From 9882db62761ba4664bd918fd362a32f00e73fd72 Mon Sep 17 00:00:00 2001
From: Richard Eisenberg <rae@richarde.dev>
Date: Thu, 17 Feb 2022 21:19:36 +0000
Subject: [PATCH] Flip some bits (directions of coercions in rewriting)
---
compiler/GHC/Tc/Solver/Rewrite.hs | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/compiler/GHC/Tc/Solver/Rewrite.hs b/compiler/GHC/Tc/Solver/Rewrite.hs
index 5f8d0886ae97..c83d5d3ad249 100644
--- a/compiler/GHC/Tc/Solver/Rewrite.hs
+++ b/compiler/GHC/Tc/Solver/Rewrite.hs
@@ -551,20 +551,20 @@ rewrite_one (FunTy { ft_af = vis, ft_mult = mult, ft_arg = ty1, ft_res = ty2 })
(rewrite_one res_rep)
; role <- getRole
- ; let arg_rep_co = snd arg_rep_redn
+ ; let arg_rep_co = mkSymCo (snd arg_rep_redn)
-- :: arg_rep ~ arg_rep_xi
arg_ki_co = mkTyConAppCo Nominal tYPETyCon [arg_rep_co]
-- :: TYPE arg_rep ~ TYPE arg_rep_xi
casted_arg_redn =
( mkCastTy arg_xi arg_ki_co
- , mkCoherenceRightCo role arg_xi arg_ki_co arg_co
+ , mkCoherenceLeftCo role arg_xi arg_ki_co arg_co
)
-- :: ty1 ~> arg_xi |> arg_ki_co
- res_ki_co = mkTyConAppCo Nominal tYPETyCon [snd res_rep_redn]
+ res_ki_co = mkTyConAppCo Nominal tYPETyCon [mkSymCo $ snd res_rep_redn]
casted_res_redn =
( mkCastTy res_xi res_ki_co
- , mkCoherenceRightCo role res_xi res_ki_co res_co
+ , mkCoherenceLeftCo role res_xi res_ki_co res_co
)
-- We must rewrite the representations, because that's what would
--
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