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[130.44.159.43]) by smtp.gmail.com with ESMTPSA id n9-20020a05620a294900b006a34918ea64sm7025157qkp.98.2022.05.29.19.11.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 29 May 2022 19:11:49 -0700 (PDT) Message-ID: <89dc1f48-0c65-a4e7-8791-3d541e074bb7@redhat.com> Date: Sun, 29 May 2022 22:11:48 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH] c++: don't substitute TEMPLATE_PARM_CONSTRAINT [PR100374] From: Jason Merrill To: Patrick Palka , gcc-patches@gcc.gnu.org References: <20220527180543.2908762-1-ppalka@redhat.com> In-Reply-To: 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: 8bit X-Spam-Status: No, score=-12.1 required=5.0 tests=BAYES_00, BODY_8BITS, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, NICE_REPLY_A, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_NONE, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) 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-List-Received-Date: Mon, 30 May 2022 02:11:54 -0000 On 5/29/22 22:10, Jason Merrill wrote: > On 5/27/22 14:05, Patrick Palka wrote: >> This makes us avoid substituting into the TEMPLATE_PARM_CONSTRAINT of >> each template parameter except as necessary for (friend) declaration >> matching, like we already do for the overall TEMPLATE_PARMS_CONSTRAINTS >> of a template parameter list. >> >> Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for >> trunk and perhaps 12.2?  Also tested on range-v3 and cmcstl2. > > Are there already tests that cover the friend cases? Also, don't you also need to handle specialization of partial instantiations? >>     PR c++/100374 >> >> gcc/cp/ChangeLog: >> >>     * pt.cc (tsubst_each_template_parm_constraint): Define. >>     (tsubst_friend_function): Use it. >>     (tsubst_friend_class): Use it. >>     (tsubst_template_parm): Don't substitute TEMPLATE_PARM_CONSTRAINT. >> >> gcc/testsuite/ChangeLog: >> >>     * g++.dg/cpp2a/concepts-template-parm11.C: New test. >> --- >>   gcc/cp/pt.cc                                  | 35 ++++++++++++++++--- >>   .../g++.dg/cpp2a/concepts-template-parm11.C   | 16 +++++++++ >>   2 files changed, 47 insertions(+), 4 deletions(-) >>   create mode 100644 >> gcc/testsuite/g++.dg/cpp2a/concepts-template-parm11.C >> >> diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc >> index 24bbe2f4060..ec168234325 100644 >> --- a/gcc/cp/pt.cc >> +++ b/gcc/cp/pt.cc >> @@ -184,6 +184,7 @@ static int unify_pack_expansion (tree, tree, tree, >>                    tree, unification_kind_t, bool, bool); >>   static tree copy_template_args (tree); >>   static tree tsubst_template_parms (tree, tree, tsubst_flags_t); >> +static void tsubst_each_template_parm_constraint (tree, tree, >> tsubst_flags_t); >>   tree most_specialized_partial_spec (tree, tsubst_flags_t); >>   static tree tsubst_aggr_type (tree, tree, tsubst_flags_t, tree, int); >>   static tree tsubst_arg_types (tree, tree, tree, tsubst_flags_t, tree); >> @@ -11254,7 +11255,12 @@ tsubst_friend_function (tree decl, tree args) >>         tree parms = DECL_TEMPLATE_PARMS (new_friend); >>         tree treqs = TEMPLATE_PARMS_CONSTRAINTS (parms); >>         treqs = maybe_substitute_reqs_for (treqs, new_friend); >> -      TEMPLATE_PARMS_CONSTRAINTS (parms) = treqs; >> +      if (treqs != TEMPLATE_PARMS_CONSTRAINTS (parms)) >> +    { >> +      TEMPLATE_PARMS_CONSTRAINTS (parms) = treqs; >> +      /* As well as each TEMPLATE_PARM_CONSTRAINT.  */ >> +      tsubst_each_template_parm_constraint (parms, args, >> tf_warning_or_error); >> +    } >>       } >>     /* The mangled name for the NEW_FRIEND is incorrect.  The function >> @@ -11500,6 +11506,8 @@ tsubst_friend_class (tree friend_tmpl, tree args) >>       { >>         tree parms = tsubst_template_parms (DECL_TEMPLATE_PARMS >> (friend_tmpl), >>                             args, tf_warning_or_error); >> +      tsubst_each_template_parm_constraint (parms, args, >> +                        tf_warning_or_error); >>             location_t saved_input_location = input_location; >>             input_location = DECL_SOURCE_LOCATION (friend_tmpl); >>             tree cons = get_constraints (tmpl); >> @@ -11534,6 +11542,8 @@ tsubst_friend_class (tree friend_tmpl, tree args) >>                          DECL_FRIEND_CONTEXT (friend_tmpl)); >>             --processing_template_decl; >>             set_constraints (tmpl, ci); >> +          tsubst_each_template_parm_constraint (DECL_TEMPLATE_PARMS >> (tmpl), >> +                            args, tf_warning_or_error); >>           } >>         /* Inject this template into the enclosing namspace scope.  */ >> @@ -13656,7 +13666,6 @@ tsubst_template_parm (tree t, tree args, >> tsubst_flags_t complain) >>     default_value = TREE_PURPOSE (t); >>     parm_decl = TREE_VALUE (t); >> -  tree constraint = TEMPLATE_PARM_CONSTRAINTS (t); >>     parm_decl = tsubst (parm_decl, args, complain, NULL_TREE); >>     if (TREE_CODE (parm_decl) == PARM_DECL >> @@ -13664,13 +13673,31 @@ tsubst_template_parm (tree t, tree args, >> tsubst_flags_t complain) >>       parm_decl = error_mark_node; >>     default_value = tsubst_template_arg (default_value, args, >>                          complain, NULL_TREE); >> -  constraint = tsubst_constraint (constraint, args, complain, >> NULL_TREE); >>     tree r = build_tree_list (default_value, parm_decl); >> -  TEMPLATE_PARM_CONSTRAINTS (r) = constraint; >> +  TEMPLATE_PARM_CONSTRAINTS (r) = TEMPLATE_PARM_CONSTRAINTS (t); >>     return r; >>   } >> +/* Substitute in-place the TEMPLATE_PARM_CONSTRAINT of each template >> +   parameter in PARMS for sake of declaration matching.  */ >> + >> +static void >> +tsubst_each_template_parm_constraint (tree parms, tree args, >> +                      tsubst_flags_t complain) >> +{ >> +  ++processing_template_decl; >> +  for (; parms; parms = TREE_CHAIN (parms)) >> +    { >> +      tree level = TREE_VALUE (parms); >> +      for (tree parm : tree_vec_range (level)) >> +    TEMPLATE_PARM_CONSTRAINTS (parm) >> +      = tsubst_constraint (TEMPLATE_PARM_CONSTRAINTS (parm), args, >> +                   complain, NULL_TREE); >> +    } >> +  --processing_template_decl; >> +} >> + >>   /* Substitute the ARGS into the indicated aggregate (or enumeration) >>      type T.  If T is not an aggregate or enumeration type, it is >>      handled as if by tsubst.  IN_DECL is as for tsubst.  If >> diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-template-parm11.C >> b/gcc/testsuite/g++.dg/cpp2a/concepts-template-parm11.C >> new file mode 100644 >> index 00000000000..f70de341a07 >> --- /dev/null >> +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-template-parm11.C >> @@ -0,0 +1,16 @@ >> +// PR c++/100374 >> +// { dg-do compile { target c++20 } } >> + >> +template >> +concept C = true; >> + >> +template >> +struct A { >> +  template U> >> +  void f(); >> + >> +  template U> >> +  struct B; >> +}; >> + >> +template struct A; >