Arch Linux

Description: using libbacktrace causes a segfault


Additional info:
* package version(s): gcc 12.2.1-2 gcc-libs 12.2.1-2

Steps to reproduce:

Compile the following:

```
#include <stacktrace>
#include <iostream>

void foo() {
auto trace = std::stacktrace::current();
std::cout << std::to_string(trace) << '\n';
}

int main() {
foo();
}
/*
expected output:
0# foo() at /app/example.cpp:5
1# at /app/example.cpp:10
2# at :0
3# at :0
4#
*/
```

with:

```
g++ --std=gnu++23 backtrace.cpp -lstdc++_libbacktrace -o backtrace
```

And execute it

```
$ ./backtrace
Segmentation fault (core dumped)
```

However, with gcc built from source with `./configure --enable-libstdcxx-backtrace=yes`, and installed to `./bin`, compiling with

```
$ ./bin/usr/local/bin/g++ --std=gnu++23 -I ./bin/usr/local/lib64/ backtrace.cpp -lstdc++_libbacktrace -o backtrace
$ LD_LIBRARY_PATH=./bin/usr/local/lib64/ ./backtrace
0# foo() at :0
1# main at :0
2# at :0
3# at :0
4# _start at :0
5#
```

Yielding the expected result. The segfault happens when accessing the trace (by converting to a string), not when constructing.