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.
