diff --git a/compiler/GHC/Tc/Deriv/Generate.hs b/compiler/GHC/Tc/Deriv/Generate.hs
index f5ef61727aa921e01b89757dca79b10866cbbf0d..e9bebf570ba67ab0d15e4f244ed6f606b48691ed 100644
--- a/compiler/GHC/Tc/Deriv/Generate.hs
+++ b/compiler/GHC/Tc/Deriv/Generate.hs
@@ -1407,7 +1407,7 @@ gen_Data_binds loc (DerivInstTys{dit_rep_tc = rep_tc})
gfoldl_eqn con
= ([nlVarPat k_RDR, z_Pat, nlConVarPat con_name as_needed],
- foldl' mk_k_app (z_Expr `nlHsApp` (eta_expand_data_con con)) as_needed)
+ foldl' mk_k_app (z_Expr `nlHsApp` (nlHsVar (getRdrName con))) as_needed)
where
con_name :: RdrName
con_name = getRdrName con
@@ -1427,18 +1427,9 @@ gen_Data_binds loc (DerivInstTys{dit_rep_tc = rep_tc})
gunfold_alt dc = mkHsCaseAlt (mk_unfold_pat dc) (mk_unfold_rhs dc)
mk_unfold_rhs dc = foldr nlHsApp
- (z_Expr `nlHsApp` (eta_expand_data_con dc))
+ (z_Expr `nlHsApp` (nlHsVar (getRdrName dc)))
(replicate (dataConSourceArity dc) (nlHsVar k_RDR))
- eta_expand_data_con dc =
- mkHsLam (noLocA eta_expand_pats)
- (foldl nlHsApp (nlHsVar (getRdrName dc)) eta_expand_hsvars)
- where
- eta_expand_pats = map nlVarPat eta_expand_vars
- eta_expand_hsvars = map nlHsVar eta_expand_vars
- eta_expand_vars = take (dataConSourceArity dc) as_RDRs
-
-
mk_unfold_pat dc -- Last one is a wild-pat, to avoid
-- redundant test, and annoying warning
| tag-fIRST_TAG == n_cons-1 = nlWildPat -- Last constructor
diff --git a/testsuite/tests/deriving/should_compile/T14682.stderr b/testsuite/tests/deriving/should_compile/T14682.stderr
index 28b0a959a08c2e44cf0f314a416c6cd9549adcda..90e8da1400e96a337dacf643f40e0b942d3a952e 100644
--- a/testsuite/tests/deriving/should_compile/T14682.stderr
+++ b/testsuite/tests/deriving/should_compile/T14682.stderr
@@ -26,9 +26,8 @@ Derived class instances:
instance GHC.Internal.Data.Data.Data T14682.Foo where
GHC.Internal.Data.Data.gfoldl k z (T14682.Foo a1 a2)
- = ((z (\ a1 a2 -> T14682.Foo a1 a2) `k` a1) `k` a2)
- GHC.Internal.Data.Data.gunfold k z _
- = k (k (z (\ a1 a2 -> T14682.Foo a1 a2)))
+ = ((z T14682.Foo `k` a1) `k` a2)
+ GHC.Internal.Data.Data.gunfold k z _ = k (k (z T14682.Foo))
GHC.Internal.Data.Data.toConstr (T14682.Foo _ _) = $cFoo
GHC.Internal.Data.Data.dataTypeOf _ = $tFoo
diff --git a/testsuite/tests/typecheck/should_fail/T15883e.stderr b/testsuite/tests/typecheck/should_fail/T15883e.stderr
index 8f0fdfb76807530e840da381b1f4b5573750083d..effaf71c313c9e87866639dfeb3dce0516fee5f6 100644
--- a/testsuite/tests/typecheck/should_fail/T15883e.stderr
+++ b/testsuite/tests/typecheck/should_fail/T15883e.stderr
@@ -1,71 +1,26 @@
-
-T15883e.hs:16:1: error: [GHC-39999]
- • Ambiguous type variable ‘d0’ arising from a use of ‘k’
- prevents the constraint ‘(Data d0)’ from being solved.
- Probable fix: use a type annotation to specify what ‘d0’ should be.
