[Bug libstdc++/102077] New: null-pointer dereference in std::thread::detach()

["florin.iucha at amd dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102077

            Bug ID: 102077
           Summary: null-pointer dereference in std::thread::detach()
           Product: gcc
           Version: 11.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: florin.iucha at amd dot com
  Target Milestone: ---

Building static GDB using crosstool-ng
(https://github.com/cpackham/crosstool-ng/tree/glibc-2.34) using: glibc 2.34,
binutils 2.37, GCC from 11 branch (2e90914b79dd1c591c8a4d663ae2319fbb15df2c),
gdb 10.2 (statically linked) I get crash on startup:


fldiag114 ~/x-tools/x86_64-tng-linux-gnu$ gdb
./x86_64-tng-linux-gnu/debug-root/usr/bin/gdb
GNU gdb (Ubuntu 10.2-0ubuntu1~18.04~2) 10.2
Copyright (C) 2021 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
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Traceback (most recent call last):
  File "<string>", line 3, in <module>
ModuleNotFoundError: No module named 'libstdcxx'
/home/fiucha/.gdbinit:7: Error in sourced command file:
Error while executing Python code.
Reading symbols from ./x86_64-tng-linux-gnu/debug-root/usr/bin/gdb...
(gdb) run
Starting program:
/home/fiucha/x-tools/x86_64-tng-linux-gnu/x86_64-tng-linux-gnu/debug-root/usr/bin/gdb
[Detaching after vfork from child process 35124]
[New LWP 35125]

Thread 1 "gdb" received signal SIGSEGV, Segmentation fault.
0x0000000000000000 in ?? ()
(gdb) bt
#0  0x0000000000000000 in ?? ()
#1  0x0000000000ac96c9 in std::thread::detach() ()
#2  0x0000000000a4424b in gdb::thread_pool::set_thread_count(unsigned long) ()
#3  0x000000000070be47 in update_thread_pool_size() ()
#4  0x000000000070cb5e in _initialize_maint_cmds() ()
#5  0x00000000008fad52 in initialize_all_files() ()
#6  0x0000000000899f0b in gdb_init(char*) ()
#7  0x0000000000703cb4 in captured_main_1(captured_main_args*) ()
#8  0x0000000000704913 in captured_main(void*) ()
#9  0x000000000070497e in gdb_main(captured_main_args*) ()
#10 0x00000000004022de in main ()
(gdb)

This is running on x86-64, built for x86-64. Os is Ubuntu 18.04 .