From patchwork Sat Jan 15 00:22:49 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marek Polacek X-Patchwork-Id: 50055 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 41F4A385E455 for ; Sat, 15 Jan 2022 00:23:35 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 41F4A385E455 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1642206215; bh=M/CPoH1THkQc5LEE0qiFt/94Y40u9L/zEb3DhhOkwNA=; h=To:Subject:Date:List-Id:List-Unsubscribe:List-Archive:List-Post: List-Help:List-Subscribe:From:Reply-To:From; b=sXNyBWvQm8CjTArCVHjtchKw57equpgWKc4squ29/pWhPQjTE4vVOfCipB6By2b5W 0LWPkOOpa+nQ4S2TkfD7f4ps8A/JFtRe1All1zLIfIGhbOdQxsjU+wEKcge9tjYfWL LflpuqniGoXxfBWsQRnk2MndqVKjxVU0BcPcd4oc= X-Original-To: gcc-patches@gcc.gnu.org Delivered-To: gcc-patches@gcc.gnu.org Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTPS id 95EC13858C39 for ; Sat, 15 Jan 2022 00:23:05 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 95EC13858C39 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-240-k-a7XGJsN1CrAGIhfmkfwQ-1; Fri, 14 Jan 2022 19:23:03 -0500 X-MC-Unique: k-a7XGJsN1CrAGIhfmkfwQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B2AC81006AA4; Sat, 15 Jan 2022 00:23:02 +0000 (UTC) Received: from pdp-11.redhat.com (unknown [10.22.33.53]) by smtp.corp.redhat.com (Postfix) with ESMTP id 423C25DBAC; Sat, 15 Jan 2022 00:22:58 +0000 (UTC) To: Jason Merrill , Nathan Sidwell , GCC Patches Subject: [PATCH] c++: ICE with noexcept and canonical types [PR101715] Date: Fri, 14 Jan 2022 19:22:49 -0500 Message-Id: <20220115002249.366484-1-polacek@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Spam-Status: No, score=-14.1 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Marek Polacek via Gcc-patches From: Marek Polacek Reply-To: Marek Polacek Errors-To: gcc-patches-bounces+patchwork=sourceware.org@gcc.gnu.org Sender: "Gcc-patches" This is a "canonical types differ for identical types" ICE, which started with r11-4682. It's a bit tricky to explain. Consider: template struct S { S bar() noexcept(T::value); // #1 S foo() noexcept(T::value); // #2 }; template S S::foo() noexcept(T::value) {} // #3 We ICE because #3 and #2 have the same type, but their canonical types differ: TYPE_CANONICAL (#3) == #2 but TYPE_CANONICAL (#2) == #1. The member functions #1 and #2 have the same type. However, since their noexcept-specifier is deferred, when parsing them, we create a variant for both of them, because DEFERRED_PARSE cannot be compared. In other words, build_cp_fntype_variant's tree v = TYPE_MAIN_VARIANT (type); for (; v; v = TYPE_NEXT_VARIANT (v)) if (cp_check_qualified_type (v, type, type_quals, rqual, raises, late)) return v; will *not* find an existing variant when creating a method_type for #2, so we have to create a new one. But then we perform delayed parsing and call fixup_deferred_exception_variants for #1 and #2. f_d_e_v will replace TYPE_RAISES_EXCEPTIONS with the newly parsed noexcept-specifier. It also sets TYPE_CANONICAL (#2) to #1. Both noexcepts turned out to be the same, so now we have two equivalent variants in the list! I.e., +-----------------+ +-----------------+ +-----------------+ | main | | #2 | | #1 | | S S::(S*) |----->| S S::(S*) |----->| S S::(S*) |----->NULL | - | | noex(T::value) | | noex(T::value) | +-----------------+ +-----------------+ +-----------------+ Then we get to #3. As for #1 and #2, grokdeclarator calls build_memfn_type, which ends up calling build_cp_fntype_variant, which will use the loop above to look for an existing variant. The first one that matches cp_check_qualified_type will be used, so we use #2 rather than #1, and the TYPE_CANONICAL mismatch follows. Hopefully that makes sense. As for the fix, I didn't think I could rewrite the method_type #2 with #1 because the type may have escaped via decltype. So my approach is to elide #2 from the list, so when looking for a matching variant, we always find #1 (#2 remains live though, which admittedly sounds sort of dodgy). Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk/11? PR c++/101715 gcc/cp/ChangeLog: * tree.c (fixup_deferred_exception_variants): Remove duplicate variants after parsing the exception specifications. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/noexcept72.C: New test. * g++.dg/cpp0x/noexcept73.C: New test. --- gcc/cp/tree.c | 16 +++++++++++++++- gcc/testsuite/g++.dg/cpp0x/noexcept72.C | 21 +++++++++++++++++++++ gcc/testsuite/g++.dg/cpp0x/noexcept73.C | 13 +++++++++++++ 3 files changed, 49 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/g++.dg/cpp0x/noexcept72.C create mode 100644 gcc/testsuite/g++.dg/cpp0x/noexcept73.C base-commit: 952b7dbb418198f86d7829aaf9d7f9fc7714a8b3 diff --git a/gcc/cp/tree.c b/gcc/cp/tree.c index 7f7de86b4e8..2efad49e7c1 100644 --- a/gcc/cp/tree.c +++ b/gcc/cp/tree.c @@ -2804,8 +2804,9 @@ fixup_deferred_exception_variants (tree type, tree raises) /* Though sucky, this walk will process the canonical variants first. */ + tree prev = NULL_TREE; for (tree variant = TYPE_MAIN_VARIANT (type); - variant; variant = TYPE_NEXT_VARIANT (variant)) + variant; prev = variant, variant = TYPE_NEXT_VARIANT (variant)) if (TYPE_RAISES_EXCEPTIONS (variant) == original) { gcc_checking_assert (variant != TYPE_MAIN_VARIANT (type)); @@ -2827,6 +2828,19 @@ fixup_deferred_exception_variants (tree type, tree raises) v = build_cp_fntype_variant (TYPE_CANONICAL (variant), rqual, cr, false); TYPE_CANONICAL (variant) = v; + + /* If VARIANT became a duplicate (cp_check_qualified_type-wise) + of an existing variant in the variant list of TYPE after we + have parsed its exception specification, elide it. Otherwise, + build_cp_fntype_variant would use it, leading to "canonical + types differ for identical types." */ + for (v = TYPE_MAIN_VARIANT (type); v; v = TYPE_NEXT_VARIANT (v)) + if (v != variant + /* The main variant will not have TYPE_RAISES_EXCEPTIONS + so PREV should never be null. */ + && cp_check_qualified_type (v, variant, var_quals, + rqual, cr, false)) + TYPE_NEXT_VARIANT (prev) = TYPE_NEXT_VARIANT (variant); } else TYPE_RAISES_EXCEPTIONS (variant) = raises; diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept72.C b/gcc/testsuite/g++.dg/cpp0x/noexcept72.C new file mode 100644 index 00000000000..f1455b3b46b --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/noexcept72.C @@ -0,0 +1,21 @@ +// PR c++/101715 +// { dg-do compile { target c++11 } } + +template struct S { + S bar() noexcept(T::value); // #1 + S foo() noexcept(T::value); // #2 +}; + +template S S::foo() noexcept(T::value) {} // #3 + +template struct S2 { + S2 bar1() noexcept(T::value); + S2 bar2() noexcept(T::value); + S2 bar3() noexcept(T::value); + S2 bar4() noexcept(T::value); + S2 bar5() noexcept(T::value); + S2 baz() noexcept(T::value2); + S2 foo() noexcept(T::value); +}; + +template S2 S2::foo() noexcept(T::value) {} diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept73.C b/gcc/testsuite/g++.dg/cpp0x/noexcept73.C new file mode 100644 index 00000000000..24524f3592a --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/noexcept73.C @@ -0,0 +1,13 @@ +// PR c++/101715 +// { dg-do compile { target c++11 } } + +template struct S { }; + +template +struct A +{ + A& foo(A&&) noexcept((S::value)); + A& assign(A&&) noexcept((S::value)); +}; +template +A& A::foo(A&&) noexcept((S::value)) {}