Infinite recursion found in Rubi-based `SetDelayed` assignments for `EqQ` and `Star`

[rocky]

Description

Rubi is not loading, failing with:

$RecursionLimit::reclim: Recursion depth of xxx  exceeded.

It is failing in IntegrationUtilityFunctions.m which is read before any Integration rules are read in.

How to Reproduce and Output Given

Run/Import/Get this file star-bug.wl:

(*Extracted from Rubi IntegrationUtilityFunctions.m Integration Utility Functions*)

(* If u-v equals 0, EqQ[u,v] returns True; else it returns False. *)

EqQ[args___] := Null /; EqQ[args]

(* Star[u,v] displays as u*v, and returns the product of u and v with u
   distributed over the terms of v." *)

Star[u_,v_] := (
  Message[Star::error];
  0 ) /;
EqQ[u,0]

Star[u_,Star[v_,w_]] :=
  Star[u*v,w]
Print["Succeeded"]

The following is output instrumented to show recursive calls to the internal function inc_recursion_depth of Evaluation

In[1]:= Get["star-bug.wl", Trace->True]
Reading file: ./star-bug.wl

    2: (* If u-v equals 0, EqQ[u,v] returns True; else it returns False. *)

    4: EqQ[args___] := Null /; EqQ[args]

    6: (* Star[u,v] displays as u*v, and returns the product of u and v with u
        distributed over the terms of v." *)
    9: Star[u_,v_] := (
  Message[Star::error];
  0 ) /;
EqQ[u,0]

   14: Star[u_,Star[v_,w_]] :=
     Star[u*v,w]

(u:_) Star(v:_) Star (w:_) := u * v Star w

(u:_) Star(v:_) Star (w:_) := u * v Star w

(u:_) Star(v:_) Star (w:_) := u * v Star w

Expected behavior

Should print "Succeeded"

Additional context

As stated above, Rubi is broken as a result of this bug. I've Mathics 10.0 and 9.0, and these both give a maximum recursion error exception as well.

[rocky]

Some additional information. I wrapped line 14 inside a TraceEvaluation;

TraceEvaluation[Star[u_,Star[v_,w_]] := Star[u*v,w]]

Also, I dumped the expression being evaluated when the nesting level depth was more than 10 or so

Now, running, the recursion is seen more clearly:

In[1]:= Get["star-bug.wl", Trace->True]
Reading file: ./star-bug.wl

    2: (* If u-v equals 0, EqQ[u,v] returns True; else it returns False. *)
    4: EqQ[args___] := Null /; EqQ[args]
    6: (* Star[u,v] displays as u*v, and returns the product of u and v with u
    9: Star[u_,v_] := (
  Message[Star::error];
  0 ) /;
EqQ[u,0]
    Evaluating: Star[u:_, Star[v:_, w:_]] := u * v \[Star] w
      Evaluating: Star[v:_, w:_]
        Evaluating: EqQ[v:_, 0]
          Evaluating: EqQ[Sequence[v:_, 0]]
            Evaluating: Sequence[v:_, 0]
            Returning : Sequence[v:_, 0] -> Sequence[v:_, 0]
            Evaluating: EqQ[Sequence[v:_, 0]]
              Evaluating: Sequence[v:_, 0]
              Returning : Sequence[v:_, 0] -> Sequence[v:_, 0]
              Evaluating: EqQ[Sequence[v:_, 0]]
                Evaluating: Sequence[v:_, 0]
XXX 10
Star[u:_, Star[v:_, w:_]] := u * v \[Star] w

                Returning : Sequence[v:_, 0] -> Sequence[v:_, 0]
                Evaluating: EqQ[Sequence[v:_, 0]]
                  Evaluating: Sequence[v:_, 0]
XXX 11
Star[u:_, Star[v:_, w:_]] := u * v \[Star] w

                  Returning : Sequence[v:_, 0] -> Sequence[v:_, 0]
                  Evaluating: EqQ[Sequence[v:_, 0]]
                    Evaluating: Sequence[v:_, 0]
XXX 12
Star[u:_, Star[v:_, w:_]] := u * v \[Star] w

                    Returning : Sequence[v:_, 0] -> Sequence[v:_, 0]
                    Evaluating: EqQ[Sequence[v:_, 0]]
                      Evaluating: Sequence[v:_, 0]
XXX 13
Star[u:_, Star[v:_, w:_]] := u * v \[Star] w

And if run set delayed assignment wrapped in the expression in wolframscript as well, I also get a recursion depth exceeded.

From this, I gather that we are doing an evaluation in setdelayed where wolframscript is not (unless wrapped in TraceEvaluation).