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Re: std::aligned_storage and [[gnu::may_alias]]

From: Jonathan Wakely <jwakely dot gcc at gmail dot com>
To: Avi Kivity <avi at scylladb dot com>
Cc: gcc-help <gcc-help at gcc dot gnu dot org>
Date: Fri, 23 Jun 2017 00:03:20 +0100
Subject: Re: std::aligned_storage and [[gnu::may_alias]]
Authentication-results: sourceware.org; auth=none
References: <b0093370-c605-d30d-ac8b-78b5b0bc13d4@scylladb.com> <CAH6eHdSowdPSazKRxWiUxD1hs6t=6hno33Zvwka-AyhZ8=OdJg@mail.gmail.com> <54b7e6c6-9f13-e3d6-b766-fdf50da45c57@scylladb.com> <CAH6eHdRmUdwX5rTm_o2KMkacn1ebouTo67Ts1qfrgYyQbsJ0SA@mail.gmail.com>

On 23 June 2017 at 00:01, Jonathan Wakely wrote:
> On 22 June 2017 at 19:06, Avi Kivity <avi@scylladb.com> wrote:
>> I agree the implicit copy constructor is broken, but I don't see how
>> operator[] is legal. It seems to give a single address two dynamic types.
>
> No it doesn't. There's only one dynamic type at a time.

And as far as I can see, operator[] only assumes the dynamic type is
T, and only access it as T. Where's the second dynamic type?

References:
- std::aligned_storage and [[gnu::may_alias]]
  - From: Avi Kivity
- Re: std::aligned_storage and [[gnu::may_alias]]
  - From: Jonathan Wakely
- Re: std::aligned_storage and [[gnu::may_alias]]
  - From: Avi Kivity
- Re: std::aligned_storage and [[gnu::may_alias]]
  - From: Jonathan Wakely

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