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Subject: gdb and core files
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From: Ken Brown via Cygwin <cygwin AT cygwin DOT com>
Reply-To: Ken Brown <kbrown AT cornell DOT edu>
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Following the instructions at 
https://cygwin.com/cygwin-ug-net/using-cygwinenv.html, I tried to create a core 
file that I could examine with gdb, but I apparently ran into a gdb bug.  I 
tried both gdb 9.2-1 and 8.3.1-1.  Here are the results with 9.2-1.

$ cat crash.c
#include <stddef.h>
int
main ()
{
   char *p = NULL;
   char c = *p;
}

$ gcc -g crash.c

$ CYGWIN='error_start:c:\cygwin64\bin\dumper.exe' ./a
*** starting debugger for pid 2034, tid 99552

$ gdb ./a.exe a.exe.core
GNU gdb (GDB) (Cygwin 9.2-1) 9.2
[...]
Reading symbols from ./a.exe...

warning: core file may not match specified executable file.
[New Thread 0x1b724]
[New Thread 0x23450]
[New Thread 0x16cb4]
[New Thread 0x1c4b4]
[New Thread 0x9050]

warning: Unexpected size of section `.reg/112420' in core file.
/wip/cygport-git/gdb/gdb-9.2-1.x86_64/src/gdb-9.2/gdb/corelow.c:640: 
internal-error: void core_target::get_core_register_section(regcache*, const 
regset*, const char*, int, int, const char*, bool): Assertion `m_core_vec != 
nullptr' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n) y

This is a bug, please report it.  For instructions, see:
<http://www.gnu.org/software/gdb/bugs/>.

/wip/cygport-git/gdb/gdb-9.2-1.x86_64/src/gdb-9.2/gdb/corelow.c:640: 
internal-error: void core_target::get_core_register_section(regcache*, const 
regset*, const char*, int, int, const char*, bool): Assertion `m_core_vec != 
nullptr' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Create a core file of GDB? (y or n) n

Did I do something wrong?

Ken
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