bug#69749: (bindat-type sint 32 t) -> unbound variable bitlen

[Eli Zaretskii]

> Date: Tue, 12 Mar 2024 16:18:58 +0100
> From: Eric Marsden <eric.marsden@risk-engineering.org>
> 
> -- file bd.el
> (require 'bindat)
> (bindat-pack (bindat-type sint 32 t) 42)
> -- 
> emacs -Q --batch -l bd.el -->
> 
> Error: void-variable (bitlen)
>    mapbacktrace(#f(compiled-function (evald func args flags) #<bytecode 
> -0x160fbb9816517825>))
>    debug-early-backtrace()
>    debug-early(error (void-variable bitlen))
>    (/ bitlen 8)
>    (+ bindat-idx (/ bitlen 8))
>    (setq bindat-idx (+ bindat-idx (/ bitlen 8)))
>    (let ((v field2)) (setq bindat-idx (+ bindat-idx (/ bitlen 8))))
>    (let ((field2 (if (< v 0) (+ v wrap) v))) (let ((v field2)) (setq 
> bindat-idx (+ bindat-idx (/ bitlen 8)))))
>    (let ((v v)) (let ((field2 (if (< v 0) (+ v wrap) v))) (let ((v 
> field2)) (setq bindat-idx (+ bindat-idx (/ bitlen 8))))))
>    (lambda (v) (let ((v v)) (let ((field2 (if (< v 0) (+ v wrap) v))) 
> (let ((v field2)) (setq bindat-idx (+ bindat-idx (/ bitlen 8)))))))(42)
>    bindat--length-group(42 #s(bindat--type :le (lambda (v) (let ((v v)) 
> (let ((field2 (if (< v 0) (+ v wrap) v))) (let ((v field2)) (setq 
> bindat-idx (+ bindat-idx (/ bitlen 8))))))) :ue (lambda nil (let ((n (if 
> t (bindat--unpack-uintr bitlen) (bindat--unpack-uint bitlen)))) (if (>= 
> n max) (- n wrap) n))) :pe (lambda (v) (let ((v v)) (let ((field2 (if (< 
> v 0) (+ v wrap) v))) (let ((v field2)) (if t (bindat--pack-uintr bitlen 
> v) (bindat--pack-uint bitlen v))))))))
>    bindat-length(#s(bindat--type :le (lambda (v) (let ((v v)) (let 
> ((field2 (if (< v 0) (+ v wrap) v))) (let ((v field2)) (setq bindat-idx 
> (+ bindat-idx (/ bitlen 8))))))) :ue (lambda nil (let ((n (if t 
> (bindat--unpack-uintr bitlen) (bindat--unpack-uint bitlen)))) (if (>= n 
> max) (- n wrap) n))) :pe (lambda (v) (let ((v v)) (let ((field2 (if (< v 
> 0) (+ v wrap) v))) (let ((v field2)) (if t (bindat--pack-uintr bitlen v) 
> (bindat--pack-uint bitlen v))))))) 42)
>    bindat-pack(#s(bindat--type :le (lambda (v) (let ((v v)) (let 
> ((field2 (if (< v 0) (+ v wrap) v))) (let ((v field2)) (setq bindat-idx 
> (+ bindat-idx (/ bitlen 8))))))) :ue (lambda nil (let ((n (if t 
> (bindat--unpack-uintr bitlen) (bindat--unpack-uint bitlen)))) (if (>= n 
> max) (- n wrap) n))) :pe (lambda (v) (let ((v v)) (let ((field2 (if (< v 
> 0) (+ v wrap) v))) (let ((v field2)) (if t (bindat--pack-uintr bitlen v) 
> (bindat--pack-uint bitlen v))))))) 42)
>    load-with-code-conversion("/tmp/bd.el" "/tmp/bd.el" nil t)
>    command-line-1(("-l" "/tmp/bd.el"))
>    command-line()
>    normal-top-level()
> Symbol’s value as variable is void: bitlen
> 
> This bug is difficult to understand. Run from an IELM buffer, this code 
> works as expected. The macroexpansion of the bindat-type declaration 
> includes a binding for bitlen.

Thanks, I added Stefan to this discussion.