From owner-sc22wg14+sc22wg14-domo2=www.open-std.org@open-std.org Wed Jun 26 17:26:58 2024 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 34D71356F53; Wed, 26 Jun 2024 17:26:58 +0200 (CEST) Delivered-To: sc22wg14@open-std.org Received: from mail-oo1-f48.google.com (mail-oo1-f48.google.com [209.85.161.48]) by www.open-std.org (Postfix) with ESMTP id AAEA2356E79 for ; Wed, 26 Jun 2024 17:26:57 +0200 (CEST) Received: by mail-oo1-f48.google.com with SMTP id 006d021491bc7-5c2011716a3so1443144eaf.1 for ; Wed, 26 Jun 2024 08:26:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=aaronballman.com; s=google; t=1719415615; x=1720020415; darn=open-std.org; h=to:subject:message-id:date:from:mime-version:from:to:cc:subject :date:message-id:reply-to; bh=OF5aFtawSZtVHB36RBfoMVizsP9faMYTmZOHduHPAA8=; b=BNTr8IRPzypYuxx+KoB743wfLlFgwVcZAClghBGSLao9qXygkYYPQvDboomYHelA0S UEJWnci8CWs6w9+Xkq0yaaBQ9isHah0UjGyR5c533SDW+xlT3I5mcqhf6fWlbfvItnqb UhHj3idP979KzTzeDIDTZyuYpsvGCipSKK8lGavPkQ1P6RoZCwbXczGp2MY/Akxe2409 hoCJ0l5EGPVXC6bkQGWCEm+ryi8P2XRhcJUeDyAdAfuSb6tzFgVG7aV9RcNjYoYJPHBG mV+o3oso+k3HuNU6mwUZZBoCMIbzDg2tVFhKvlMcRZ78umJgLXFvOV/r351P7GaWGX6d 2ItA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1719415615; x=1720020415; h=to:subject:message-id:date:from:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=OF5aFtawSZtVHB36RBfoMVizsP9faMYTmZOHduHPAA8=; b=dasvDXyEQswkVnhir4OF6GDqmGJsUOhFU7PyNBoY5SrQsKbJyrVC+O0i/JZ0kYc0ph 4laCGHP3ub8TCT5guST0Cx1au7L8ipSqfEbZQeQ5hd3DEyxnWs/flO+IgwDnfJtaPMWC +yUx6eziVA80xdvAN13C7T7FZHkqw6wJd91B0FaUCxaQevTWSINmQaTXd7H676dK8zCE gOnTdsKaHXK6Go6NbxC2mv8oRBV46UqWzkefLblMtFkFFu1ejo3hYbi9vr1XLjj7dOh5 MRju8tQQbSG6Fjfkrp7zuyFz1vJ2678UfsvW+uo9WrX7sh94tgHuLwWbT7qHDoaZRQ4U ZwKQ== X-Gm-Message-State: AOJu0YwxbdLORhcb4TPXXzyI2VykqwZ+aKcA9wuhJGxN0FZXADchmT/Q tQyXGujjiPT2D4WSJjA25dBR/zUz8lcsVVrd18pC5DMHxUllFFe7nujaTz+9ayKKZJ+uOJ0TNR9 T X-Google-Smtp-Source: AGHT+IETJ5GwLwkz7Gdj16/qzwrQN3CAVIPLHdHeZegragAz5X4iC5lCz2Qch43Vl66wwB79ZbgqQg== X-Received: by 2002:a4a:6557:0:b0:5c2:25d1:70f7 with SMTP id 006d021491bc7-5c225d17332mr1998374eaf.5.1719415614860; Wed, 26 Jun 2024 08:26:54 -0700 (PDT) Received: from mail-oa1-f49.google.com (mail-oa1-f49.google.com. [209.85.160.49]) by smtp.gmail.com with ESMTPSA id 006d021491bc7-5c223eeb1basm218973eaf.14.2024.06.26.08.26.54 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 26 Jun 2024 08:26:54 -0700 (PDT) Received: by mail-oa1-f49.google.com with SMTP id 586e51a60fabf-25c9ef2701fso3836307fac.1 for ; Wed, 26 Jun 2024 08:26:54 -0700 (PDT) X-Received: by 2002:a05:6870:8183:b0:25d:921:75ec with SMTP id 586e51a60fabf-25d0921ad16mr11881649fac.36.1719415613788; Wed, 26 Jun 2024 08:26:53 -0700 (PDT) MIME-Version: 1.0 From: Aaron Ballman Date: Wed, 26 Jun 2024 11:26:42 -0400 X-Gmail-Original-Message-ID: Message-ID: Subject: Can you get a qualified rvalue? To: wg14 Content-Type: text/plain; charset="UTF-8" Sender: owner-sc22wg14@open-std.org Precedence: bulk I think the answer to this is intended to be "no", but member access expressions leave me with some questions. Consider the following example: struct { const int i; } foo(); My understanding of the expression `foo().i` is that the `return` statement within `foo()` produces an rvalue of anonymous structure type which is used as the left-hand side of the member access expression `.`. From there, C23 6.5.3.4p3 says: A postfix expression followed by the . operator and an identifier designates a member of a structure or union object. The value is that of the named member,93) and is an lvalue if the first expression is an lvalue. If the first expression has qualified type, the result has the so-qualified version of the type of the designated member. By my reading of that, foo().i is of type 'const int' but is still an rvalue. Do I have this correct? If so, in places where we say "as if it had undergone an lvalue conversion" are a bit odd because lvalue conversion only applies to lvalues. e.g., _Generic(foo().i, ...) seems like it would still result in a `const int` as the type for the controlling expression because we'd get a qualified rvalue from foo().i and then do the as-if lvalue conversion which ends up being a noop because it's already an rvalue, leaving the qualifier in place. Wording oversight? Poor reading comprehension on my part? FWIW, implementations disagree: https://godbolt.org/z/W64hxa4jj Thanks! ~Aaron