Michael Spencer via SG15 <sg15_at_[hidden]> writes:

> This paper makes the following ill-formed by forbidding macro expansion
> in the name of module declarations.
>
> version.h:
> #ifndef VERSION_H
> #define VERSION_H
>
> #define VERSION libv5
>
> #endif
>
> lib.cppm:
> module;
> #include "version.h"
> export module VERSION;

What about something like this:

#ifdef VERSION
export module version;
#else
export module final;
#endif

Sounds like it will pose the same issue but banning it feels more
drastic.

Even the use of a macro in the module name could probably have
plausible use-cases. Say if you are trying to make a module
that includes a version in its name:

#define VERSION 2
#define VERSIONED_NAME(n) n ## _v2

And then:

export module VERSIONED_NAME(utility);

#if VERSION >= 2
export void only_available_in_v2 ();
#endif