diff options
Diffstat (limited to 'compiler/GHC/Tc/Deriv/Generate.hs')
| -rw-r--r-- | compiler/GHC/Tc/Deriv/Generate.hs | 28 |
1 files changed, 20 insertions, 8 deletions
diff --git a/compiler/GHC/Tc/Deriv/Generate.hs b/compiler/GHC/Tc/Deriv/Generate.hs index e3856765ec..a061674af9 100644 --- a/compiler/GHC/Tc/Deriv/Generate.hs +++ b/compiler/GHC/Tc/Deriv/Generate.hs @@ -1632,11 +1632,14 @@ Example: ==> instance (Lift a) => Lift (Foo a) where - lift (Foo a) = [| Foo a |] - lift ((:^:) u v) = [| (:^:) u v |] + lift (Foo a) = [| Foo $(lift a) |] + lift ((:^:) u v) = [| (:^:) $(lift u) $(lift v) |] - liftTyped (Foo a) = [|| Foo a ||] - liftTyped ((:^:) u v) = [|| (:^:) u v ||] + liftTyped (Foo a) = [|| Foo $$(liftTyped a) ||] + liftTyped ((:^:) u v) = [|| (:^:) $$(liftTyped u) $$(liftTyped v) ||] + +Note that we use explicit splices here in order to not trigger the implicit +lifting warning in derived code. (See #20688) -} @@ -1646,15 +1649,18 @@ gen_Lift_binds loc (DerivInstTys{ dit_rep_tc = tycon (listToBag [lift_bind, liftTyped_bind], emptyBag) where lift_bind = mkFunBindEC 1 loc lift_RDR (nlHsApp pure_Expr) - (map (pats_etc mk_exp) data_cons) + (map (pats_etc mk_exp mk_usplice liftName) data_cons) liftTyped_bind = mkFunBindEC 1 loc liftTyped_RDR (nlHsApp unsafeCodeCoerce_Expr . nlHsApp pure_Expr) - (map (pats_etc mk_texp) data_cons) + (map (pats_etc mk_texp mk_tsplice liftTypedName) data_cons) mk_exp = ExpBr noExtField mk_texp = TExpBr noExtField + + mk_usplice = HsUntypedSplice EpAnnNotUsed DollarSplice + mk_tsplice = HsTypedSplice EpAnnNotUsed DollarSplice data_cons = getPossibleDataCons tycon tycon_args - pats_etc mk_bracket data_con + pats_etc mk_bracket mk_splice lift_name data_con = ([con_pat], lift_Expr) where con_pat = nlConVarPat data_con_RDR as_needed @@ -1663,7 +1669,13 @@ gen_Lift_binds loc (DerivInstTys{ dit_rep_tc = tycon as_needed = take con_arity as_RDRs lift_Expr = noLocA (HsBracket noAnn (mk_bracket br_body)) br_body = nlHsApps (Exact (dataConName data_con)) - (map nlHsVar as_needed) + (map lift_var as_needed) + + lift_var :: RdrName -> LHsExpr (GhcPass 'Parsed) + lift_var x = noLocA (HsSpliceE EpAnnNotUsed (mk_splice x (nlHsPar (mk_lift_expr x)))) + + mk_lift_expr :: RdrName -> LHsExpr (GhcPass 'Parsed) + mk_lift_expr x = nlHsApps (Exact lift_name) [nlHsVar x] {- ************************************************************************ |