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| author | Simon Peyton Jones <simonpj@microsoft.com> | 2014-06-19 17:26:11 +0100 |
|---|---|---|
| committer | Simon Peyton Jones <simonpj@microsoft.com> | 2014-06-20 08:16:46 +0100 |
| commit | 9c621e9b1c7d8a02b48f06f041da605ce27f4d80 (patch) | |
| tree | 3d4ce53250acf5185924d42f7c02dae5ae8d456b /compiler/typecheck/TcHsType.lhs | |
| parent | 64224f19d1cccd1104e323016a1481ddaa9db464 (diff) | |
| download | haskell-9c621e9b1c7d8a02b48f06f041da605ce27f4d80.tar.gz | |
Reject forall types in constraints in signatures
Fixes Trac #9196. Thanks to archblob for an initial stab at this.
In the end I fixed it in the kind checker rather than the subsequent
validity check, (a) so that the error messages look more uniform,
and (b) so that I did not need to meddle with isPredTy.
Diffstat (limited to 'compiler/typecheck/TcHsType.lhs')
| -rw-r--r-- | compiler/typecheck/TcHsType.lhs | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/compiler/typecheck/TcHsType.lhs b/compiler/typecheck/TcHsType.lhs index 69579ada30..59aafeafba 100644 --- a/compiler/typecheck/TcHsType.lhs +++ b/compiler/typecheck/TcHsType.lhs @@ -396,13 +396,17 @@ tc_hs_type hs_ty@(HsAppTy ty1 ty2) exp_kind (fun_ty, arg_tys) = splitHsAppTys ty1 [ty2] --------- Foralls -tc_hs_type hs_ty@(HsForAllTy _ hs_tvs context ty) exp_kind - = tcHsTyVarBndrs hs_tvs $ \ tvs' -> +tc_hs_type hs_ty@(HsForAllTy _ hs_tvs context ty) exp_kind@(EK exp_k _) + | isConstraintKind exp_k + = failWithTc (hang (ptext (sLit "Illegal constraint:")) 2 (ppr hs_ty)) + + | otherwise + = tcHsTyVarBndrs hs_tvs $ \ tvs' -> -- Do not kind-generalise here! See Note [Kind generalisation] do { ctxt' <- tcHsContext context ; ty' <- if null (unLoc context) then -- Plain forall, no context tc_lhs_type ty exp_kind -- Why exp_kind? See Note [Body kind of forall] - else + else -- If there is a context, then this forall is really a -- _function_, so the kind of the result really is * -- The body kind (result of the function can be * or #, hence ekOpen |