitTy cmd_ty ids) cmd)) = do
+dsProcExpr pat (L _ (HsCmdTop (CmdTopTc _unitTy cmd_ty ids) cmd)) = do
     (meth_binds, meth_ids) <- mkCmdEnv ids
     let locals = mkVarSet (collectPatBinders pat)
     (core_cmd, _free_vars, env_ids)
@@ -455,8 +455,8 @@ dsCmd ids local_vars stack_ty res_ty (HsCmdApp _ cmd arg) env_ids = do
 
 dsCmd ids local_vars stack_ty res_ty
         (HsCmdLam _ (MG { mg_alts
-          = (dL->L _ [dL->L _ (Match { m_pats  = pats
-                       , m_grhss = GRHSs _ [dL->L _ (GRHS _ [] body)] _ })]) }))
+          = (L _ [L _ (Match { m_pats  = pats
+                             , m_grhss = GRHSs _ [L _ (GRHS _ [] body)] _ })]) }))
         env_ids = do
     let pat_vars = mkVarSet (collectPatsBinders pats)
     let
@@ -567,7 +567,7 @@ case bodies, containing the following fields:
 -}
 
 dsCmd ids local_vars stack_ty res_ty
-      (HsCmdCase _ exp (MG { mg_alts = (dL->L l matches)
+      (HsCmdCase _ exp (MG { mg_alts = L l matches
                            , mg_ext = MatchGroupTc arg_tys _
                            , mg_origin = origin }))
       env_ids = do
@@ -616,7 +616,7 @@ dsCmd ids local_vars stack_ty res_ty
         in_ty = envStackType env_ids stack_ty
 
     core_body <- dsExpr (HsCase noExtField exp
-                         (MG { mg_alts = cL l matches'
+                         (MG { mg_alts = L l matches'
                              , mg_ext = MatchGroupTc arg_tys sum_ty
                              , mg_origin = origin }))
         -- Note that we replace the HsCase result type by sum_ty,
@@ -632,7 +632,7 @@ dsCmd ids local_vars stack_ty res_ty
 --
 --              ---> premap (\ ((xs),stk) -> let binds in ((ys),stk)) c
 
-dsCmd ids local_vars stack_ty res_ty (HsCmdLet _ lbinds@(dL->L _ binds) body)
+dsCmd ids local_vars stack_ty res_ty (HsCmdLet _ lbinds@(L _ binds) body)
                                                                     env_ids = do
     let
         defined_vars = mkVarSet (collectLocalBinders binds)
@@ -660,7 +660,7 @@ dsCmd ids local_vars stack_ty res_ty (HsCmdLet _ lbinds@(dL->L _ binds) body)
 --              ---> premap (\ (env,stk) -> env) c
 
 dsCmd ids local_vars stack_ty res_ty do_block@(HsCmdDo stmts_ty
-                                               (dL->L loc stmts))
+                                               (L loc stmts))
                                                                    env_ids = do
     putSrcSpanDs loc $
       dsNoLevPoly stmts_ty
@@ -706,7 +706,7 @@ dsTrimCmdArg
         -> DsM (CoreExpr,       -- desugared expression
                 DIdSet)         -- subset of local vars that occur free
 dsTrimCmdArg local_vars env_ids
-                       (dL->L _ (HsCmdTop
+                       (L _ (HsCmdTop
                                  (CmdTopTc stack_ty cmd_ty ids) cmd )) = do
     (meth_binds, meth_ids) <- mkCmdEnv ids
     (core_cmd, free_vars, env_ids')
@@ -778,7 +778,7 @@ dsCmdDo _ _ _ [] _ = panic "dsCmdDo"
 --
 --              ---> premap (\ (xs) -> ((xs), ())) c
 
-dsCmdDo ids local_vars res_ty [dL->L loc (LastStmt _ body _ _)] env_ids = do
+dsCmdDo ids local_vars res_ty [L loc (LastStmt _ body _ _)] env_ids = do
     putSrcSpanDs loc $ dsNoLevPoly res_ty
                          (text "In the command:" <+> ppr body)
     (core_body, env_ids') <- dsLCmd ids local_vars unitTy res_ty body env_ids
@@ -1139,8 +1139,8 @@ matchSimplys _ _ _ _ _ = panic "matchSimplys"
 
 leavesMatch :: LMatch GhcTc (Located (body GhcTc))
             -> [(Located (body GhcTc), IdSet)]
-leavesMatch (dL->L _ (Match { m_pats = pats
-                            , m_grhss = GRHSs _ grhss (dL->L _ binds) }))
+leavesMatch (L _ (Match { m_pats = pats
+                        , m_grhss = GRHSs _ grhss (L _ binds) }))
   = let
         defined_vars = mkVarSet (collectPatsBinders pats)
                         `unionVarSet`
@@ -1149,7 +1149,7 @@ leavesMatch (dL->L _ (Match { m_pats = pats
     [(body,
       mkVarSet (collectLStmtsBinders stmts)
         `unionVarSet` defined_vars)
-    | (dL->L _ (GRHS _ stmts body)) <- grhss]
+    | L _ (GRHS _ stmts body) <- grhss]
 leavesMatch _ = panic "leavesMatch"
 
