On Monday, 22 June 2015 at 06:38:57 UTC, Andrei Alexandrescu
wrote:
On 6/21/15 11:31 PM, Andrei Alexandrescu wrote:
On 6/21/15 10:25 PM, Walter Bright wrote:
The idea is that fun(5) would be lowered to:
auto tmp = 5;
fun(tmp);
I don't think that lowering is recommended - it prolongs the
lifetime of
the temporary through the end of the caller. But that may be
actually a
good thing.
On second thought - Walter's lowering, which makes the rvalue
last more than strictly necessary, may be the most flexible of
all at the cost of more resource consumption (for types that
define destructors). -- Andrei
I would think in the general case, the variable would need to
stick around until the statement was completed in order to avoid
problems with it going away prematurely, though maybe the recent
changes with return as an attribute fix that problem. But as long
as its legal for the function to return an auto ref argument via
ref or auto ref, keeping the variable around for the duration of
the call - or even just the expression - rather than the
statement would risk using the variable after it was destroyed.
- Jonathan M Davis
