https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109718
Bug ID: 109718 Summary: Dependency generation for header-units and modules not possible Product: gcc Version: 14.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: klaus.doldinger64 at googlemail dot com Target Milestone: --- To generate make-dependencies I use the following command line: g++ -c -MD -MG -std=c++23 -fconcepts -fmodules-ts test.cc where test.cc is: ----------------- import <array>; int main() { } ----------------- It gives the error: cc1plus: error: '-MG' may only be used with '-M' or '-MM' Removing -MG gives also an error, because the precompiled header does not yet exist: /usr/local/include/c++/14.0.0/iostream: error: failed to read compiled module: No such file or directory /usr/local/include/c++/14.0.0/iostream: note: compiled module file is 'gcm.cache/./usr/local/include/c++/14.0.0/iostream.gcm' /usr/local/include/c++/14.0.0/iostream: note: imports must be built before being imported /usr/local/include/c++/14.0.0/iostream: fatal error: returning to the gate for a mechanical issue So, it looks that there is no possiblity to create a valid dependency file with gcc.