Circularity detected when adding a constraint to an &infix:<+> candidate

[grondilu]

The Problem

I encountered a circularity detection error when adding a multi candidate to &infix:<+>. It was very likely a false positive as this candidate was precisely added to fix a message from the compiler about the lack of a candidate.

Expected Behavior

No circularity detection.

Actual Behavior

Circularity detected.

Steps to Reproduce

Here is my attempt at a minimal code to reproduce the error :

class {
  class Foo { has $.x; }
  multi method new(Real $r) { ::?CLASS }

  multi infix:<+>(::?CLASS $a, ::?CLASS $b) { ::?CLASS }
  multi infix:<+>(Real $r, ::?CLASS $y) { samewith ::?CLASS.new($r), $y }

  # When removing the constraint below, no circularity is detected.
  multi infix:<+>(Real $r, Foo $y where $y.x == 1) { samewith $r, ::?CLASS }

  say 1 + Foo.new;
}

Notice that the issue does not occur if instead of adding candidates to &infix:<+>, I create a brand new sub, say &foo.

Environment

• Operating system: fedora-37
• Compiler version: v2022.12-1-gd52342eb0