diff options
Diffstat (limited to 'compiler/GHC/Tc/Solver/Canonical.hs')
| -rw-r--r-- | compiler/GHC/Tc/Solver/Canonical.hs | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/compiler/GHC/Tc/Solver/Canonical.hs b/compiler/GHC/Tc/Solver/Canonical.hs index fd608c3314..ce8bf24632 100644 --- a/compiler/GHC/Tc/Solver/Canonical.hs +++ b/compiler/GHC/Tc/Solver/Canonical.hs @@ -956,6 +956,11 @@ can_eq_nc' -> Type -> Type -- RHS, after and before type-synonym expansion, resp -> TcS (StopOrContinue Ct) +-- See Note [Comparing nullary type synonyms] in GHC.Core.Type. +can_eq_nc' _flat _rdr_env _envs ev eq_rel ty1@(TyConApp tc1 []) _ps_ty1 (TyConApp tc2 []) _ps_ty2 + | tc1 == tc2 + = canEqReflexive ev eq_rel ty1 + -- Expand synonyms first; see Note [Type synonyms and canonicalization] can_eq_nc' rewritten rdr_env envs ev eq_rel ty1 ps_ty1 ty2 ps_ty2 | Just ty1' <- tcView ty1 = can_eq_nc' rewritten rdr_env envs ev eq_rel ty1' ps_ty1 ty2 ps_ty2 |