Hello,

Trying to address a more narrow scope this time around. I was
discussing with Ben about how the build system would know when a bmi
would be reusable or not from a prebuilt library, and it turns out
that is still a gap.

IOW, as things stand right now the build system would have no option
but to assume that no bmi in the system is compatible with the current
build, and it would have to create rules for all the BMIs it needs.

This paper tries to establish a mechanism by which the build system
and the compiler can communicate in order to establish the identity of
the format of the bmi file, and then establish that the identity of
the format will become a part of the metadata when a library is
distributed, which will allow the build system to consume a bmi
shipped with a prebuilt library.

https://wg21.link/P2581R0

daniel