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use lint;
use rustc::dep_graph::DepNode;
use rustc::ty::TyCtxt;
use syntax::ast;
use syntax_pos::{Span, DUMMY_SP};
use rustc::hir;
use rustc::hir::itemlikevisit::ItemLikeVisitor;
use rustc::util::nodemap::DefIdSet;
struct CheckVisitor<'a, 'tcx: 'a> {
tcx: TyCtxt<'a, 'tcx, 'tcx>,
used_trait_imports: DefIdSet,
}
impl<'a, 'tcx> CheckVisitor<'a, 'tcx> {
fn check_import(&self, id: ast::NodeId, span: Span) {
if !self.tcx.maybe_unused_trait_imports.contains(&id) {
return;
}
let import_def_id = self.tcx.hir.local_def_id(id);
if self.used_trait_imports.contains(&import_def_id) {
return;
}
let msg = if let Ok(snippet) = self.tcx.sess.codemap().span_to_snippet(span) {
format!("unused import: `{}`", snippet)
} else {
"unused import".to_string()
};
self.tcx.sess.add_lint(lint::builtin::UNUSED_IMPORTS, id, span, msg);
}
}
impl<'a, 'tcx, 'v> ItemLikeVisitor<'v> for CheckVisitor<'a, 'tcx> {
fn visit_item(&mut self, item: &hir::Item) {
if item.vis == hir::Public || item.span == DUMMY_SP {
return;
}
if let hir::ItemUse(ref path, _) = item.node {
self.check_import(item.id, path.span);
}
}
fn visit_trait_item(&mut self, _trait_item: &hir::TraitItem) {
}
fn visit_impl_item(&mut self, _impl_item: &hir::ImplItem) {
}
}
pub fn check_crate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) {
let _task = tcx.dep_graph.in_task(DepNode::UnusedTraitCheck);
let mut used_trait_imports = DefIdSet();
for &body_id in tcx.hir.krate().bodies.keys() {
let item_id = tcx.hir.body_owner(body_id);
let item_def_id = tcx.hir.local_def_id(item_id);
if let Some(tables) = tcx.maps.typeck_tables.borrow().get(&item_def_id) {
let imports = &tables.used_trait_imports;
debug!("GatherVisitor: item_def_id={:?} with imports {:#?}", item_def_id, imports);
used_trait_imports.extend(imports);
} else {
debug!("GatherVisitor: item_def_id={:?} with no imports", item_def_id);
}
}
let mut visitor = CheckVisitor { tcx, used_trait_imports };
tcx.hir.krate().visit_all_item_likes(&mut visitor);
}