[Bug c++/126440] New: ICE when importing iostream after export import a module partition: in write_location, at cp/module.cc:18772

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126440

            Bug ID: 126440
           Summary: ICE when importing iostream after export import a
                    module partition: in write_location, at
                    cp/module.cc:18772
           Product: gcc
           Version: 16.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hxxu96 at gmail dot com
  Target Milestone: ---

The bug is confirmed in g++ 16.1.0 and 15.2.0.

$ cat list-node.cc

export module list:node;
export struct Node {};

$ cat list.cc

export module list;
export import :node;
import <iostream>;

$ cat build.sh

g++ -std=c++20 -fmodules-ts -Wall -g -x c++-system-header -c iostream
g++ -std=c++20 -fmodules-ts -Wall -g -x c++-system-header -c string
g++ -std=c++20 -fmodules-ts -Wall -g -c list-node.cc
g++ -std=c++20 -fmodules-ts -Wall -g -c list.cc -freport-bug


preprocessed source:

// Target: x86_64-linux-gnu
// Configured with: /usr/src/gcc/configure --build=x86_64-linux-gnu
--disable-multilib --enable-languages=c,c++,fortran,go
// Thread model: posix
// Supported LTO compression algorithms: zlib zstd
// gcc version 16.1.0 (GCC)
//
// list.cc:1:8: internal compiler error: in write_location, at
cp/module.cc:18772
//     1 | export module list;
//       |        ^~~~~~
// 0x2401276 diagnostics::context::diagnostic_impl(rich_location*,
diagnostics::metadata const*, diagnostics::option_id, char const*,
__va_list_tag (*) [1], diagnostics::kind)
//      ???:0
// 0x23fa23f internal_error(char const*, ...)
//      ???:0
// 0x7f646d fancy_abort(char const*, int, char const*)
//      ???:0
// 0x9429d8 module_state::write_cluster(elf_out*, depset**, unsigned int,
depset::hash&, unsigned int*, unsigned int*)
//      ???:0
// 0x944386 module_state::write_begin(elf_out*, cpp_reader*,
module_state_config&, unsigned int&)
//      ???:0
// 0x944eed finish_module_processing(cpp_reader*)
//      ???:0
// 0x8d45b3 c_parse_final_cleanups()
//      ???:0
// 0xb14b60 c_common_parse_file()
//      ???:0
// -quiet -imultiarch x86_64-linux-gnu -D_GNU_SOURCE list.cc -quiet -dumpbase
list.cc -dumpbase-ext .cc -mtune=generic -march=x86-64 -g -Wall -std=c++20
-fmodules -freport-bug -o - -frandom-seed=0 -fdump-noaddr
// Please submit a full bug report, with preprocessed source.
// Please include the complete backtrace with any bug report.
// See <https://gcc.gnu.org/bugs/> for instructions.

// /usr/local/libexec/gcc/x86_64-linux-gnu/16.1.0/cc1plus -quiet -imultiarch
x86_64-linux-gnu -D_GNU_SOURCE list.cc -quiet -dumpbase list.cc -dumpbase-ext
.cc -mtune=generic -march=x86-64 -g -Wall -std=c++20 -fmodules -freport-bug -o
- -frandom-seed=0 -fdump-noaddr

# 0 "list.cc"
# 1 "/home//"
# 0 "<built-in>"
# 0 "<command-line>"
# 1 "/usr/include/stdc-predef.h" 1 3
# 0 "<command-line>" 2
# 1 "list.cc"
export module list;
export import :node;
import "/usr/local/include/c++/16.1.0/iostream";