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=-15.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 33335C433C1 for ; Thu, 25 Mar 2021 23:34:22 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9ED2261A21 for ; Thu, 25 Mar 2021 23:34:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9ED2261A21 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:57524 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lPZUa-0004wZ-IO for qemu-devel@archiver.kernel.org; Thu, 25 Mar 2021 19:34:20 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:46648) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lPZTE-0004AK-3Q for qemu-devel@nongnu.org; Thu, 25 Mar 2021 19:32:56 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:23058) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lPZT9-00041B-V0 for qemu-devel@nongnu.org; Thu, 25 Mar 2021 19:32:54 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616715168; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=4yngWWBir7exyAFsPwgl75UVzW72Eac1Oq3PYNY1JMc=; b=EjjEf7+Uz4Tmk6X/WnP318THQTmFpY0L4kOQZA03ypyNgCZU+Dq4dYFeBYGSTXWCCQRT4f 0cR/j5e33hWDqKDnE0bV08waWCNNuoXgF6VauBfqj+ha0xdiSdQLYefgWW5CAmV7dWUX0o b5Wdh93cFBvn05xpTzAeiqDg7moDvjc= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-340-H4Q4Tx_sNjqbGhVCSEzsbg-1; Thu, 25 Mar 2021 19:32:46 -0400 X-MC-Unique: H4Q4Tx_sNjqbGhVCSEzsbg-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 92D06501E0; Thu, 25 Mar 2021 23:32:45 +0000 (UTC) Received: from [10.10.117.181] (ovpn-117-181.rdu2.redhat.com [10.10.117.181]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1CAFE5D9CA; Thu, 25 Mar 2021 23:32:45 +0000 (UTC) Subject: Re: [PATCH v4 10/19] qapi/expr.py: Add casts in a few select cases To: Markus Armbruster References: <20210325060356.4040114-1-jsnow@redhat.com> <20210325060356.4040114-11-jsnow@redhat.com> <87mturs3p8.fsf@dusky.pond.sub.org> From: John Snow Message-ID: <5ee87276-ed28-30dd-ff51-b81443d71b7b@redhat.com> Date: Thu, 25 Mar 2021 19:32:44 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <87mturs3p8.fsf@dusky.pond.sub.org> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=jsnow@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=jsnow@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Michael Roth , Cleber Rosa , qemu-devel@nongnu.org, Eduardo Habkost Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 3/25/21 10:33 AM, Markus Armbruster wrote: > John Snow writes: > >> Casts are instructions to the type checker only, they aren't "safe" and >> should probably be avoided in general. In this case, when we perform >> type checking on a nested structure, the type of each field does not >> "stick". >> >> (See PEP 647 for an example of "type narrowing" that does "stick". >> It is available in Python 3.10, so we can't use it yet.) >> >> We don't need to assert that something is a str if we've already checked >> or asserted that it is -- use a cast instead for these cases. >> >> Signed-off-by: John Snow >> --- >> scripts/qapi/expr.py | 10 +++++----- >> 1 file changed, 5 insertions(+), 5 deletions(-) >> >> diff --git a/scripts/qapi/expr.py b/scripts/qapi/expr.py >> index ca5ab7bfda..505e67bd21 100644 >> --- a/scripts/qapi/expr.py >> +++ b/scripts/qapi/expr.py >> @@ -15,7 +15,7 @@ >> # See the COPYING file in the top-level directory. >> >> import re >> -from typing import Dict, Optional >> +from typing import Dict, Optional, cast >> >> from .common import c_name >> from .error import QAPISemError >> @@ -259,7 +259,7 @@ def check_enum(expr, info): >> >> >> def check_struct(expr, info): >> - name = expr['struct'] >> + name = cast(str, expr['struct']) # Asserted in check_exprs > > "Asserted" suggests an an assert statement. It's actually the > check_name_is_str() visible in the last hunk. What about "Checked in > check_exprs()" or "Ensured by check_exprs()"? > I missed these. "Checked" is fine.