posted from the wrong address, sorry,

> Begin forwarded message:
>
> From: Iain Sandoe <idsandoe_at_[hidden]>
> Subject: Re: [SG15] [isocpp-ext] Can we expect that all C++ source files can have the same suffix?
> Date: 25 April 2022 at 21:02:03 BST
> To: sg15_at_[hidden]
> Cc: Evolution Working Group mailing list <ext_at_[hidden]>, Steve Downey <sdowney_at_[hidden]>, Peter Dimov <pdimov_at_[hidden]>, Tom Honermann <tom_at_[hidden]>, Nathan Sidwell <nathan_at_[hidden]>
>
>
>
>> On 25 Apr 2022, at 19:43, Steve Downey via SG15 <sg15_at_[hidden]> wrote:
>>
>>
>>
>> On Mon, Apr 25, 2022 at 1:55 PM Peter Dimov via Ext <ext_at_[hidden]> wrote:
>> Tom Honermann wrote:
>>> On 4/25/22 1:12 PM, Gabriel Dos Reis wrote:
>>>> [Peter]
>>>>> You are correct that the requests don't stop here.
>>>> Please, go talk to Tom 😊
>>>> Let me know when you're on the same page and what the actual request
>>>> is 😉
>>>
>>> I think Peter and I are pretty well aligned. At a minimum, we're aligned on
>>> support for the standard library.
>>>
>>> Supporting Boost as Peter suggested would require something like what the
>>> SG15 TR intends to specify or some other form of deeper integration between
>>> the compiler and the Boost installation; I'm content to categorize those
>>> integrations as falling on the sky scraper side. Like Peter, I would like for the
>>> compiler to just support those integrations, but I would also like for build
>>> systems to just never be required at all and I don't see that happening any time
>>> soon :)
>>
>> Boost here is just an example. The `import <boost/smart_ptr.hpp>` scenario
>> concerns a header-only library that is, as today, installed somewhere in the
>> default compiler include path. #include works today, we'd ideally want import
>> to work tomorrow without additional friction, so that people can painlessly
>> migrate to using modules.
>>
>> The Regex scenario describes a C++ compiled library that is installed in the
>> default include path and the default library path (by e.g. the system package
>> manager, although not necessarily.) The question here is would it be possible,
>> in the brave new module world, for the system package manager to install
>> some things somewhere such that `import <boost/regex.hpp>` or
>> `import boost.regex` works as well as #include works today.
>>
>> (I'm assuming here that both libraries have been changed in whatever way
>> is needed to support modules.)
>>
>>
>> Possibly for the system compiler, so that the BMI for <boost/smart_ptr.hpp> could be produced upon installation of the boost library.
>
> With at least two of the current implementations, this is not a viable proposition - since the BMI is dependent on the compile options - therefore there is no single “BMI to install” - and the set of permutations would be too large to be practicable.
>
> Iain
>
>> However, this will also make compiler upgrades and secondary compilers a nightmare to install as the entire world gets rebuilt to generate some set of ABI compatible importable objects.
>>
>>
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