On OpenBSD-current (and I suppose any other OBSD version) there's a PITA bug in latest Gambit when compiled with --enable-cplusplus. I tried it with G++ 4.7.2 and 4.6.3. Possibly this bug exists also with any Gambit version.

terminate called after throwing an instance of '___throw_struct'

terminate called recursively

Abort trap (core dumped)

I've been hunting this bug down quite extensively now and it appears to me that Gambit's normal way of terminating (at least on OBSD and Debian) is by throwing an uncaught exception, containing a ___throw_struct whose content is a __SCMOBJ containing a fixnum by the number one (1)???

But if so, why is not an uncaught exception error printed at gsc termination on every platform (which is g++'s default behavior)???

Would greatly appreciate a hand in resolving this bug, it takes time generating the core file, clutters the terminal by requiring you to run reset after every gsc session, and primarily, it gives a terrible 'out of control' sense to the console interaction!..

Find my notes in hunting this one down below. If I can check for or try anything particular as to resolve the originating cause, please just tell me what.

I've tried to track this down while comparing execution flows between OpenBSD and Debian and I'm a but puzzled:

Fundamentally the error is caused by the ___THROW (err); inside ___propagate_error defined in lib/setup.c, row ~1895 , see GDB session below for this.

The invocation to ___propagate_error is made from one place in all Gambit namely |##exit-with-err-code-no-cleanup| in lib/_kernel.scm:~4356.

On both OBSD and Debian, ___USE_SETJMP is *not defined* so it's the *second* set of exception handling macros including ___THROW in include/gambit.h that are used i.e.:

#define ___BEGIN_TRY { ___err = ___FIX(___NO_ERR); try {

#define ___END_TRY } catch (___throw_struct ts) { ___err = ts.err; } }

#define ___THROW(e)do { ___throw_struct ts; ts.err = e; throw (ts); } while (0)

#define ___ON_THROW(stat1,stat2) \

___ON_THROW_AUX(,stat1,stat2)

So this is the throw() that causes the uncaught exception, that produces this entire error.

On both OBSD and Debian, on normal Gambit termination, |##exit-with-err-code-no-cleanup| is invoked with the fixnum 1 as argument, leading to a ___THROW with 4 as argument, 4 is Gambit's internal object representation for the fixnum 1.

I tried to trace the source of the invocation to |##exit-with-err-code-no-cleanup| but didn't quite succeed.

I tried in three ways of catching this thrown exception, and they failed (listing of methods and code used below).

Below are the outputs from a related GDB session and failed attempts to hunt down

The console output doesn't show anything, and except for a section highlighted below, configure doesn't seem to show anything.

GDB output: Tracking down the location of the throw() for the uncaught exception

# egdb gsc

GNU gdb (GDB) 7.5

License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>

This is free software: you are free to change and redistribute it.

There is NO WARRANTY, to the extent permitted by law. Type "show copying"

and "show warranty" for details.

This GDB was configured as "x86_64-unknown-openbsd5.2".

For bug reporting instructions, please see:

<http://www.gnu.org/software/gdb/bugs/>...

Reading symbols from /usr/bin/gsc...done.

(gdb) run

Starting program: /usr/bin/gsc

Gambit v4.6.6

Program received signal SIGTSTP, Stopped (user).

0x000016f1c39a951a in select () at <stdin>:2

2 <stdin>: No such file or directory.

(gdb) catch catch

Catchpoint 1 (catch)

(gdb) catch throw

Catchpoint 2 (throw)

(gdb) catch exception

Unable to insert catchpoint. Is this an Ada main program?

(gdb) catch unknown exception

Undefined catch command: "unknown exception". Try "help catch".

(gdb) catch exception unhandled

Unable to insert catchpoint. Is this an Ada main program?

(gdb) cont

Continuing.

Catchpoint 2 (exception thrown), __cxxabiv1::__cxa_throw (obj=0x16f1c758c480, tinfo=0x16efbce1e490 <typeinfo for ___throw_struct>, dest=0x0)

at /usr/obj/gcc-4.7.2/gcc-4.7.2/libstdc++-v3/libsupc++/eh_throw.cc:70

70 /usr/obj/gcc-4.7.2/gcc-4.7.2/libstdc++-v3/libsupc++/eh_throw.cc: No such file or directory.