 -- Replace the leaf commands in a match
@@ -1161,12 +1161,12 @@ replaceLeavesMatch
         -> ([Located (body' GhcTc)],            -- remaining leaf expressions
             LMatch GhcTc (Located (body' GhcTc))) -- updated match
 replaceLeavesMatch _res_ty leaves
-                        (dL->L loc
+                        (L loc
                           match@(Match { m_grhss = GRHSs x grhss binds }))
   = let
         (leaves', grhss') = mapAccumL replaceLeavesGRHS leaves grhss
     in
-    (leaves', cL loc (match { m_ext = noExtField, m_grhss = GRHSs x grhss' binds }))
+    (leaves', L loc (match { m_ext = noExtField, m_grhss = GRHSs x grhss' binds }))
 replaceLeavesMatch _ _ _ = panic "replaceLeavesMatch"
 
 replaceLeavesGRHS
@@ -1174,8 +1174,8 @@ replaceLeavesGRHS
         -> LGRHS GhcTc (Located (body GhcTc))     -- rhss of a case command
         -> ([Located (body' GhcTc)],              -- remaining leaf expressions
             LGRHS GhcTc (Located (body' GhcTc)))  -- updated GRHS
-replaceLeavesGRHS (leaf:leaves) (dL->L loc (GRHS x stmts _))
-  = (leaves, cL loc (GRHS x stmts leaf))
+replaceLeavesGRHS (leaf:leaves) (L loc (GRHS x stmts _))
+  = (leaves, L loc (GRHS x stmts leaf))
 replaceLeavesGRHS [] _ = panic "replaceLeavesGRHS []"
 replaceLeavesGRHS _ _ = panic "replaceLeavesGRHS"
 
@@ -1221,14 +1221,14 @@ collectPatsBinders pats = foldr collectl [] pats
 ---------------------
 collectl :: LPat GhcTc -> [Id] -> [Id]
 -- See Note [Dictionary binders in ConPatOut]
-collectl (dL->L _ pat) bndrs
+collectl (L _ pat) bndrs
   = go pat
   where
-    go (VarPat _ (dL->L _ var))   = var : bndrs
+    go (VarPat _ (L _ var))       = var : bndrs
     go (WildPat _)                = bndrs
     go (LazyPat _ pat)            = collectl pat bndrs
     go (BangPat _ pat)            = collectl pat bndrs
-    go (AsPat _ (dL->L _ a) pat)  = a : collectl pat bndrs
+    go (AsPat _ (L _ a) pat)      = a : collectl pat bndrs
     go (ParPat _ pat)             = collectl pat bndrs
 
     go (ListPat _ pats)           = foldr collectl bndrs pats
@@ -1241,7 +1241,7 @@ collectl (dL->L _ pat) bndrs
                                     ++ foldr collectl bndrs (hsConPatArgs ps)
     go (LitPat _ _)               = bndrs
     go (NPat {})                  = bndrs
-    go (NPlusKPat _ (dL->L _ n) _ _ _ _) = n : bndrs
+    go (NPlusKPat _ (L _ n) _ _ _ _) = n : bndrs
 
     go (SigPat _ pat _)           = collectl pat bndrs
     go (CoPat _ _ pat _)          = collectl (noLoc pat) bndrs

compiler/deSugar/DsBinds.hs

@@ -101,7 +101,7 @@ dsTopLHsBinds binds
     unlifted_binds = filterBag (isUnliftedHsBind . unLoc) binds
     bang_binds     = filterBag (isBangedHsBind   . unLoc) binds
 
