None of that is normative and as far as I remember we explicitly said
implementations are free to diagnose incompatible modes...

On Mon, Oct 20, 2025 at 5:16 PM Ville Voutilainen <
ville.voutilainen_at_[hidden]> wrote:

> On Mon, 20 Oct 2025 at 19:09, Joshua Berne <berne_at_[hidden]> wrote:
> >
> >
> >
> > On Mon, Oct 20, 2025 at 12:01 PM Ville Voutilainen <
> ville.voutilainen_at_[hidden]> wrote:
> >>
> >> The contracts specification specifies them to be compatible.
> >
> >
> > Where?
>
> Everywhere. Multiple definitions of inline functions with different
> contract evaluation semantics are ODR-equivalent,
> multiple TUs in general can have whichever contract-evaluation
> semantics chosen by whichever implementation-defined
> mechanism, but that mechanism must select one of the standardized
> semantics. And none of that is said to be in any way
> incompatible anywhere. You can even have different evaluation
> semantics for different calls of the same function, defined
> just once, including defined in the same TU, and nowhere in the
> standard does anything say that any of that is incompatible
> in any way.
>