diff options
| -rw-r--r-- | compiler/deSugar/DsBinds.hs | 25 |
1 files changed, 17 insertions, 8 deletions
diff --git a/compiler/deSugar/DsBinds.hs b/compiler/deSugar/DsBinds.hs index b6edf7c35f..55c82dd0dc 100644 --- a/compiler/deSugar/DsBinds.hs +++ b/compiler/deSugar/DsBinds.hs @@ -67,9 +67,7 @@ import Bag import BasicTypes hiding ( TopLevel ) import DynFlags import FastString -import ErrUtils( MsgDoc ) import Util -import Control.Monad( when ) import MonadUtils import Control.Monad(liftM) import Fingerprint(Fingerprint(..), fingerprintString) @@ -460,8 +458,10 @@ dsSpec mb_poly_rhs (L loc (SpecPrag poly_id spec_co spec_inl)) ; spec_rhs <- dsHsWrapper spec_co poly_rhs - ; when (isInlinePragma id_inl && wopt Opt_WarnPointlessPragmas dflags) - (warnDs (specOnInline poly_name)) +-- Commented out: see Note [SPECIALISE on INLINE functions] +-- ; when (isInlinePragma id_inl) +-- (warnDs $ ptext (sLit "SPECIALISE pragma on INLINE function probably won't fire:") +-- <+> quotes (ppr poly_name)) ; return (Just (unitOL (spec_id, spec_rhs), rule)) -- NB: do *not* use makeCorePair on (spec_id,spec_rhs), because @@ -503,11 +503,20 @@ dsSpec mb_poly_rhs (L loc (SpecPrag poly_id spec_co spec_inl)) | otherwise = spec_prag_act -- Specified by user -specOnInline :: Name -> MsgDoc -specOnInline f = ptext (sLit "SPECIALISE pragma on INLINE function probably won't fire:") - <+> quotes (ppr f) -{- +{- Note [SPECIALISE on INLINE functions] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +We used to warn that using SPECIALISE for a function marked INLINE +would be a no-op; but it isn't! Especially with worker/wrapper split +we might have + {-# INLINE f #-} + f :: Ord a => Int -> a -> ... + f d x y = case x of I# x' -> $wf d x' y + +We might want to specialise 'f' so that we in turn specialise '$wf'. +We can't even /name/ '$wf' in the source code, so we can't specialise +it even if we wanted to. Trac #10721 is a case in point. + Note [Activation pragmas for SPECIALISE] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ From a user SPECIALISE pragma for f, we generate |