From owner-sc22wg14+sc22wg14-domo2=www.open-std.org@open-std.org Wed Apr 5 01:25:20 2017 Return-Path: X-Original-To: sc22wg14-domo2 Delivered-To: sc22wg14-domo2@www.open-std.org Received: by www.open-std.org (Postfix, from userid 521) id 30E2835886E; Wed, 5 Apr 2017 01:25:19 +0200 (CEST) Delivered-To: sc22wg14@open-std.org Received: from mail-io0-f171.google.com (mail-io0-f171.google.com [209.85.223.171]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by www.open-std.org (Postfix) with ESMTP id 49544356E08 for ; Wed, 5 Apr 2017 01:25:16 +0200 (CEST) Received: by mail-io0-f171.google.com with SMTP id l7so105495333ioe.3 for ; Tue, 04 Apr 2017 16:25:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:subject:to:message-id:date:user-agent:mime-version :content-transfer-encoding; bh=wHD0QlzgEShQNRozQbIZ+zkZeGaOHPmoPRTewwTpxcg=; b=A/aiGlKNV4gf/WjHqYiMsIy4vzWYQYLG9V4VjXTa102UXyI9aJJmvbLsQBhyIePqbT cFkZqESd+HANkmPLFW0Gc/MiHIZimeBfwyjvBPnPMHdVgWLZtf5BRn8TNqVgCEgEBppc gZkIDSn4QBBHyNDikSBEIVlAKGDei1u+7Zc0M/TRXZ/BcRr0nw0ghNPNgccgg9FPRsgc 033VppXyzeh+ZMIpemUPq16N+NZm8UAmu+Jx8e7MUnR7gTnD/9roPkdfe6FrcJlizLnh DInfAw8xtgY3Vi4t9BcX95I50M1YEdJTC+/3EHSA+sj3kqni59UqSK+aooElcDMVaB7Q WFeA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:subject:to:message-id:date:user-agent :mime-version:content-transfer-encoding; bh=wHD0QlzgEShQNRozQbIZ+zkZeGaOHPmoPRTewwTpxcg=; b=o6liw9Ej8A1elfDIzT0DJlGGeZRe/AofG54jCEoH+k7b/Pqf2w8MzkvoNTy7GChjiC 71xXEZpJcrmpFMcikhfqUW/QP0H8QK6sVXcY4CxrD1B6aONPK0O8FVNIVG4TJkHMBQgE +9Tc+PaH7o3k3eqDcElj090E/a5pSSfg6SE10rmt+GkVv47MjrQPIqszmqNHCS9GWBxT sLEJUIOYXXmv9KxIHitL4QScUXVx4zzGonLBx94vxIReKt8z0k7R/PCu4NEeQxkhG2BP x+/OXP4bm+PrWLwCrWRD2vhVmmnUJGt1c4zo0sqgH0n+ev88VAQ8GTm8fogJW/vBGJtW AD9w== X-Gm-Message-State: AFeK/H2cwG74tPw8UR5pXyh3pcHLJUJERCNQqc+uB2/ub8ERPklLbGAFeAut2cpElWJrgg== X-Received: by 10.107.59.149 with SMTP id i143mr25775190ioa.196.1491348314905; Tue, 04 Apr 2017 16:25:14 -0700 (PDT) Received: from [192.168.0.253] ([173.243.43.130]) by smtp.gmail.com with ESMTPSA id l129sm12143808ite.1.2017.04.04.16.25.13 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 04 Apr 2017 16:25:13 -0700 (PDT) From: Martin Sebor Subject: DR 485 wording for TC 2017 To: sc22wg14@open-std.org Message-ID: <55bd3d70-9fdc-5e7a-cab9-6c22d138b4a2@gmail.com> Date: Tue, 4 Apr 2017 17:25:12 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-sc22wg14@open-std.org Precedence: bulk During today's discussion of DR 485 I volunteered to write up proposed words to include in the upcoming 2017 C TC/update to reflect WG14's position on the future direction in this area. The suggested changes do two things. Change (1) acknowledges that the macro can only be used to initialize scalars, updates Future Library directions with the expected removal of the ATOMIC_VAR_INIT macro, and adds a footnote to 7.17.2.1 pointing to the Future Library Directions section. Going a step further, (2) is the minimum change necessary to make direct initialization of atomic objects work. Change 1. In 7.17.2.1 The ATOMIC_VAR_INIT macro, change paragraph 2 as follows: The ATOMIC_VAR_INIT macro expands to a token sequence suitable for initializing an atomic object of a scalar type that is initialization-compatible with value. new footnote new footnote) An atomic object of any type can be initialized the same way as an object of the corresponding non-atomic type. See future library directions. Add a new paragraph to 7.31.8 Atomics : The macro ATOMIC_VAR_INIT() cannot be used to explicitly initialize objects of user-defined types. Since the macro is not necessary to initialize objects of any atomic types it will be removed in a future revision of the standard. Change 2. In 7.17.2.1 The ATOMIC_VAR_INIT macro, further modify paragraph 2 as follows: An atomic object with automatic storage duration that is not explicitly initialized using ATOMIC_VAR_INIT is initially in an indeterminate state;