diff options
Diffstat (limited to 'compiler/typecheck')
| -rw-r--r-- | compiler/typecheck/TcBinds.hs | 11 | ||||
| -rw-r--r-- | compiler/typecheck/TcSimplify.hs | 2 |
2 files changed, 10 insertions, 3 deletions
diff --git a/compiler/typecheck/TcBinds.hs b/compiler/typecheck/TcBinds.hs index dc701d360b..54adc10ffe 100644 --- a/compiler/typecheck/TcBinds.hs +++ b/compiler/typecheck/TcBinds.hs @@ -241,7 +241,11 @@ tcCompleteSigs sigs = mkMatch :: [ConLike] -> TyCon -> CompleteMatch mkMatch cls ty_con = CompleteMatch { - completeMatchConLikes = map conLikeName cls, + -- foldM is a left-fold and will have accumulated the ConLikes in + -- the reverse order. foldrM would accumulate in the correct order, + -- but would type-check the last ConLike first, which might also be + -- confusing from the user's perspective. Hence reverse here. + completeMatchConLikes = reverse (map conLikeName cls), completeMatchTyCon = tyConName ty_con } doOne _ = return Nothing @@ -287,7 +291,10 @@ tcCompleteSigs sigs = <+> parens (quotes (ppr tc) <+> text "resp." <+> quotes (ppr tc')) - in mapMaybeM (addLocM doOne) sigs + -- For some reason I haven't investigated further, the signatures come in + -- backwards wrt. declaration order. So we reverse them here, because it makes + -- a difference for incomplete match suggestions. + in mapMaybeM (addLocM doOne) (reverse sigs) -- process in declaration order tcHsBootSigs :: [(RecFlag, LHsBinds GhcRn)] -> [LSig GhcRn] -> TcM [Id] -- A hs-boot file has only one BindGroup, and it only has type diff --git a/compiler/typecheck/TcSimplify.hs b/compiler/typecheck/TcSimplify.hs index 34bc4a8448..37015b30bc 100644 --- a/compiler/typecheck/TcSimplify.hs +++ b/compiler/typecheck/TcSimplify.hs @@ -693,7 +693,7 @@ It does *not* reduce type or data family applications or look through newtypes. Why is this useful? As one example, when coverage-checking an EmptyCase expression, it's possible that the type of the scrutinee will only reduce if some local equalities are solved for. See "Wrinkle: Local equalities" -in Note [Type normalisation for EmptyCase] in Check. +in Note [Type normalisation] in Check. To accomplish its stated goal, tcNormalise first feeds the local constraints into solveSimpleGivens, then stuffs the argument type in a CHoleCan, and feeds |