From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 20748 invoked by alias); 17 Jan 2014 09:39:51 -0000 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org Received: (qmail 20719 invoked by uid 48); 17 Jan 2014 09:39:48 -0000 From: "josh at joshtriplett dot org" To: gcc-bugs@gcc.gnu.org Subject: [Bug c/59852] Support sparse-style __attribute__((bitwise)) (type attribute) Date: Fri, 17 Jan 2014 09:39:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: c X-Bugzilla-Version: unknown X-Bugzilla-Keywords: X-Bugzilla-Severity: enhancement X-Bugzilla-Who: josh at joshtriplett dot org X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2014-01/txt/msg01816.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59852 --- Comment #1 from Josh Triplett --- Note in particular the bit about typedefs. Two identical declarations both using __attribute__((bitwise)) create two variables with different types, but two declarations both usin the same typedef declared with __attribute__((bitwise)) create two variables with the same type. In code: __attribute__((bitwise)) unsigned a, b; __attribute__((bitwise)) unsigned c, d; typedef __attribute__((bitwise)) unsigned foo_t; foo_t e, f; foo_t g, h; a and b have the same type. c and d have the same type. e, f, g, and h have the same type.