syntax->annotation and improper list.

[uu27183141]

Hi.

At first, I'm not native english speaker.
I am trying scheme's improper list and chezscheme's annotation.

(import (chezscheme))
(define-syntax (test-1 stx) 
 (syntax-case stx () 
  ((this (a . b)) 
   (begin 
    (assert (annotation? (syntax->annotation #'a))) 
    (display '(test-1 (assert (annotation? (syntax->annotation #'a))))) (newline)
    ; this is ok.
    (assert (annotation? (syntax->annotation #'b))) 
    (display '(test-1 (assert (annotation? (syntax->annotation #'b))))) (newline)
    #'(void)))))
(define-syntax (test-2 stx) 
 (syntax-case stx () 
  ((this (a0 ... a . b)) 
   (begin 
    (for-each 
     (lambda (c) 
      (assert (annotation? (syntax->annotation c)))) 
     #'(a0 ...)) 
    (display '(test-2 (assert (annotation? (syntax->annotation #'(a0 ...)))))) (newline)
    (assert (annotation? (syntax->annotation #'a))) 
    (display '(test-2 (assert (annotation? (syntax->annotation #'a))))) (newline)
    ; i think that this should be ok too.
    (assert (annotation? (syntax->annotation #'b))) 
    (display '(test-2 (assert (annotation? (syntax->annotation #'b))))) (newline)
    #'(void)))))
(test-1 (1 . 2))
(test-2 (1 2 . 3))

this is output.

(test-1 (assert (annotation? (syntax->annotation #'a))))
(test-1 (assert (annotation? (syntax->annotation #'b))))
(test-2 (assert (annotation? (syntax->annotation #'(a0 ...)))))
(test-2 (assert (annotation? (syntax->annotation #'a))))
Exception: failed assertion (annotation? (syntax->annotation (syntax b))) at line 24, char 13 of /data/data/com.termux/files/home/bug-report.scm
Type (debug) to enter the debugger.

this is implementation version information.

Chez Scheme Version 10.3.0
Copyright 1984-2025 Cisco Systems, Inc.
>

this is my machine information.

         -o          o-             u0_a326@localhost
          +hydNNNNdyh+              -----------------
        +mMMMMMMMMMMMMm+            OS: Android REL 13 aarch64
      `dMMm:NMMMMMMN:mMMd`          Host: samsung SM-P610
      hMMMMMMMMMMMMMMMMMMh          Kernel: Linux 4.14.113-27209537
  ..  yyyyyyyyyyyyyyyyyyyy  ..      Uptime: 51 days, 14 hours, 51 mins
.mMMm`MMMMMMMMMMMMMMMMMMMM`mMMm.    Packages: 293 (dpkg)
:MMMM-MMMMMMMMMMMMMMMMMMMM-MMMM:    Shell: bash
:MMMM-MMMMMMMMMMMMMMMMMMMM-MMMM:    DE: TP1A.220624.014.P610KSU4FWH7
:MMMM-MMMMMMMMMMMMMMMMMMMM-MMMM:    WM: WindowManager (SurfaceFlinger)
:MMMM-MMMMMMMMMMMMMMMMMMMM-MMMM:    Terminal: Termux googleplay.2025.10.05
-MMMM-MMMMMMMMMMMMMMMMMMMM-MMMM-    Terminal Font: monospace
 +yy+ MMMMMMMMMMMMMMMMMMMM +yy+     CPU: 2 x Exynos 9611 (8) @ 2.31 GHz
      mMMMMMMMMMMMMMMMMMMm          GPU: ARM Mali-G72
      `/++MMMMh++hMMMM++/`          Memory: 3.05 GiB / 3.62 GiB (84%)
          MMMMo  oMMMM              Swap: 1.91 GiB / 4.00 GiB (48%)
          MMMMo  oMMMM              Disk (/): 4.29 GiB / 4.31 GiB (99%) - ext4 [Read-only]
          oNMm-  -mMNs              Disk (/storage/emulated): 15.53 GiB / 50.49 GiB (31%) - fuse
                                    Local IP (wlan0): 192.168.15.202/24
                                    Locale: en_US.UTF-8

In this code, the code (assert (annotation? (syntax->annotation #'b))) does not work as my expectation.
I can't make sure whether this is a bug or not.
Can anyone verify this?

Thanks for reading.