https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116807
--- Comment #4 from wxy_it at 163 dot com --- I obtained the following GCC command from the files generated by CMake. This command can also reproduce the bug. g++ -std=c++20 -fmodules-ts -MD -fdeps-format=p1689r5 -xc++ -c b.ixx g++ -std=c++20 -fmodules-ts -MD -fdeps-format=p1689r5 -xc++ -c a.ixx g++ -std=c++20 -fmodules-ts -MD -fdeps-format=p1689r5 -c b.cpp g++ -std=c++20 -fmodules-ts -MD -fdeps-format=p1689r5 -c a.cpp
