From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by sourceware.org (Postfix) with ESMTPS id A699E3858404 for ; Thu, 13 Oct 2022 13:58:06 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org A699E3858404 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1665669486; 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=GIIROPPpkfUvg1JYihxWPVsrBIWLFd8y+8A54cmS2yI=; b=CLJGmpHaGkVPVcqxIH/CV3ONhh6EDCSrncjcz87nRJx6EOYA4ISkuHqz5nRrne+mT+Gme4 +bHVIkC/BgX98s6EL6VQNoPnAe54xFtWPMBW0YKEXfv5sILep7+XpLaLquONLDWSAK5pGT IXhFHr8O6e9sOYcC/xkqDD/995081f8= Received: from mail-qt1-f197.google.com (mail-qt1-f197.google.com [209.85.160.197]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-621-65ixHdyfOPSCZ5y1PPPnRw-1; Thu, 13 Oct 2022 09:58:04 -0400 X-MC-Unique: 65ixHdyfOPSCZ5y1PPPnRw-1 Received: by mail-qt1-f197.google.com with SMTP id 17-20020ac85711000000b0039ccd4c9a37so1113391qtw.20 for ; Thu, 13 Oct 2022 06:58:04 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=GIIROPPpkfUvg1JYihxWPVsrBIWLFd8y+8A54cmS2yI=; b=5oQ2JhvXUWpu2aXcFRLBfCiWUseI6QlDB007wzjnudxlNbjKV4BqlOiqAHTkztn6or 5xYmg1+sb32QIK2o9QzQeBoWG7NBW6DAsu5D4bS2uZoo86HQu8aZHmq/8nCY20KPIU7e uZ6L24F7DYQHQ4lyKNTSZBWbboE8wztlNIu90ySj6MV2tpJ8jMPec40z8B4jXzQQ0jIb ypKEmtsy27ZT0KcQXQPBi0nosJrIPPEpLl3gzHwDM7sntjRf0JttnI18P93QZbr5gkwC O7Tifk2Xa3GhSlPtkx/kyr5ExcgNgsJX4DyyX79cOISWhJAU/9ZF3J4of/Nl75dcKXGU 6wjQ== X-Gm-Message-State: ACrzQf0mYrAvVmx8fMltMBjfJvTWanxzSyP8FFyqGOw7ObMD7tm/zDkV OUl25effY1F0AJQ4oy+gDeMROgXQHtCjQAESR5hyu32PIKbPo2pjXq1IrQs6NO8pxkS7lRWE4iT Be5fPgG2hvCopwhKsTQ== X-Received: by 2002:a05:620a:2587:b0:6cf:7ece:e1f9 with SMTP id x7-20020a05620a258700b006cf7ecee1f9mr22233qko.182.1665669483607; Thu, 13 Oct 2022 06:58:03 -0700 (PDT) X-Google-Smtp-Source: AMsMyM4gT8go3vfCrJnm2iH+lezAZw41tq2yeJMYwHIIrtOZ4nS7avhJ43nE8/T9HlapyM3ByC7pxQ== X-Received: by 2002:a05:620a:2587:b0:6cf:7ece:e1f9 with SMTP id x7-20020a05620a258700b006cf7ecee1f9mr22219qko.182.1665669483363; Thu, 13 Oct 2022 06:58:03 -0700 (PDT) Received: from redhat.com (2603-7000-9500-2e39-0000-0000-0000-1db4.res6.spectrum.com. [2603:7000:9500:2e39::1db4]) by smtp.gmail.com with ESMTPSA id s4-20020a05620a254400b006bbc09af9f5sm18350337qko.101.2022.10.13.06.58.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Oct 2022 06:58:02 -0700 (PDT) Date: Thu, 13 Oct 2022 09:58:01 -0400 From: Marek Polacek To: Jason Merrill Cc: GCC Patches Subject: Re: [PATCH v2] c++: ICE with VEC_INIT_EXPR and defarg [PR106925] Message-ID: References: <20221011200003.695682-1-polacek@redhat.com> <778ca670-6623-77f9-e941-51302007da64@redhat.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/2.2.7 (2022-08-07) X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Spam-Status: No, score=-6.4 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_NONE,TXREP autolearn=ham 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 Wed, Oct 12, 2022 at 02:23:40PM -0400, Marek Polacek wrote: > On Wed, Oct 12, 2022 at 01:12:57PM -0400, Marek Polacek wrote: > > On Wed, Oct 12, 2022 at 12:47:21PM -0400, Jason Merrill wrote: > > > On 10/12/22 12:27, Marek Polacek wrote: > > > > On Tue, Oct 11, 2022 at 04:28:11PM -0400, Jason Merrill wrote: > > > > > On 10/11/22 16:00, Marek Polacek wrote: > > > > > > Since r12-8066, in cxx_eval_vec_init we perform expand_vec_init_expr > > > > > > while processing the default argument in this test. > > > > > > > > > > Hmm, why are we calling cxx_eval_vec_init during parsing of the default > > > > > argument? In particular, any expansion that depends on the enclosing > > > > > function context should be deferred until the default arg is used by a call. > > > > > > > > I think this is part of the semantic constraints checking [dcl.fct.default]/5 > > > > talks about, as in, this doesn't compile even though the default argument is > > > > not executed: > > > > > > > > struct S { > > > > S() = delete; > > > > }; > > > > void foo (S = S()) { } > > > > In the test below we parse '= MyVector<1>()' and end up calling mark_used > > > > on the implicit "constexpr MyVector<1>::MyVector() noexcept ()" > > > > ctor. mark_used calls maybe_instantiate_noexcept. Since the ctor has > > > > a DEFERRED_NOEXCEPT, we have to figure out if the ctor should be noexcept > > > > or not using get_defaulted_eh_spec. That means walking the members of > > > > MyVector. Thus we reach > > > > /* Core 1351: If the field has an NSDMI that could throw, the > > > > default constructor is noexcept(false). */ > > > > > > Maybe we need a cp_unevaluated here? The operand of noexcept should be > > > unevaluated. > > > > That wouldn't help since get_nsdmi specifically does "cp_evaluated ev;", > > so... > > > > > > and call get_nsdmi on 'data'. There we digest its initializer which is {}. > > > > massage_init_elt calls digest_init_r on the {} and produces > > > > TARGET_EXPR > > > D.2518 > > > > {} >>>> > > > > and the subsequent fold_non_dependent_init leads to cxx_eval_vec_init > > > > -> expand_vec_init_expr. > > > > > > > > I think this is all correct except that the fold_non_dependent_init is > > > > somewhat questionable to me; do we really have to fold in order to say > > > > if the NSDMI init can throw? Sure, we need to digest the {}, maybe > > > > the field's ctors can throw, but I don't know about the folding. > > > > > > And we can check cp_unevaluated_operand to avoid the > > > fold_non_dependent_init? > > > > ...we'd still fold. I'm not sure if we want a LOOKUP_ flag that says > > "we're just checking if we can throw, don't fold". > > Eh, a new flag is overkill. Maybe don't do cp_evaluated in get_nsdmi if > we're called from walk_field_subobs would be worth a try? FWIW, my experiments with cp_unevaluated_operand failed because then we'd miss warnings as in g++.dg/ext/cond5.C which warns from the get_defaulted_eh_spec context -- so I'd have no way to distinguish that from the test in this PR. Should we just go back to my patch? Marek