It was also suggested to talk to the Linux Foundation folks to make sure
the choices are appropriate with respect to the Linux Filesystem Hierarchy
Standard (FHS). Possibly the module interfaces themselves could live in a
subdirectory of $prefix/include but the metadata file will sometimes be
less portable than that (that is, contain different flags depending on the
consumption use case). That is because the metadata will be describing the
library binary too, so the lib part of the hierarchy seems appropriate.

Bret

On Thu, Dec 14, 2023, 04:51 Michael Spencer via SG15 <sg15_at_[hidden]>
wrote:

> On Wed, Dec 13, 2023 at 8:23 AM Chuanqi Xu via SG15 <sg15_at_[hidden]>
> wrote:
>
>> Hi Guys,
>>
>> I didn't take part in the meeting so I am curious. After the meeting,
>> I see plenty of discussions about module metadata files. I am not against
>> this.
>> But I am wondering if the initial question got answered. I didn't see it
>> anywhere. Sorry if I missed.
>>
>> In my mind, the motivation of the meeting should be the location of
>> the std modules. Should it be <PREFIX>/modules/c++/v1? Should it be
>> `/usr/include/c++/$version`? Or should it be `$PREFIX/share/c++/modules`?
>> ....
>>
>> Do we have any consensus on this?
>>
>>
>> Thanks,
>> Chuanqi
>>
>
> To expand on Daniel's answer a bit more (still waiting on the meeting
> notes to get posted).
>
> We agreed that:
> * We need a metadata file because there are additional flags needed and
> how you compile it depends on the library binary you're linking against
> * The compiler needs to say where that file is given a base command line
> (so including target and ABI affecting flags)
> * GCC compatible compiler drivers already have `-print-file-name` that
> can be used for this purpose
> * Ecosystem IS should document this
>
> Also discussed that GCC and LLVM can talk to each other to coordinate on
> filesystem layout, but isn't 100% required because of the metadata file
>
> - Michael Spencer
>
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