Re: recent master core dumps building on FreeBSD i386

[Joseph Mingrone]

Paul Eggert <address@hidden> writes:

> On 10/17/18 9:10 AM, Eli Zaretskii wrote:
>>> As far as I can tell, the core dump began with f5896e2.
>> This is unexpected.  Can you run the offending command under GDB and
>> show the backtrace from the crash, please?

> Quite possibly this is yet another obscure bug involving dumping. I hope the 
> portable dumper will be merged soon. Could you please remind me what the 
> remaining trouble spots are with pdumper, i.e., the
> issues that are preventing merging that branch in?

> Anyway, I struggled a bit with Joseph's report (trying lots of ways to build 
> Emacs master on Fedora 28) and managed to reproduce a similar problem that 
> does indeed involve dumping. I installed into Emacs
> master the attached patch, which fixed that bug for me. Joseph, please try 
> the latest master, and if that doesn't work then GDB may well be your friend 
> (though it may not be; dumping leads to reaaaally
> obscure problems).

The core dump still occurs with that commit (e511b9d).  With `CFLAGS+=-O0 
-ggdb` the build completed without problems.  With just `CFLAGS+=-ggdb` it did 
core dump.  A back trace is below.

address@hidden:/wrkdirs/usr/ports/editors/emacs-devel/work-full/emacs-e511b9d/src
 # /usr/local/bin/gdb ./temacs
GNU gdb (GDB) 8.2 [GDB v8.2 for FreeBSD]
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License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
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For help, type "help".
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Reading symbols from ./temacs...done.
SIGINT is used by the debugger.
Are you sure you want to change it? (y or n) [answered Y; input not from 
terminal]
Environment variable "DISPLAY" not defined.
TERM = screen-256color
Breakpoint 1 at 0x81599de: file emacs.c, line 370.
Temporary breakpoint 2 at 0x8177f95: file sysdep.c, line 1080.
(gdb) run --batch --no-build-details --load loadup bootstrap
Starting program: 
/wrkdirs/usr/ports/editors/emacs-devel/work-full/emacs-e511b9d/src/temacs 
--batch --no-build-details --load loadup bootstrap

./lisp.h:1170: Emacs fatal error: assertion failed: TAGGEDP (a, type) && XUNTAG 
(a, type, char) == ptr

Breakpoint 1, terminate_due_to_signal (sig=6, backtrace_limit=2147483647) at 
emacs.c:370
370       signal (sig, SIG_DFL);
(gdb) bt
#0  terminate_due_to_signal (sig=6, backtrace_limit=2147483647) at emacs.c:370
#1  0x081b6b7b in die (msg=0x8280b68 "TAGGEDP (a, type) && XUNTAG (a, type, 
char) == ptr", file=0x828071a "./lisp.h", line=1170) at alloc.c:7096
#2  0x08249a00 in make_lisp_ptr (type=Lisp_Vectorlike, ptr=<optimized out>) at 
./lisp.h:1170
#3  syms_of_threads () at thread.c:1133
#4  0x0815b280 in main (argc=<optimized out>, argv=0xffffda6c) at emacs.c:1630
(gdb)

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