https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98386
Bug ID: 98386 Summary: C++20 module: file exists failure and success happen alternatively for windows. Product: gcc Version: 11.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: unlvsur at live dot com Target Milestone: --- D:\Desktop\module>g++ -c main.cc -Ofast -std=c++20 -s -flto -fmodules-ts -march=native D:\Desktop\module>g++ -c hello.cc -Ofast -std=c++20 -s -flto -fmodules-ts -march=native hello.cc:4:8: error: failed to write compiled module: File exists 4 | export module hello; | ^~~~~~ hello.cc:4:8: note: compiled module file is 'gcm.cache/hello.gcm' D:\Desktop\module>g++ -c hello.cc -Ofast -std=c++20 -s -flto -fmodules-ts -march=native D:\Desktop\module>g++ -c hello.cc -Ofast -std=c++20 -s -flto -fmodules-ts -march=native hello.cc:4:8: error: failed to write compiled module: File exists 4 | export module hello; | ^~~~~~ hello.cc:4:8: note: compiled module file is 'gcm.cache/hello.gcm' D:\Desktop\module>g++ -c hello.cc -Ofast -std=c++20 -s -flto -fmodules-ts -march=native D:\Desktop\module>g++ -c hello.cc -Ofast -std=c++20 -s -flto -fmodules-ts -march=native hello.cc:4:8: error: failed to write compiled module: File exists 4 | export module hello; | ^~~~~~ hello.cc:4:8: note: compiled module file is 'gcm.cache/hello.gcm' You have a succ-error-succ-error loop. It must be something bugged here.