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[130.44.159.43]) by smtp.gmail.com with ESMTPSA id e26-20020ac8491a000000b003e394714c07sm5431507qtq.10.2023.03.29.13.28.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 29 Mar 2023 13:28:02 -0700 (PDT) Message-ID: Date: Wed, 29 Mar 2023 16:28:00 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 Subject: Re: [PATCH] c++: NTTP constraint depending on outer args [PR109160] To: Patrick Palka , gcc-patches@gcc.gnu.org References: <20230317152629.3944138-1-ppalka@redhat.com> From: Jason Merrill In-Reply-To: <20230317152629.3944138-1-ppalka@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=-12.6 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_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE,TXREP autolearn=ham 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 3/17/23 11:26, Patrick Palka wrote: > Here we're crashing during satisfaction for the NTTP 'C auto' from > do_auto_deduction ultimately because convert_template_argument / unify > don't pass all outer template arguments to do_auto_deduction, and during > satisfaction we need to know all arguments. While these callers do > pass some outer arguments, they are only sufficient to properly > substitute the 'auto' and are not necessarily the complete set. > > Fortunately it seems it's possible to obtain the full set of outer > arguments from these callers via convert_template_argument's IN_DECL > parameter and unify's TPARMS parameter. So this patch adds a TMPL > parameter to do_auto_deduction, used only during adc_unify deduction, > which contains the (partially instantiated) template corresponding to > this auto and from which we can obtain all outer template arguments for > satisfaction. > > This patch also adjusts the IN_DECL argument passed to > coerce_template_parms from tsubst_decl so that we could in turn safely > assume convert_template_argument's IN_DECL is always a TEMPLATE_DECL, > and thus could pass it as-is to do_auto_deduction. (tsubst_decl seems > to be the only caller that passes a non-empty non-template IN_DECL to > coerce_template_parms.) > > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for > trunk/12? > > PR c++/109160 > > gcc/cp/ChangeLog: > > * cp-tree.h (do_auto_deduction): Add defaulted TMPL parameter. > * pt.cc (convert_template_argument): Pass IN_DECL as TMPL to > do_auto_deduction. > (tsubst_decl) : Pass TMPL instead of T as > IN_DECL to coerce_template_parms. > (unify) : Pass the corresponding > template as TMPL to do_auto_deduction. > (do_auto_deduction): Document default arguments. Use TMPL > to obtain a full set of template arguments for satisfaction > in the adc_unify case. > > gcc/testsuite/ChangeLog: > > * g++.dg/cpp2a/concepts-placeholder12.C: New test. > --- > gcc/cp/cp-tree.h | 3 +- > gcc/cp/pt.cc | 30 ++++++++++++++----- > .../g++.dg/cpp2a/concepts-placeholder12.C | 29 ++++++++++++++++++ > 3 files changed, 53 insertions(+), 9 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-placeholder12.C > > diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h > index dfc1c845768..e7190c5cc62 100644 > --- a/gcc/cp/cp-tree.h > +++ b/gcc/cp/cp-tree.h > @@ -7324,7 +7324,8 @@ extern tree do_auto_deduction (tree, tree, tree, > auto_deduction_context > = adc_unspecified, > tree = NULL_TREE, > - int = LOOKUP_NORMAL); > + int = LOOKUP_NORMAL, > + tree = NULL_TREE); > extern tree type_uses_auto (tree); > extern tree type_uses_auto_or_concept (tree); > extern void append_type_to_template_for_access_check (tree, tree, tree, > diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc > index ddbd73371b9..6400b686a58 100644 > --- a/gcc/cp/pt.cc > +++ b/gcc/cp/pt.cc > @@ -8638,7 +8638,7 @@ convert_template_argument (tree parm, > else if (tree a = type_uses_auto (t)) > { > t = do_auto_deduction (t, arg, a, complain, adc_unify, args, > - LOOKUP_IMPLICIT); > + LOOKUP_IMPLICIT, in_decl); > if (t == error_mark_node) > return error_mark_node; > } > @@ -15243,7 +15243,7 @@ tsubst_decl (tree t, tree args, tsubst_flags_t complain) > the template. */ > argvec = (coerce_template_parms > (DECL_TEMPLATE_PARMS (gen_tmpl), > - argvec, t, complain)); > + argvec, tmpl, complain)); > if (argvec == error_mark_node) > RETURN (error_mark_node); > hash = spec_hasher::hash (gen_tmpl, argvec); > @@ -24655,7 +24655,9 @@ unify (tree tparms, tree targs, tree parm, tree arg, int strict, > if (tree a = type_uses_auto (tparm)) > { > tparm = do_auto_deduction (tparm, arg, a, > - complain, adc_unify, targs); > + complain, adc_unify, targs, > + LOOKUP_NORMAL, > + TPARMS_PRIMARY_TEMPLATE (tparms)); > if (tparm == error_mark_node) > return 1; > } > @@ -30643,13 +30645,20 @@ unparenthesized_id_or_class_member_access_p (tree init) > adc_requirement contexts to communicate the necessary template arguments > to satisfaction. OUTER_TARGS is ignored in other contexts. > > - For partial-concept-ids, extra args may be appended to the list of deduced > - template arguments prior to determining constraint satisfaction. */ > + Additionally for adc_unify contexts TMPL is the template for which this > + auto is a template parameter type. > + > + For partial-concept-ids, extra args from OUTER_TARGS, TMPL and the current > + scope may be appended to the list of deduced template arguments prior to > + determining constraint satisfaction as appropriate. */ > > tree > do_auto_deduction (tree type, tree init, tree auto_node, > - tsubst_flags_t complain, auto_deduction_context context, > - tree outer_targs, int flags) > + tsubst_flags_t complain /* = tf_warning_or_error */, > + auto_deduction_context context /* = adc_unspecified */, > + tree outer_targs /* = NULL_TREE */, > + int flags /* = LOOKUP_NORMAL */, > + tree tmpl /* = NULL_TREE */) > { > if (init == error_mark_node) > return error_mark_node; > @@ -30839,7 +30848,12 @@ do_auto_deduction (tree type, tree init, tree auto_node, > } > } > > - tree full_targs = add_to_template_args (outer_targs, targs); > + tree full_targs = outer_targs; > + > + if (context == adc_unify) > + full_targs = add_outermost_template_args (tmpl, full_targs); I recently noticed that sometimes TPARMS_PRIMARY_TEMPLATE isn't set properly for partially instantiated template template parameters, so let's make this more robust by only doing this if tmpl is non-null, maybe with a checking_assert that it is. OK with that change. > + full_targs = add_to_template_args (full_targs, targs); > > /* HACK: Compensate for callers not always communicating all levels of > outer template arguments by filling in the outermost missing levels > diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder12.C b/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder12.C > new file mode 100644 > index 00000000000..3d4d138720e > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder12.C > @@ -0,0 +1,29 @@ > +// PR c++/109160 > +// { dg-do compile { target c++20 } } > + > +template > +concept C = B; > + > +template struct X { }; > + > +template > +struct A { > + template auto V> static void f(); > + template auto V> static void g(X); > + template auto V> static inline int value = V; > + template auto V> struct D { }; > +}; > + > +int main() { > + A::f<0>(); > + A::f<0>(); // { dg-error "no match|constraints" } > + > + A::g(X<0>{}); > + A::g(X<0>{}); // { dg-error "no match|constraints" } > + > + bool v1 = A::value<0>; > + bool v2 = A::value<0>; // { dg-error "constraints" } > + > + A::D<0> d1; > + A::D<0> d2; // { dg-error "constraints" } > +}