Message ID | 20220115002249.366484-1-polacek@redhat.com |
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State | New |
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Return-Path: <gcc-patches-bounces+patchwork=sourceware.org@gcc.gnu.org> 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 <patchwork@sourceware.org>; 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 <gcc-patches@gcc.gnu.org>; 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 <jason@redhat.com>, Nathan Sidwell <nathan@acm.org>, GCC Patches <gcc-patches@gcc.gnu.org> 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 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="US-ASCII" 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 <gcc-patches.gcc.gnu.org> List-Unsubscribe: <https://gcc.gnu.org/mailman/options/gcc-patches>, <mailto:gcc-patches-request@gcc.gnu.org?subject=unsubscribe> List-Archive: <https://gcc.gnu.org/pipermail/gcc-patches/> List-Post: <mailto:gcc-patches@gcc.gnu.org> List-Help: <mailto:gcc-patches-request@gcc.gnu.org?subject=help> List-Subscribe: <https://gcc.gnu.org/mailman/listinfo/gcc-patches>, <mailto:gcc-patches-request@gcc.gnu.org?subject=subscribe> From: Marek Polacek via Gcc-patches <gcc-patches@gcc.gnu.org> Reply-To: Marek Polacek <polacek@redhat.com> Errors-To: gcc-patches-bounces+patchwork=sourceware.org@gcc.gnu.org Sender: "Gcc-patches" <gcc-patches-bounces+patchwork=sourceware.org@gcc.gnu.org> |
Series |
c++: ICE with noexcept and canonical types [PR101715]
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Commit Message
Marek Polacek
Jan. 15, 2022, 12:22 a.m. UTC
This is a "canonical types differ for identical types" ICE, which started with r11-4682. It's a bit tricky to explain. Consider: template <typename T> struct S { S<T> bar() noexcept(T::value); // #1 S<T> foo() noexcept(T::value); // #2 }; template <typename T> S<T> S<T>::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::<T379>(S*) |----->| S S::<T37c>(S*) |----->| S S::<T37a>(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
Comments
On Fri, 14 Jan 2022, Marek Polacek via Gcc-patches wrote: > This is a "canonical types differ for identical types" ICE, which started > with r11-4682. It's a bit tricky to explain. Consider: > > template <typename T> struct S { > S<T> bar() noexcept(T::value); // #1 > S<T> foo() noexcept(T::value); // #2 > }; > > template <typename T> S<T> S<T>::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::<T379>(S*) |----->| S S::<T37c>(S*) |----->| S S::<T37a>(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). I wonder about instead making build_cp_fntype_variant set the TYPE_CANONICAL for #3 to TYPE_CANONICAL(#2) (i.e. #1) instead of to #2? Something like: -- >8 -- gcc/cp/tree.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/gcc/cp/tree.c b/gcc/cp/tree.c index 7f7de86b4e8..b89135fa121 100644 --- a/gcc/cp/tree.c +++ b/gcc/cp/tree.c @@ -2779,8 +2779,9 @@ build_cp_fntype_variant (tree type, cp_ref_qualifier rqual, else if (TYPE_CANONICAL (type) != type || cr != raises || late) /* Build the underlying canonical type, since it is different from TYPE. */ - TYPE_CANONICAL (v) = build_cp_fntype_variant (TYPE_CANONICAL (type), - rqual, cr, false); + TYPE_CANONICAL (v) + = TYPE_CANONICAL (build_cp_fntype_variant (TYPE_CANONICAL (type), + rqual, cr, false)); else /* T is its own canonical type. */ TYPE_CANONICAL (v) = v;
On 1/14/22 19:22, Marek Polacek wrote: > This is a "canonical types differ for identical types" ICE, which started > with r11-4682. It's a bit tricky to explain. Consider: > > template <typename T> struct S { > S<T> bar() noexcept(T::value); // #1 > S<T> foo() noexcept(T::value); // #2 > }; > > template <typename T> S<T> S<T>::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::<T379>(S*) |----->| S S::<T37c>(S*) |----->| S S::<T37a>(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. Why doesn't the TYPE_CANONICAL (v) == v check prevent this? > 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 > > 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 <typename T> struct S { > + S<T> bar() noexcept(T::value); // #1 > + S<T> foo() noexcept(T::value); // #2 > +}; > + > +template <typename T> S<T> S<T>::foo() noexcept(T::value) {} // #3 > + > +template <typename T> struct S2 { > + S2<T> bar1() noexcept(T::value); > + S2<T> bar2() noexcept(T::value); > + S2<T> bar3() noexcept(T::value); > + S2<T> bar4() noexcept(T::value); > + S2<T> bar5() noexcept(T::value); > + S2<T> baz() noexcept(T::value2); > + S2<T> foo() noexcept(T::value); > +}; > + > +template <typename T> S2<T> S2<T>::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 <typename T> struct S { }; > + > +template<typename T> > +struct A > +{ > + A& foo(A&&) noexcept((S<T>::value)); > + A& assign(A&&) noexcept((S<T>::value)); > +}; > +template<typename T> > +A<T>& A<T>::foo(A&&) noexcept((S<T>::value)) {} > > base-commit: 952b7dbb418198f86d7829aaf9d7f9fc7714a8b3
On Mon, Jan 17, 2022 at 01:48:48PM -0500, Jason Merrill wrote: > On 1/14/22 19:22, Marek Polacek wrote: > > This is a "canonical types differ for identical types" ICE, which started > > with r11-4682. It's a bit tricky to explain. Consider: > > > > template <typename T> struct S { > > S<T> bar() noexcept(T::value); // #1 > > S<T> foo() noexcept(T::value); // #2 > > }; > > > > template <typename T> S<T> S<T>::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::<T379>(S*) |----->| S S::<T37c>(S*) |----->| S S::<T37a>(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. > > Why doesn't the TYPE_CANONICAL (v) == v check prevent this? In other words, I think you're asking: why did fixup_deferred_exception_variants set TYPE_CANONICAL (#2) to #1 (which then differs from TYPE_CANONICAL (#3), which is #2)? The method_type for #1 (I'll mark is as #1 here) is built with it being its own canonical type. The first call to fixup_deferred_exception_variants does not change it: in there, VARIANT is #1, the loop with 'TYPE_CANONICAL (v) == v' cannot find an existing variant that would match, so when we do v = build_cp_fntype_variant (TYPE_CANONICAL (variant), rqual, cr, false); we get #1 so TYPE_CANONICAL (variant) = v; is just TYPE_CANONICAL (#1) = #1; so no change. The second call to fixup_deferred_exception_variants: here we're working with VARIANT #2. Now we again scan the list of variants {main, #2, #1} where we find a match for #2: #1. #1's TYPE_CANONICAL is #1 as per above, so we set TYPE_CANONICAL (#2) = #1; which I think is correct. I think TYPE_CANONICAL (#3) should also be #1, not #2, which my patch attempts to do. Hope this explanation makes some sense, please ask away if it doesn't! > > 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 > > > > 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 <typename T> struct S { > > + S<T> bar() noexcept(T::value); // #1 > > + S<T> foo() noexcept(T::value); // #2 > > +}; > > + > > +template <typename T> S<T> S<T>::foo() noexcept(T::value) {} // #3 > > + > > +template <typename T> struct S2 { > > + S2<T> bar1() noexcept(T::value); > > + S2<T> bar2() noexcept(T::value); > > + S2<T> bar3() noexcept(T::value); > > + S2<T> bar4() noexcept(T::value); > > + S2<T> bar5() noexcept(T::value); > > + S2<T> baz() noexcept(T::value2); > > + S2<T> foo() noexcept(T::value); > > +}; > > + > > +template <typename T> S2<T> S2<T>::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 <typename T> struct S { }; > > + > > +template<typename T> > > +struct A > > +{ > > + A& foo(A&&) noexcept((S<T>::value)); > > + A& assign(A&&) noexcept((S<T>::value)); > > +}; > > +template<typename T> > > +A<T>& A<T>::foo(A&&) noexcept((S<T>::value)) {} > > > > base-commit: 952b7dbb418198f86d7829aaf9d7f9fc7714a8b3 > Marek
On Sat, Jan 15, 2022 at 09:24:05AM -0500, Patrick Palka wrote: > On Fri, 14 Jan 2022, Marek Polacek via Gcc-patches wrote: > > > This is a "canonical types differ for identical types" ICE, which started > > with r11-4682. It's a bit tricky to explain. Consider: > > > > template <typename T> struct S { > > S<T> bar() noexcept(T::value); // #1 > > S<T> foo() noexcept(T::value); // #2 > > }; > > > > template <typename T> S<T> S<T>::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::<T379>(S*) |----->| S S::<T37c>(S*) |----->| S S::<T37a>(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). > > I wonder about instead making build_cp_fntype_variant set the TYPE_CANONICAL for > #3 to TYPE_CANONICAL(#2) (i.e. #1) instead of to #2? Something like: > > -- >8 -- > > gcc/cp/tree.