From patchwork Wed May 5 08:20:05 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pierre-Marie de Rodat X-Patchwork-Id: 1474165 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org (client-ip=2620:52:3:1:0:246e:9693:128c; helo=sourceware.org; envelope-from=gcc-patches-bounces@gcc.gnu.org; receiver=) Received: from sourceware.org (server2.sourceware.org [IPv6:2620:52:3:1:0:246e:9693:128c]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 4FZqRh5Jdfz9sRR for ; Wed, 5 May 2021 18:21:19 +1000 (AEST) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 6A8623989C84; Wed, 5 May 2021 08:20:20 +0000 (GMT) X-Original-To: gcc-patches@gcc.gnu.org Delivered-To: gcc-patches@gcc.gnu.org Received: from rock.gnat.com (rock.gnat.com [205.232.38.15]) by sourceware.org (Postfix) with ESMTP id 189B039A4001 for ; Wed, 5 May 2021 08:20:09 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 189B039A4001 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=adacore.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=derodat@adacore.com Received: from localhost (localhost.localdomain [127.0.0.1]) by filtered-rock.gnat.com (Postfix) with ESMTP id 84EC0561EC; Wed, 5 May 2021 04:20:05 -0400 (EDT) X-Virus-Scanned: Debian amavisd-new at gnat.com Received: from rock.gnat.com ([127.0.0.1]) by localhost (rock.gnat.com [127.0.0.1]) (amavisd-new, port 10024) with LMTP id TjligrMFR17K; Wed, 5 May 2021 04:20:05 -0400 (EDT) Received: from tron.gnat.com (tron.gnat.com [IPv6:2620:20:4000:0:46a8:42ff:fe0e:e294]) by rock.gnat.com (Postfix) with ESMTP id 65A48116F94; Wed, 5 May 2021 04:20:05 -0400 (EDT) Received: by tron.gnat.com (Postfix, from userid 4862) id 64EDF103; Wed, 5 May 2021 04:20:05 -0400 (EDT) Date: Wed, 5 May 2021 04:20:05 -0400 From: Pierre-Marie de Rodat To: gcc-patches@gcc.gnu.org Subject: [Ada] Spurious warning on useless assignment with target name Message-ID: <20210505082005.GA31338@adacore.com> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.5.23 (2014-03-12) X-Spam-Status: No, score=-12.4 required=5.0 tests=BAYES_00, GIT_PATCH_0, KAM_DMARC_STATUS, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Ed Schonberg Errors-To: gcc-patches-bounces@gcc.gnu.org Sender: "Gcc-patches" An assignment to an entity E triggers an improper warning that an immediately preceding assignment to E is useless, when the right-hand side of the new assignment includes a target name, that is to say the Ada2020 use of "@" to designate the left-hand side of the assignment. Tested on x86_64-pc-linux-gnu, committed on trunk gcc/ada/ * sem_ch5.adb (Analyze_Assignment): Do not emit the warning that a previous value of the target object is useless if the right-hand side of the assignment includes target names. diff --git a/gcc/ada/sem_ch5.adb b/gcc/ada/sem_ch5.adb --- a/gcc/ada/sem_ch5.adb +++ b/gcc/ada/sem_ch5.adb @@ -1108,6 +1108,12 @@ package body Sem_Ch5 is -- warnings when an assignment is rewritten as another -- assignment, and gets tied up with itself. + -- We also omit the warning if the RHS includes target names, + -- that is to say the Ada2020 "@" that denotes an instance of + -- the LHS, which indicates that the current value is being + -- used. Note that this implicit reference to the entity on + -- the RHS is not treated as a source reference. + -- There may have been a previous reference to a component of -- the variable, which in general removes the Last_Assignment -- field of the variable to indicate a relevant use of the @@ -1126,6 +1132,7 @@ package body Sem_Ch5 is and then Comes_From_Source (N) and then In_Extended_Main_Source_Unit (Ent) and then not Has_Deferred_Reference (Ent) + and then not Has_Target_Names (N) then Warn_On_Useless_Assignment (Ent, N); end if;