[m-rev.] for preliminary review: bug 493 & 532 alterative fix

[Zoltan Somogyi]

2021-05-14 17:18 GMT+10:00 "Peter Wang" <novalazy at gmail.com>:
> Before that, though, it establishes the equivalence V = Base:
> 
>     eqvclass.ensure_equivalence(Var, OldVar, VarEqv1, VarEqv),
>     !Common·var_eqv := VarEqv,

That call to ensure_equivalence is required to avoid bad behavior when
ArgVars is not [], as per commit 98c498673d70d2f6840586db8d8e72c134d20f52.
I will look into whether avoiding that call when ArgVars is [], or using
the oldest synonym (Base) instead of a newer one (V) only when ArgVars
is not empty, has any bad effects.

Zoltan.