Fix flags in signature of remove, member and assoc

[gus-massa]

They can not be discarded in case they are comparing records with a custom equal procedure that has side effects.

[burgerrg]

Thanks for finding this! Do you have a short example that demonstrates the problem? If so, adding a mat for it would be helpful.

[gus-massa]

Something like this commit? I couldn't write a shorter version. (Note that if you test it in the current version of Chez Scheme, it fails for #3%remove, but it's ok #2%remove.)

If you like the example, I can copy it to the mats of assoc and member and squash the commits.

[jltaylor-us]

Seems like a reasonable test to me, and I can confirm that without the fix in this PR you get different results at optimize levels 2 and 3.

[burgerrg]

Thanks, the short example tests whether remove calls the equality predicate. You don't need the box:

(let ()
  (define called #f)
  (define-record-type r)
  (record-type-equal-procedure (record-type-descriptor r)
   (lambda (x y eql?) (set! called #t) #t))
  (remove (make-r) (list (make-r)))
  called)

Please use this kind of example for assoc and member. Please update the release notes by explaining that an optimization bug with these predicates was fixed when using custom record equality predicates with side effects in optimize-level 3.

[gus-massa]

Done.