[Bug c++/107033] New: [13 Regression] [modules] ICE converting to span

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107033

            Bug ID: 107033
           Summary: [13 Regression] [modules] ICE converting to span
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Keywords: rejects-valid
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: johelegp at gmail dot com
                CC: johelegp at gmail dot com
  Target Milestone: ---

See GCC trunk: https://godbolt.org/z/KoP5qo1Ks.
See GCC 12: https://godbolt.org/z/EfGjdcYaW.


```sh
CXX=/home/johel/root/gcc/bin/g++
echo "./std.hpp std.gcm
mod mod.gcm" > mm.txt
echo "#include <array>
#include <span>" > std.hpp
echo "export module mod;
import \"std.hpp\";
constexpr std::array<int, 1> a = {};
export constexpr std::span s   = a;" > mod.cpp
$CXX -std=c++23 -fmodules-ts -fmodule-mapper=mm.txt -x c++-header -c std.hpp
$CXX -std=c++23 -fmodules-ts -fmodule-mapper=mm.txt -c mod.cpp
```

Output:
```
mod.cpp:1:8: internal compiler error: Segmentation fault
    1 | export module mod;
      |        ^~~~~~
0x22c23ec internal_error(char const*, ...)
        ???:0
0xba7787 walk_specializations(bool, void (*)(bool, spec_entry*, void*), void*)
        ???:0
0xafa362 depset::hash::add_specializations(bool)
        ???:0
0xb0ab3c module_state::write_begin(elf_out*, cpp_reader*, module_state_config&,
unsigned int&)
        ???:0
0xb0c044 finish_module_processing(cpp_reader*)
        ???:0
0xa95334 c_parse_final_cleanups()
        ???:0
0xccde92 c_common_parse_file()
        ???:0
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://bugs.archlinux.org/> for instructions.
```