When parsing

    extremumNewton :: (Eq a, Fractional a) =>
                  (forall tag. forall tag1.
                          Tower tag1 (Tower tag a)
                              -> Tower tag1 (Tower tag a))
                      -> a -> [a]

the nested `forall` declarations are parsed by

    ctypedoc :: { LHsType RdrName }
          : 'forall' tv_bndrs '.' ctypedoc {% hintExplicitForall (getLoc $1) >>
                                              ams (sLL $1 $> $ mkExplicitHsForAllTy $2
                                                                    (noLoc []) $4)
                                                  [mj AnnForall $1,mj AnnDot $3] }

This generates a HsForAllTy for the first forall that simply wraps the second one, which is also a `ctypedoc`.

But, when looking at the AST provided via ParsedSource, the two `forall`s are collapsed into a single one, containing both `tag` and `tag1` in the TyVarBndrs.

In the process the annotation for the second forall loses its anchor, as that span is no longer in the AST.

I cannot find where this collapsing takes place, can anyone point me at it?

Thanks

Alan