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[130.44.159.43]) by smtp.gmail.com with ESMTPSA id l67-20020a37bb46000000b0071d0f1d01easm12572047qkf.57.2023.02.14.14.15.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 14 Feb 2023 14:15:06 -0800 (PST) Message-ID: <1a709771-253a-780c-335e-a5819a063483@redhat.com> Date: Tue, 14 Feb 2023 17:15:05 -0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.7.2 Subject: Re: [PATCH 1/2] c++: factor out TYPENAME_TYPE substitution To: Patrick Palka , gcc-patches@gcc.gnu.org References: <20230213172340.849204-1-ppalka@redhat.com> From: Jason Merrill In-Reply-To: <20230213172340.849204-1-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,KAM_SHORT,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 2/13/23 09:23, Patrick Palka wrote: > [N.B. this is a corrected version of > https://gcc.gnu.org/pipermail/gcc-patches/2022-November/607443.html ] > > This patch factors out the TYPENAME_TYPE case of tsubst into a separate > function tsubst_typename_type. It also factors out the two tsubst flags > controlling TYPENAME_TYPE substitution, tf_keep_type_decl and tf_tst_ok, > into distinct boolean parameters of this new function (and of > make_typename_type). Consequently, callers which used to pass tf_tst_ok > to tsubst now instead must directly call tsubst_typename_type when > appropriate. Hmm, I don't love how that turns 4 lines into 8 more complex lines in each caller. And the previous approach of saying "a CTAD placeholder is OK" seem like better abstraction than repeating the specific TYPENAME_TYPE handling in each place. > In a subsequent patch we'll add another flag to > tsubst_typename_type controlling whether we want to ignore non-types > during the qualified lookup. > > gcc/cp/ChangeLog: > > * cp-tree.h (enum tsubst_flags): Remove tf_keep_type_decl > and tf_tst_ok. > (make_typename_type): Add two trailing boolean parameters > defaulted to false. > * decl.cc (make_typename_type): Replace uses of > tf_keep_type_decl and tf_tst_ok with the corresponding new > boolean parameters. > * pt.cc (tsubst_typename_type): New, factored out from tsubst > and adjusted after removing tf_keep_type_decl and tf_tst_ok. > (tsubst_decl) : Conditionally call > tsubst_typename_type directly instead of using tf_tst_ok. > (tsubst) : Call tsubst_typename_type. > (tsubst_copy) : Conditionally call > tsubst_typename_type directly instead of using tf_tst_ok. > (tsubst_copy_and_build) : Likewise. > : Likewise. > --- > gcc/cp/cp-tree.h | 9 +- > gcc/cp/decl.cc | 17 ++-- > gcc/cp/pt.cc | 223 +++++++++++++++++++++++++---------------------- > 3 files changed, 134 insertions(+), 115 deletions(-) > > diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h > index 06bc64a6b8d..a7c5765fc33 100644 > --- a/gcc/cp/cp-tree.h > +++ b/gcc/cp/cp-tree.h > @@ -5573,8 +5573,7 @@ enum tsubst_flags { > tf_error = 1 << 0, /* give error messages */ > tf_warning = 1 << 1, /* give warnings too */ > tf_ignore_bad_quals = 1 << 2, /* ignore bad cvr qualifiers */ > - tf_keep_type_decl = 1 << 3, /* retain typedef type decls > - (make_typename_type use) */ > + /* 1 << 3 available */ > tf_ptrmem_ok = 1 << 4, /* pointers to member ok (internal > instantiate_type use) */ > tf_user = 1 << 5, /* found template must be a user template > @@ -5594,8 +5593,7 @@ enum tsubst_flags { > (build_target_expr and friends) */ > tf_norm = 1 << 11, /* Build diagnostic information during > constraint normalization. */ > - tf_tst_ok = 1 << 12, /* Allow a typename-specifier to name > - a template (C++17 or later). */ > + /* 1 << 12 available */ > tf_dguide = 1 << 13, /* Building a deduction guide from a ctor. */ > /* Convenient substitution flags combinations. */ > tf_warning_or_error = tf_warning | tf_error > @@ -6846,7 +6844,8 @@ extern tree declare_local_label (tree); > extern tree define_label (location_t, tree); > extern void check_goto (tree); > extern bool check_omp_return (void); > -extern tree make_typename_type (tree, tree, enum tag_types, tsubst_flags_t); > +extern tree make_typename_type (tree, tree, enum tag_types, tsubst_flags_t, > + bool = false, bool = false); > extern tree build_typename_type (tree, tree, tree, tag_types); > extern tree make_unbound_class_template (tree, tree, tree, tsubst_flags_t); > extern tree make_unbound_class_template_raw (tree, tree, tree); > diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc > index d606b31d7a7..430533606b0 100644 > --- a/gcc/cp/decl.cc > +++ b/gcc/cp/decl.cc > @@ -4228,14 +4228,17 @@ build_typename_type (tree context, tree name, tree fullname, > /* Resolve `typename CONTEXT::NAME'. TAG_TYPE indicates the tag > provided to name the type. Returns an appropriate type, unless an > error occurs, in which case error_mark_node is returned. If we > - locate a non-artificial TYPE_DECL and TF_KEEP_TYPE_DECL is set, we > + locate a non-artificial TYPE_DECL and KEEP_TYPE_DECL is true, we > return that, rather than the _TYPE it corresponds to, in other > - cases we look through the type decl. If TF_ERROR is set, complain > - about errors, otherwise be quiet. */ > + cases we look through the type decl. If TEMPLATE_OK is true and > + we found a TEMPLATE_DECL then we return a CTAD placeholder for the > + TEMPLATE_DECL. If TF_ERROR is set, complain about errors, otherwise > + be quiet. */ > > tree > make_typename_type (tree context, tree name, enum tag_types tag_type, > - tsubst_flags_t complain) > + tsubst_flags_t complain, bool keep_type_decl /* = false */, > + bool template_ok /* = false */) > { > tree fullname; > tree t; > @@ -4352,8 +4355,8 @@ make_typename_type (tree context, tree name, enum tag_types tag_type, > } > if (!want_template && TREE_CODE (t) != TYPE_DECL) > { > - if ((complain & tf_tst_ok) && cxx_dialect >= cxx17 > - && DECL_TYPE_TEMPLATE_P (t)) > + if (template_ok && DECL_TYPE_TEMPLATE_P (t) > + && cxx_dialect >= cxx17) > /* The caller permits this typename-specifier to name a template > (because it appears in a CTAD-enabled context). */; > else > @@ -4383,7 +4386,7 @@ make_typename_type (tree context, tree name, enum tag_types tag_type, > t = TYPE_NAME (t); > } > > - if (DECL_ARTIFICIAL (t) || !(complain & tf_keep_type_decl)) > + if (DECL_ARTIFICIAL (t) || !keep_type_decl) > t = TREE_TYPE (t); > > maybe_record_typedef_use (t); > diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc > index e89dbf47097..bc47bf15d38 100644 > --- a/gcc/cp/pt.cc > +++ b/gcc/cp/pt.cc > @@ -13949,6 +13949,94 @@ tsubst_aggr_type_1 (tree t, > return t; > } > > +/* Substitute ARGS into the TYPENAME_TYPE T. The flag TEMPLATE_OK > + is passed to make_typename_type. */ > + > +static tree > +tsubst_typename_type (tree t, tree args, tsubst_flags_t complain, tree in_decl, > + bool template_ok = false) > +{ > + tree ctx = TYPE_CONTEXT (t); > + if (TREE_CODE (ctx) == TYPE_PACK_EXPANSION) > + { > + ctx = tsubst_pack_expansion (ctx, args, complain, in_decl); > + if (ctx == error_mark_node > + || TREE_VEC_LENGTH (ctx) > 1) > + return error_mark_node; > + if (TREE_VEC_LENGTH (ctx) == 0) > + { > + if (complain & tf_error) > + error ("%qD is instantiated for an empty pack", > + TYPENAME_TYPE_FULLNAME (t)); > + return error_mark_node; > + } > + ctx = TREE_VEC_ELT (ctx, 0); > + } > + else > + ctx = tsubst_aggr_type (ctx, args, complain, in_decl, > + /*entering_scope=*/1); > + if (ctx == error_mark_node) > + return error_mark_node; > + > + tree f = tsubst_copy (TYPENAME_TYPE_FULLNAME (t), args, > + complain, in_decl); > + if (f == error_mark_node) > + return error_mark_node; > + > + if (!MAYBE_CLASS_TYPE_P (ctx)) > + { > + if (complain & tf_error) > + error ("%qT is not a class, struct, or union type", ctx); > + return error_mark_node; > + } > + else if (!uses_template_parms (ctx) && !TYPE_BEING_DEFINED (ctx)) > + { > + /* Normally, make_typename_type does not require that the CTX > + have complete type in order to allow things like: > + > + template struct S { typename S::X Y; }; > + > + But, such constructs have already been resolved by this > + point, so here CTX really should have complete type, unless > + it's a partial instantiation. */ > + if (!complete_type_or_maybe_complain (ctx, NULL_TREE, complain)) > + return error_mark_node; > + } > + > + f = make_typename_type (ctx, f, typename_type, complain, > + /*keep_type_decl=*/true, template_ok); > + if (f == error_mark_node) > + return f; > + if (TREE_CODE (f) == TYPE_DECL) > + { > + complain |= tf_ignore_bad_quals; > + f = TREE_TYPE (f); > + } > + > + if (TREE_CODE (f) != TYPENAME_TYPE) > + { > + if (TYPENAME_IS_ENUM_P (t) && TREE_CODE (f) != ENUMERAL_TYPE) > + { > + if (complain & tf_error) > + error ("%qT resolves to %qT, which is not an enumeration type", > + t, f); > + else > + return error_mark_node; > + } > + else if (TYPENAME_IS_CLASS_P (t) && !CLASS_TYPE_P (f)) > + { > + if (complain & tf_error) > + error ("%qT resolves to %qT, which is not a class type", > + t, f); > + else > + return error_mark_node; > + } > + } > + > + return cp_build_qualified_type > + (f, cp_type_quals (f) | cp_type_quals (t), complain); > +} > + > /* Map from a FUNCTION_DECL to a vec of default argument instantiations, > indexed in reverse order of the parameters. */ > > @@ -15193,10 +15281,13 @@ tsubst_decl (tree t, tree args, tsubst_flags_t complain) > && VAR_HAD_UNKNOWN_BOUND (t) > && type != error_mark_node) > type = strip_array_domain (type); > - tsubst_flags_t tcomplain = complain; > - if (VAR_P (t)) > - tcomplain |= tf_tst_ok; > - type = tsubst (type, args, tcomplain, in_decl); > + if (VAR_P (t) > + && TREE_CODE (type) == TYPENAME_TYPE > + && !typedef_variant_p (type)) > + type = tsubst_typename_type (type, args, complain, in_decl, > + /*template_ok=*/true); > + else > + type = tsubst (type, args, complain, in_decl); > /* Substituting the type might have recursively instantiated this > same alias (c++/86171). */ > if (gen_tmpl && DECL_ALIAS_TEMPLATE_P (gen_tmpl) > @@ -15889,9 +15980,6 @@ tsubst (tree t, tree args, tsubst_flags_t complain, tree in_decl) > bool fndecl_type = (complain & tf_fndecl_type); > complain &= ~tf_fndecl_type; > > - bool tst_ok = (complain & tf_tst_ok); > - complain &= ~tf_tst_ok; > - > if (type > && code != TYPENAME_TYPE > && code != TEMPLATE_TYPE_PARM > @@ -16424,89 +16512,7 @@ tsubst (tree t, tree args, tsubst_flags_t complain, tree in_decl) > } > > case TYPENAME_TYPE: > - { > - tree ctx = TYPE_CONTEXT (t); > - if (TREE_CODE (ctx) == TYPE_PACK_EXPANSION) > - { > - ctx = tsubst_pack_expansion (ctx, args, complain, in_decl); > - if (ctx == error_mark_node > - || TREE_VEC_LENGTH (ctx) > 1) > - return error_mark_node; > - if (TREE_VEC_LENGTH (ctx) == 0) > - { > - if (complain & tf_error) > - error ("%qD is instantiated for an empty pack", > - TYPENAME_TYPE_FULLNAME (t)); > - return error_mark_node; > - } > - ctx = TREE_VEC_ELT (ctx, 0); > - } > - else > - ctx = tsubst_aggr_type (ctx, args, complain, in_decl, > - /*entering_scope=*/1); > - if (ctx == error_mark_node) > - return error_mark_node; > - > - tree f = tsubst_copy (TYPENAME_TYPE_FULLNAME (t), args, > - complain, in_decl); > - if (f == error_mark_node) > - return