On 2015-04-17 22:06, Adam Butcher wrote:
On 2015-04-17 20:58, Jason Merrill wrote:
On 04/09/2015 11:31 PM, Adam Butcher wrote:
+ /* For generic lambdas, resolve default captured 'this' now. */
This isn't quite right. We don't want to capture 'this' any time we
see a member function call, as overload resolution might choose a
static member function that doesn't need 'this'. The special
handling
we want is for the case where the call depends on a generic lambda
parameter, in which case we capture 'this' because the call "names
[this] in a potentially-evaluated expression (3.2) where the
enclosing
full-expression depends on a generic lambda parameter declared
within
the reaching scope of the lambda-expression."
Good point. I'll look into it. So for a nullary member call we will
always capture 'this', but for N-ary, we only capture if we find one
of the lambda's parameters (or a parameter from an enclosing generic
lambda?) in the call's arguments right?
Test like this?
/* { dg-do run { target c++14 } } */
/* { dg-final { scan-assembler-not "..." } } */
struct X
{
int f (int, double) { return 255; }
static int f (int, int) { return 65535; }
auto m1 ()
{
return [=] (auto a) {
return f (7, a);
};
}
auto m2 ()
{
return [=] (auto a) {
return f (9, 10) + a;
};
}
};
#include <cassert>
int main()
{
X x;
assert (x.m1 () (42.0) == 255);
assert (x.m1 () (42) == 65535);
assert (x.m2 () (42.0) == (65535 + 42));
assert (x.m2 () (42) == (65535 + 42));
assert (sizeof x.m2 () < sizeof x.m1 ());
}
