Re: std::atomic<T>::is_lock_free()

From	Bonita Montero <Bonita.Montero@gmail.com>
Newsgroups	comp.lang.c++
Subject	Re: std::atomic<T>::is_lock_free()
Date	2019-11-16 19:47 +0100
Organization	albasani.net
Message-ID	<qqpg75$d6m$1@news.albasani.net> (permalink)
References	(13 earlier) <4a9ef580-84eb-4782-8d9a-440504086ca1@googlegroups.com> <qqp76b$o3q$1@news.albasani.net> <c000d68d-bc76-4ff9-bc54-d23d6067ebc8@googlegroups.com> <qqpf3c$ff3$1@news.albasani.net> <633f2371-1a23-4ba5-a2ac-1de2b8109a9b@googlegroups.com>

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>>> Seems that you don't know standard and also you don't know any
>>> use cases for packed structs and therefore wiggle pathetically.

>> You can't even read what I said.

> You just try to wiggle away from giving 3 examples when packed
> structs are most commonly used.

They might be used, but packed structures with result in unaligned
members have undefined behaviour. C an C++ knows a natural alignment
for any complete datatype and every datatype must have this align-
ment to be portable.
So you can assume that a conformant implmentation of std:atomic
has an appropriate alignment on std::atomic<T> for any T. So there
is no inherent need to support is_lock_free for alignment-issues
and there must be another good reason because for this is evaluated
at runtime.

> Nonsense claims that standard does not allow implementations
> to have those packed structs do not hold.

The discussion was about the need for is_lock_Free because of any
alignment-issues.

> The packed structs (supported by all compilers) are not violating
> standard.

Of course they do. Accessing a non-aligned variable is not portable.