error_mark_node; > - > - if (!MAYBE_CLASS_TYPE_P (ctx)) > - { > - if (complain & tf_error) > - error ("%qT is not a class, struct, or union type", ctx); > - return error_mark_node; > - } > - else if (!uses_template_parms (ctx) && !TYPE_BEING_DEFINED (ctx)) > - { > - /* Normally, make_typename_type does not require that the CTX > - have complete type in order to allow things like: > - > - template struct S { typename S::X Y; }; > - > - But, such constructs have already been resolved by this > - point, so here CTX really should have complete type, unless > - it's a partial instantiation. */ > - if (!complete_type_or_maybe_complain (ctx, NULL_TREE, complain)) > - return error_mark_node; > - } > - > - tsubst_flags_t tcomplain = complain | tf_keep_type_decl; > - if (tst_ok) > - tcomplain |= tf_tst_ok; > - f = make_typename_type (ctx, f, typename_type, tcomplain); > - if (f == error_mark_node) > - return f; > - if (TREE_CODE (f) == TYPE_DECL) > - { > - complain |= tf_ignore_bad_quals; > - f = TREE_TYPE (f); > - } > - > - if (TREE_CODE (f) != TYPENAME_TYPE) > - { > - if (TYPENAME_IS_ENUM_P (t) && TREE_CODE (f) != ENUMERAL_TYPE) > - { > - if (complain & tf_error) > - error ("%qT resolves to %qT, which is not an enumeration type", > - t, f); > - else > - return error_mark_node; > - } > - else if (TYPENAME_IS_CLASS_P (t) && !CLASS_TYPE_P (f)) > - { > - if (complain & tf_error) > - error ("%qT resolves to %qT, which is not a class type", > - t, f); > - else > - return error_mark_node; > - } > - } > - > - return cp_build_qualified_type > - (f, cp_type_quals (f) | cp_type_quals (t), complain); > - } > + return tsubst_typename_type (t, args, complain, in_decl); > > case UNBOUND_CLASS_TEMPLATE: > { > @@ -17391,10 +17397,14 @@ tsubst_copy (tree t, tree args, tsubst_flags_t complain, tree in_decl) > case IMPLICIT_CONV_EXPR: > CASE_CONVERT: > { > - tsubst_flags_t tcomplain = complain; > - if (code == CAST_EXPR) > - tcomplain |= tf_tst_ok; > - tree type = tsubst (TREE_TYPE (t), args, tcomplain, in_decl); > + tree type = TREE_TYPE (t); > + if (code == CAST_EXPR > + && TREE_CODE (type) == TYPENAME_TYPE > + && !typedef_variant_p (type)) > + type = tsubst_typename_type (type, args, complain, in_decl, > + /*template_ok=*/true); > + else > + type = tsubst (type, args, complain, in_decl); > tree op0 = tsubst_copy (TREE_OPERAND (t, 0), args, complain, in_decl); > return build1 (code, type, op0); > } > @@ -20430,13 +20440,16 @@ tsubst_copy_and_build (tree t, > case DYNAMIC_CAST_EXPR: > case STATIC_CAST_EXPR: > { > - tree type; > + tree type = TREE_TYPE (t); > tree op, r = NULL_TREE; > > - tsubst_flags_t tcomplain = complain; > - if (TREE_CODE (t) == CAST_EXPR) > - tcomplain |= tf_tst_ok; > - type = tsubst (TREE_TYPE (t), args, tcomplain, in_decl); > + if (TREE_CODE (t) == CAST_EXPR > + && TREE_CODE (type) == TYPENAME_TYPE > + && !typedef_variant_p (type)) > + type = tsubst_typename_type (type, args, complain, in_decl, > + /*template_ok=*/true); > + else > + type = tsubst (type, args, complain, in_decl); > > op = RECUR (TREE_OPERAND (t, 0)); > > @@ -21421,10 +21434,14 @@ tsubst_copy_and_build (tree t, > bool need_copy_p = false; > tree r; > > - tsubst_flags_t tcomplain = complain; > - if (COMPOUND_LITERAL_P (t)) > - tcomplain |= tf_tst_ok; > - tree type = tsubst (TREE_TYPE (t), args, tcomplain, in_decl); > + tree type = TREE_TYPE (t); > + if (COMPOUND_LITERAL_P (t) > + && TREE_CODE (type) == TYPENAME_TYPE > + && !typedef_variant_p (type)) > + type = tsubst_typename_type (type, args, complain, in_decl, > + /*template_ok=*/true); > + else > + type = tsubst (type, args, complain, in_decl); > if (type == error_mark_node) > RETURN (error_mark_node); >