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Subject: Re: [boost] Boost.Outcome review - First questions
From: Paul A. Bristow (pbristow_at_[hidden])
Date: 2017-05-24 16:42:27

> -----Original Message-----
> From: Boost [mailto:boost-bounces_at_[hidden]] On Behalf Of Niall Douglas via Boost
> Sent: 24 May 2017 16:21
> To: boost_at_[hidden]
> Cc: Niall Douglas
> Subject: Re: [boost] Boost.Outcome review - First questions
> clang 4.0+ and GCC 6.0+ with -O3 optimisation appear to now be clever
> enough to spot trivial move constructors and trivial types, and not copy
> memory when the bits in memory would not change.
> I would therefore expect that your reference Expected implementation
> would now be identical or very similar in runtime performance to Outcome
> on clang 4.0+ and GCC 6.0+. MSVC does, of course, still have some way to
> go yet, but VS2017 is a world of improvement over VS2015.

For this review, I doubt if we should worry too much about *current released* compiler's performance.

If Outcome becomes popular, we can expect compiler optimisers to focus their attention on optimising Outcome.


Paul A. Bristow
Prizet Farmhouse
Kendal UK LA8 8AB
+44 (0) 1539 561830

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