https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98718
--- Comment #2 from Nathan Sidwell <nathan at gcc dot gnu.org> --- reduced testcase: // b_a.ii module ; # 4 "inc_a" 1 #define _GLIBCXX_VISIBILITY(V) __attribute__ ((__visibility__ (#V))) namespace std _GLIBCXX_VISIBILITY(default) { } # 11 "" 2 export module hello:format; // b_b.ii module ; # 4 "inc_b" 1 #define _GLIBCXX_VISIBILITY(V) __attribute__ ((__visibility__ (#V))) #define _GLIBCXX_BEGIN_NAMESPACE_VERSION namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION } # 11 "" 2 export module hello; export import :format; zathras:210>./cc1plus -std=c++20 -fmodules-ts -quiet -fpreprocessed -fdirectives-only b_a.ii && ./cc1plus -std=c++20 -fmodules-ts -quiet -fpreprocessed -fdirectives-only b_b.ii b_b.ii:12:9: internal compiler error: in write_macro_maps, at cp/module.cc:16154 12 | export module hello; | ^~~~~~ 0xce1ab0 module_state::write_macro_maps(elf_out*, location_map_info&, module_state_config*, unsigned int*) ../../../src/gcc/cp/module.cc:16154 0xce662b module_state::write(elf_out*, cpp_reader*) ../../../src/gcc/cp/module.cc:17771 0xcec7d8 finish_module_processing(cpp_reader*) ../../../src/gcc/cp/module.cc:19860