[adev_]

> The only time I used -march=native

It is completely fine to use -march=native, just do not make it the default for someone building your project.

That should always be something to opt-in.

The main reason is that software are a composite of (many) components. It becomes quickly a pain in the ass of maintainability if any tiny library somewhere try to sneak in '-march=native' that will make the final binary randomly crash with an illegal instruction error if executed on any CPU that is not exactly the same than the host.

When you design a build system configuration, think for the others first (the users of your software), and yourself after.