Various improper results from fresh compiled repl-min.scm

[apg]

Have been exploring ribbit a bit lately, and working on a Zig implementation (which will probably diverge a lot from this as I explore additions to the RVM). Anyway, in the midst of trying to understand the RVM decoding, I encountered the following on a fresh git clone:

~/tmp/ribbit/src $ csi -q rsc.scm -t c -l min -m repl-min.scm 
~/tmp/ribbit/src $ gcc -o rvm.min repl-min.scm.c
~/tmp/ribbit/src $ ./rvm.min
> (string-length "hello")
()
> (string-ref "hello" 1)
Segmentation fault (core dumped)
apg@hc-apg:~/tmp/ribbit/src $ grep fer-gnirts repl-min.scm.c
    "Detouq,htgnel-gnirts,fer-gnirts,fi,!rdc-tes,tsil>-rotcev,!tes-gnirts,"
char *input = "E!rdc-tes,rddc,=,htgnel-gnirts,fer-gnirts,!tes-gnirts,gnirts-ekam,?rotcev,tsil>-
    ***SNIP***

As you can see, string-ref is in there, so the segfault is not occurring due to an unknown procedure or something (it would seem). Loading gdb:

~/tmp/ribbit/src $ gcc -g -o rvm.min.g repl-min.scm.c 
~/tmp/ribbit/src $ ./rvm.min.g 
> (string-ref "hello" 1)
Segmentation fault (core dumped)
~/tmp/ribbit/src $ gdb ./rvm.min.g 
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Reading symbols from ./rvm.min.g...
(gdb) run
Starting program: /home/apg/tmp/ribbit/src/rvm.min.g 
> (string-ref "hello" 1)

Program received signal SIGSEGV, Segmentation fault.
prim (no=6) at repl-min.scm.c:440
440         push2(CAR(x), PAIR_TAG);

I'd try this with min-tc, which I suspect might provide more clues, but that doesn't exist.

I did test the min defintions of list-ref and list-tail in chicken "just to be sure":

#;1> (define (list-ref lst i)
   (car (list-tail lst i)))

Note: assignment to imported value binding: list-ref
#;2> (define (list-tail lst i)
     (if (< 0 i) (list-tail (cdr lst) (- i 1)) lst))

Note: assignment to imported value binding: list-tail
#;3> (list-ref (string->list "hello") 1)
#\e

Finally, doing the same thing with the repl-max, I get correct results:

~/tmp/ribbit/src $ csi -q rsc.scm -t c -l max -m repl-max.scm 
~/tmp/ribbit/src $ ls
host  minify.scm    repl-max.scm.c  repl-min.scm.c  rvm.min
lib   repl-max.scm  repl-min.scm    rsc.scm         tests
~/tmp/ribbit/src $ gcc -o rvm.max repl-max.scm.c 
~/tmp/ribbit/src $ ./rvm.max
> (string-length "hello")
5
> (string-ref "hello" 1)
101
> 

In the min.scm, library string-length is an alias to field1 which makes this pretty interesting. I would say that field1 is somehow not linked properly, but it's of course a primitive. Also, car and cdr work just fine.

Also of note that using -l max and compiling repl-min works just fine. I guess it's possible that I should have no expectation that this works, but figured I'd raise it anyway.