You've described it correctly.

> The problem is that the warning should be emitted only for users that use incorrect API. But it shouldn't be emitted for users that use just 3.2 API

This is why I suggested #warn and not #error. It's okay to ignore warnings if you know what you're doing, but if there's no warning then people who don't know what they're doing will get it wrong. We know that some people are subtly broken here, and ought to tell them.

Further, if we make the warning only appear for "defined(Py_LIMITED_API) && Py_LIMITED_API+0<0x03000000" then the warning can be suppressed by setting the exact version you intend to use (even though this doesn't prevent you from using the incorrect functions).