Dear Maintainer,

   * What led up to the situation?

When working on the conversion of existing projectss to projects using modules
the compiler reported an (unclear) error message when compiling a source file
defining a module.

   * What exactly did you do that caused the issue?

First I prepared in /usr/include/c++/14/ filesystem.gcm and memory.gcm,
calling

    g++ --std=c++26 -Wall -fmodules-ts -x c++-system-header filesystem
and
    g++ --std=c++26 -Wall -fmodules-ts -x c++-system-header memory

followed by
    mv gcm.cache/usr/include/c++/14/*.gcm .
so they're located in /usr/include/c++/14/ and can be imported.


Then I wrote this source file (e.g., modsupport.cc, stripped down to its bare
essentials):