(gdb) bt

#0 __cxxabiv1::__cxa_throw (obj=0x16f1c758c480, tinfo=0x16efbce1e490 <typeinfo for ___throw_struct>, dest=0x0)

at /usr/obj/gcc-4.7.2/gcc-4.7.2/libstdc++-v3/libsupc++/eh_throw.cc:70

#1 0x000016efbc830f78 in ___propagate_error(long) ()

#2 0x000016efbc855a7b in ___H__20___kernel(___processor_state_struct*) ()

#3 0x000016efbc831026 in ___call(int, long, long) ()

#4 0x000016efbc832cee in ___setup(___setup_params_struct*) ()

#5 0x000016efbc847a0e in ___main(___mod_or_lnk_union* (*)(___global_state_struct*)) ()

#6 0x000016efbc83c3b3 in ___main_char(int, char**, ___mod_or_lnk_union* (*)(___global_state_struct*), char*) ()

#7 0x000016efbc830216 in main (argc=1, argv=0x7f7ffffbdfa0) at _gsc_.c:13627

(gdb)

Failed attempts to catch the exception

(A) Hooking the uncaught exception handler via std::set_terminate(); , see example code for this below. Funny enough this did not work, it gave "no active exception".

(B) Tried running a REPL inside a try { .. } catch statement and do ,q from it. Did not work.

(C) Tried to put debug output include/gambit.h and lib/os_base.c around 1) Gambit's main() procedure and 2) around the try { .. } catch-code that actually is there. I would guess the code modified in 2) not runs though as it only runs when longjumps are not on. Printed "Gambit Started.\Past ___setup_base_module()\nInto ___main.\n". and that's all, all the way until C++' uncaught exception handler prints its error message. So, did not work.

* (A) code

; http://efesx.com/2010/03/21/catching-uncaught-exceptions-within-terminate/

(c-declare #<<c-declare

#include <iostream>

#include <stdexcept>

#include <exception>

void our_terminate (void) {

printf("Terminating..\n");

static bool tried_throw = false;

try {

if (!tried_throw++) throw;

std::cout << "no active exception" << std::endl;

}

catch (___SCMOBJ err) {

printf("Got SCMOBJ %lld.\n",err);

}

catch (const std::runtime_error &err) {

std::cout << "caught a runtime_error. what(): " <<

err.what() << std::endl;

}

catch (...) {

std::cout << "unknown exception occurred." <<

std::endl;

}

c-declare

)

(c-initialize #<<c-initialize

std::set_terminate(our_terminate);

c-initialize

)

* (B) code

(c-define (runscm thunk) (scheme-object) void "runscm" ""

(print "(runscm): Running thunk.\n")

(thunk)

(print "(runscm): Back from thunk.\n"))

(define (c++-try-catch thunk)

((c-lambda (scheme-object) void #<<c-lambda-end

___SCMOBJ thunk = ___arg1;

try {

runscm(thunk);

} catch (___throw_struct e) {

fprintf(stderr,"Caught a ___throw_struct!\n");

} catch (...) {

fprintf(stderr,"Caught some other excepion.\n");

}

c-lambda-end

) thunk))

(c++-try-catch ##repl)

* (C) code

include/gambit.h

#ifdef ___USE_SETJMP

...