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/gcc/cp/tree.c b/gcc/cp/tree.c > index 7f7de86b4e8..b89135fa121 100644 > --- a/gcc/cp/tree.c > +++ b/gcc/cp/tree.c > @@ -2779,8 +2779,9 @@ build_cp_fntype_variant (tree type, cp_ref_qualifier rqual, > else if (TYPE_CANONICAL (type) != type || cr != raises || late) > /* Build the underlying canonical type, since it is different > from TYPE. */ > - TYPE_CANONICAL (v) = build_cp_fntype_variant (TYPE_CANONICAL (type), > - rqual, cr, false); > + TYPE_CANONICAL (v) > + = TYPE_CANONICAL (build_cp_fntype_variant (TYPE_CANONICAL (type), > + rqual, cr, false)); > else > /* T is its own canonical type. */ > TYPE_CANONICAL (v) = v; Thanks for looking. I can dig that (and verified it works), but it strikes me more as a workaround for the duplicity problem. I also don't see TYPE_CANONICAL (...) = TYPE_CANONICAL (build_cp_fntype_variant (...)) anywhere in the codebase, if that means anything. Marek
On 1/18/22 11:05, Marek Polacek wrote: > On Mon, Jan 17, 2022 at 01:48:48PM -0500, Jason Merrill wrote: >> On 1/14/22 19:22, Marek Polacek wrote: >>> This is a "canonical types differ for identical types" ICE, which started >>> with r11-4682. It's a bit tricky to explain. Consider: >>> >>> template <typename T> struct S { >>> S<T> bar() noexcept(T::value); // #1 >>> S<T> foo() noexcept(T::value); // #2 >>> }; >>> >>> template <typename T> S<T> S<T>::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::<T379>(S*) |----->| S S::<T37c>(S*) |----->| S S::<T37a>(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. >> >> Why doesn't the TYPE_CANONICAL (v) == v check prevent this? > > In other words, I think you're asking: why did fixup_deferred_exception_variants > set TYPE_CANONICAL (#2) to #1 (which then differs from TYPE_CANONICAL (#3), > which is #2)? I meant to ask why TYPE_CANONICAL (#3) got set to #2 instead of #1? And to answer my own question, it's because the check I mention is in fixup_deferred_exception_variants, and #3 doesn't go through there at all; the loop in build_cp_fntype_variant assumes no duplicate variants, which your patch fixes. > The method_type for #1 (I'll mark is as #1 here) is built with it being its own > canonical type. > > The first call to fixup_deferred_exception_variants does not change it: in > there, VARIANT is #1, the loop with 'TYPE_CANONICAL (v) == v' cannot find > an existing variant that would match, so when we do > > v = build_cp_fntype_variant (TYPE_CANONICAL (variant), > rqual, cr, false); > we get #1 so > TYPE_CANONICAL (variant) = v; > is just > TYPE_CANONICAL (#1) = #1; > so no change. > > The second call to fixup_deferred_exception_variants: here we're working with > VARIANT #2. Now we again scan the list of variants {main, #2, #1} where we > find a match for #2: #1. #1's TYPE_CANONICAL is #1 as per above, so we set > TYPE_CANONICAL (#2) = #1; > which I think is correct. > > > I think TYPE_CANONICAL (#3) should also be #1, not #2, which my patch attempts > to do. > > > Hope this explanation makes some sense, please ask away if it doesn't! > >>> 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 >>> >>> 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); I think we don't two loops through the variants. It ought to work to replace the existing loop with yours; if we find v, we prune and use its TYPE_CANONICAL. Jason
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 <typename T> struct S { + S<T> bar() noexcept(T::value); // #1 + S<T> foo() noexcept(T::value); // #2 +}; + +template <typename T> S<T> S<T>::foo() noexcept(T::value) {} // #3 + +template <typename T> struct S2 { + S2<T> bar1() noexcept(T::value); + S2<T> bar2() noexcept(T::value); + S2<T> bar3() noexcept(T::value); + S2<T> bar4() noexcept(T::value); + S2<T> bar5() noexcept(T::value); + S2<T> baz() noexcept(T::value2); + S2<T> foo() noexcept(T::value); +}; + +template <typename T> S2<T> S2<T>::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 <typename T> struct S { }; + +template<typename T> +struct A +{ + A& foo(A&&) noexcept((S<T>::value)); + A& assign(A&&) noexcept((S<T>::value)); +}; +template<typename T> +A<T>& A<T>::foo(A&&) noexcept((S<T>::value)) {}