Thread

std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-12 10:54 +0100
  Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-12 11:24 +0100
    Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-12 14:11 +0100
      Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-12 14:39 +0100
        Re: std::atomic<T>::is_lock_free() Bo Persson <bo@bo-persson.se> - 2019-11-12 16:46 +0100
          Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-12 17:40 +0100
            Re: std::atomic<T>::is_lock_free() Bo Persson <bo@bo-persson.se> - 2019-11-12 20:23 +0100
              Re: std::atomic<T>::is_lock_free() "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-11-12 15:21 -0800
              Re: std::atomic<T>::is_lock_free() "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-11-14 13:09 -0800
              Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-13 06:34 +0100
                Re: std::atomic<T>::is_lock_free() "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-11-13 22:00 -0800
                Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-14 07:26 +0100
                Re: std::atomic<T>::is_lock_free() "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-11-13 22:33 -0800
                Re: std::atomic<T>::is_lock_free() "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-11-13 22:33 -0800
                Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-14 07:51 +0100
                Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-14 07:50 +0100
                Re: std::atomic<T>::is_lock_free() "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-11-13 23:14 -0800
                Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-14 10:43 +0100
  Re: std::atomic<T>::is_lock_free() "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-11-12 15:14 -0800
    Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-14 13:11 +0100
  Re: std::atomic<T>::is_lock_free() Öö Tiib <ootiib@hot.ee> - 2019-11-14 07:53 -0800
    Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-14 16:57 +0100
      Re: std::atomic<T>::is_lock_free() Öö Tiib <ootiib@hot.ee> - 2019-11-14 08:16 -0800
        Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-14 17:26 +0100
          Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-14 17:28 +0100
          Re: std::atomic<T>::is_lock_free() Öö Tiib <ootiib@hot.ee> - 2019-11-14 08:30 -0800
            Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-14 17:33 +0100
              Re: std::atomic<T>::is_lock_free() "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-11-14 13:41 -0800
                Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-15 09:31 +0100
                Re: std::atomic<T>::is_lock_free() "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-11-15 12:59 -0800
                Re: std::atomic<T>::is_lock_free() scott@slp53.sl.home (Scott Lurndal) - 2019-11-15 21:47 +0000
                Re: std::atomic<T>::is_lock_free() "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-11-15 13:56 -0800
                Re: std::atomic<T>::is_lock_free() scott@slp53.sl.home (Scott Lurndal) - 2019-11-16 18:07 +0000
                Re: std::atomic<T>::is_lock_free() "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-11-16 13:55 -0800
                Re: std::atomic<T>::is_lock_free() scott@slp53.sl.home (Scott Lurndal) - 2019-11-16 22:13 +0000
                Re: std::atomic<T>::is_lock_free() "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-11-16 18:40 -0800
                Re: std::atomic<T>::is_lock_free() James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-11-17 18:39 -0500
                Re: std::atomic<T>::is_lock_free() "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-11-17 20:59 -0800
                Re: std::atomic<T>::is_lock_free() "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-11-17 21:00 -0800
                Re: std::atomic<T>::is_lock_free() James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-11-18 08:25 -0500
                Re: std::atomic<T>::is_lock_free() "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-11-18 18:24 -0800
                Re: std::atomic<T>::is_lock_free() "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-11-15 13:59 -0800
                Re: std::atomic<T>::is_lock_free() Ian Collins <ian-news@hotmail.com> - 2019-11-16 11:08 +1300
                Re: std::atomic<T>::is_lock_free() Öö Tiib <ootiib@hot.ee> - 2019-11-15 15:39 -0800
                Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-16 07:22 +0100
                Re: std::atomic<T>::is_lock_free() Öö Tiib <ootiib@hot.ee> - 2019-11-16 08:06 -0800
                Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-16 17:13 +0100
                Re: std::atomic<T>::is_lock_free() Öö Tiib <ootiib@hot.ee> - 2019-11-16 08:26 -0800
                Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-16 19:27 +0100
                Re: std::atomic<T>::is_lock_free() Öö Tiib <ootiib@hot.ee> - 2019-11-16 10:37 -0800
                Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-16 19:47 +0100
                Re: std::atomic<T>::is_lock_free() Öö Tiib <ootiib@hot.ee> - 2019-11-16 11:34 -0800
                Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-17 09:17 +0100
                Re: std::atomic<T>::is_lock_free() Öö Tiib <ootiib@hot.ee> - 2019-11-17 01:52 -0800
                Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-17 11:23 +0100
                Re: std::atomic<T>::is_lock_free() Öö Tiib <ootiib@hot.ee> - 2019-11-17 03:22 -0800
                Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-17 14:20 +0100
                Re: std::atomic<T>::is_lock_free() Öö Tiib <ootiib@hot.ee> - 2019-11-17 06:39 -0800
                Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-17 15:49 +0100
                Re: std::atomic<T>::is_lock_free() Öö Tiib <ootiib@hot.ee> - 2019-11-17 22:54 -0800
                Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-18 08:03 +0100
                Re: std::atomic<T>::is_lock_free() Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-11-28 15:39 -0800
                Re: std::atomic<T>::is_lock_free() Öö Tiib <ootiib@hot.ee> - 2019-11-28 16:33 -0800
                Re: std::atomic<T>::is_lock_free() Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-01-10 22:48 -0800
                Re: std::atomic<T>::is_lock_free() Öö Tiib <ootiib@hot.ee> - 2020-01-11 00:24 -0800
                Re: std::atomic<T>::is_lock_free() Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-01-14 07:16 -0800
                Re: std::atomic<T>::is_lock_free() Öö Tiib <ootiib@hot.ee> - 2020-01-14 08:55 -0800
                Re: std::atomic<T>::is_lock_free() Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-01-21 02:01 -0800
                Re: std::atomic<T>::is_lock_free() James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-01-21 06:00 -0800
                Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-17 15:58 +0100
                Re: std::atomic<T>::is_lock_free() "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-11-17 21:01 -0800
                Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-18 07:00 +0100
                Re: std::atomic<T>::is_lock_free() Öö Tiib <ootiib@hot.ee> - 2019-11-17 22:45 -0800
                Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-18 07:52 +0100
                Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-18 08:10 +0100
                Re: std::atomic<T>::is_lock_free() Öö Tiib <ootiib@hot.ee> - 2019-11-17 23:23 -0800
                Re: std::atomic<T>::is_lock_free() Ian Collins <ian-news@hotmail.com> - 2019-11-18 20:26 +1300
                Re: std::atomic<T>::is_lock_free() Öö Tiib <ootiib@hot.ee> - 2019-11-17 23:05 -0800
                Re: std::atomic<T>::is_lock_free() Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-11-28 15:44 -0800
                Re: std::atomic<T>::is_lock_free() Öö Tiib <ootiib@hot.ee> - 2019-11-28 16:43 -0800
                Re: std::atomic<T>::is_lock_free() Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-01-11 06:41 -0800
        Re: std::atomic<T>::is_lock_free() "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-11-14 13:33 -0800
  Re: std::atomic<T>::is_lock_free() Melzzzzz <Melzzzzz@zzzzz.com> - 2019-11-14 19:08 +0000
    Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-14 20:12 +0100
      Re: std::atomic<T>::is_lock_free() "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-11-14 13:35 -0800
  Re: std::atomic<T>::is_lock_free() "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-11-14 13:32 -0800
    Re: std::atomic<T>::is_lock_free() "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-11-14 13:37 -0800
    Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-15 09:32 +0100
      Re: std::atomic<T>::is_lock_free() "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-11-15 13:06 -0800
  Re: std::atomic<T>::is_lock_free() Öö Tiib <ootiib@hot.ee> - 2019-11-14 02:29 -0800
    Re: std::atomic<T>::is_lock_free() Bonita Montero <Bonita.Montero@gmail.com> - 2019-11-14 11:45 +0100

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