#define ___BEGIN_TRY { ___err = ___FIX(___NO_ERR); try {

#define ___END_TRY } catch (___throw_struct ts) { printf("___END_TRY caught a ___throw_struct.\n"); ___err = ts.err; } }

#define ___THROW(e)do { ___throw_struct ts; ts.err = e; printf(stderr,"___THROW throws a ___throw_struct.\n"); throw (ts); } while (0)

#define ___ON_THROW(stat1,stat2) \

___ON_THROW_AUX(,stat1,stat2)

#endif

#define ___ON_THROW_AUX(decl,stat1,stat2) \

do { \

fprintf(stderr,"___ON_THROW_AUX\n"); \

___SCMOBJ ___err; decl \

___BEGIN_TRY stat1; ___END_TRY \

if (___err != ___FIX(___NO_ERR)) stat2; \

} while (0)

lib/os_base.c:

___EXP_FUNC(int,___main_char)

___P((int argc,

char *argv[],

___mod_or_lnk (*linker)(___global_state_struct*),

char *script_line),

(argc,

argv,

linker,

script_line)

int argc;

char *argv[];

___mod_or_lnk (*linker)();

char *script_line;)

{

int result;

fprintf(stderr,"Gambit started.\n");

try {

if (___setup_base_module () != ___FIX(___NO_ERR))

result = ___EXIT_CODE_OSERR;

else

{

fprintf(stderr,"Past ___setup_base_module()\n");

if (___NONNULLCHARSTRINGLIST_to_NONNULLUCS_2STRINGLIST

(argv,

&___program_startup_info.argv)

!= ___FIX(___NO_ERR))

result = ___EXIT_CODE_SOFTWARE;

else

{

if (___CHARSTRING_to_UCS_2STRING

(script_line,

&___program_startup_info.script_line)

!= ___FIX(___NO_ERR))

result = ___EXIT_CODE_SOFTWARE;

else

{

fprintf(stderr,"Into ___main\n");

result = ___main (linker);

fprintf(stderr,"Out of ___main\n");

___free_UCS_2STRING (___program_startup_info.script_line);

}

___free_NONNULLUCS_2STRINGLIST (___program_startup_info.argv);

}

fprintf(stderr,"Into ___cleanup_base_module\n");

___cleanup_base_module ();

fprintf(stderr,"Out of ___cleanup_base_module.\n");

}

} catch (___throw_struct e) {

fprintf(stderr,"Caught a ___throw_struct!\n");

} catch (...) {

fprintf(stderr,"Caught some other excepion.\n");

}

fprintf(stderr,"Gambit ended.\n");

return result;

}

./configure log

$ CXFLAGS="-g -ggdb -gdwarf-3 -gstrict-dwarf -O0" ./configure --enable-cplusplus --enable-single-host (note misspelling on env var, anyhow)

checking build system type... amd64-unknown-openbsd5.2

checking host system type... amd64-unknown-openbsd5.2

checking target system type... amd64-unknown-openbsd5.2

checking for gcc... gcc

checking for C compiler default output file name... a.out

checking whether the C compiler works... yes

checking whether we are cross compiling... no

checking for suffix of executables...

checking for suffix of object files... o

checking whether we are using the GNU C compiler... yes

checking whether gcc accepts -g... yes

checking for gcc option to accept ISO C89... none needed

checking how to run the C preprocessor... gcc -E

checking for g++... g++

checking whether we are using the GNU C++ compiler... yes

checking whether g++ accepts -g... yes

checking how to run the C++ preprocessor... g++ -E

checking for grep that handles long lines and -e... /usr/bin/grep

checking for egrep... /usr/bin/grep -E

checking for ANSI C header files... yes

checking for sys/types.h... yes

checking for sys/stat.h... yes

checking for stdlib.h... yes

checking for string.h... yes

checking for memory.h... yes

checking for strings.h... yes

checking for inttypes.h... yes

checking for stdint.h... yes

checking for unistd.h... yes

checking for void*... yes

checking size of void*... 8

checking for long... yes

checking size of long... 8

checking for bool... yes

checking whether g++ defines __GNUC__... yes

checking whether g++ defines __clang__...

checking whether g++ defines __llvm__...

checking whether g++ defines _MSC_VER...

