dumper does not produce core that gdb recognizes?

["Lavrentiev, Anton (NIH/NLM/NCBI) [C]" <lavr@ncbi.nlm.nih.gov>]

Hi all,

I need to do some deep debugging on Cygwin so I need to produce a core...  And it does not work.

So I reduced the problem to this minimal test case:

$ cat a.c
#include <stdlib.h>

int main()
{
    abort();
}

$ gcc -Wall -g a.c

$ echo $CYGWIN
error_start=c:\cygwin64\bin\dumper.exe

$ ulimit -a
core file size          (blocks, -c) unlimited
data seg size           (kbytes, -d) unlimited
file size               (blocks, -f) unlimited
open files                      (-n) 3200
pipe size            (512 bytes, -p) 8
stack size              (kbytes, -s) 2036
cpu time               (seconds, -t) unlimited
max user processes              (-u) 256
virtual memory          (kbytes, -v) unlimited

$ ./a
*** starting debugger for pid 19934, tid 9332

$ ls -l a.*
-rw-r--r-- 1 ANTON None      49 Jul  8 17:40 a.c
-rwxr-xr-x 1 ANTON None  161487 Jul  8 17:41 a.exe*
-rw-r--r-- 1 ANTON None 3331640 Jul  8 17:46 a.exe.core

$ file a.*
a.c:        C source, ASCII text
a.exe:      PE32+ executable (console) x86-64, for MS Windows
a.exe.core: ELF 64-bit LSB core file, x86-64, version 1 (SYSV)

BUT: gdb does not want this core file:

$ gdb ./a.exe a.exe.core
GNU gdb (GDB) (Cygwin 9.2-1) 9.2
Copyright (C) 2020 Free Software Foundation, Inc.
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-pc-cygwin".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from ./a.exe...
"/home/ANTON/a.exe.core": no core file handler recognizes format
(gdb)

What I am doing wrong?

TIA,

Anton Lavrentiev
Contractor NIH/NLM/NCBI