From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C24EBC282C3 for ; Tue, 22 Jan 2019 08:33:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8D21121721 for ; Tue, 22 Jan 2019 08:33:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548146009; bh=oskaqloGxzpVlEB9EoI/Hzkqp8YIG8E7IGPgpL/k7Qc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=KJS2QqCWEwaWioQwBm0wdzYqoHnFbpiMaIMcocV0RtdHc1RsMkNJcdnACTLa3WYQI gky2sHU7k4VjktmjN3uLcq1bI1iEkwWS0mSkJiFvTGIPKt7V9pCEM1yG+E8PZDyLfi 0PG/E7oV4hQ8Sf7vGbsPJk/qTr897kcTrTvppZik= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727347AbfAVId1 (ORCPT ); Tue, 22 Jan 2019 03:33:27 -0500 Received: from mail.kernel.org ([198.145.29.99]:45606 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727062AbfAVId1 (ORCPT ); Tue, 22 Jan 2019 03:33:27 -0500 Received: from bbrezillon (91-160-177-164.subs.proxad.net [91.160.177.164]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4B39920854; Tue, 22 Jan 2019 08:33:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548146005; bh=oskaqloGxzpVlEB9EoI/Hzkqp8YIG8E7IGPgpL/k7Qc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=SN6uOnX8QcU7tNGU9shqUyIV1FcOmx2EDwewPXEUA3j1HSQ1E2IRndoza8MPxJC6c fkBhLVgEvC7v1lP/src3CD9wEldzKuVx1B2M3jjQaQpC+qwCvnYdW+qrA7vJUtuKn2 7LQCt/AbXQjWhAPSGjDbdtPd190CEKmkxTGV4H84= Date: Tue, 22 Jan 2019 09:33:13 +0100 From: Boris Brezillon To: Miquel Raynal Cc: Masahiro Yamada , Lucas Stach , Marek Vasut , Richard Weinberger , Linus Walleij , Janusz Krzysztofik , Linux Kernel Mailing List , Stefan Agner , Jonathan Hunter , Boris Brezillon , Thierry Reding , linux-mtd , linux-tegra@vger.kernel.org, Brian Norris , David Woodhouse Subject: Re: [PATCH 2/2] mtd: rawnand: use unnamed union in struct nand_op_parser_pattern_elem Message-ID: <20190122093313.67375948@bbrezillon> In-Reply-To: <20190122090830.118eb6be@xps13> References: <1548142975-14219-1-git-send-email-yamada.masahiro@socionext.com> <1548142975-14219-3-git-send-email-yamada.masahiro@socionext.com> <20190122084944.420fcd4a@xps13> <20190122090830.118eb6be@xps13> X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 22 Jan 2019 09:08:30 +0100 Miquel Raynal wrote: > Hi Masahiro, > > Masahiro Yamada wrote on Tue, 22 Jan > 2019 17:00:54 +0900: > > > On Tue, Jan 22, 2019 at 4:50 PM Miquel Raynal wrote: > > > > > > Hi Masahiro, > > > > > > Masahiro Yamada wrote on Tue, 22 Jan > > > 2019 16:42:55 +0900: > > > > > > > Although drivers do not directly get access to the private data of > > > > instruction patterns, let's use unnamed union field to be consistent > > > > with nand_op_instr. > > > > > > > > > > Actually this is how we wrote it the first time. Then we got robots > > > reporting that anonymous unions where not allowed with older (still > > > supported) GCC versions and I had to do this: > > > > > > > > > commit c1a72e2dbb4abb90bd408480d7c48ba40cb799ce > > > Author: Miquel Raynal > > > Date: Fri Jan 19 19:11:27 2018 +0100 > > > > > > mtd: nand: Fix build issues due to an anonymous union > > > > > > GCC-4.4.4 raises errors when assigning a parameter in an anonymous > > > union, leading to this kind of failure: > > > > > > drivers/mtd/nand/marvell_nand.c:1936: > > > warning: missing braces around initializer > > > warning: (near initialization for '(anonymous)[1].') > > > error: unknown field 'data' specified in initializer > > > error: unknown field 'addr' specified in initializer > > > > > > Work around the situation by naming these unions. > > > > > > Fixes: 8878b126df76 ("mtd: nand: add ->exec_op() implementation") > > > Reported-by: Andrew Morton > > > Signed-off-by: Miquel Raynal > > > Tested-by: Andrew Morton > > > Signed-off-by: Boris Brezillon > > > > > > > > > Hmm, how come Andrew's compiler was fine with the following? > > > > struct nand_flash_dev { > > char *name; > > union { > > struct { > > uint8_t mfr_id; > > uint8_t dev_id; > > }; > > uint8_t id[NAND_MAX_ID_LEN]; > > }; > > unsigned int pagesize; > > ... > > }; > > > > It is probably not :) It was compile fine. I don't know all the subtleties, but maybe it's because ->id[] is a base type and not a struct. > > > > > > > The current minimum version is GCC 4.6 > > (commit cafa0010cd51fb7) > > but I am not sure if this restriction is remaining. > > > > That's right, can you please test if this limitation is still > ongoing wit GCC 4.6? I have a more important question: why should we go bad back to unnamed unions? Why is that a problem to have a named union? Sure, we initially started with an unnamed ones because it made lines shorter, but now that we switched to named unions I don't see the point of going back and patching all drivers again (at the risk of seeing this problem appear again when compiled with an old compiler version).