checking errno.h usability... yes

checking errno.h presence... yes

checking for errno.h... yes

checking float.h usability... yes

checking float.h presence... yes

checking for float.h... yes

checking signal.h usability... yes

checking signal.h presence... yes

checking for signal.h... yes

checking stdio.h usability... yes

checking stdio.h presence... yes

checking for stdio.h... yes

checking for stdlib.h... (cached) yes

checking for string.h... (cached) yes

checking time.h usability... yes

checking time.h presence... yes

checking for time.h... yes

checking for unistd.h... (cached) yes

checking pwd.h usability... yes

checking pwd.h presence... yes

checking for fcntl.h... yes

checking sys/ioctl.h usability... yes

checking sys/ioctl.h presence... yes

checking for sys/ioctl.h... yes

checking sys/socket.h usability... yes

checking sys/socket.h presence... yes

checking for sys/socket.h... yes

checking for strings.h... (cached) yes

checking for memory.h... (cached) yes

checking sys/sysctl.h usability... no

checking sys/sysctl.h presence... yes

configure: WARNING: sys/sysctl.h: present but cannot be compiled - This is documented at http://fxr.watson.org/fxr/source/sys/sysctl.h?v=OPENBSD , doesn't look like anything that would crash an ordinary Gambit session??

configure: WARNING: sys/sysctl.h: check for missing prerequisite headers?

configure: WARNING: sys/sysctl.h: see the Autoconf documentation

configure: WARNING: sys/sysctl.h: section "Present But Cannot Be Compiled"

configure: WARNING: sys/sysctl.h: proceeding with the preprocessor's result

configure: WARNING: sys/sysctl.h: in the future, the compiler will take precedence

configure: WARNING: ## -------------------------------------- ##

configure: WARNING: ## Report this to gambit@iro.umontreal.ca ##

configure: WARNING: ## -------------------------------------- ##

checking for sys/sysctl.h... yes

checking crt_externs.h usability... no

checking crt_externs.h presence... no

checking for crt_externs.h... no

checking ws2tcpip.h usability... no

checking ws2tcpip.h presence... no

checking for ws2tcpip.h... no

checking TargetConditionals.h usability... no

checking TargetConditionals.h presence... no

checking for TargetConditionals.h... no

checking for socklen_t... yes

checking for library containing asin... none required

checking for library containing dlopen... none required

checking for library containing shl_load... no

checking for library containing socket... none required

checking for library containing gethostbyname... none required

checking for library containing hstrerror... none required

checking for library containing openpty... -lutil

checking for library containing WSAStartup... no

checking for pipe... yes

checking for socketpair... yes

checking for chdir... yes

checking for execvp... yes

checking for getgrnam... yes

checking for getpid... yes

checking for getppid... yes

checking for getpwnam... yes

checking for ioctl... yes

checking for link... yes

checking for mkdir... yes

checking for mkfifo... yes

checking for opendir... yes

checking for rename... yes

checking for rmdir... yes

checking for socket... yes

checking for stat... yes

checking for stat64... no

checking for strerror... yes

checking for symlink... yes

checking for sysconf... yes

checking for sysctl... yes

checking for unlink... yes

checking for waitpid... yes

checking for mmap... yes

checking for tcgetattr... yes

checking for sigaction... yes

checking for sigemptyset/sigaddset... yes

checking for sigprocmask... yes

checking for signal... yes

checking for environ... yes

checking for _NSGetEnviron... no

checking for clock_gettime... yes

checking for getclock... no

checking for gettimeofday... yes

checking for ftime... no

checking for time... yes

checking for nanosleep... yes

checking for sleep... yes

checking for getrusage... yes

checking for times... yes

checking for clock... yes

checking for DosQuerySysInfo... no

checking for setitimer... yes

checking for dos_setvect... no

checking for DosStartTimer... no

checking for VInstall... no

checking for shl_load... no

checking for DosLoadModule... no

checking for dxe_load... no

checking for GetDiskFragment... no

checking for dlopen... yes

checking for NSLinkModule... no

checking for gethostname... yes

checking for inet_pton... yes

checking for getaddrinfo... yes

checking for gethostbyname... yes

checking for gethostbyaddr... yes

checking for getservbyname... yes

checking for getservbyport... yes

checking for getprotobyname... yes

checking for getprotobynumber... yes

checking for getnetbyname... yes

checking for select... yes

checking for openpty... yes

checking for getpt... no

checking for ptsname... no

checking for ctermid... yes

checking for isastream... no

checking for hstrerror... yes

checking for get_fpc_csr... no

checking for struct stat64... no

checking how g++'s preprocessor evaluates (__GNUC__*1000+__GNUC_MINOR__)>=4002&&(__GNUC__*1000+__GNUC_MINOR__)<=4003...

