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 EFFDEC636CD for ; Fri, 10 Feb 2023 15:45:20 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pQVZZ-0002oF-Fw; Fri, 10 Feb 2023 10:44:25 -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 1pQVZX-0002ny-JW for qemu-devel@nongnu.org; Fri, 10 Feb 2023 10:44:24 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pQVZV-0006SR-IN for qemu-devel@nongnu.org; Fri, 10 Feb 2023 10:44:23 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1676043860; 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=uI4d0JQ2YR8owrwq7q25+R1RLKwG/nIEgPpWwzQSIXc=; b=gl8DqhfK+PyoHUXfbnj6d0Q39wdsSBNtiNrIP4BvbyljKIf0G/wZDYgTjxnvD384qkFyzf xPa3UwYGTp1XnLIfpI4MdlZ0vhXgFnqmeNHAPDrD0qXwLP2CPbBBoncICaRwQmDBqAp2lT rzGEtLZPezC5cPzdtO4Lv9TPWvq23Rk= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-554-SLuM8bybM_aXbeiwY9mQwQ-1; Fri, 10 Feb 2023 10:44:19 -0500 X-MC-Unique: SLuM8bybM_aXbeiwY9mQwQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id C9192857F4E; Fri, 10 Feb 2023 15:44:18 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.193.101]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A1952140EBF4; Fri, 10 Feb 2023 15:44:18 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 8F22421E6A1F; Fri, 10 Feb 2023 16:44:17 +0100 (CET) From: Markus Armbruster To: John Snow Cc: qemu-devel@nongnu.org, Michael Roth Subject: Re: [PATCH v3 4/7] qapi/expr: add typing workaround for AbstractSet References: <20230209184758.1017863-1-jsnow@redhat.com> <20230209184758.1017863-5-jsnow@redhat.com> Date: Fri, 10 Feb 2023 16:44:17 +0100 In-Reply-To: <20230209184758.1017863-5-jsnow@redhat.com> (John Snow's message of "Thu, 9 Feb 2023 13:47:55 -0500") Message-ID: <87sffd5xv2.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 3.1 on 10.11.54.7 Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-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: 2.1.29 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: > mypy can only narrow the type of `Mapping[str, ...].keys() & Set[str]` > to `AbstractSet[str]` and not a `Set[str]`. As a result, if the type of > an expression is changed to a Mapping[], mypy is unsure if the .pop() is > safe. > > A forthcoming commit does exactly that, so wrap the expression in a > set() constructor to force the intermediate expression to be resolved as > a mutable type. > > Signed-off-by: John Snow > --- > scripts/qapi/expr.py | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/scripts/qapi/expr.py b/scripts/qapi/expr.py > index b56353bdf84..af802367eff 100644 > --- a/scripts/qapi/expr.py > +++ b/scripts/qapi/expr.py > @@ -622,8 +622,8 @@ def check_expr(expr_elem: _JSONObject) -> None: > if 'include' in expr: > return > > - metas = expr.keys() & {'enum', 'struct', 'union', 'alternate', > - 'command', 'event'} > + metas = set(expr.keys() & { > + 'enum', 'struct', 'union', 'alternate', 'command', 'event'}) > if len(metas) != 1: > raise QAPISemError( > info, "expression must have exactly one key" " 'enum', 'struct', 'union', 'alternate'," " 'command', 'event'") meta = metas.pop() I'm mildly surprised that the result of operator & is considered immutable. How could it *not* be a freshly created set? Oh well. Passing a set to set() is a no-op, so Reviewed-by: Markus Armbruster Regardless, the code feels a bit too clever to me. It actually did already when I wrote it, but I the less clever ways I could think of were also much more verbose. The code checks that exactly one of a set of keys is present, and which one it is. Any ideas?