From 0c7bce0ac184c057bacad9c8e615ce82923835fd Mon Sep 17 00:00:00 2001 From: Patrick Palka Date: Mon, 9 May 2022 09:53:27 -0400 Subject: [PATCH] c++: constexpr init of union sub-aggr w/ base [PR105491] Here ever since r10-7313-gb599bf9d6d1e18, reduced_constant_expression_p in C++11/14 is rejecting the marked sub-aggregate initializer (of type S) W w = {.D.2445={.s={.D.2387={.m=0}, .b=0}}}; ^ ultimately because said initializer has CONSTRUCTOR_NO_CLEARING set, hence the function must verify that all fields of S are initialized. And before C++17 it doesn't expect to see base class fields (since next_initializable_field skips over them), so the presence thereof causes r_c_e_p to return false. The reason r10-7313-gb599bf9d6d1e18 causes this is because in that commit we began using CONSTRUCTOR_NO_CLEARING to precisely track whether we're in middle of activating a union member. This ends up affecting clear_no_implicit_zero, which recurses into sub-aggregate initializers only if the outer initializer has CONSTRUCTOR_NO_CLEARING set. After that commit, the outer union initializer above no longer has the flag set at this point and so clear_no_implicit_zero no longer recurses into the marked inner initializer. But arguably r_c_e_p should be able to accept the marked initializer regardless of whether CONSTRUCTOR_NO_CLEARING is set. The primary bug therefore seems to be that r_c_e_p relies on next_initializable_field which skips over base class fields in C++11/14. To fix this, this patch introduces a new helper function next_subobject_field which is like next_initializable_field except that it never skips base class fields, and makes r_c_e_p use it. This patch then renames next_initializable_field to next_aggregate_field (and makes it skip over vptr fields again). PR c++/105491 gcc/cp/ChangeLog: * call.cc (field_in_pset): Adjust after next_initializable_field renaming. (build_aggr_conv): Likewise. (convert_like_internal): Likewise. (type_has_extended_temps): Likewise. * class.cc (default_init_uninitialized_part): Likewise. (finish_struct): Likewise. * constexpr.cc (cx_check_missing_mem_inits): Likewise. (reduced_constant_expression_p): Use next_subobject_field instead. * cp-gimplify.cc (get_source_location_impl_type): Adjust after next_initializable_field renaming. (fold_builtin_source_location): Likewise. * cp-tree.h (next_initializable_field): Rename to ... (next_aggregate_field): ... this. (next_subobject_field): Declare. * decl.cc (next_aggregate_field): Renamed from ... (next_initializable_field): ... this. Skip over vptr fields again. (next_subobject_field): Define. (reshape_init_class): Adjust after next_initializable_field renaming. * init.cc (build_value_init_noctor): Likewise. (emit_mem_initializers): Likewise. * lambda.cc (build_capture_proxy): Likewise. * method.cc (build_comparison_op): Likewise. * pt.cc (maybe_aggr_guide): Likewise. * tree.cc (structural_type_p): Likewise. * typeck2.cc (split_nonconstant_init_1): Likewise. (digest_init_r): Likewise. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/constexpr-union7.C: New test. * g++.dg/cpp0x/constexpr-union7a.C: New test. * g++.dg/cpp2a/constinit17.C: New test. --- gcc/cp/call.cc | 14 ++++---- gcc/cp/class.cc | 8 ++--- gcc/cp/constexpr.cc | 10 +++--- gcc/cp/cp-gimplify.cc | 4 +-- gcc/cp/cp-tree.h | 3 +- gcc/cp/decl.cc | 36 +++++++++++++------ gcc/cp/init.cc | 6 ++-- gcc/cp/lambda.cc | 4 +-- gcc/cp/method.cc | 8 ++--- gcc/cp/pt.cc | 2 +- gcc/cp/tree.cc | 4 +-- gcc/cp/typeck2.cc | 4 +-- gcc/testsuite/g++.dg/cpp0x/constexpr-union7.C | 17 +++++++++ .../g++.dg/cpp0x/constexpr-union7a.C | 15 ++++++++ gcc/testsuite/g++.dg/cpp2a/constinit17.C | 24 +++++++++++++ 15 files changed, 116 insertions(+), 43 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp0x/constexpr-union7.C