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Re: P2898R0: Importable Headers are Not Universally Implementable

From: Jens Maurer <jens.maurer_at_[hidden]>
Date: Fri, 19 May 2023 07:41:09 +0200
 - This should also go to the Modules Study Group.

 - "Include the Local Preprocessor Arguments for those as an input to the dependency
scanning process"

I don't think that's accurate. Header units are specified, I believe, intentionally
such that the preprocessor state from the importing site has no effect on the
contents of the header unit.


On 18/05/2023 22.46, Daniel Ruoso via SG15 wrote:
> Hello,
> After lots of discussions and trying to find solutions on how to make
> Importable Headers work, I have come to the unfortunate conclusion
> that they are not implementable in a way that would be acceptable in
> all environments where C++ is used.
> Moreover, I believe the goals that were set for the specification of
> Importable Headers can be achieved in a much simpler way, without
> introducing the special semantics that those provide.
> In other words, we can make the standard allow the optimizations
> achieved by Explicit Clang Header Modules as well as the early
> adoption reports from MSVC, while at the same time maintaining the
> semantics of source inclusion as the "canonical" behavior for when a
> given environment cannot make use of those optimizations.
> This revision of the paper does not include wording changes yet, as I
> want to build consensus on this prior to going through the effort of
> figuring out what wording needs changing.
> See the paper at: https://wg21.link/P2898R0
> daniel
> _______________________________________________
> SG15 mailing list
> SG15_at_[hidden]
> https://lists.isocpp.org/mailman/listinfo.cgi/sg15

Received on 2023-05-19 05:41:13