From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 62013 invoked by alias); 24 Feb 2020 22:16:14 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 61900 invoked by uid 89); 24 Feb 2020 22:15:58 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-19.8 required=5.0 tests=AWL,BAYES_00,GIT_PATCH_0,GIT_PATCH_1,GIT_PATCH_2,GIT_PATCH_3,KAM_SHORT,RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 spammy= X-HELO: us-smtp-1.mimecast.com Received: from us-smtp-delivery-1.mimecast.com (HELO us-smtp-1.mimecast.com) (207.211.31.120) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Mon, 24 Feb 2020 22:15:57 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1582582555; 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=MbTueXCqVcJj3iVfpvGWsqG2/1hh1w7c1PhgxKUjCEY=; b=c149N6SGTROJ3o47bCRAdKD0siv6sBRVz9cFdh+aJUGbL9aEf16RoUYgCHIHaEcz8g3aO6 Mrzxcs25UZQS8Gt75VPC4wmHSIV4HgZG08GcYTHRFqv3RXmv/xIzIjcsNznBt+HUNeJlWO t9Q7c5XMakMOeXG7mpkU3llDnKZvT5g= Received: from mail-qv1-f72.google.com (mail-qv1-f72.google.com [209.85.219.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-19-Jp0sdS_yPFaMoH-Pp4Dusg-1; Mon, 24 Feb 2020 17:15:48 -0500 Received: by mail-qv1-f72.google.com with SMTP id b8so10557421qvw.3 for ; Mon, 24 Feb 2020 14:15:48 -0800 (PST) Return-Path: Received: from [192.168.1.148] (209-6-216-142.s141.c3-0.smr-cbr1.sbo-smr.ma.cable.rcncustomer.com. [209.6.216.142]) by smtp.gmail.com with ESMTPSA id j22sm6307078qkk.45.2020.02.24.14.15.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 24 Feb 2020 14:15:46 -0800 (PST) Subject: Re: [PATCH v3] c++: Fix value-init crash in template [PR93676] To: Marek Polacek Cc: GCC Patches References: <20200211195459.358172-1-polacek@redhat.com> <6eb452b2-c291-8a14-9e33-303a789db065@redhat.com> <20200219211523.GC3559@redhat.com> <1e9fd58e-f6d2-cc4a-185f-0bbbf0c0096e@redhat.com> <20200220165224.GA3554@redhat.com> From: Jason Merrill Message-ID: <03345539-e36f-66c8-4e57-f40eb8c377c1@redhat.com> Date: Mon, 24 Feb 2020 22:16:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: <20200220165224.GA3554@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-IsSubscribed: yes X-SW-Source: 2020-02/txt/msg01344.txt.bz2 On 2/20/20 11:52 AM, Marek Polacek wrote: > On Thu, Feb 20, 2020 at 12:13:07AM +0000, Jason Merrill wrote: >> On 2/19/20 10:15 PM, Marek Polacek wrote: >>> On Fri, Feb 14, 2020 at 12:24:30AM +0100, Jason Merrill wrote: >>>> On 2/11/20 8:54 PM, Marek Polacek wrote: >>>>> Since we >>>>> attempt to value-initialize in build_vec_init even when there's no >>>>> initializer but the type has a constexpr default constructor. But >>>>> build_value_init doesn't work in templates, so I think let's avoid >>>>> this scenario; we'll go to the normal build_aggr_init path then. >>>>> >>>>> Bootstrapped/regtested on x86_64-linux, ok for trunk and branches? >>>>> >>>>> PR c++/93676 - value-init crash in template. >>>>> * init.c (build_vec_init): Don't perform value-init in a template. >>>> >>>> Hmm, we really shouldn't even be calling build_vec_init in a template, that >>>> builds up a lot of garbage that we'll throw away at the end of build_new. >>> >>> Ah, it's true that build_new will just creates a NEW_EXPR in a template and >>> doesn't use the result of build_new_1. Unfortunately I can't just call >>> build_special_member_call like we do in build_new_1 since that crashes for >>> array types. >> >> We should call it for strip_array_types (type). > > Since build_special_member_call takes an expression we'd have to modify > its type which I think is not pretty, but it works. Is this along the > lines you had in mind? > I think I still like the v1 patch best but if you're fine with the > following, then am I. > > -- >8 -- > Since we > attempt to value-initialize in build_vec_init even when there's no > initializer but the type has a constexpr default constructor. But > build_value_init doesn't work in templates, and build_vec_init > creates a lot of garbage that would not be used anyway, so don't > call it in a template. > > PR c++/93676 - value-init crash in template. > * init.c (build_new_1): Don't call build_vec_init in a template. > > * g++.dg/cpp0x/nsdmi-template19.C: New test. > --- > gcc/cp/init.c | 6 +++++- > gcc/testsuite/g++.dg/cpp0x/nsdmi-template19.C | 13 +++++++++++++ > 2 files changed, 18 insertions(+), 1 deletion(-) > create mode 100644 gcc/testsuite/g++.dg/cpp0x/nsdmi-template19.C > > diff --git a/gcc/cp/init.c b/gcc/cp/init.c > index d480660445e..c60f332313a 100644 > --- a/gcc/cp/init.c > +++ b/gcc/cp/init.c > @@ -3511,13 +3511,17 @@ build_new_1 (vec **placement, tree type, tree nelts, > explicit_value_init_p = true; > } > > - if (processing_template_decl && explicit_value_init_p) > + if (processing_template_decl) > { > /* build_value_init doesn't work in templates, and we don't need > the initializer anyway since we're going to throw it away and > rebuild it at instantiation time, so just build up a single > constructor call to get any appropriate diagnostics. */ > init_expr = cp_build_fold_indirect_ref (data_addr); > + /* Avoid an ICE when converting to a base in build_simple_base_path. > + We'll throw this all away anyway, and build_new will create > + a NEW_EXPR. */ > + TREE_TYPE (init_expr) = strip_array_types (TREE_TYPE (init_expr)); instead of this, how about casting data_addr to elt_type* before cp_build_fold_indirect_ref? Jason