diff options
Diffstat (limited to 'ghc/compiler')
| -rw-r--r-- | ghc/compiler/typecheck/TcPat.lhs | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/ghc/compiler/typecheck/TcPat.lhs b/ghc/compiler/typecheck/TcPat.lhs index 2ab8d19988..ae55767868 100644 --- a/ghc/compiler/typecheck/TcPat.lhs +++ b/ghc/compiler/typecheck/TcPat.lhs @@ -88,7 +88,8 @@ tcPats ctxt pats tys res_ty thing_inside = do { let init_state = PS { pat_ctxt = ctxt, pat_reft = emptyTvSubst } ; (pats', ex_tvs, res) <- tc_lpats init_state pats tys $ \ pstate' -> - thing_inside (refineType (pat_reft pstate') res_ty) + refineEnvironment (pat_reft pstate') $ + thing_inside (refineType (pat_reft pstate') res_ty) ; tcCheckExistentialPat ctxt pats' ex_tvs tys res_ty @@ -605,10 +606,10 @@ refineAlt pstate con pat_tvs arg_flags pat_res_tys ctxt_res_tys thing_inside -- to refine the environment or pstate -> do { traceTc trace_msg ; thing_inside pstate pat_tvs' } - | otherwise -- New bindings affect the context, so refine - -- the environment and pstate - -> refineEnvironment (pat_reft pstate') $ - do { traceTc trace_msg + | otherwise -- New bindings affect the context, so pass down pstate'. + -- DO NOT refine the envt, because we might be inside a + -- lazy pattern + -> do { traceTc trace_msg ; thing_inside pstate' pat_tvs' } where pat_tvs' = map (substTyVar new_subst) pat_tvs |