I've noticed the following issues with the module mapper in the -fdirectives-only mode:
1. When partially preprocessing the module interface unit, the mapper receives the MODULE-EXPORT request that's unnecessary (BMI is not written): g++ ... -x c++ -E -fdirectives-only -o hello.gcm.ii hello.mxx Similarly, in this mode, the mapper receives MODULE-IMPORT for (non-header) module imports. Again, this is not necessary and replying with a non-existent BMI works. 2. When doing full preprocessing of a partially preprocessed unit, the mapper again receives MODULE-EXPORT and MODULE-IMPORT for non-header modules: g++-m ... -E -x c++ -fpreprocessed -fdirectives-only hello.gcm.ii These are also unnecessary.