create mode 100644 gcc/testsuite/g++.dg/cpp0x/constexpr-union7a.C create mode 100644 gcc/testsuite/g++.dg/cpp2a/constinit17.C diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc index 959279d6216..0240e364324 100644 --- a/gcc/cp/call.cc +++ b/gcc/cp/call.cc @@ -948,7 +948,7 @@ field_in_pset (hash_set &pset, tree field) for (field = TYPE_FIELDS (TREE_TYPE (field)); field; field = DECL_CHAIN (field)) { - field = next_initializable_field (field); + field = next_aggregate_field (field); if (field == NULL_TREE) break; if (field_in_pset (pset, field)) @@ -965,7 +965,7 @@ build_aggr_conv (tree type, tree ctor, int flags, tsubst_flags_t complain) { unsigned HOST_WIDE_INT i = 0; conversion *c; - tree field = next_initializable_field (TYPE_FIELDS (type)); + tree field = next_aggregate_field (TYPE_FIELDS (type)); tree empty_ctor = NULL_TREE; hash_set pset; @@ -1011,7 +1011,7 @@ build_aggr_conv (tree type, tree ctor, int flags, tsubst_flags_t complain) } } - for (; field; field = next_initializable_field (DECL_CHAIN (field))) + for (; field; field = next_aggregate_field (DECL_CHAIN (field))) { tree ftype = TREE_TYPE (field); tree val; @@ -8098,10 +8098,10 @@ convert_like_internal (conversion *convs, tree expr, tree fn, int argnum, totype = complete_type_or_maybe_complain (totype, NULL_TREE, complain); if (!totype) return error_mark_node; - tree field = next_initializable_field (TYPE_FIELDS (totype)); + tree field = next_aggregate_field (TYPE_FIELDS (totype)); vec *vec = NULL; CONSTRUCTOR_APPEND_ELT (vec, field, array); - field = next_initializable_field (DECL_CHAIN (field)); + field = next_aggregate_field (DECL_CHAIN (field)); CONSTRUCTOR_APPEND_ELT (vec, field, size_int (len)); tree new_ctor = build_constructor (totype, vec); return get_target_expr_sfinae (new_ctor, complain); @@ -13267,8 +13267,8 @@ type_has_extended_temps (tree type) { if (is_std_init_list (type)) return true; - for (tree f = next_initializable_field (TYPE_FIELDS (type)); - f; f = next_initializable_field (DECL_CHAIN (f))) + for (tree f = next_aggregate_field (TYPE_FIELDS (type)); + f; f = next_aggregate_field (DECL_CHAIN (f))) if (type_has_extended_temps (TREE_TYPE (f))) return true; } diff --git a/gcc/cp/class.cc b/gcc/cp/class.cc index bc94ed45e17..3c195b35396 100644 --- a/gcc/cp/class.cc +++ b/gcc/cp/class.cc @@ -5494,8 +5494,8 @@ default_init_uninitialized_part (tree type) if (r) return r; } - for (t = next_initializable_field (TYPE_FIELDS (type)); t; - t = next_initializable_field (DECL_CHAIN (t))) + for (t = next_aggregate_field (TYPE_FIELDS (type)); t; + t = next_aggregate_field (DECL_CHAIN (t))) if (!DECL_INITIAL (t) && !DECL_ARTIFICIAL (t)) { r = default_init_uninitialized_part (TREE_TYPE (t)); @@ -7781,10 +7781,10 @@ finish_struct (tree t, tree attributes) bool ok = false; if (processing_template_decl) { - tree f = next_initializable_field (TYPE_FIELDS (t)); + tree f = next_aggregate_field (TYPE_FIELDS (t)); if (f && TYPE_PTR_P (TREE_TYPE (f))) { - f = next_initializable_field (DECL_CHAIN (f)); + f = next_aggregate_field (DECL_CHAIN (f)); if (f && same_type_p (TREE_TYPE (f), size_type_node)) ok = true; } diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc index 6c204ab2265..e560d842e8c 100644 --- a/gcc/cp/constexpr.cc +++ b/gcc/cp/constexpr.cc @@ -784,7 +784,7 @@ cx_check_missing_mem_inits (tree ctype, tree body, bool complain) if (TREE_CODE (ctype) == UNION_TYPE) { - if (nelts == 0 && next_initializable_field (field)) + if (nelts == 0 && next_aggregate_field (field)) { if (complain) error ("% constructor for union %qT must " @@ -3053,7 +3053,7 @@ reduced_constant_expression_p (tree t) field = NULL_TREE; } else - field = next_initializable_field (TYPE_FIELDS (TREE_TYPE (t))); + field = next_subobject_field (TYPE_FIELDS (TREE_TYPE (t))); } else field = NULL_TREE; @@ -3065,15 +3065,15 @@ reduced_constant_expression_p (tree t) return false; /* Empty class field may or may not have an initializer. */ for (; field && e.index != field; - field = next_initializable_field (DECL_CHAIN (field))) + field = next_subobject_field (DECL_CHAIN (field))) if (!is_really_empty_class (TREE_TYPE (field), /*ignore_vptr*/false)) return false; if (field) - field = next_initializable_field (DECL_CHAIN (field)); + field = next_subobject_field (DECL_CHAIN (field)); } /* There could be a non-empty field at the end. */ - for (; field; field = next_initializable_field (DECL_CHAIN (field))) + for (; field; field = next_subobject_field (DECL_CHAIN (field))) if (!is_really_empty_class (TREE_TYPE (field), /*ignore_vptr*/false)) return false; ok: diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc index 7ab44efa058..6f84d157c98 100644 --- a/gcc/cp/cp-gimplify.cc +++ b/gcc/cp/cp-gimplify.cc @@ -3106,7 +3106,7 @@ get_source_location_impl_type (location_t loc) int cnt = 0; for (tree field = TYPE_FIELDS (type); - (field = next_initializable_field (field)) != NULL_TREE; + (field = next_aggregate_field (field)) != NULL_TREE; field = DECL_CHAIN (field)) { if (DECL_NAME (field) != NULL_TREE) @@ -3281,7 +3281,7 @@ fold_builtin_source_location (location_t loc) vec *v = NULL; vec_alloc (v, 4); for (tree field = TYPE_FIELDS (source_location_impl); - (field = next_initializable_field (field)) != NULL_TREE; + (field = next_aggregate_field (field)) != NULL_TREE; field = DECL_CHAIN (field)) { const char *n = IDENTIFIER_POINTER (DECL_NAME (field)); diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h index 10ecab76082..7e50db0e35a 100644 --- a/gcc/cp/cp-tree.h +++ b/gcc/cp/cp-tree.h @@ -6870,7 +6870,8 @@ extern bool is_direct_enum_init (tree, tree); extern void initialize_artificial_var (tree, vec *); extern tree check_var_type (tree, tree, location_t); extern tree reshape_init (tree, tree, tsubst_flags_t); -extern tree next_initializable_field (tree); +extern tree next_aggregate_field (tree); +extern tree next_subobject_field (tree); extern tree first_field (const_tree); extern tree fndecl_declared_return_type (tree); extern bool undeduced_auto_decl (tree); diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc index 0fa758ff214..872b02d55bd 100644 --- a/gcc/cp/decl.cc +++ b/gcc/cp/decl.cc @@ -6384,20 +6384,36 @@ static tree reshape_init_r (tree, reshape_iter *, tree, tsubst_flags_t); /* FIELD is an element of TYPE_FIELDS or NULL. In the former case, the value returned is the next FIELD_DECL (possibly FIELD itself) that can be - initialized. If there are no more such fields, the return value - will be NULL. */ + initialized as if for an aggregate class. If there are no more such fields, + the return value will be NULL. */ tree -next_initializable_field (tree field) +next_aggregate_field (tree field) { while (field && (TREE_CODE (field) != FIELD_DECL || DECL_UNNAMED_BIT_FIELD (field) || (DECL_ARTIFICIAL (field) - /* In C++17, don't skip base class fields. */ - && !(cxx_dialect >= cxx17 && DECL_FIELD_IS_BASE (field)) - /* Don't skip vptr fields. We might see them when we're - called from reduced_constant_expression_p. */ + /* In C++17, aggregates can have bases. */ + && !