http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53202
--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-05-03
01:14:28 UTC ---
If I change some of the functions to forward lvalues instead of using perfect
forwarding then I see one call to a copy constructor
e.g. just changing the thread::Impl ctor to
Impl(const T& t) : t(t) { }
produces:
default ctor called, this=0x7fffd878f35f
copy ctor called
destructor called, this=0x7fffd878f327
void background_hello::operator()() called, this=0x1258010
destructor called, this=0x1258010
destructor called, this=0x7fffd878f35f
The gimple dump shows:
thread::Impl<T>::Impl(const T&) [with T = Bind_simple<background_hello>]
(struct Impl * const this, const struct Bind_simple & t)
{
struct Bind_simple * D.8913;
struct Bind_simple * D.8914;
thread::ImplBase::ImplBase (this);
D.8913 = &this->t;
Bind_simple<background_hello>::Bind_simple (D.8913, t);
try
{
}
catch
{
D.8914 = &this->t;
Bind_simple<background_hello>::~Bind_simple (D.8914);
}
}
Note the copy construction of the Bind_simple member that was missing
previously