- Potentially matching instances:
- instance (Data a, Data b) => Data (Either a b)
- -- Defined in ‘GHC.Internal.Data.Data’
- instance Data a => Data (Down a)
- -- Defined in ‘GHC.Internal.Data.Data’
- ...plus 20 others
- ...plus 47 instances involving out-of-scope types
- (use -fprint-potential-instances to see them all)
- • In the expression: z (\ a1 -> MkFoo a1) `k` a1
- In an equation for ‘GHC.Internal.Data.Data.gfoldl’:
- GHC.Internal.Data.Data.gfoldl k z (MkFoo a1)
- = (z (\ a1 -> MkFoo a1) `k` a1)
- When typechecking the code for ‘GHC.Internal.Data.Data.gfoldl’
- in a derived instance for ‘Data (Foo LiftedRep)’:
- To see the code I am typechecking, use -ddump-deriv
- In the instance declaration for ‘Data (Foo LiftedRep)’
-
-T15883e.hs:16:1: error: [GHC-46956]
- • Couldn't match expected type ‘a’ with actual type ‘d0’
- because type variable ‘a’ would escape its scope
- This (rigid, skolem) type variable is bound by
- a type expected by the context:
- forall a. a
- at T15883e.hs:16:1-52
- • In the first argument of ‘MkFoo’, namely ‘a1’
- In the expression: MkFoo a1
- In the first argument of ‘z’, namely ‘(\ a1 -> MkFoo a1)’
+T15883e.hs:16:1: error: [GHC-91028]
+ • Couldn't match type ‘d0’ with ‘forall a. a’
+ Expected: d0 -> Foo LiftedRep
+ Actual: (forall a. a) -> Foo LiftedRep
+ Cannot instantiate unification variable ‘d0’
+ with a type involving polytypes: forall a. a
+ • In the first argument of ‘z’, namely ‘MkFoo’
+ In the first argument of ‘k’, namely ‘z MkFoo’
+ In the expression: z MkFoo `k` a1
When typechecking the code for ‘GHC.Internal.Data.Data.gfoldl’
in a derived instance for ‘Data (Foo LiftedRep)’:
To see the code I am typechecking, use -ddump-deriv
- • Relevant bindings include a1 :: d0 (bound at T15883e.hs:16:1)
-T15883e.hs:16:1: error: [GHC-39999]
- • Ambiguous type variable ‘b0’ arising from a use of ‘k’
- prevents the constraint ‘(Data b0)’ from being solved.
- Probable fix: use a type annotation to specify what ‘b0’ should be.
- Potentially matching instances:
- instance (Data a, Data b) => Data (Either a b)
- -- Defined in ‘GHC.Internal.Data.Data’
- instance Data a => Data (Down a)
- -- Defined in ‘GHC.Internal.Data.Data’
- ...plus 20 others
- ...plus 47 instances involving out-of-scope types
- (use -fprint-potential-instances to see them all)
- • In the expression: k (z (\ a1 -> MkFoo a1))
- In an equation for ‘GHC.Internal.Data.Data.gunfold’:
- GHC.Internal.Data.Data.gunfold k z _ = k (z (\ a1 -> MkFoo a1))
+T15883e.hs:16:1: error: [GHC-91028]
+ • Couldn't match type ‘b0’ with ‘forall a. a’
+ Expected: b0 -> Foo LiftedRep
+ Actual: (forall a. a) -> Foo LiftedRep
+ Cannot instantiate unification variable ‘b0’
+ with a type involving polytypes: forall a. a
+ • In the first argument of ‘z’, namely ‘MkFoo’
+ In the first argument of ‘k’, namely ‘(z MkFoo)’
+ In the expression: k (z MkFoo)
When typechecking the code for ‘GHC.Internal.Data.Data.gunfold’
in a derived instance for ‘Data (Foo LiftedRep)’:
To see the code I am typechecking, use -ddump-deriv
- In the instance declaration for ‘Data (Foo LiftedRep)’
-T15883e.hs:16:1: error: [GHC-46956]
- • Couldn't match expected type ‘a’ with actual type ‘b0’
- because type variable ‘a’ would escape its scope
- This (rigid, skolem) type variable is bound by
- a type expected by the context:
- forall a. a
- at T15883e.hs:16:1-52
- • In the first argument of ‘MkFoo’, namely ‘a1’
- In the expression: MkFoo a1
- In the first argument of ‘z’, namely ‘(\ a1 -> MkFoo a1)’
- When typechecking the code for ‘GHC.Internal.Data.Data.gunfold’
- in a derived instance for ‘Data (Foo LiftedRep)’:
- To see the code I am typechecking, use -ddump-deriv
- • Relevant bindings include a1 :: b0 (bound at T15883e.hs:16:1)