CC: Objects not properly tracked

[bracevac]

Compiler version

3.8.1-RC1-bin-20251204-241f261-NIGHTLY

Minimized code

import language.experimental.captureChecking

def foo(c: AnyRef^, d: AnyRef^, e: AnyRef^): Unit =
  object O:
    val x = c
    def foo = println(d)

  val w: O.type = O // O should not be pure, but O^{c,d} 

Output

It's happily accepted by the capture checker.

Expectation

It shouldn't!

[odersky]

In fact, the checking seems to be correct here. w: O.type is correct, the question is what does O capture? We can find out by adding another line to the program:

  val _: AnyRef = w     // error on this line

This gives:

10 |  val _: AnyRef = w // error on this line
   |                  ^
   |               Found:    (w : O.type)
   |               Required: AnyRef
   |
   |               Note that capability c is not included in capture set {}.
   |
   | longer explanation available when compiling with `-explain`

So in fact, O does capture c. I'll add the test case.