From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-x533.google.com (mail-ed1-x533.google.com [IPv6:2a00:1450:4864:20::533]) by sourceware.org (Postfix) with ESMTPS id 00CEF385843A; Thu, 2 Mar 2023 10:43:43 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 00CEF385843A Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-ed1-x533.google.com with SMTP id d30so65800567eda.4; Thu, 02 Mar 2023 02:43:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1677753822; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=Jp3M9ZV4yfyisbulKY/tcgxDsHsrn2jaw5a59bk/7rE=; b=LI4tBWJQ0TEqdTqpZb0PJYPL4b4Hz7FS9CC1T2Ax7urXeFzjDmBb7ABokySxvjaC7Z fLsmDpQrSd6apZ0/nh/EhW7m/VWDBsUmMafVeFFwNI42RnghTNxnT9V/VQEnFRUZxihe +68mdjdceAUS04rJNTgCTSEM7KOssMXKhnZcuV3fw8WyDkhKIsvZ1xSNt8Fvks9guXiP hcKD6m+CDY+8io2XN/pJcftaYQOCFgnZdZ1xLQc9ULZFS9l8dS37cUoK8a6D077suocN bRV6xocYR8BZYW11UOez6LOnYvDgtOXTuPIC/0ao2NNdr7PWJ+5GRJU8O30AxCJIzRMJ 904Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1677753822; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=Jp3M9ZV4yfyisbulKY/tcgxDsHsrn2jaw5a59bk/7rE=; b=pUIt+KKLjDzkKsh3On7osNnITK4hB/LEBPkcLwXnMMUjQy/4RIVaD6J+UnMk67NpDr u1rO2EGh1alGrwVLNgxeMQI8/QExY5DSZke44cnayPh3L3PWCveB8H22YQaBdWtJlTE1 5ugpedK28ev5dZmgTVU0nQLR76JV6iApYL6cLf0qh9TFc3a4WOEpeAKXfQJBxJlcTpzC uJ77oaRzH24TWblvpFpYsBGnr2u4jHZsymhwnZKn4tzMvE6YvknHy0cmD0np6J2Rj8qQ qI6SPU6Suv1O5hrVObcVVmlrOVanFrv6ucSC1fu/ZYG91Nsr8g+2qlEY+Pxb1nGienWC KGgw== X-Gm-Message-State: AO0yUKVAqhuKZkYWwdKjdEahAlAnOPK/2DXZjjsFZIKdghnBD3ngz4Qn oUjJpc+GmBmdThfrb5upLmIKLWqR2Mgjevthzyg= X-Google-Smtp-Source: AK7set/Ccs5XlJ5aJMo+A/YTfWN2ZllLYXSXo9P4A4AldZNfBJXEeM7WTDK3u/T6lFf9/pjbVorSiew0W32pu6HE264= X-Received: by 2002:a50:9f82:0:b0:4c0:2126:ac34 with SMTP id c2-20020a509f82000000b004c02126ac34mr924740edf.6.1677753822249; Thu, 02 Mar 2023 02:43:42 -0800 (PST) MIME-Version: 1.0 References: <43172ea5-6729-02c5-d374-9537fff7eb4c@gmail.com> <7313d189-ae56-4582-6f23-9263dbf57dd3@gmail.com> <98823f83-ae62-f3e4-4091-01841b08fbb7@gmail.com> <195c8a11-acc7-1e78-091f-c7417d147e64@gmail.com> In-Reply-To: <195c8a11-acc7-1e78-091f-c7417d147e64@gmail.com> From: Jonathan Wakely Date: Thu, 2 Mar 2023 10:43:31 +0000 Message-ID: Subject: Re: [PATCH] libstdc++: Limit allocations in _Rb_tree 2/2 To: =?UTF-8?Q?Fran=C3=A7ois_Dumont?= Cc: "libstdc++@gcc.gnu.org" , gcc-patches Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-0.4 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,KAM_NUMSUBJECT,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Thu, 2 Mar 2023 at 05:40, Fran=C3=A7ois Dumont via Libstdc++ wrote: > > Just forget about this patch, bad idea. > > The key_type might have additional data not used for the comparison. > This data would not be preserved if we were inserting the already stored > equivalent key instead of the user provided. Right. Key equivalence does not imply substitutability, or even equality. struct Key { int i =3D 0; int j =3D 0; bool operator<(const Key& k) const { return i < k.j; } bool operator=3D=3D(const Key& k) const { return i =3D=3D k.i && j =3D=3D= k.j; } };