bug#33530: 26.1.90; D-Bus crashes Emacs: consp, Fatal error 7: Bus error

[Damien Cassou <damien@cassou.me>]

The following line crashes both Emacs 26 and Emacs master.

emacs -Q -batch --eval "(require 'dbus)" --eval "(dbus-call-method :system \"org.freedesktop.NetworkManager\" \"/org/freedesktop/NetworkManager/Devices/1\" \"org.freedesktop.NetworkManager.Device.Wireless\" \"RequestScan\" :dict-entry)"

Here is a trace on emacs-master.

Wrong type argument: consp, Fatal error 11: Segmentation fault

#0  0x00000000005870c8 in PSEUDOVECTOR_TYPE (v=0xc8c7000c8421c6c0) at lisp.h:1573
        size = -3979211692002130235
#1  0x0000000000675c88 in print_vectorlike (obj=XIL(0xc8c7000c8421c6c5), printcharfun=XIL(0x58b0), escapeflag=true, buf=0x7fffffffca10 "\004") at print.c:1368
#2  0x0000000000678de5 in print_object (obj=XIL(0xc8c7000c8421c6c5), printcharfun=XIL(0x58b0), escapeflag=true) at print.c:2152
        buf = "\004\000\000\000\000\000\000\000\001\000\000\000\000\000\000\000\320\321\000\000\000\000\000\000\260X\000\000\000\000\000\000`\312\377\377\377\177\000\000\tzd\000\000\000\000\000\202\000\000\000\000"
#3  0x000000000067503c in print (obj=XIL(0xc8c7000c8421c6c5), printcharfun=XIL(0x58b0), escapeflag=true) at print.c:1145
#4  0x00000000006727d1 in Fprin1 (object=XIL(0xc8c7000c8421c6c5), printcharfun=XIL(0x58b0)) at print.c:653
        old = 0xcd5800 <bss_sbrk_buffer+457984>
        old_point = -1
        start_point = -1
        old_point_byte = -1
        start_point_byte = -1
        specpdl_count = 4
        free_print_buffer = false
        multibyte = true
        original = XIL(0x58b0)
#5  0x0000000000674b2d in print_error_message (data=XIL(0x13472d3), stream=XIL(0x58b0), context=0xbc093e <pure+3999998> "", caller=XIL(0x2a90)) at print.c:980
        obj = XIL(0xc8c7000c8421c6c5)
        sep = 0x786fef ", "
        errname = XIL(0xe3a0)
        errmsg = XIL(0x7fb874)
        file_error = XIL(0)
        tail = XIL(0x13473b3)
#6  0x0000000000591321 in Fcommand_error_default_function (data=XIL(0x13472d3), context=XIL(0x7f0064), signal=XIL(0x2a90)) at keyboard.c:1005
        sf = 0xce2830 <bss_sbrk_buffer+511280>
#7  0x00000000006485fa in funcall_subr (subr=0x7ebe80 <Scommand_error_default_function>, numargs=3, args=0x7fffffffce48) at eval.c:2939
        internal_argbuf = {XIL(0x7fffffffcdb0), make_number(16107774448), XIL(0x7ebe80), XIL(0x7fffffffcd78), XIL(0x58716b), XIL(0xf00000000), XIL(0x7ebe85), XIL(0x7fffffffcd90)}
        internal_args = 0x7fffffffce48
#8  0x00000000006480ef in Ffuncall (nargs=4, args=0x7fffffffce40) at eval.c:2859
        fun = XIL(0x7ebe85)
        original_fun = XIL(0x9a9d0)
        funcar = XIL(0x7fffffffceb0)
        numargs = 3
        val = XIL(0)
        count = 3
#9  0x0000000000647a93 in call3 (fn=XIL(0x9a9d0), arg1=XIL(0x13472d3), arg2=XIL(0x7f0064), arg3=XIL(0x2a90)) at eval.c:2726
#10 0x00000000005911d8 in cmd_error_internal (data=XIL(0x13472d3), context=0x7fffffffceb0 "") at keyboard.c:972
#11 0x00000000005910b7 in cmd_error (data=XIL(0x13472d3)) at keyboard.c:941
        old_level = XIL(0)
        old_length = XIL(0)
        macroerror = "\000\316\377\377\001", '\000' <repeats 12 times>, "\317\377\377\377\177\000\000s_d", '\000' <repeats 13 times>, "ӛ1\001\000\000\000\000", <incomplete sequence \317>
#12 0x0000000000644047 in internal_condition_case (bfun=0x591523 <top_level_2>, handlers=XIL(0x54c0), hfun=0x590f67 <cmd_error>) at eval.c:1369
        val = XIL(0x13472d3)
        c = 0x2c9b710
#13 0x0000000000591584 in top_level_1 (ignore=XIL(0)) at keyboard.c:1096
#14 0x000000000064356e in internal_catch (tag=XIL(0xcc30), func=0x591542 <top_level_1>, arg=XIL(0)) at eval.c:1136
        val = XIL(0)
        c = 0x2c998e0
#15 0x0000000000591473 in command_loop () at keyboard.c:1057
#16 0x0000000000590a79 in recursive_edit_1 () at keyboard.c:703
        count = 1
        val = XIL(0x7fffffffd040)
#17 0x0000000000590c5b in Frecursive_edit () at keyboard.c:774
        count = 0
        buffer = XIL(0)
#18 0x000000000058e85d in main (argc=7, argv=0x7fffffffd288) at emacs.c:1716
        stack_bottom_variable = 0x7ffff5ed6f40
        do_initial_setlocale = true
        dumping = false
        skip_args = 1
        no_loadup = false
        junk = 0x0
        dname_arg = 0x0
        ch_to_dir = 0x0
        original_pwd = 0x0
        rlim = {
          rlim_cur = 10022912, 
          rlim_max = 18446744073709551615
        }
        sockfd = -1

Lisp Backtrace:
"command-error-default-function" (0xffffce48)

Windowing system distributor 'Fedora Project', version 11.0.12003000
System Description:	Fedora release 29 (Twenty Nine)

-- 
Damien Cassou
http://damiencassou.seasidehosting.st

"Success is the ability to go from one failure to another without
losing enthusiasm." --Winston Churchill