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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 18B56C5AD4C for ; Thu, 23 Nov 2023 11:01:33 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1r67Ro-0005LV-07; Thu, 23 Nov 2023 06:00:40 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1r67Rm-0005L1-AT for qemu-devel@nongnu.org; Thu, 23 Nov 2023 06:00:38 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1r67Rj-0002P7-R8 for qemu-devel@nongnu.org; Thu, 23 Nov 2023 06:00:37 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1700737232; 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: in-reply-to:in-reply-to:references:references; bh=fzicTtAGE0p9GRXFmLcc3j0J5ehXaozwtFR3rQngrj8=; b=AiGJHSKO9G7Xc2Z+xVFByAB/7i8My9/YizrQHjb3cQAOV+FyR8BKDVjJ2zcpX8CG6ahZ83 qgFSKcxpOdnBohLD2utKAu5HaJhqjtvKRFCtccDXYXvFDFunBXNttntSOtrElG5Jz8LGqF 9s+W1ggMXMAo1+yYf4cSE7koOYR3iXk= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-67-dJKHcEaSN5CW3SlMODt-3w-1; Thu, 23 Nov 2023 06:00:21 -0500 X-MC-Unique: dJKHcEaSN5CW3SlMODt-3w-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 96C4E280A9C7; Thu, 23 Nov 2023 11:00:21 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.192.148]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 74CD01121309; Thu, 23 Nov 2023 11:00:21 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 8579721E6A1F; Thu, 23 Nov 2023 12:00:20 +0100 (CET) From: Markus Armbruster To: John Snow Cc: qemu-devel , Peter Maydell , Michael Roth Subject: Re: [PATCH 06/19] qapi/schema: adjust type narrowing for mypy's benefit References: <20231116014350.653792-1-jsnow@redhat.com> <20231116014350.653792-7-jsnow@redhat.com> <87ttpf2o6t.fsf@pond.sub.org> <87cyw2uhee.fsf@pond.sub.org> Date: Thu, 23 Nov 2023 12:00:20 +0100 In-Reply-To: (John Snow's message of "Wed, 22 Nov 2023 13:12:27 -0500") Message-ID: <87il5s7n0b.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.3 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.058, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org John Snow writes: > On Wed, Nov 22, 2023, 7:00 AM Markus Armbruster wrote: > >> John Snow writes: >> >> > On Tue, Nov 21, 2023, 9:09 AM Markus Armbruster wrote: [...] >> >> Harmless enough. I can't quite see the mypy problem, though. Care to >> >> elaborate a bit? >> >> >> > >> > self.arg_type has a narrower type- or, it WILL at the end of this series - >> > so we need to narrow a temporary variable first before assigning it to the >> > object state. >> > >> > We already perform the necessary check/narrowing, so this is really just >> > pointing out that it's a bad idea to assign the state before the type >> > check. Now we type check before assigning state. >> >> After PATCH 16, .resolve_type() will return QAPISchemaType, and >> self.arg_type will be Optional[QAPISchemaObjectType]. Correct? >> > > Sounds right. Sometimes it's a little hard to see what the error is before > the rest of the types go in, a hazard of needing all patches to bisect > without regression. > > Do you want a more elaborate commit message? Your commit messages of PATCH 3+4 show the error. Helps. Maybe qapi/schema: Adjust type narrowing for mypy's benefit We already take care to perform some type narrowing for arg_type and ret_type, but not in a way where mypy can utilize the result once we add type hints: error message goes here A simple change to use a temporary variable helps the medicine go down.