How does nativecomp compile circular lists?

[Jimmy Yuen Ho Wong <wyuenho@gmail.com>]

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I'm not exactly sure how to even ask this question, as I've seen various
packages fail to natively compile circular lists
<https://github.com/milkypostman/powerline/pull/189> or optimize it wrongly
<https://github.com/jrblevin/markdown-mode/pull/624>. So I've come up with
a simple test case for me to be able to disassemble the bytecode and the
native code, and see if I could spot the problem, but disassembling
natively compiled code doesn't seem to work.

Test case:

(defun test-circular-list ()
  (let ((l (list 1 2 3)))
    (setcdr (last l) l)
    l))

(print (test-circular-list))

(provide 'test-circular-list)

M-x emacs-lisp-byte-compile-and-load
M-x disassemble RET test-circular-list (works)

M-x emacs-lisp-native-compile-and-load
M-x disassemble RET test-circular-list (doesn't work)

Debugger entered--Lisp error: (search-failed
"^.*<F746573742d63697263756c61722d6c697374_test_cir...")
  re-search-forward("^.*<F746573742d63697263756c61722d6c697374_test_cir...")
  disassemble-internal(test-circular-list 0 nil)
  disassemble(test-circular-list nil 0 t)
  funcall-interactively(disassemble test-circular-list nil 0 t)
  command-execute(disassemble record)
  execute-extended-command(nil "disassemble" nil)
  funcall-interactively(execute-extended-command nil "disassemble" nil)
  command-execute(execute-extended-command)

Furthermore, this test case, though superficially similar, doesn't seem to
be able to reproduce the same failure to natively compile issue as seen in
powerline.

There seems to be more than one thing wrong with this journey into my deep
dive into how native compiling circular lists work.

Jimmy Yuen Ho Wong

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