-    top_level_err desc (dL->L loc bind)
+    top_level_err desc (L loc bind)
       = putSrcSpanDs loc $
         errDs (hang (text "Top-level" <+> text desc <+> text "aren't allowed:")
                   2 (ppr bind))
@@ -118,8 +118,8 @@ dsLHsBinds binds
 ------------------------
 dsLHsBind :: LHsBind GhcTc
           -> DsM ([Id], [(Id,CoreExpr)])
-dsLHsBind (dL->L loc bind) = do dflags <- getDynFlags
-                                putSrcSpanDs loc $ dsHsBind dflags bind
+dsLHsBind (L loc bind) = do dflags <- getDynFlags
+                            putSrcSpanDs loc $ dsHsBind dflags bind
 
 -- | Desugar a single binding (or group of recursive binds).
 dsHsBind :: DynFlags
@@ -143,7 +143,7 @@ dsHsBind dflags (VarBind { var_id = var
                           else []
         ; return (force_var, [core_bind]) }
 
-dsHsBind dflags b@(FunBind { fun_id = (dL->L _ fun)
+dsHsBind dflags b@(FunBind { fun_id = L _ fun
                            , fun_matches = matches
                            , fun_co_fn = co_fn
                            , fun_tick = tick })
@@ -657,7 +657,7 @@ dsSpec :: Maybe CoreExpr        -- Just rhs => RULE is for a local binding
                                 --            rhs is in the Id's unfolding
        -> Located TcSpecPrag
        -> DsM (Maybe (OrdList (Id,CoreExpr), CoreRule))
-dsSpec mb_poly_rhs (dL->L loc (SpecPrag poly_id spec_co spec_inl))
+dsSpec mb_poly_rhs (L loc (SpecPrag poly_id spec_co spec_inl))
   | isJust (isClassOpId_maybe poly_id)
   = putSrcSpanDs loc $
     do { warnDs NoReason (text "Ignoring useless SPECIALISE pragma for class method selector"

compiler/deSugar/DsExpr.hs

@@ -72,11 +72,11 @@ import Control.Monad
 -}
 
 dsLocalBinds :: LHsLocalBinds GhcTc -> CoreExpr -> DsM CoreExpr
-dsLocalBinds (dL->L _   (EmptyLocalBinds _))  body = return body
-dsLocalBinds (dL->L loc (HsValBinds _ binds)) body = putSrcSpanDs loc $
-                                                   dsValBinds binds body
-dsLocalBinds (dL->L _ (HsIPBinds _ binds))    body = dsIPBinds  binds body
-dsLocalBinds _                                _    = panic "dsLocalBinds"
+dsLocalBinds (L _   (EmptyLocalBinds _))  body = return body
+dsLocalBinds (L loc (HsValBinds _ binds)) body = putSrcSpanDs loc $
+                                                 dsValBinds binds body
+dsLocalBinds (L _ (HsIPBinds _ binds))    body = dsIPBinds  binds body
+dsLocalBinds _                            _    = panic "dsLocalBinds"
 
 -------------------------
 -- caller sets location
@@ -94,7 +94,7 @@ dsIPBinds (IPBinds ev_binds ip_binds) body
                 -- dependency order; hence Rec
         ; foldrM ds_ip_bind inner ip_binds }
   where
-    ds_ip_bind (dL->L _ (IPBind _ ~(Right n) e)) body
+    ds_ip_bind (L _ (IPBind _ ~(Right n) e)) body
       = do e' <- dsLExpr e
            return (Let (NonRec n e') body)
     ds_ip_bind _ _ = panic "dsIPBinds"
@@ -108,7 +108,7 @@ ds_val_bind :: (RecFlag, LHsBinds GhcTc) -> CoreExpr -> DsM CoreExpr
 -- a tuple and doing selections.
 -- Silently ignore INLINE and SPECIALISE pragmas...
 ds_val_bind (NonRecursive, hsbinds) body
-  | [dL->L loc bind] <- bagToList hsbinds
+  | [L loc bind] <- bagToList hsbinds
         -- Non-recursive, non-overloaded bindings only come in ones
         -- ToDo: in some bizarre case it's conceivable that there
         --       could be dict binds in the 'binds'.  (See the notes
@@ -192,13 +192,13 @@ dsUnliftedBind (AbsBinds { abs_tvs = [], abs_ev_vars = []
        ; ds_binds <- dsTcEvBinds_s ev_binds
        ; return (mkCoreLets ds_binds body2) }
 
