> Joe Groff via swift-dev <swift-dev <at> swift.org> writes:
>
> return local // returning forms a closure, so ref is escapable
My plan was to check all return statements with FuncDecl as results, if
any of them has inout captures, complain.
But this diagnosis is too coarse. A function can capture from any level of
outer scope, so sometimes it's safe to let a inout escape, as long as the
reference is still inside the scope it's captured from. Example:
func a(inout x: Int) -> () -> Void {
func b() -> () -> Void {
func c() {
_ = x
}
return c // is this safe? We'll see…
}
let f = b() // 'x' captured by f hasn't *really* escaped.
return f // now we have a problem
}
It's unclear whether the statement 'return c' is problematic.
So there are two paths:
1. make *any* escaping inout capture an error
2. track down original scope of each inout capture, compare it with the return
statement.
At the moment I haven't looked into how feasible 2 is.
What's your opinion?
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