[PATCH] D121589: [C++20][Modules][Driver][HU 2/N] Add fmodule-header, fmodule-header=

Tue Mar 15 03:28:57 PDT 2022

ChuanqiXu accepted this revision.
ChuanqiXu added a comment.
This revision is now accepted and ready to land.

In D121589#3381894 <https://reviews.llvm.org/D121589#3381894>, @iains wrote:

> In D121589#3381343 <https://reviews.llvm.org/D121589#3381343>, @ChuanqiXu wrote:
>
>>> It's not practical to recognise a header without any suffix so
>>
>> -fmodule-header=system foo isn't going to happen.
>>
>> May I ask the reason? It looks not so good with `-fmodule-header=system -xc++-header vector`
>
> OK. One should never say "never" ;) , it would be nicer if we could avoid this.
>
> ... it would require a policy change in the driver - since we cannot recognise files like 'vector' as headers, they are currently unclaimed (which means that they default to being considered as linker inputs).
>
> This is a long-standing (forever, I suspect) situation;
> Although we could make it so that if we see certain options, all unknown inputs get claimed as source files (or headers) I wonder how much build system code that might break.

If this is the policy, I am OK. For the build systems, due to the dependences, all build systems want to support C++20 modules should do works. So if we are doing our best, I think it might not be bad.

Repository:
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  https://reviews.llvm.org/D121589/new/

https://reviews.llvm.org/D121589