Do `IntoSet` conversions outside of the future returned by the async function

[Veetaha]

There is a warning from the compiler that reproduces in this test:

bon/bon/tests/integration/builder/mod.rs

Lines 36 to 46 in d59ff12

	#[cfg(feature = "std")]
	#[tokio::test]
	async fn async_func() {
	#[builder]
	async fn sut<Fut: std::future::Future>(fut: Fut) -> Fut::Output {
	fut.await
	}
	let actual = sut().fut(async { 42 }).call().await;
	assert_eq!(actual, 42);
	}

It is shown only when you enable the clippy::future_not_send clippy lint. The problem is that the generic param that implements IntoSet is captured by the future when instead we should do that conversion outside of the future. The finish_fn method needs to return an impl Future with an async move {} block at the end.

[Veetaha]

I've revisited this. There is no problem with doing conversions inside of the async fn. The lint is just too aggressive and doesn't work in a generic context. Also, if bon were to generate a variant of this using impl Future syntax, then that would complicate the signature in ide hints and rustdoc, so probably not worth it.

I'm closing this prematurely. The PR #125 adds an ignore for this lint to the finishing method. There are some explanations in the code comment near the lint allow attribute