checking how g++'s preprocessor evaluates __llvm__ && !__clang__ && (__GNUC__*1000+__GNUC_MINOR__)<4005...

checking whether g++ accepts -no-cpp-precomp...

checking whether g++ accepts -fschedule-insns2... -fschedule-insns2

checking whether g++ accepts -fno-trapping-math... -fno-trapping-math

checking whether g++ accepts -fno-move-loop-invariants... -fno-move-loop-invariants

checking whether g++ accepts -fno-keep-inline-dllexport...

checking whether g++ accepts -mieee...

checking whether g++ accepts -mieee-with-inexact...

checking whether g++ accepts -mieee-fp... -mieee-fp

checking whether g++ accepts -Wall... -Wall

checking whether g++ accepts -W... -W

checking whether g++ accepts -Wno-unused... -Wno-unused

checking whether g++ accepts -Wno-write-strings... -Wno-write-strings

checking whether g++ accepts -ftest-coverage... -ftest-coverage

checking whether g++ accepts -fprofile-arcs... -fprofile-arcs

checking whether g++ accepts -fbranch-probabilities... -fbranch-probabilities

checking whether g++ accepts -O1... -O1

checking whether g++ accepts -O2... -O2

checking whether g++ accepts -fno-math-errno... -fno-math-errno

checking whether g++ accepts -fno-strict-aliasing... -fno-strict-aliasing

checking whether g++ accepts -fwrapv... -fwrapv

checking whether g++ accepts -fomit-frame-pointer... -fomit-frame-pointer

checking whether g++ accepts -fPIC... -fPIC

checking whether g++ accepts -fpic... -fpic

checking whether g++ accepts -fno-common... -fno-common

checking whether g++ accepts -rdynamic...

checking whether g++ accepts -shared... -shared

checking for X... libraries /usr/X11R6/lib, headers /usr/X11R6/include

checking whether -R must be followed by a space... no

checking for gethostbyname... (cached) yes

checking for connect... yes

checking for remove... yes

checking for shmat... yes

checking for IceConnectionNumber in -lICE... yes

checking whether ln -s works... yes

checking for ranlib... ranlib

checking whether make sets $(MAKE)... yes

configure: creating ./config.status

config.status: creating makefile

config.status: creating include/makefile

config.status: creating include/gambit.h

config.status: creating lib/makefile

config.status: creating lib/guide/guidepro

config.status: creating lib/guide/makefile

config.status: creating lib/guide/images/makefile

config.status: creating gsi/makefile

config.status: creating gsc/makefile

config.status: creating bin/makefile

config.status: creating bin/gambc-cc.unix

config.status: creating bin/gambc-cc.bat.windows

config.status: creating bin/gambc-doc.unix

config.status: creating bin/gambc-doc.bat.windows

config.status: creating misc/makefile

config.status: creating doc/makefile

config.status: creating tests/makefile

config.status: creating examples/makefile

config.status: creating examples/distr-comp/makefile

config.status: creating examples/pi/makefile

config.status: creating examples/ring/makefile

config.status: creating examples/web-repl/makefile

config.status: creating examples/web-server/makefile

config.status: creating examples/tcltk/makefile

config.status: creating examples/Xlib-simple/makefile

config.status: creating examples/pthread/makefile

config.status: creating examples/misc/makefile

config.status: creating contrib/makefile

config.status: creating contrib/GambitREPL/makefile

config.status: creating prebuilt/makefile

config.status: creating prebuilt/macosx/makefile

config.status: creating prebuilt/macosx/build-phase2

config.status: creating prebuilt/windows/makefile

config.status: creating prebuilt/windows/build-phase2

config.status: creating include/config.h