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[69.118.112.187]) by smtp.gmail.com with ESMTPSA id h18-20020a05620a13f200b0075bb2aa9a67sm6636661qkl.59.2023.06.01.07.49.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 01 Jun 2023 07:49:46 -0700 (PDT) From: Patrick Palka To: gcc-patches@gcc.gnu.org Cc: jason@redhat.com, Patrick Palka Subject: [PATCH 2/2] c++: partial ordering and dep alias tmpl specs [PR90679] Date: Thu, 1 Jun 2023 10:49:37 -0400 Message-ID: <20230601144938.765175-2-ppalka@redhat.com> X-Mailer: git-send-email 2.41.0.rc1.10.g9e49351c30 In-Reply-To: <20230601144938.765175-1-ppalka@redhat.com> References: <20230601144938.765175-1-ppalka@redhat.com> MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="US-ASCII"; x-default=true X-Spam-Status: No, score=-13.8 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_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 List-Id: During partial ordering, we want to look through dependent alias template specializations within template arguments and otherwise treat them as opaque in other contexts (see e.g. r7-7116-g0c942f3edab108 and r11-7011-g6e0a231a4aa240). To that end template_args_equal was given a partial_order flag that controls this behavior. This flag does the right thing when a dependent alias template specialization appears as template argument of the partial specialization, e.g. in template using first_t = T; template struct traits; template struct traits> { }; // #1 template struct traits> { }; // #2 we correctly consider #2 to be more specialized than #1. But if the alias specialization appears as a template argument of another class template specialization, e.g. in template struct traits>> { }; // #1 template struct traits>> { }; // #2 then we incorrectly consider #1 and #2 to be unordered. This is because 1. we don't propagate the flag to recursive template_args_equal calls 2. we don't use structural equality for class template specializations written in terms of dependent alias template specializations This patch fixes the first issue by turning the partial_order flag into a global. This patch fixes the second issue by making us propagate structural equality appropriately when building a class template specialization. In passing this patch also improves hashing of specializations that use structural equality. Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for trunk? PR c++/90679 gcc/cp/ChangeLog: * cp-tree.h (comp_template_args): Remove partial_order parameter. (template_args_equal): Likewise. * pt.cc (iterative_hash_template_arg) : Hash the template and arguments for specializations that use structural equality. (comparing_for_partial_ordering): New flag. (template_args_equal): Remove partial order parameter and use comparing_for_partial_ordering instead. (comp_template_args): Likewise. (comp_template_args_porder): Set comparing_for_partial_ordering instead. Make static. (any_template_arguments_need_structural_equality_p): Return true for an argument that's a dependent alias template specialization or a class template specialization that itself needs structural equality. * tree.cc (cp_tree_equal) : Adjust call to comp_template_args. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/alias-decl-75a.C: New test. * g++.dg/cpp0x/alias-decl-75b.C: New test. --- gcc/cp/cp-tree.h | 4 +-- gcc/cp/pt.cc | 40 +++++++++++++++++---- gcc/cp/tree.cc | 2 +- gcc/testsuite/g++.dg/cpp0x/alias-decl-75a.C | 26 ++++++++++++++ gcc/testsuite/g++.dg/cpp0x/alias-decl-75b.C | 26 ++++++++++++++ 5 files changed, 88 insertions(+), 10 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp0x/alias-decl-75a.C create mode 100644 gcc/testsuite/g++.dg/cpp0x/alias-decl-75b.C diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h index 5330d1e1f62..f08e5630a5c 100644 --- a/gcc/cp/cp-tree.h +++ b/gcc/cp/cp-tree.h @@ -7381,8 +7381,8 @@ extern int template_class_depth (tree); extern int is_specialization_of (tree, tree); extern bool is_specialization_of_friend (tree, tree); extern bool comp_template_args (tree, tree, tree * = NULL, - tree * = NULL, bool = false); -extern int template_args_equal (tree, tree, bool = false); + tree * = NULL); +extern int template_args_equal (tree, tree); extern tree maybe_process_partial_specialization (tree); extern tree most_specialized_instantiation (tree); extern tree most_specialized_partial_spec (tree, tsubst_flags_t); diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc index 1b28195e10d..1a32f10b22b 100644 --- a/gcc/cp/pt.cc +++ b/gcc/cp/pt.cc @@ -1913,6 +1913,11 @@ iterative_hash_template_arg (tree arg, hashval_t val) default: if (tree canonical = TYPE_CANONICAL (arg)) val = iterative_hash_object (TYPE_HASH (canonical), val); + else if (tree ti = TYPE_TEMPLATE_INFO (arg)) + { + val = iterative_hash_template_arg (TI_TEMPLATE (ti), val); + val = iterative_hash_template_arg (TI_ARGS (ti), val); + } break; } @@ -9296,6 +9301,12 @@ coerce_template_parms (tree parms, return return_full_args ? new_args : new_inner_args; } +/* Whether we are comparing template arguments during partial ordering + (and therefore want the comparison to look through dependent alias + template specializations). */ + +static int comparing_for_partial_ordering; + /* Returns true if T is a wrapper to make a C++20 template parameter object const. */ @@ -9312,7 +9323,7 @@ class_nttp_const_wrapper_p (tree t) /* Returns 1 if template args OT and NT are equivalent. */ int -template_args_equal (tree ot, tree nt, bool partial_order /* = false */) +template_args_equal (tree ot, tree nt) { if (nt == ot) return 1; @@ -9335,7 +9346,7 @@ template_args_equal (tree ot, tree nt, bool partial_order /* = false */) During partial ordering, however, we need to treat them normally so we can order uses of the same alias with different cv-qualification (79960). */ auto cso = make_temp_override (comparing_dependent_aliases); - if (!partial_order) + if (!comparing_for_partial_ordering) ++comparing_dependent_aliases; if (TREE_CODE (nt) == TREE_VEC || TREE_CODE (ot) == TREE_VEC) @@ -9383,8 +9394,7 @@ template_args_equal (tree ot, tree nt, bool partial_order /* = false */) bool comp_template_args (tree oldargs, tree newargs, - tree *oldarg_ptr /* = NULL */, tree *newarg_ptr /* = NULL */, - bool partial_order /* = false */) + tree *oldarg_ptr /* = NULL */, tree *newarg_ptr /* = NULL */) { if (oldargs == newargs) return true; @@ -9400,7 +9410,7 @@ comp_template_args (tree oldargs, tree newargs, tree nt = TREE_VEC_ELT (newargs, i); tree ot = TREE_VEC_ELT (oldargs, i); - if (! template_args_equal (ot, nt, partial_order)) + if (! template_args_equal (ot, nt)) { if (oldarg_ptr != NULL) *oldarg_ptr = ot; @@ -9412,10 +9422,13 @@ comp_template_args (tree oldargs, tree newargs, return true; } -inline bool +static bool comp_template_args_porder (tree oargs, tree nargs) { - return comp_template_args (oargs, nargs, NULL, NULL, true); + ++comparing_for_partial_ordering; + bool equal = comp_template_args (oargs, nargs); + --comparing_for_partial_ordering; + return equal; } /* Implement a freelist interface for objects of type T. @@ -28839,6 +28852,19 @@ any_template_arguments_need_structural_equality_p (tree args) mutated after the fact by duplicate_decls), so just require structural equality in this case (PR52830). */ return true; + else if (TYPE_P (arg) + && TYPE_STRUCTURAL_EQUALITY_P (arg) + && dependent_alias_template_spec_p (arg, nt_transparent)) + /* Require structural equality for specializations written + in terms of a dependent alias template specialization. */ + return true; + else if (CLASS_TYPE_P (arg) + && TYPE_TEMPLATE_INFO (arg) + && TYPE_STRUCTURAL_EQUALITY_P (arg)) + /* Require structural equality for specializations written + in terms of a class template specialization that itself + needs structural equality. */ + return true; } } } diff --git a/gcc/cp/tree.cc b/gcc/cp/tree.cc index 19dfb3ed782..775c0c9cd57 100644 --- a/gcc/cp/tree.cc +++ b/gcc/cp/tree.cc @@ -4136,7 +4136,7 @@ cp_tree_equal (tree t1, tree t2) case TREE_VEC: /* These are template args. Really we should be getting the caller to do this as it knows it to be true. */ - if (!comp_template_args (t1, t2, NULL, NULL, false)) + if (!comp_template_args (t1, t2)) return false; return true; diff --git a/gcc/testsuite/g++.dg/cpp0x/alias-decl-75a.C b/gcc/testsuite/g++.dg/cpp0x/alias-decl-75a.C new file mode 100644 index 00000000000..8adbd6f65ac --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/alias-decl-75a.C @@ -0,0 +1,26 @@ +// PR c++/90679 +// A version of alias-decl-75.C where the specializations of the +// complex alias template first_t are dependent. +// { dg-do compile { target c++11 } } + +template +using first_t = T; + +template +struct A; + +template +struct traits; + +template +struct traits>> { + static constexpr int value = 1; +}; + +template +struct traits>> { + static constexpr int value = 2; +}; + +static_assert(traits>::value == 1, ""); +static_assert(traits>::value == 2, ""); // { dg-bogus "ambiguous" } diff --git a/gcc/testsuite/g++.dg/cpp0x/alias-decl-75b.C b/gcc/testsuite/g++.dg/cpp0x/alias-decl-75b.C new file mode 100644 index 00000000000..b89ea5cad1e --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/alias-decl-75b.C @@ -0,0 +1,26 @@ +// PR c++/90679 +// A version of alias-decl-75a.C where the alias template specialization +// appears as a more deeply nested template argument. +// { dg-do compile { target c++11 } } + +template +using first_t = T; + +template +struct A; + +template +struct traits; + +template +struct traits>>> { + static constexpr int value = 1; +}; + +template +struct traits>>> { + static constexpr int value = 2; +}; + +static_assert(traits>>::value == 1, ""); +static_assert(traits>>::value == 2, ""); // { dg-bogus "ambiguous" } -- 2.41.0.rc1.10.g9e49351c30