Proposed resolution (04/01): In 6.8.4 [basic.life] paragraph 1, change to
If T is a class type with a non-trivial constructor
(11.4.5 [class.ctor]), the constructor call has
completed.
If T is a class type with a non-trivial constructor
(11.4.5 [class.ctor]), the initialization is complete.
[Note: the initialization can be performed by a
constructor call or, in the case of an aggregate with an
implicitly-declared non-trivial default constructor, an
aggregate initialization (9.5.2 [dcl.init.aggr]).]
Jack Rouse:
6.8.4 [basic.life] paragraph 1
includes:
Mike Miller:
I see a couple of ways of fixing the problem. One way would be
to change "the constructor call has completed" to "the object's
initialization is complete." Another would be to add following "a class type with a non-trivial
constructor" the phrase "that is not initialized with the brace
notation (9.5.2 [dcl.init.aggr]
)." The first formulation treats aggregate initialization like a
constructor call; even POD-type members of an aggregate could
not be accessed before the aggregate initialization completed.
The second is less restrictive; the POD-type members of the
aggregate would be usable before the initialization, and the
members with non-trivial constructors (the only way an
aggregate can acquire a non-trivial constructor) would be
protected by recursive application of the lifetime rule.
The lifetime of an object is a runtime property of the object. The
lifetime of an object of type T begins when:
Consider the code:
struct B {
B( int = 0 );
~B();
};
struct S {
B b1;
};
int main()
{
S s = { 1 };
return 0;
}
In the code above, class S does have a non-trivial constructor, the
default constructor generated by the compiler. According the text
above, the lifetime of the auto s would never begin because a
constructor for S is never called. I think the second case in the
text needs to include aggregate initialization.