diff options
Diffstat (limited to 'compiler/GHC/Tc/Deriv/Generate.hs')
| -rw-r--r-- | compiler/GHC/Tc/Deriv/Generate.hs | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/compiler/GHC/Tc/Deriv/Generate.hs b/compiler/GHC/Tc/Deriv/Generate.hs index 49d97e81e1..e51eee9841 100644 --- a/compiler/GHC/Tc/Deriv/Generate.hs +++ b/compiler/GHC/Tc/Deriv/Generate.hs @@ -1403,7 +1403,6 @@ gen_Data_binds loc (DerivInstTys{dit_rep_tc = rep_tc}) where data_cons = tyConDataCons rep_tc n_cons = length data_cons - one_constr = n_cons == 1 ------------ gfoldl gfoldl_bind = mkFunBindEC 3 loc gfoldl_RDR id (map gfoldl_eqn data_cons) @@ -1420,11 +1419,11 @@ gen_Data_binds loc (DerivInstTys{dit_rep_tc = rep_tc}) ------------ gunfold gunfold_bind = mkSimpleGeneratedFunBind loc gunfold_RDR - [k_Pat, z_Pat, if one_constr then nlWildPat else c_Pat] + [k_Pat, z_Pat, if n_cons == 1 then nlWildPat else c_Pat] gunfold_rhs gunfold_rhs - | one_constr = mk_unfold_rhs (head data_cons) -- No need for case + | [con] <- data_cons = mk_unfold_rhs con -- No need for case | otherwise = nlHsCase (nlHsVar conIndex_RDR `nlHsApp` c_Expr) (map gunfold_alt data_cons) |