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* [gcc r13-211] c++: constexpr init of union sub-aggr w/ base [PR105491]
@ 2022-05-09 13:53 Patrick Palka
0 siblings, 0 replies; only message in thread
From: Patrick Palka @ 2022-05-09 13:53 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:0c7bce0ac184c057bacad9c8e615ce82923835fd
commit r13-211-g0c7bce0ac184c057bacad9c8e615ce82923835fd
Author: Patrick Palka <ppalka@redhat.com>
Date: Mon May 9 09:53:27 2022 -0400
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.
Diff:
---
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 ++++++++++++
gcc/testsuite/g++.dg/cpp0x/constexpr-union7a.C | 15 +++++++++++
gcc/testsuite/g++.dg/cpp2a/constinit17.C | 24 +++++++++++++++++
15 files changed, 116 insertions(+), 43 deletions(-)
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<tree, true> &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<tree, true> 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<constructor_elt, va_gc> *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 ("%<constexpr%> 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<constructor_elt, va_gc> *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<constructor_elt, va_gc> *);
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<tree,va_gc> *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_;
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