Anonymous function-body class expression: its outer binding inside its own members resolves to the shared template (C.tag, constructor === C, C.prototype writes) #11153

Summary

Inside the members of an anonymous class expression in a function body, the outer binding name (C in const C = class { … }) resolves to the shared class template. In Node it resolves to the class object that this evaluation produced. For a class that gets a separate class object per evaluation (ClassExprFresh), this means:

• C.tag reads the template's static, not this evaluation's;
• this.constructor === C is false;
• C.prototype.x = v inside a method writes to the template (shared by every evaluation).

A named class expression (class C { … }) is not affected, because its inner self-binding already resolves to the evaluation.

Repro

function mk(v: number) {
  const C = class {
    static tag = v;
    who() { return C.tag; }
    same() { return (this as any).constructor === C; }
  };
  return C;
}
const fs: any[] = [mk];
const A = fs[0](1), B = fs[0](2);
console.log((new A() as any).who(), (new B() as any).who(), (new A() as any).same());

• Node 26.5.1: 1 2 true
• Perry origin/main 36892b7: 0 0 false

Prototype-write variant: a static init() { C.prototype.z = v } / set() { C.prototype.q = v } pair called once per evaluation prints ["z","q"] 1 2 1 2 true in Node and [] 2 2 2 2 false in Perry. This happens both on main and with #11143: the member body is lowered before the outer binding exists, so C is ClassRef(template) and the write becomes a template-keyed RegisterPrototypeMethod.

Found while verifying a CodeRabbit comment on #11143.