Egregious bug in tcLHsConResTy

This terrible bug in tcLHsConTy is pretty much guaranteed to show up
on an program involving a GADT with more than one type parameter.

This bug isn't present in the STABLE branch.

Manuel: it is *not* necesary to merge this patch into the FC branch;
just ignore it.

diff --git a/compiler/typecheck/TcHsType.lhs b/compiler/typecheck/TcHsType.lhs
index d906381..b7e5b0b 100644 (file)
--- a/compiler/typecheck/TcHsType.lhs
+++ b/compiler/typecheck/TcHsType.lhs
@@ -561,8 +561,8 @@ tcLHsConResTy res_ty
     get_largs (L _ ty) args = get_args ty args
     get_args (HsAppTy fun arg)                   args = get_largs fun (arg:args)
     get_args (HsParTy ty)                        args = get_largs ty  args
-    get_args (HsOpTy ty1 (L span tc) ty2) args = get_args (HsTyVar tc) (ty1:ty2:args)
-    get_args ty                          args = (ty, reverse args)
+    get_args (HsOpTy ty1 (L span tc) ty2) args = (HsTyVar tc, ty1:ty2:args)
+    get_args ty                          args = (ty, args)
 
 gadtResCtxt ty
   = hang (ptext SLIT("In the result type of a data constructor:"))