Default argument expressions should inherit throwability from calling context

[awesomekling]

We currently refuse to compile this:

fn foo(x: [i64] = []) {
}

fn main() throws {
    foo()
}

We should allow it, since any error thrown would be thrown in the main context, which is throwsy :)

[0GreenClover0]

Default argument expressions that throw are supported, but the function (foo, in this example) has to be marked as throws

[awesomekling]

Ah, good point! But yeah, we're not throwing inside foo, so it's still the calling context that needs to be throwsy IMO :)

[ADKaster]

Another thought is that it would be nice if [] didn't throw at all. In the C++ it won't allocate anything on the heap, and is actually infallible. (or if that's not true either, we should make it true in the C++).

[awesomekling]

Another thought is that it would be nice if [] didn't throw at all. In the C++ it won't allocate anything on the heap, and is actually infallible. (or if that's not true either, we should make it true in the C++).

Trouble there is that arrays have reference semantics, so after passing an empty array ("by value") to a function that pushes something into it, the caller and the callee would see different array backing stores.