diff options
Diffstat (limited to 'compiler/GHC/Tc/Errors.hs')
| -rw-r--r-- | compiler/GHC/Tc/Errors.hs | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/compiler/GHC/Tc/Errors.hs b/compiler/GHC/Tc/Errors.hs index 8b50d5e719..37dc095f71 100644 --- a/compiler/GHC/Tc/Errors.hs +++ b/compiler/GHC/Tc/Errors.hs @@ -438,8 +438,13 @@ reportImplic ctxt implic@(Implic { ic_skols = tvs where tcl_env = ic_env implic insoluble = isInsolubleStatus status - (env1, tvs') = mapAccumL tidyVarBndr (cec_tidy ctxt) tvs - info' = tidySkolemInfo env1 info + (env1, tvs') = mapAccumL tidyVarBndr (cec_tidy ctxt) $ + scopedSort tvs + -- scopedSort: the ic_skols may not be in dependency order + -- (see Note [Skolems in an implication] in GHC.Tc.Types.Constraint) + -- but tidying goes wrong on out-of-order constraints; + -- so we sort them here before tidying + info' = tidySkolemInfo env1 info implic' = implic { ic_skols = tvs' , ic_given = map (tidyEvVar env1) given , ic_info = info' } @@ -507,7 +512,7 @@ warnRedundantConstraints ctxt env info ev_vars = any isImprovementPred (pred : transSuperClasses pred) reportBadTelescope :: ReportErrCtxt -> TcLclEnv -> SkolemInfo -> [TcTyVar] -> TcM () -reportBadTelescope ctxt env (ForAllSkol _ telescope) skols +reportBadTelescope ctxt env (ForAllSkol telescope) skols = do { msg <- mkErrorReport ctxt env (important doc) ; reportError msg } where |