On Sunday, 30 December 2012 at 09:18:30 UTC, Jonathan M Davis
wrote:
On Sunday, December 30, 2012 10:04:01 Daniel Kozak wrote:
IMHO, try to return ref to local variable should be error, and
such a code shouldn't be compilable
You can disallow that in the easy case of
ref int boo(int i)
{
return i;
}
and in fact, that's already illegal. The problem is the wrapper
function.
You'd also have to disallow functions from returning ref
parameters by ref.
Otherwise,
ref int foo(ref int i)
{
return i;
}
ref int baz(int i)
{
return foo(i);
}
continues to cause problems. And making it illegal to return
ref parameters by
ref would be a serious problem for wrapper ranges, because they
do that sort
of thing all the time with front. So, that's not really going
to work.
- Jonathan M Davis
Wouldn't it be enough to disallow functions that both take and
return by ref? There would still be some limitations, but at
least:
//----
@property ref T front(T)(T[] a);
//----
Would still be @safe.
It seams the only code that is unsafe always boils down to taking
an argument by ref and returning it by ref...
At best, we'd (try) to only make that illegal (when we can), or
(seeing things the other (safer) way around), only allow
returning by ref, if the compiler is able to prove it is not also
an input by ref?