(cxx_dialect >= cxx17 && DECL_FIELD_IS_BASE (field))))) + field = DECL_CHAIN (field); + + return field; +} + +/* FIELD is an element of TYPE_FIELDS or NULL. In the former case, the value + returned is the next FIELD_DECL (possibly FIELD itself) that corresponds + to a subobject. If there are no more such fields, the return value will be + NULL. */ + +tree +next_subobject_field (tree field) +{ + while (field + && (TREE_CODE (field) != FIELD_DECL + || DECL_UNNAMED_BIT_FIELD (field) + || (DECL_ARTIFICIAL (field) + && !DECL_FIELD_IS_BASE (field) && !DECL_VIRTUAL_P (field)))) field = DECL_CHAIN (field); @@ -6595,7 +6611,7 @@ reshape_init_class (tree type, reshape_iter *d, bool first_initializer_p, if (base_binfo) field = base_binfo; else - field = next_initializable_field (TYPE_FIELDS (type)); + field = next_aggregate_field (TYPE_FIELDS (type)); if (!field) { @@ -6762,10 +6778,10 @@ reshape_init_class (tree type, reshape_iter *d, bool first_initializer_p, if (BINFO_BASE_ITERATE (binfo, ++binfo_idx, base_binfo)) field = base_binfo; else - field = next_initializable_field (TYPE_FIELDS (type)); + field = next_aggregate_field (TYPE_FIELDS (type)); } else - field = next_initializable_field (DECL_CHAIN (field)); + field = next_aggregate_field (DECL_CHAIN (field)); } /* A trailing aggregate element that is a pack expansion is assumed to diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc index 75ab965a218..f1ed9336dc9 100644 --- a/gcc/cp/init.cc +++ b/gcc/cp/init.cc @@ -422,7 +422,7 @@ build_value_init_noctor (tree type, tsubst_flags_t complain) && !COMPLETE_TYPE_P (ftype) && !TYPE_DOMAIN (ftype) && COMPLETE_TYPE_P (TREE_TYPE (ftype)) - && (next_initializable_field (DECL_CHAIN (field)) + && (next_aggregate_field (DECL_CHAIN (field)) == NULL_TREE)) continue; @@ -1477,9 +1477,9 @@ emit_mem_initializers (tree mem_inits) /* Initially that is all of them. */ if (warn_uninitialized) - for (tree f = next_initializable_field (TYPE_FIELDS (current_class_type)); + for (tree f = next_aggregate_field (TYPE_FIELDS (current_class_type)); f != NULL_TREE; - f = next_initializable_field (DECL_CHAIN (f))) + f = next_aggregate_field (DECL_CHAIN (f))) if (!DECL_ARTIFICIAL (f) && !is_really_empty_class (TREE_TYPE (f), /*ignore_vptr*/false)) uninitialized.add (f); diff --git a/gcc/cp/lambda.cc b/gcc/cp/lambda.cc index 0a9f0f8f310..3fb98a98057 100644 --- a/gcc/cp/lambda.cc +++ b/gcc/cp/lambda.cc @@ -425,9 +425,9 @@ build_capture_proxy (tree member, tree init) if (DECL_VLA_CAPTURE_P (member)) { /* Rebuild the VLA type from the pointer and maxindex. */ - tree field = next_initializable_field (TYPE_FIELDS (type)); + tree field = next_aggregate_field (TYPE_FIELDS (type)); tree ptr = build_simple_component_ref (object, field); - field = next_initializable_field (DECL_CHAIN (field)); + field = next_aggregate_field (DECL_CHAIN (field)); tree max = build_simple_component_ref (object, field); type = build_cplus_array_type (TREE_TYPE (TREE_TYPE (ptr)), build_index_type (max)); diff --git a/gcc/cp/method.cc b/gcc/cp/method.cc index 903ee666ef3..0dffd648b0b 100644 --- a/gcc/cp/method.cc +++ b/gcc/cp/method.cc @@ -1465,7 +1465,7 @@ build_comparison_op (tree fndecl, bool defining, tsubst_flags_t complain) /* A defaulted comparison operator function for class C is defined as deleted if ... C has variant members. */ if (TREE_CODE (ctype) == UNION_TYPE - && next_initializable_field (TYPE_FIELDS (ctype))) + && next_aggregate_field (TYPE_FIELDS (ctype))) { if (complain & tf_error) inform (info.loc, "cannot default compare union %qT", ctype); @@ -1518,9 +1518,9 @@ build_comparison_op (tree fndecl, bool defining, tsubst_flags_t complain) } /* Now compare the field subobjects. */ - for (tree field = next_initializable_field (TYPE_FIELDS (ctype)); + for (tree field = next_aggregate_field (TYPE_FIELDS (ctype)); field; - field = next_initializable_field (DECL_CHAIN (field))) + field = next_aggregate_field (DECL_CHAIN (field))) { if (DECL_VIRTUAL_P (field) || DECL_FIELD_IS_BASE (field)) /* We ignore the vptr, and we already handled bases. */ @@ -1542,7 +1542,7 @@ build_comparison_op (tree fndecl, bool defining, tsubst_flags_t complain) continue; } else if (ANON_UNION_TYPE_P (expr_type) - && next_initializable_field (TYPE_FIELDS (expr_type))) + && next_aggregate_field (TYPE_FIELDS (expr_type))) { if (complain & tf_error) inform (field_loc, "cannot default compare " diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc index fe2608c65f1..6e666c2cde3 100644 --- a/gcc/cp/pt.cc +++ b/gcc/cp/pt.cc @@ -29586,7 +29586,7 @@ maybe_aggr_guide (tree tmpl, tree init, vec *args) len; --len, field = DECL_CHAIN (field)) { - field = next_initializable_field (field); + field = next_aggregate_field (field); if (!field) return NULL_TREE; tree ftype = finish_decltype_type (field, true, complain); diff --git a/gcc/cp/tree.cc b/gcc/cp/tree.cc index 979728027ed..633cc164a3a 100644 --- a/gcc/cp/tree.cc +++ b/gcc/cp/tree.cc @@ -4852,8 +4852,8 @@ structural_type_p (tree t, bool explain) explain_non_literal_class (t); return false; } - for (tree m = next_initializable_field (TYPE_FIELDS (t)); m; - m = next_initializable_field (DECL_CHAIN (m))) + for (tree m = next_aggregate_field (TYPE_FIELDS (t)); m; + m = next_aggregate_field (DECL_CHAIN (m))) { if (TREE_PRIVATE (m) || TREE_PROTECTED (m)) { diff --git a/gcc/cp/typeck2.cc b/gcc/cp/typeck2.cc index 63d95c1529a..1d92310edd0 100644 --- a/gcc/cp/typeck2.cc +++ b/gcc/cp/typeck2.cc @@ -606,7 +606,7 @@ split_nonconstant_init_1 (tree dest, tree init, bool last, : TYPE_FIELDS (type)); ; prev = DECL_CHAIN (prev)) { - prev = next_initializable_field (prev); + prev = next_aggregate_field (prev); if (prev == field_index) break; tree ptype = TREE_TYPE (prev); @@ -1304,7 +1304,7 @@ digest_init_r (tree type, tree init, int nested, int flags, the first element of d, which is the B base subobject. The base of type B is copy-initialized from the D temporary, causing object slicing. */ - tree field = next_initializable_field (TYPE_FIELDS (type)); + tree field = next_aggregate_field (TYPE_FIELDS (type)); if (field && DECL_FIELD_IS_BASE (field)) { if (warning_at (loc, 0, "initializing a base class of type %qT " diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-union7.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-union7.C new file mode 100644 index 00000000000..b3147d9db50 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-union7.C @@ -0,0 +1,17 @@ +// PR c++/105491 +// { dg-do compile { target c++11 } } + +struct V { + int m = 0; +}; +struct S : V { + constexpr S(int) : b() { } + bool b; +}; +struct W { + constexpr W() : s(0) { } + union { + S s; + }; +}; +constexpr W w; diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-union7a.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-union7a.C new file mode 100644 index 00000000000..b676e7d1748 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-union7a.C @@ -0,0 +1,15 @@ +// PR c++/105491 +// { dg-do compile { target c++11 } } + +struct V { + int m = 0; +}; +struct S : V { + constexpr S(int) : b() { } + bool b; +}; +union W { + constexpr W() : s(0) { } + S s; +}; +constexpr W w; diff --git a/gcc/testsuite/g++.dg/cpp2a/constinit17.C b/gcc/testsuite/g++.dg/cpp2a/constinit17.C new file mode 100644 index 00000000000..6431654ac85 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/constinit17.C @@ -0,0 +1,24 @@ +// PR c++/105491 +// { dg-do compile { target c++11 } } + +class Message { + virtual int GetMetadata(); +}; +class ProtobufCFileOptions : Message { +public: + constexpr ProtobufCFileOptions(int); + bool no_generate_; + bool const_strings_; + bool use_oneof_field_name_; + bool gen_pack_helpers_; + bool gen_init_helpers_; +}; +constexpr ProtobufCFileOptions::ProtobufCFileOptions(int) + : no_generate_(), const_strings_(), use_oneof_field_name_(), + gen_pack_helpers_(), gen_init_helpers_() {} +struct ProtobufCFileOptionsDefaultTypeInternal { + constexpr ProtobufCFileOptionsDefaultTypeInternal() : _instance({}) {} + union { + ProtobufCFileOptions _instance; + }; +} __constinit _ProtobufCFileOptions_default_instance_;