From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 122156 invoked by alias); 25 Feb 2020 18:27:27 -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 122144 invoked by uid 89); 25 Feb 2020 18:27:27 -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; Tue, 25 Feb 2020 18:27:25 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1582655244; 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=+qZXqCQAf5ZuILaOhGnGa7+K+ELwBXnCjmCGc8wIuT4=; b=OQeSQ5ZhyGjIFH1Tm+4fkVlP+SGmLGpK40oupP8rr/D7sgnEY2wU5Qq1WEdyAeYQxtdzEv sp4zBJVwBN9BKMqYNSsa8Pz7odkRcOzkGeV1gqqPEFYOM9GajikLUhPqoGaRHb5U+Pwr7f fpBRh7L/KhVlWNyQrX74nDPxEXN4cf0= Received: from mail-qk1-f199.google.com (mail-qk1-f199.google.com [209.85.222.199]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-97-yb3fMdPwM3amJqrcdpkIiw-1; Tue, 25 Feb 2020 13:27:14 -0500 Received: by mail-qk1-f199.google.com with SMTP id c206so16055825qkg.6 for ; Tue, 25 Feb 2020 10:27:14 -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 j127sm7689905qkc.36.2020.02.25.10.27.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 25 Feb 2020 10:27:12 -0800 (PST) Subject: Re: [PATCH v4] 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> <03345539-e36f-66c8-4e57-f40eb8c377c1@redhat.com> <20200225175256.GI3554@redhat.com> From: Jason Merrill Message-ID: <36806f8f-7705-bc48-064b-385d7bd83782@redhat.com> Date: Tue, 25 Feb 2020 18:27:00 -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: <20200225175256.GI3554@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/msg01412.txt.bz2 On 2/25/20 12:52 PM, Marek Polacek wrote: > On Mon, Feb 24, 2020 at 05:15:45PM -0500, Jason Merrill wrote: >> 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? > > That seems to work, thanks! > > Bootstrapped/regtested on x86_64-linux, ok for trunk? > > -- >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..31a130422af 100644 > --- a/gcc/cp/init.c > +++ b/gcc/cp/init.c > @@ -3511,8 +3511,12 @@ 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) > { > + /* 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. */ > + data_addr = build_nop (build_pointer_type (elt_type), data_addr); Let's use a new local variable instead of changing data_addr, which following code expects to still have its old type. And as a minor tweak, data_addr might already have the right type, so let's use fold_convert like other places in the function. > /* 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 > diff --git a/gcc/testsuite/g++.dg/cpp0x/nsdmi-template19.C b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template19.C > new file mode 100644 > index 00000000000..f3e2cb87fd6 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template19.C > @@ -0,0 +1,13 @@ > +// PR c++/93676 - value-init crash in template. > +// { dg-do compile { target c++11 } } > + > +struct P { > + int x = 0; > +}; > + > +template > +struct S { > + S() { new P[2][2]; } > +}; > + > +S s; > > base-commit: a71f2193d0df71a86c4743aab22891bb0003112e >