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Core 234 - allow const objects with no initializer or user-provided default...

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Core 234 - allow const objects with no initializer or
	user-provided default constructor if the defaulted constructor
	initializes all the subobjects.
	PR c++/20039
	PR c++/42844
	* class.c (default_init_uninitialized_part): New.
	* cp-tree.h: Declare it.
	* decl.c (check_for_uninitialized_const_var): Use it.
	* init.c (perform_member_init): Likewise.
	(build_new_1): Likewise.
	* method.c (walk_field_subobs): Likewise.

From-SVN: r179130
This commit is contained in:
Jason Merrill 2011-09-23 17:30:48 -04:00 committed by Jason Merrill
parent d303ec8e17
commit 6132bdd72e
13 changed files with 95 additions and 17 deletions
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14
gcc/cp/ChangeLog
View File

@ -1,3 +1,17 @@
2011-09-23 Jason Merrill <jason@redhat.com>
Core 234 - allow const objects with no initializer or
user-provided default constructor if the defaulted constructor
initializes all the subobjects.
PR c++/20039
PR c++/42844
* class.c (default_init_uninitialized_part): New.
* cp-tree.h: Declare it.
* decl.c (check_for_uninitialized_const_var): Use it.
* init.c (perform_member_init): Likewise.
(build_new_1): Likewise.
* method.c (walk_field_subobs): Likewise.
2011-09-23 Paolo Carlini <paolo.carlini@oracle.com>
PR c++/50258

34
gcc/cp/class.c
View File

@ -4356,6 +4356,40 @@ type_has_user_provided_default_constructor (tree t)
return false;
}
/* If default-initialization leaves part of TYPE uninitialized, returns
a DECL for the field or TYPE itself (DR 253). */
tree
default_init_uninitialized_part (tree type)
{
tree t, r, binfo;
int i;
type = strip_array_types (type);
if (!CLASS_TYPE_P (type))
return type;
if (type_has_user_provided_default_constructor (type))
return NULL_TREE;
for (binfo = TYPE_BINFO (type), i = 0;
BINFO_BASE_ITERATE (binfo, i, t); ++i)
{
r = default_init_uninitialized_part (BINFO_TYPE (t));
if (r)
return r;
}
for (t = TYPE_FIELDS (type); t; t = DECL_CHAIN (t))
if (TREE_CODE (t) == FIELD_DECL
&& !DECL_ARTIFICIAL (t)
&& !DECL_INITIAL (t))
{
r = default_init_uninitialized_part (TREE_TYPE (t));
if (r)
return DECL_P (r) ? r : t;
}
return NULL_TREE;
}
/* Returns true iff for class T, a trivial synthesized default constructor
would be constexpr. */

1
gcc/cp/cp-tree.h
View File

@ -4838,6 +4838,7 @@ extern tree in_class_defaulted_default_constructor (tree);
extern bool user_provided_p (tree);
extern bool type_has_user_provided_constructor (tree);
extern bool type_has_user_provided_default_constructor (tree);
extern tree default_init_uninitialized_part (tree);
extern bool trivial_default_constructor_is_constexpr (tree);
extern bool type_has_constexpr_default_constructor (tree);
extern bool type_has_virtual_destructor (tree);

11
gcc/cp/decl.c
View File

@ -4899,15 +4899,16 @@ check_for_uninitialized_const_var (tree decl)
if (TREE_CODE (decl) == VAR_DECL
&& TREE_CODE (type) != REFERENCE_TYPE
&& CP_TYPE_CONST_P (type)
&& (!TYPE_NEEDS_CONSTRUCTING (type)
|| !type_has_user_provided_default_constructor (type))
&& !DECL_INITIAL (decl))
{
tree field = default_init_uninitialized_part (type);
if (!field)
return;
permerror (DECL_SOURCE_LOCATION (decl),
"uninitialized const %qD", decl);
if (CLASS_TYPE_P (type)
&& !type_has_user_provided_default_constructor (type))
if (CLASS_TYPE_P (type))
{
tree defaulted_ctor;
@ -4918,6 +4919,8 @@ check_for_uninitialized_const_var (tree decl)
inform (DECL_SOURCE_LOCATION (defaulted_ctor),
"constructor is not user-provided because it is "
"explicitly defaulted in the class body");
inform (0, "and the implicitly-defined constructor does not "
"initialize %q+#D", field);
}
}
}

4
gcc/cp/init.c
View File

@ -579,7 +579,7 @@ perform_member_init (tree member, tree init)
flags |= LOOKUP_DEFAULTED;
if (CP_TYPE_CONST_P (type)
&& init == NULL_TREE
&& !type_has_user_provided_default_constructor (type))
&& default_init_uninitialized_part (type))
/* TYPE_NEEDS_CONSTRUCTING can be set just because we have a
vtable; still give this diagnostic. */
permerror (DECL_SOURCE_LOCATION (current_function_decl),
@ -2088,7 +2088,7 @@ build_new_1 (VEC(tree,gc) **placement, tree type, tree nelts,
}
if (CP_TYPE_CONST_P (elt_type) && *init == NULL
&& !type_has_user_provided_default_constructor (elt_type))
&& default_init_uninitialized_part (elt_type))
{
if (complain & tf_error)
error ("uninitialized const in %<new%> of %q#T", elt_type);

