[Bug c++/100584] New: [modules] ICE when using import <thread>; with std::jthread

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100584

            Bug ID: 100584
           Summary: [modules] ICE when using import <thread>; with
                    std::jthread
           Product: gcc
           Version: 11.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: andreemalcher at gmail dot com
  Target Milestone: ---

$ cat thread.cpp
import <iostream>; // Compiles & runs fine with include or if order if swapped
with next line
#include <thread>

int main() {
  std::jthread t{[]{}}; // Compiles & runs fine with std::thread
}
$ g++ -fmodules-ts -std=c++20 -c -x c++-system-header iostream$ g++
-fmodules-ts -std=c++20 -o prog thread.cpp -pthread
during IPA pass: visibility
thread.cpp:6:1: internal compiler error: in function_and_variable_visibility,
at ipa-visibility.c:712
    6 | }
      | ^
0x1702697 internal_error(char const*, ...)
        ???:0
0x64082b fancy_abort(char const*, int, char const*)
        ???:0
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <file:///usr/share/doc/gcc-11/README.Bugs> for instructions.


If you replace std::jthread with std::thread (optionally, with corresponding
join()), it compiles just fine.


Also, the order of import vs. include seems to matter (see comment in code).
Same ICE for import <string>;, for example, but not for import <vector>;.
Haven't tried others.