clippy::suspicious_else_formatting triggered by fake_return_edge

[str4d]

tracing/tracing-attributes/src/expand.rs

Lines 66 to 79 in 02903cb

	let fake_return_edge = quote_spanned! {return_span=>
	#[allow(unreachable_code, clippy::diverging_sub_expression, clippy::let_unit_value, clippy::unreachable)]
	if false {
	let __tracing_attr_fake_return: #return_type =
	unreachable!("this is just for type inference, and is unreachable code");
	return __tracing_attr_fake_return;
	}
	};
	let block = quote! {
	{
	#fake_return_edge
	#block
	}
	};

This generates code (with Rust 1.56.0) like:

        #[allow(clippy::suspicious_else_formatting)]
        {
            let __tracing_attr_span;
            let __tracing_attr_guard;
            if tracing::Level::INFO <= ::tracing::level_filters::STATIC_MAX_LEVEL
                && tracing::Level::INFO <= ::tracing::level_filters::LevelFilter::current()
            {
                // span
            }
            #[warn(clippy::suspicious_else_formatting)]
            {
                #[allow(
                    unreachable_code,
                    clippy::diverging_sub_expression,
                    clippy::let_unit_value
                )]
                if false {
                    let __tracing_attr_fake_return = ...;
                    return __tracing_attr_fake_return;
                }
                {
                    // Function content
                }
            }
        }

We can see that the code added to fix #1613 looks correct, but we need to do the same thing for fake_return_edge.

[str4d]

We noticed this because we tried to fix it ourselves in our code, but because the new instance is nested inside the first one, the fix to #1613 insulates the new instance and prevents external attributes from affecting it.

[str4d]

Alternatively, we could move the #[warn(clippy::suspicious_else_formatting)] onto where the user's block now occurs. Given that fake_return_edge is used to redefine block, I presume that is how the issue slipped in.