3
gcc/cp/method.c
View File

@ -1015,8 +1015,7 @@ walk_field_subobs (tree fields, tree fnname, special_function_kind sfk,
{
bool bad = true;
if (CP_TYPE_CONST_P (mem_type)
&& (!CLASS_TYPE_P (mem_type)
|| !type_has_user_provided_default_constructor (mem_type)))
&& default_init_uninitialized_part (mem_type))
{
if (msg)
error ("uninitialized non-static const member %q#D",

10
gcc/testsuite/ChangeLog
View File

@ -1,3 +1,13 @@
2011-09-23 Jason Merrill <jason@redhat.com>
Core 234
* g++.dg/init/const8.C: New.
* g++.dg/cpp0x/constexpr-object1.C: Add a data member.
* g++.dg/cpp0x/defaulted2.C: Likewise.
* g++.dg/cpp0x/pr42844-2.C: Likewise.
* g++.dg/init/pr20039.C: Likewise.
* g++.dg/init/pr42844.C: Likewise.
2011-09-23 Jan Hubicka <jh@suse.cz>
* gcc.dg/ipa/inline-1.c: new testcase.

2
gcc/testsuite/g++.dg/cpp0x/constexpr-object1.C
View File

@ -7,7 +7,7 @@
// p 1 constexpr specifier
// objects, static const data
struct A1 { }; // { dg-message "no user-provided default constructor" }
struct A1 { int i; }; // { dg-message "no user-provided default constructor" }
constexpr int i1 = 1024;
constexpr A1 a1 = A1();

3
gcc/testsuite/g++.dg/cpp0x/defaulted2.C
View File

@ -17,7 +17,8 @@ void g() = delete; // { dg-error "redefinition" }
struct B // { dg-message "user-provided default constructor" }
{
B() = default; // { dg-message "not user-provided" }
int i;
B() = default; // { dg-message "not user-provided" }
};
const B b; // { dg-error "uninitialized const" }

4
gcc/testsuite/g++.dg/cpp0x/pr42844-2.C
View File

@ -4,6 +4,7 @@
struct A // { dg-message "user-provided default constructor" }
{
int i;
A() = default; // { dg-message "not user-provided" }
};
@ -14,17 +15,20 @@ struct Base
struct Derived : Base // { dg-message "user-provided default constructor" }
{
int i;
Derived() = default; // { dg-message "not user-provided" }
};
struct Derived2 : Base // { dg-message "user-provided default constructor" }
{
int i;
Derived2() = default; // { dg-message "not user-provided" }
Derived2( Derived2 const& ) = default;
};
struct Derived3 : Base // { dg-message "user-provided default constructor" }
{
int i;
Derived3( Derived3 const& ) = default;
Derived3() = default; // { dg-message "not user-provided" }
};

11
gcc/testsuite/g++.dg/init/const8.C Normal file
View File

@ -0,0 +1,11 @@
// DR 234 - it should be OK to leave off the initializer of a const
// variable if the default constructor fully initializes the object.
struct A { };
const A a;
struct B { A a; };
const B b;
struct C { virtual void f(); };
const C c;

1
gcc/testsuite/g++.dg/init/pr20039.C
View File

@ -10,6 +10,7 @@ struct M
struct X
{
M m;
int i;
};
int mymain()

14
gcc/testsuite/g++.dg/init/pr42844.C
View File

@ -6,19 +6,19 @@ struct A
A(){}
};
struct B : A {}; // { dg-message "user-provided default constructor" }
struct B : A { int i; }; // { dg-message "user-provided default constructor" }
struct C : A {}; // { dg-message "user-provided default constructor" }
struct C : A { int i; }; // { dg-message "user-provided default constructor" }
struct D : B { D() {} };
struct E {}; // { dg-message "user-provided default constructor" }
struct E { int i; }; // { dg-message "user-provided default constructor" }
template <class T>
struct F : A {}; // { dg-message "user-provided default constructor" }
struct F : A { T t; }; // { dg-message "user-provided default constructor" }
template <class T>
struct G {}; // { dg-message "user-provided default constructor" }
struct G { T t; }; // { dg-message "user-provided default constructor" }
void f ()
{
@ -41,9 +41,9 @@ void f ()
extern G<int> const gext;
}
struct H {}; // { dg-message "user-provided default constructor" }
struct H { int i; }; // { dg-message "user-provided default constructor" }
struct I : A {}; // { dg-message "user-provided default constructor" }
struct I : A { int i; }; // { dg-message "user-provided default constructor" }
template <class T>
void g ()