diff options
Diffstat (limited to 'compiler/GHC/Tc/Gen/Sig.hs')
| -rw-r--r-- | compiler/GHC/Tc/Gen/Sig.hs | 36 |
1 files changed, 27 insertions, 9 deletions
diff --git a/compiler/GHC/Tc/Gen/Sig.hs b/compiler/GHC/Tc/Gen/Sig.hs index 466191b3c7..6d6a74c65d 100644 --- a/compiler/GHC/Tc/Gen/Sig.hs +++ b/compiler/GHC/Tc/Gen/Sig.hs @@ -41,6 +41,7 @@ import GHC.Tc.Utils.Unify( tcSkolemise, unifyType ) import GHC.Tc.Utils.Instantiate( topInstantiate, tcInstTypeBndrs ) import GHC.Tc.Utils.Env( tcLookupId ) import GHC.Tc.Types.Evidence( HsWrapper, (<.>) ) +import GHC.Core( hasSomeUnfolding ) import GHC.Core.Type ( mkTyVarBinders ) import GHC.Core.Multiplicity @@ -48,7 +49,8 @@ import GHC.Driver.Session import GHC.Driver.Backend import GHC.Driver.Ppr import GHC.Types.Var ( TyVar, Specificity(..), tyVarKind, binderVars ) -import GHC.Types.Id ( Id, idName, idType, idInlinePragma, setInlinePragma, mkLocalId ) +import GHC.Types.Id ( Id, idName, idType, setInlinePragma + , mkLocalId, realIdUnfolding ) import GHC.Builtin.Names( mkUnboundName ) import GHC.Types.Basic import GHC.Unit.Module( getModule ) @@ -807,20 +809,36 @@ tcImpPrags prags tcImpSpec :: (Name, Sig GhcRn) -> TcM [TcSpecPrag] tcImpSpec (name, prag) = do { id <- tcLookupId name - ; if isAnyInlinePragma (idInlinePragma id) + ; if hasSomeUnfolding (realIdUnfolding id) + -- See Note [SPECIALISE pragmas for imported Ids] then tcSpecPrag id prag else do { addWarnTc NoReason (impSpecErr name) ; return [] } } - -- If there is no INLINE/INLINABLE pragma there will be no unfolding. In - -- that case, just delete the SPECIALISE pragma altogether, lest the - -- desugarer fall over because it can't find the unfolding. See #18118. impSpecErr :: Name -> SDoc impSpecErr name = hang (text "You cannot SPECIALISE" <+> quotes (ppr name)) - 2 (vcat [ text "because its definition has no INLINE/INLINABLE pragma" - , parens $ sep - [ text "or its defining module" <+> quotes (ppr mod) - , text "was compiled without -O"]]) + 2 (vcat [ text "because its definition is not visible in this module" + , text "Hint: make sure" <+> ppr mod <+> text "is compiled with -O" + , text " and that" <+> quotes (ppr name) + <+> text "has an INLINABLE pragma" ]) where mod = nameModule name + +{- Note [SPECIALISE pragmas for imported Ids] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +An imported Id may or may not have an unfolding. If not, we obviously +can't specialise it here; indeed the desugar falls over (#18118). + +We used to test whether it had a user-specified INLINABLE pragma but, +because of Note [Worker-wrapper for INLINABLE functions] in +GHC.Core.Opt.WorkWrap, even an INLINABLE function may end up with +a wrapper that has no pragma, just an unfolding (#19246). So now +we just test whether the function has an unfolding. + +There's a risk that a pragma-free function may have an unfolding now +(because it is fairly small), and then gets a bit bigger, and no +longer has an unfolding in the future. But then you'll get a helpful +error message suggesting an INLINABLE pragma, which you can follow. +That seems enough for now. +-} |