Incorrect suggestion location for import with outer attribute at top of file

[nrc]

E.g.,

#[derive(Clone, Debug)] // this is line 1 in this file
pub struct Service;

pub struct Response<T> where T: Bar { pub item: T }

gives

error[E0405]: cannot find trait `Bar` in this scope                                                                                       
 --> src/main.rs:4:33                                                                                                                     
  |                                                                                                                                       
4 | pub struct Response<T> where T: Bar { pub item: T }                                                                                   
  |                                 ^^^ not found in this scope                                                                           
help: possible candidate is found in another module, you can import it into scope                                                         
  |                                                                                                                                       
2 | use crate::foo::Bar; 

Note that line 2 is between the derive and the the struct.

Moved from rust-lang/rls#1085

[estebank]

This is the code that selects the suggestion span:

rust/src/librustc_resolve/lib.rs

Lines 634 to 700 in f99911a

	struct UsePlacementFinder {
	target_module: NodeId,
	span: Option<Span>,
	found_use: bool,
	}
	impl UsePlacementFinder {
	fn check(krate: &Crate, target_module: NodeId) -> (Option<Span>, bool) {
	let mut finder = UsePlacementFinder {
	target_module,
	span: None,
	found_use: false,
	};
	visit::walk_crate(&mut finder, krate);
	(finder.span, finder.found_use)
	}
	}
	impl<'tcx> Visitor<'tcx> for UsePlacementFinder {
	fn visit_mod(
	&mut self,
	module: &'tcx ast::Mod,
	_: Span,
	_: &[ast::Attribute],
	node_id: NodeId,
	) {
	if self.span.is_some() {
	return;
	}
	if node_id != self.target_module {
	visit::walk_mod(self, module);
	return;
	}
	// find a use statement
	for item in &module.items {
	match item.node {
	ItemKind::Use(..) => {
	// don't suggest placing a use before the prelude
	// import or other generated ones
	if item.span.ctxt().outer().expn_info().is_none() {
	self.span = Some(item.span.shrink_to_lo());
	self.found_use = true;
	return;
	}
	},
	// don't place use before extern crate
	ItemKind::ExternCrate(_) => {}
	// but place them before the first other item
	_ => if self.span.map_or(true, |span| item.span < span ) {
	if item.span.ctxt().outer().expn_info().is_none() {
	// don't insert between attributes and an item
	if item.attrs.is_empty() {
	self.span = Some(item.span.shrink_to_lo());
	} else {
	// find the first attribute on the item
	for attr in &item.attrs {
	if self.span.map_or(true, |span| attr.span < span) {
	self.span = Some(attr.span.shrink_to_lo());
	}
	}
	}
	}
	},
	}
	}
	}
	}

[euclio]

This is caused by #45216. The suggestion is correct if the derive attribute is replaced by #[allow(warnings)], etc.

[estebank]

Current output:

error[E0405]: cannot find trait `Bar` in this scope
 --> src/lib.rs:7:33
  |
7 | pub struct Response<T> where T: Bar { pub item: T }
  |                                 ^^^ not found in this scope
  |
help: consider importing this trait
  |
1 + use crate::foo::Bar;
  |