CoreLint error in SpecConstr output for lateCC branch.

In !7797 (closed) I know hit a different core lint error in the output for SpecConstr.

In particular we try to specialise this function for True/False:

Input to SpecConstr:

              $wlistRest_s5qS [InlPrag=[2], Occ=LoopBreaker]
                :: Bool
                   -> forall b.
                      ([a_a23u] -> Text.ParserCombinators.ReadP.P b)
                      -> Text.ParserCombinators.ReadP.P b
              [LclId,
               Arity=1,
               Str=<L>,
               Unf=Unf{Src=<vanilla>, TopLvl=False, Value=True, ConLike=True,
                       WorkFree=True, Expandable=True, Guidance=IF_ARGS [30] 280 60}]
              $wlistRest_s5qS
                = \ (started_s4ge :: Bool) (@b1_a3fH) ->
                    tick<$c>>=>
                    \ (k1_a3fI
                         :: [a_a23u] -> Text.ParserCombinators.ReadP.P b1_a3fH) ->
                      scc<$c>>=>
                      let {
                        lvl_s5n5 :: Text.ParserCombinators.ReadP.P b1_a3fH
                        [LclId,
                         Unf=Unf{Src=<vanilla>, TopLvl=False, Value=False, ConLike=False,
                                 WorkFree=False, Expandable=False, Guidance=IF_ARGS [] 30 0}]
                        lvl_s5n5
                          = scc<$c>>=>
                            ((((pfail @[a_a23u])
                               `cast` <Co:3> :: ReadPrec [a_a23u] ~R# (Prec -> P.ReadP [a_a23u]))
                                n_s5mY)
                             `cast` <Co:3> :: P.ReadP [a_a23u]
                                              ~R# (forall b.
                                                   ([a_a23u] -> Text.ParserCombinators.ReadP.P b)
                                                   -> Text.ParserCombinators.ReadP.P b))
                              @b1_a3fH k1_a3fI } in
                      let {
                        lvl_s5na :: Text.ParserCombinators.ReadP.P b1_a3fH
                        [LclId,
                         Unf=Unf{Src=<vanilla>, TopLvl=False, Value=False, ConLike=False,
                                 WorkFree=False, Expandable=False, Guidance=IF_ARGS [] 20 0}]
                        lvl_s5na
                          = scc<$c>>=> scc<$cpure> k1_a3fI (GHC.Types.[] @a_a23u) } in
                      let {
                        lvl_s5n8 :: Text.ParserCombinators.ReadP.P b1_a3fH
                        [LclId,
                         Unf=Unf{Src=<vanilla>, TopLvl=False, Value=False, ConLike=False,
                                 WorkFree=False, Expandable=False, Guidance=IF_ARGS [] 20 0}]
                        lvl_s5n8
                          = scc<$c>>=>
                            (lvl_s5mZ
                             `cast` <Co:3> :: P.ReadP [a_a23u]
                                              ~R# (forall b.
                                                   ([a_a23u] -> Text.ParserCombinators.ReadP.P b)
                                                   -> Text.ParserCombinators.ReadP.P b))
                              @b1_a3fH k1_a3fI } in
                      scctick<$c>>=>
                      (ds1_s5n4
                       `cast` <Co:2> :: P.ReadP L.Lexeme
                                        ~R# (forall b.
                                             (L.Lexeme -> Text.ParserCombinators.ReadP.P b)
                                             -> Text.ParserCombinators.ReadP.P b))
                        @b1_a3fH
                        (\ (a1_a3fJ [Dmd=SL] :: L.Lexeme) ->
                           case a1_a3fJ of {
                             __DEFAULT -> Text.ParserCombinators.ReadP.Fail @b1_a3fH;
                             L.Punc c_a1CI [Dmd=SL] ->
                               case c_a1CI of {
                                 [] -> lvl_s5n5;
                                 : ds_d2Vb [Dmd=S!P(SL)] ds_d2Vc ->
                                   case ds_d2Vb of { C# ds_d2Vd [Dmd=SL] ->
                                   case ds_d2Vd of {
                                     __DEFAULT -> lvl_s5n5;
                                     ','# ->
                                       case ds_d2Vc of {
                                         [] ->
                                           case started_s4ge of {
                                             False -> lvl_s5n5;
                                             True -> lvl_s5n8
                                           };
                                         : ipv_s3i2 [Dmd=A] ipv_s3i3 [Dmd=A] -> lvl_s5n5
                                       };
                                     ']'# ->
                                       case ds_d2Vc of {
                                         [] -> tick<$cpure> lvl_s5na;
                                         : ipv_s3i5 [Dmd=A] ipv_s3i6 [Dmd=A] -> lvl_s5n5
                                       }
                                   }
                                   }
                               }
                           }); } in

But we generate a RULE mentioning a out of scope type variable:

Output of SpecConstr:

$wlistRest_s5qS [InlPrag=[2], Occ=LoopBreaker]
                :: Bool -> forall b. ([a_a23u] -> P b) -> P b
              [LclId,
               Arity=1,
               Str=<L>,
               RULES: "SC:$wlistRest1" [2]
                          forall. $wlistRest_s5qS True = $s$wlistRest_s5rr @b1_a3fH
                      "SC:$wlistRest0" [2]
                          forall. $wlistRest_s5qS False = $s$wlistRest_s5rq @b1_a3fH]
              $wlistRest_s5qS
                = \ (started_s4ge :: Bool) (@b1_a3fH) -> ...

Really @b1_a3fH should just be dropped by the rules RHS but clearly it isn't.

I think this is because we remove type arguments from the patterns we match on the rules left hand side.

I think the core issue is the SpecConstr implicitly assumes type variables come first in some places which goes awry here.