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[130.44.159.43]) by smtp.gmail.com with ESMTPSA id l23-20020a37f917000000b006bbb07ebd83sm907598qkj.108.2022.09.27.05.53.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 27 Sep 2022 05:53:44 -0700 (PDT) Message-ID: Date: Tue, 27 Sep 2022 08:53:43 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.13.1 Subject: Re: [PATCH] c++: Make __is_{,nothrow_}convertible SFINAE on access [PR107049] To: Jonathan Wakely , gcc-patches@gcc.gnu.org, libstdc++@gcc.gnu.org Cc: Marek Polacek References: <20220927103510.2321453-1-jwakely@redhat.com> From: Jason Merrill In-Reply-To: <20220927103510.2321453-1-jwakely@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-14.2 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,GIT_PATCH_0,NICE_REPLY_A,RCVD_IN_DNSWL_LOW,SPF_HELO_NONE,SPF_NONE,TXREP autolearn=unavailable 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 9/27/22 06:35, Jonathan Wakely wrote: > Tested powerpc64le-linux. OK for trunk? OK, thanks. > -- >8 -- > > The is_convertible built-ins should return false if the conversion fails > an access check, not report an error. > > PR c++/107049 > > gcc/cp/ChangeLog: > > * method.cc (is_convertible_helper): Use access check sentinel. > > gcc/testsuite/ChangeLog: > > * g++.dg/ext/is_convertible4.C: New test. > * g++.dg/ext/is_nothrow_convertible4.C: New test. > > libstdc++-v3/ChangeLog: > > * testsuite/20_util/is_convertible/requirements/access.cc: New > test. > --- > gcc/cp/method.cc | 1 + > gcc/testsuite/g++.dg/ext/is_convertible4.C | 33 +++++++++++++++++++ > .../g++.dg/ext/is_nothrow_convertible4.C | 33 +++++++++++++++++++ > .../is_convertible/requirements/access.cc | 18 ++++++++++ > 4 files changed, 85 insertions(+) > create mode 100644 gcc/testsuite/g++.dg/ext/is_convertible4.C > create mode 100644 gcc/testsuite/g++.dg/ext/is_nothrow_convertible4.C > create mode 100644 libstdc++-v3/testsuite/20_util/is_convertible/requirements/access.cc > > diff --git a/gcc/cp/method.cc b/gcc/cp/method.cc > index 9f917f13134..55af5c43c18 100644 > --- a/gcc/cp/method.cc > +++ b/gcc/cp/method.cc > @@ -2246,6 +2246,7 @@ is_convertible_helper (tree from, tree to) > return integer_one_node; > cp_unevaluated u; > tree expr = build_stub_object (from); > + deferring_access_check_sentinel acs (dk_no_deferred); > return perform_implicit_conversion (to, expr, tf_none); > } > > diff --git a/gcc/testsuite/g++.dg/ext/is_convertible4.C b/gcc/testsuite/g++.dg/ext/is_convertible4.C > new file mode 100644 > index 00000000000..8a7724c5852 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/ext/is_convertible4.C > @@ -0,0 +1,33 @@ > +// PR c++/107049 > +// { dg-do compile { target c++11 } } > +// Failed access check should be a substitution failure, not an error. > + > +template > +struct bool_constant { static constexpr bool value = B; }; > + > +template > +struct is_convertible > +: public bool_constant<__is_convertible(From, To)> > +{ }; > + > +#if __cpp_variable_templates > +template > +constexpr bool is_convertible_v = __is_convertible(From, To); > +#endif > + > +class Private > +{ > + operator int() const > + { > + static_assert( not is_convertible::value, "" ); > +#if __cpp_variable_templates > + static_assert( not is_convertible_v, "" ); > +#endif > + return 0; > + } > +}; > + > +static_assert( not is_convertible::value, "" ); > +#if __cpp_variable_templates > +static_assert( not is_convertible_v, "" ); > +#endif > diff --git a/gcc/testsuite/g++.dg/ext/is_nothrow_convertible4.C b/gcc/testsuite/g++.dg/ext/is_nothrow_convertible4.C > new file mode 100644 > index 00000000000..f81b5944ca2 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/ext/is_nothrow_convertible4.C > @@ -0,0 +1,33 @@ > +// PR c++/107049 > +// { dg-do compile { target c++11 } } > +// Failed access check should be a substitution failure, not an error. > + > +template > +struct bool_constant { static constexpr bool value = B; }; > + > +template > +struct is_nt_convertible > +: public bool_constant<__is_nothrow_convertible(From, To)> > +{ }; > + > +#if __cpp_variable_templates > +template > +constexpr bool is_nt_convertible_v = __is_nothrow_convertible(From, To); > +#endif > + > +class Private > +{ > + operator int() const > + { > + static_assert( not is_nt_convertible::value, "" ); > +#if __cpp_variable_templates > + static_assert( not is_nt_convertible_v, "" ); > +#endif > + return 0; > + } > +}; > + > +static_assert( not is_nt_convertible::value, "" ); > +#if __cpp_variable_templates > +static_assert( not is_nt_convertible_v, "" ); > +#endif > diff --git a/libstdc++-v3/testsuite/20_util/is_convertible/requirements/access.cc b/libstdc++-v3/testsuite/20_util/is_convertible/requirements/access.cc > new file mode 100644 > index 00000000000..04a8c525961 > --- /dev/null > +++ b/libstdc++-v3/testsuite/20_util/is_convertible/requirements/access.cc > @@ -0,0 +1,18 @@ > +// { dg-do compile { target c++11 } } > +// PR c++/107049 > + > +#include > + > +class Private > +{ > + operator int() const > + { > + static_assert( not std::is_convertible::value, "" ); > +#if __cpp_lib_type_trait_variable_templates > + static_assert( not std::is_convertible_v, "" ); > +#endif > + return 0; > + } > +}; > + > +static_assert( not std::is_convertible::value, "" );