Walter Bright Wrote:
> Consider the code:
>
> @safe:
> T[] foo(T[] a) { return a; }
>
> T[] bar()
> {
> T[10] x;
> return foo(x);
> }
>
> Now we've got an escaping reference to bar's stack. This is not memory
> safe. But giving up slices is a heavy burden.
>
> So it occurred to me that the same solution for closures can be used
> here. If the address is taken of a stack variable in a safe function,
> that variable is instead allocated on the heap. If a more advanced
> compiler could prove that the address does not escape, it could be put
> back on the stack.
>
> The code will be a little slower, but it will be memory safe. This
> change wouldn't be done in trusted or unsafe functions.
At a fundamental level, safety isn't about pointers or references to stack
variables, but rather preventing their escape beyond function scope. Scope
parameters could be very useful. Scope delegates were introduced for a similar
reason.
