[Bug c++/99569] New: segfault when running a module

["ryan.burn at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99569

            Bug ID: 99569
           Summary: segfault when running a module
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ryan.burn at gmail dot com
  Target Milestone: ---

Here's how to reproduce

// a-m.cc
module;

#include <string>

export module a;

export std::string do_a() {
        return "abc";
}

// main.cc
#include <iostream>

import a;

int main() {
        std::cout << do_a() << "\n";
        return 0;
}

If I then run

g++ -fmodules-ts -std=c++20 -c a-m.cc
g++ -fmodules-ts -std=c++20 -c main.cc
g++ *.o
./a.out

the program prints

abc
Segmentation fault

This is the version of gcc I used

root@15a43977d8e1:/t/strfunc# g++ --version
g++ (GCC) 11.0.1 20210311 (experimental)
Copyright (C) 2021 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.