-dsUnliftedBind (FunBind { fun_id = (dL->L l fun)
+dsUnliftedBind (FunBind { fun_id = L l fun
                         , fun_matches = matches
                         , fun_co_fn = co_fn
                         , fun_tick = tick }) body
                -- Can't be a bang pattern (that looks like a PatBind)
                -- so must be simply unboxed
-  = do { (args, rhs) <- matchWrapper (mkPrefixFunRhs (cL l $ idName fun))
+  = do { (args, rhs) <- matchWrapper (mkPrefixFunRhs (L l $ idName fun))
                                      Nothing matches
        ; MASSERT( null args ) -- Functions aren't lifted
        ; MASSERT( isIdHsWrapper co_fn )
@@ -231,7 +231,7 @@ dsUnliftedBind bind body = pprPanic "dsLet: unlifted" (ppr bind $$ ppr body)
 
 dsLExpr :: LHsExpr GhcTc -> DsM CoreExpr
 
-dsLExpr (dL->L loc e)
+dsLExpr (L loc e)
   = putSrcSpanDs loc $
     do { core_expr <- dsExpr e
    -- uncomment this check to test the hsExprType function in TcHsSyn
@@ -246,7 +246,7 @@ dsLExpr (dL->L loc e)
 -- See Note [Levity polymorphism checking] in DsMonad
 -- See Note [Levity polymorphism invariants] in CoreSyn
 dsLExprNoLP :: LHsExpr GhcTc -> DsM CoreExpr
-dsLExprNoLP (dL->L loc e)
+dsLExprNoLP (L loc e)
   = putSrcSpanDs loc $
     do { e' <- dsExpr e
        ; dsNoLevPolyExpr e' (text "In the type of expression:" <+> ppr e)
@@ -260,7 +260,7 @@ ds_expr :: Bool   -- are we directly inside an HsWrap?
         -> HsExpr GhcTc -> DsM CoreExpr
 ds_expr _ (HsPar _ e)            = dsLExpr e
 ds_expr _ (ExprWithTySig _ e _)  = dsLExpr e
-ds_expr w (HsVar _ (dL->L _ var)) = dsHsVar w var
+ds_expr w (HsVar _ (L _ var))    = dsHsVar w var
 ds_expr _ (HsUnboundVar {})      = panic "dsExpr: HsUnboundVar" -- Typechecker eliminates them
 ds_expr w (HsConLikeOut _ con)   = dsConLike w con
 ds_expr _ (HsIPVar {})           = panic "dsExpr: HsIPVar"
@@ -285,7 +285,7 @@ ds_expr _ (HsWrap _ co_fn e)
        ; warnAboutIdentities dflags e' wrapped_ty
        ; return wrapped_e }
 
-ds_expr _ (NegApp _ (dL->L loc
+ds_expr _ (NegApp _ (L loc
                       (HsOverLit _ lit@(OverLit { ol_val = HsIntegral i})))
                   neg_expr)
   = do { expr' <- putSrcSpanDs loc $ do
@@ -377,12 +377,12 @@ ds_expr _ e@(SectionR _ op expr) = do
                                                           core_op [Var x_id, Var y_id]))
 
 ds_expr _ (ExplicitTuple _ tup_args boxity)
-  = do { let go (lam_vars, args) (dL->L _ (Missing ty))
+  = do { let go (lam_vars, args) (L _ (Missing ty))
                     -- For every missing expression, we need
                     -- another lambda in the desugaring.
                = do { lam_var <- newSysLocalDsNoLP ty
                     ; return (lam_var : lam_vars, Var lam_var : args) }
-             go (lam_vars, args) (dL->L _ (Present _ expr))
+             go (lam_vars, args) (L _ (Present _ expr))
                     -- Expressions that are present don't generate
                     -- lambdas, just arguments.
                = do { core_expr <- dsLExprNoLP expr
@@ -419,11 +419,11 @@ ds_expr _ (HsLet _ binds body) = do
 -- We need the `ListComp' form to use `deListComp' (rather than the "do" form)
 -- because the interpretation of `stmts' depends on what sort of thing it is.
 --
-ds_expr _ (HsDo res_ty ListComp (dL->L _ stmts)) = dsListComp stmts res_ty
-ds_expr _ (HsDo _ DoExpr        (dL->L _ stmts)) = dsDo stmts
-ds_expr _ (HsDo _ GhciStmtCtxt  (dL->L _ stmts)) = dsDo stmts
-ds_expr _ (HsDo _ MDoExpr       (dL->L _ stmts)) = dsDo stmts
-ds_expr _ (HsDo _ MonadComp     (dL->L _ stmts)) = dsMonadComp stmts
+ds_expr _ (HsDo res_ty ListComp (L _ stmts)) = dsListComp stmts res_ty
+ds_expr _ (HsDo _ DoExpr        (L _ stmts)) = dsDo stmts
+ds_expr _ (HsDo _